asymmetrical catamaran hull design

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Theses and Dissertations

Dynamics of asymmetrical configurations of catamaran hull forms.

Vaibhav Aribenchi , Florida Institute of Technology

Date of Award

Document type, degree name.

Master of Science (MS)

Ocean Engineering and Marine Sciences

First Advisor

Prasanta Sahoo

Second Advisor

Ronnal Reichard

Third Advisor

Hamid Hefazi

Fourth Advisor

Stephen Wood

It is important to understand asymmetrical catamarans motions since it influences the loads which increases stress on structures while causing discomfort to passengers and crew members. Researchers so far have been mainly focused on motions characteristics of the conventional catamaran hull forms. There is scant literature or research work in the public domain on asymmetrical catamaran hull form, with regards to its seakeeping performance. This thesis undertakes a comparative analysis of the motion characteristics between newly developed alternative catamaran hull forms of different asymmetrical configurations. The asymmetrical catamarans developed from the original NPL round bilge catamaran hull forms have a hull length of 40 m and separation ratios (s/L) of 0.2 and 0.4 Salvesen et al. (1970) developed the theoretical background of strip theory which forms the basis for computing the heave and pitch responses of marine vessels. The hulls were tested in sea state 3 with a mean significant wave height of 1.25 m and at Froude numbers 0.2, 0.5 and 0.8. The aim of this study was to compute heave and pitch response along with added resistance in waves between the two new asymmetrical catamaran hulls against conventional catamaran hull forms. It is anticipated that this study would provide a tool to designers to improve the designs of catamaran hull forms based on the seakeeping performance. This study provides a pathway for a better understanding of asymmetrical catamaran hull forms.

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Aribenchi, Vaibhav, "Dynamics Of Asymmetrical Configurations Of Catamaran Hull Forms" (2017). Theses and Dissertations . 1130. https://repository.fit.edu/etd/1130

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Asymmetrical Racing Hulls Catamaran

represents a zero-order approximation for the wave resistance. This is not good enough for our purposes, however.

An exact theory was given by Havelock in 1932. A simplified, but still quite general form of Havelock's equation has been found by Castles for hulls with lateral and longitudinal symmetry. A discussion of the physical basis of Havelock's theory and Castle's equations for single or multiple hulls is given in Appendix A. Castles' equation for a single hull is

Rw = iPH{T)2VB2Cw (2-16)

" .00 x2e-aX2dx

x0 = CP/F2. (2-18)

The quantity 5 is the depth of the centroid of the maximum cross section for which a is the area. The prismatic coefficient CP is defined by

and therefore describes the distribution of cross sectional area along the length of the boat.

The wave resistance is more or less insensitive to the shape of the hull cross section. This is not true for the frictional resistance which depends directly upon the wetted surface area Aw. This quantity is given quite accurately ( + 1 percent) for a wide variety of forms by

The minimum girth for a given enclosed area is featured by the semicircular cross section for which Gm = \nB and Aw = 1.16BL. Since the wave resistance is shape independent, we are free to concentrate our interest on semi-circular sections. For this case a = 7iB2/8, 3 = B/n, and the total resistance can be written in terms of the Froude number F, the length-to-beam ratio L/B, and the prismatic coefficient CP as

r - 1 48 f2il\c +1 lb

lgh speed One of the first numbers to be generated when planning a boat is sailing the displacement-length ratio DLR = A/(.01L)3 where A is the displacement in long tons (A = jy/2240). Using Eq. (2-19), we find for semicircular cross sections that

In formulating a design, one is always limited by material strength-to-weight ratios and other factors to some minimum DLR. From Eq. (2-22) we see that an infinite variety of values of CP and L/B correspond to a given DLR. The problem is to find the best set of values from the point of view of minimizing the total resistance. Both components of the resistance, friction and wave, increase with F2, however the wave term also contains an additional function of F2 that is

16 I*ig 2-3. Specific running rcsistancc as a function of L/B for V^JyjL - 2,

16 I*ig 2-3. Specific running rcsistancc as a function of L/B for V^JyjL - 2, zero for very small or very large value of F2 and reaches a maximum hulls and value for Fi * 0.281(7*^/1 » 1.78). It therefore makes good sense to outriggers compare the resistance of hulls for this value of Froude number or one only slightly higher. We have calculated R/W using Eq. (2-21) for a range of prismatic coefficients from 0.50 to 0.80 and length-to-beam ratio from 8 to 32 at a fixed value of F2 = 0.355 {VjjL = 2.0).

The results are shown in Fig. 2-3. We see that higher prismatic coefficients are better than lower ones and that hulls in the L/B range from 12-16 are maximally efficient. The waterline length L has been taken as 25 feet in calculating the friction, however, the overall result is a very weak function of size, hence this choice does not limit the generality of these results.

!gh speed Interesting though it is, Fig. 2-3 still does not answer the basic sailing question which is: for a given weight and length (DLR), what is the optimum value of prismatic coefficient in order that R (not R/W) be a minimum? This is answered by replotting the data as shown in Fig. 2-4. (The calculated values from which Figs. 2-3 and 2-4 were drawn are presented in tabular form in Appendix B.) The figure shows that high prismatics are best and, indeed implies that coefficients even higher than 0.80 are desirable. The choice of CP is seen to be much less critical for the lower DLR's than for higher ones. In order to properly evaluate the data of Fig. 2-4, we must remember that eddy and flow separation effects owing to projections or small local radius of hull curvature are ignored. For high CP, the hull tends to a scow shape (for which CP = 1.0) and flow discontinuities at the bow can be expected to arise. These effects will tend to increase the resistance on the high CP end of the curves. Thus it seems likely that the ideal value of CP for the low-DLR hulls in which we are interested will lie in the range 0.65-0.75.

The effect of some variations from our standard hull (see Appendix A) for which the above results are derived should be noted. The effect of moving the cross section of maximum area forward of the midship position is an increase in the total resistance at all speeds. By moving the maximum section somewhat aft of amidships an average reduction of RjW by about 5 percent for L/B = 12 between the SLR values 0.8 to 3.0 is possible. Outside this speed range the logitudinally symmetrical hull is superior. The sensitivity of R/W to the position of the maximum section decreases with increasing L/B and CP. For the high L/B, high CP hulls of interest to us, placement of the maximum section can be dictated to a large extent by design factors other than resistance minimization.

Another possible modification is to broaden and flatten the sections of the after half of the hull. The effect of this on R/W is similar in magnitude and dependence on DLR to that of moving the maximum section aft. As in that case, stern flattening is disadvantageous for SLR's less than 0.8 and greater than 3.0. This modification also has the effect of damping pitching motion. The mechanism of this damping effect is discussed in some detail in Chapter 6. The pitching motion of low-DLR hulls is already highly damped even without stern flattening, thus proas pay only a marginal penalty for their longitudinal symmetry.

In order to make specific recommendations concerning the various multihull configurations, we must establish a working definition. We shall always refer to the weight-carrying hull as the hull and the float (or ama) as the outrigger. As a general rule, outriggers should be as light as possible and should not be used for stores and certainly not for accommodation.

A catamaran is a configuration of two identical hulls, or, in the case ofassymetrical hulls, mirror images. In the daysailing sizes, catamarans are faster than trimarans owing to their ability to fly the windward hull and sail on one hull at a modest angle of heel. We shall discuss this question of hull flying further in Chapter 4. For catamarans to be sailed in relatively smooth waters, the hull sections should be serni-circular for most of the length with some flattening in the after third and a fairly rapid transition to elliptical, parabolic, and vee sections hulls and at the bow. For larger craft intended for offshore sailing, the drag outriggers that arises owing to the presence of ocean waves must be taken into account. This drag roughly doubles the effective resistance of a typical monohull racer sailing to windward in seas having a wavelength greater than the length of the boat. Rough water drag decreases with increasing

L/B and is more or less insensitive to the beam-to-draught ratio B/H.

This suggests that a practical optimum hull section for offshore use will correspond to B/H somewhat less than the semicircular value of 2.

In rough water, large portions of the windward hull will be exiting and entering the water at high speed. In order to avoid pounding, the semi-circular section should be distorted into a rounded vee or parabolic section.

The question of whether to make catamaran hulls symmetrical or asymmetrical can be argued both ways. The intended purpose of an asymmetrical hull is, usually, to create horizontal lift on the more highly curved side. In the case of a catamaran with more or less flat outer sides and curved inner sides, the horizontal lift of the two hulls only serves to compress the cross beams unless heeling occurs. This is shown in Fig. 2-5. Only daysailers are sailed at such angles of heel and then only for short times. Even more discouraging to the notion of using hull asymmetry to enhance the lifting action of a long shallow hull is the fact that only for large angles of attack (>10°) does asymmetry make a significant contribution. Such a high angle of attack between the centreline of the boat and the course line would create an intolerable drag and is therefore out of the question. Asymmetric hulls have, however, been found to be highly resistant to broaching

when running in heavy seas. This can be understood as shown in Fig. 2-6. When the boat, beginning to broach, reaches a yaw angle of 10 or so, the lift effect of the asymmetry in the leeward hull is strongly excited; the windward hull is at a negative angle of attack ^

GH SPEED and is not producing a significant lift. The lift of the leeward hull is SAILING accompanied by a large induced drag. The excess in drag of the leeward hull over the windward hull times the overall beam of the boat constitutes a torque to counter the broach. The superiority of asymmetrical hulls under these conditions is a matter of practical experience as well as theory. In making the decision of whether or not to use asymmetrical hulls, bear in mind that for a hull section having B/H =1.5, a reasonable amount of asymmetry will cost a 5 percent increase in the wetted surface area and thus in frictional resistance. Friction is the dominant component of hull resistance when sailing in light airs (where multihulls are at a natural disadvantage anyway) and at very high speeds (SLR > 2.8).

Fig. 2-6. Hull asymmetry as an anti-broaching feature.

The question of full, transom-type sterns or fine canoe-type sterns for catamarans where load carrying is not a major consideration can be settled in favour of the fine stern. At low speeds (SLR < 1.8) form drag acts against a full-sterned hull. The pressure of the water against the hull forward of the maximum section resulting in a resistive force is cancelled in a fine-sterned hull by the vector sum of the pressures aft of the maximum section except for a small amount that we lumped into the friction calculation [see Eq. (2-6)]. If the hull is terminated suddenly as is the case with full sterns, then this cancellation is not achieved. This is not the case in air where, for example, racing sports car bodies are found to give less resistance if the rear ends are chopped abruptly. At high speeds (SLR > 1.8) the difference between the resistance of full- and fine-sterned hulls is small with a slight advantage to the full stern. If we are considering an ocean racer, then we must take into account the fact that the sterns will often be buried in the seas that accompany high winds and fast sailing. Under these conditions, fine stcrncd hulls experience significantly less rough water drag.

20 Trimarans pose a different set of problems. Since all of the weight

is effectively carried by the central hull, this hull should have a semicircular section over most of its length. This section may be somewhat flattened toward the stern and should be sharpened toward the bow. Since the DLR of the trimaran hull will be roughly twice that of either hull of a catamaran of similar overall specifications, it makes sense to use a transom stern. The transom should be narrow, however, and should not extend below the load water line.

The design of trimaran outriggers and their positioning with respect to the hull require special discussion. There are two schools of thought on the question of whether to fit full-buoyancy outriggers, either one of which can support the full weight of the craft without being driven under, or submersible outriggers that heel easily within a larger range of stable angles and give a better indication of when the boat is being over-driven. This question was settled (for me, at least) by a rash of capsizes in 1976-77 involving tris with low-buoyancy outriggers. It seems that when lying ahull in bad conditions, a wave may heel the trimaran in such a way as to drive the lee outrigger under. This outrigger having a high resistance to lateral motion then acts as a fixed pivot axis about which the boat can be capsized. The choice of low or full buoyancy outriggers is therefore the choice between the increased possibility of a wave capsize and the increased possibility of sailing the boat over. I personally feel that the latter is more acceptable.

For high performance, the outriggers should have semicircular sections over the after 70 percent of their length going over into a sharpening spade section toward the bow. In designing the outrigger and hull bows we want a configuration that will pierce small waves with minimum retardation and rise to large waves in order to avoid burying the bows with the possible consequence of a diagonal or stern-over-bow capsize. These requirements call for reasonably fine bows with moderate overhang and sheer, but little flare except in the main hull. The outrigger bows can be fitted with lifting plates as shown in Fig. 2-7.

lig. 2-7. Lift plates and sheer as dive preventors for outriggers.

w speed sailing

In driving hard to windward, the deep running lee outrigger will generate a large resistance acting along a line to leeward of the driving force. The result is a torque that tends to yaw the boat to leeward (lee helm). This can be countered by designing the outrigger so that its centre of lateral resistance is 8-15 percent (depending on overall beam) ahead of the centre of lateral resistance of the hull. The keel action of the outrigger then acts along a line forward of the line of action of the centreboard and cancels the above-described lee helm. This is shown schematically in Fig. 2-8. The outriggers should be

Fig. 2-8. Balance of yawing torques in a trimaran sailing to windward.

mounted in such a way that both are clear of the water with the boat at rest under average load conditions. In this way the trimaran can sail on its central hull alone when running and thereby gain a distinct advantage in resistance over a similar catamaran. For windward work, the high positioning will allow a somewhat greater heel angle. This has the effect of putting the windward outrigger several feet out of the water where its round bottom will not often encounter a wave. When going to windward, the centreline of the hull lies at an angle X, the leeway angle, to the course line if the keel (centreboard, dagger board, leeboard, etc.) is laterally symmetrical. In this case drag can be reduced by toeing the outriggers out by an angle equal to the leeway angle experienced on a beam reach (Edwin Doran, Jr., AYRS 83 B, 18 (1976).) It is also advantageous to incline the vertical centreline of the outriggers outward at the bottom by an angle of not more than 15°. This has the effect of making the outrigger a smooth extension of the curved cross beams, thus reducing the stresses at that junction. As the boat heels the outrigger is brought into an upright position corresponding to minimum drag.

In order to prevent a rapid rise in outrigger drag with increasing hulls and immersion, the DLR of the fully pressed outrigger must be quite low. outriggers This means that the reserve volume must be contained in length rather than freeboard. The limitation of such a long needle-like outrigger is the strength-to-weight ratio of its construction. It is likely that the current (1977) practice of making outriggers about 80% as long as the hull is too conservative and that longer outriggers should be contemplated.

Proas are the least understood multihull type. The original Micro-nesian proa consisted of a lean asymmetric hull to leeward and a heavy log outrigger (counterbalance weight, really) to windward. This craft was sailed by a large and agile crew who arranged themselves to windward as needed to keep the log flying just clear of the water. The few modern adaptations of the proa that have been built in a size suitable for offshore sailing have been 'Atlantic' proas with the hull to windward and a submersible or low-buoyancy outrigger to leeward. The exception to this is Newick's Cheers, a schooner -rigged proa that featured equal hulls. Cheers was the only one of the lot to have enjoyed any racing success.

The best way to think of a proa in modern terms is to visualise a trimaran with the windward outrigger and cross beams sawn off. The Micronesian outrigger or counterweight becomes our hull and the Micronesian hull becomes our full-buoyancy outrigger. So far as the hull and outrigger shapes are concerned, they should resemble the forward half of the trimaran repeated on both ends.

Comparing the proa with a catamaran in terms of performance, we see that in the daysailing sizes, the concentration of crew weight to windward gives the catamaran all the advantage of the proa. In the larger size where mobile crew weight is not a factor, the proa retains (he advantage of permanent weight bias to windward. In comparison with the trimaran, the fact of not having to carry a windward outrigger and cross beams constitutes a big advantage in weight and windage. The weight saved can go into huskier and longer cross beams to put the centre of gravity further to windward. Clearly, in the oceangoing sizes, proas will be faster than either catamarans or trimarans on all courses. Catamarans may be faster than trimarans going to windward owing to a possible windage advantage. Trimarans will usually be faster than catamarans on a run or in light airs to the extent that outrigger drag can be minimized or eliminated. The difference in performance between these two types is much less than the performance advantage of the proa.

On the basis of Eq. (2-21) and the fact that rough water drag is proportional to WF2, we might suppose that multihulls having a sufficiently low DLR might obey a simplified drag equation such as

where a is approximately constant. This turns out to be true. In a paper MTHcntcd at the 1977 Royal Yachting Association Speed Sailing Symposium, Derek Kelsall reported that tank testing of a five-foot inmumn model and resistance calculations for several multihulls using 23

high speed the International Offshore Multihull Rule (IOMR) equations both sailing resulted in smooth parabolic curves of the form of Eq. (2-23) where the constant a varied from boat to boat over a range of 0.025-0.032. Notably, Kelsall sees no hump in the curves owing to wave drag as is seen in monohull data. This is apparently obscured by the rough water drag.

Now let us discuss the question of accommodation arrangement. The minimum requirement is a bunk for each crew member, a galley, head, a few shelves and storage lockers, and a place to sit in comfort for eating, navigating, or what-have-you. The facilities and arrangements required by individuals vary too much for detailed recommendations containing my own biases to be useful. Some general observations on accommodation where performance is the overriding consideration are in order, however.

The waterline beam of the hull must be kept small as we have seen; however the hull can be flared or stepped above the waterline. This allows bunks, lockers, shelves, and so on to be fitted in the narrow hull and still give room for movement without too much elbow friction.

In a catamaran, there will be a strong temptation to build accommodation space on the deck between the hulls, because of the narrowness of the individual hulls. This has the effect of raising the centre of gravity higher off the water and adding windage. As we shall see when we discuss structural problems, there is good reason to have some sort of thick connecting structure which can comprise a cockpit and enclosed space with seated headroom.

In the trimaran and proa, accommodation is restricted to the hull. The proa, needing longitudinal symmetry, will have a centre cockpit. In the trimaran, cockpit location is optional. Other than that, the accommodation space and layout of proa and trimaran may be similar.

Weight must be kept out of the ends of the hull or hulls in order to keep the moment of inertia about the pitching axis low. This will have the effect of limiting the amplitude of pitching motions and ensure that they are rapidly damped. This is vital in reducing rough water drag. Only the central half of the hull should be regarded as habitable. Human nature being what it is, any small spaces that you as a designer do not wish to have heavy stores put into can be filled with plastic foam. This will serve to absorb shock in case of damage, though foam is heavy in large volumes and should not be overdone. Do not regard standing headroom as a necessity in small yachts. I would not build a coach house structure at all but would continue a fair line from the beams straight across the hull. In the fore-and-aft direction, the sheer line of the hull should curve smoothly into this raised deck. Flat areas should be avoided everywhere. They are structurally, aero-dynamically, and aesthetically unsound. The trimaran Three Cheers designed by Dick Newick and shown in Fig. 2-9 is a good example of the type of continuous deck and outrigger beam structure recommended.

To close this chapter on hulls and outriggers, I would like to pass along some thoughts on drawing hull lines . This method is used 24 by a number of naval architects but docs not seem to have entered

the text books; I learned it from Newick who revealed it at the World Multihull Symposium in Toronto, Canada, 14-17 June, 1976.

Hull fairness is all important. Hollows or abrupt changes of hull curvature through deviations from fairness constitute sources of eddies and turbulence that can ruin a boat's performance.

One first draws the profile and load waterline onto the station lines (Fig. 2-10a). Next draw the plan view showing the sheer line and keel (Fig. 2-10b). Finally, draw the maximum cross section (Fig. 2-10c). The centreline and sheer intersect points for the cross sections can now be transferred from the profile and plan views to a body plan. The problem is now to draw the remaining cross sections such that the hull will everywhere be fair, without curvature changes or reversals over short distances. For a hull of fairly simple shape such as the proa hull (by Newick) shown here, a template can be constructed that includes the curve of the maximum section with a fair extension on either end. The master template for Newick's proa is shown in Fig. 2-10d). By keeping the x mark on the template along the reference line AA' and either set of intersect points on the template curve, all cross sections will change proportionally and the lines will be fair. The problem is therefore reduced from one of constructing the sections by experienced eyeball to one of finding one suitable reference line. It will usually be a straight line as is the case here, although it can also be a smooth curve. 25

igh speed sailing

Fig. 2-10. Line drawing technique illustrated by Newick's PROa.

Continue reading here: Sails And Lateral Stability

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• PERFORMANCE TOPICS

Optimising Hull Lines for Performance

This article was inspired by a question about the rocker line in the new 8.5m cat Design 256 and I want to stick to the point, so we won’t turn it into a book, but I’ll discuss two issues, hull fineness ratio and some aspects of the rocker profile.

When you manipulate the hull form you’re adjusting the lines in three planes, waterplanes (plan view), buttocks (side view including the keel rocker) and the section shapes. So you need to be aware of how the shapes are changing in the other two planes as you manipulate any one of these three, or all three globally as is now possible with computer modelling.

There are two fundamental constants that you start with and don’t change throughout the process. The big one is the displacement or the amount of buoyancy you need.

If you make the hull finer by narrowing the waterlines you have to increase the draft or make the ends fuller to get back to the required displacement number.

If you flatten the rocker line you have to increase the hull width, fill out the ends, or square up the section shapes rather than having a V or rounded V. 

The other constant is the longitudinal centre of buoyancy. You really can’t do any meaningful shaping of the hull form until you have settled on the these two constants.

A third number that we can plug in as a constant if we want to is the prismatic coefficient which describes bow much volume there is end the ends relative to the cross section shape in the middle of the boat, but in sailing boats this is of less importance compared to other factors. 

The hull lines for Design 256, 8.5m Cat. It's that hump in the rocker line - right under the back of the cabin that brought up the question and is one of the key points discussed here.

Hull fineness.

Fine hulls are fast, but only in the higher speed range. There’s a misconception I come across quite a bit that you can add weight and windage and you’ll still be fast as long as your hulls are fine.

Well you won’t be. Your boat will simply sink to find the new state of equilibrium. If your transoms are submerged you’ll have more drag. If your bridge deck is too close to the water you’ll have slamming. Much better to be conservative with your displacement figure in the design stage than overly optimistic.

And fine hulls have more wetted area so you have more drag in light air where friction resistance is the primary drag factor. 

I’ve seen promotional material for catamarans stating that the boat has less wetted area because it has fine hulls. For a given displacement the minimum wetted area is described by a sphere (or a semi sphere in the case of a floating object). The more you stretch it out in length, keeping the displacement constant, the more wetted area you have.

The more you make the section shape into a deep V or a broad U with tight corners, as opposed to a semicircle, the more wetted area you have. Add into the equation finer hulls are slower to tack.

So fine hulls are only an advantage if your boat is light and has enough sail area to ensure you’re travelling at speeds where form resistance is greater than skin resistance.

In my view the advantage of fine hulls is often overrated as it applies to cruising cats.

At the other end of the scale the resistance curve is fairly flat up to about 1:9 which is still quite fast in most conditions. From there the resistance rises steeply as the hull gets fatter and at 1:8 and fatter you’re suffering from some serious form drag.

This is the rocker line isolated from the lines plan above (in blue) and and the red line shows a more moderate rocker line that achieves the same buoyancy and maintains the centre of buoyancy in the same position.  The bow is to the right.

In the image lower right I've squashed it up and increased the height to make the difference in the lines more obvious.

The difference in the two lines is quite subtle, but races are often won or lost by seconds.

Rocker Profile

So if we’re looking for low wetted area we would want a rocker profile that was even and rounded, relatively deep in the middle and rising smoothly to the surface at each end. But this would give us a low prismatic which is not ideal in the higher speed range, and it’s not ideal for pitch damping which in my view is the critical design factor that is often underrated. 

Pitching is slow. It destroys the airflow in your sails and the flow around the hulls, and your performance is suffering from slamming loads.

The single most effective way to counter pitching is with asymmetry in the water planes. You can achieve that in the with a fine bow and broad transom. Or you can achieve it with V sections forward and a flattened U shape aft. Or you can achieve it in the profile view with a very straight run forward and a bump in the aft sections. A flatter rocker line is better for resisting pitching than an evenly curved one with deeper draft in the middle.

The final result is a combination of all three of these factors.

On a cat like Design 256 the weight is concentrated well aft so we need to get buoyancy well aft.

The kink you see in the rocker profile helps to do this. It also helps to keep the rocker straight for most of its length and smooth the water flow exiting the hull aft at higher speeds, possibly promoting some planing effect.

If we had a more even rocker line we would slightly reduce the wetted area, but we would increase the pitching and the water would exit the hull aft at a steeper angle, increasing form drag in the higher speed range.

How much of a bump can you put in there without creating a flow separation, and how damaging would that flow separation be? I really don’t know. The way all of these factors interplay in the various conditions we sail in is very complex.

Ultimately a lot of this work is gut feel nurtured by experience, observing things in nature and most importantly experimenting and trying new ideas.

Is the new Groupama AC45 a breakthrough that will influence the form of racing catamarans into the future? I don’t think anyone has a computer that can answer that. We have to wait and see.

Symmetric and non symmetric water-planes. The blue line with grey fill is the DWL from the design above. As is typical with modern cat hulls the bow is long and fine, the stern is full and rounded. This is the asymmetry that has a damping effect on pitching. The red line on the other hand is more like you would see on a double ended monohull and quite a few multihulls have also used this shape in the past. It's quite symmetric about the pitch axis and does not have good pitch resistance.

The hull lines of the new 8.5m Sports Cat Design 256

Mad Max , Previously Carbon Copy . She was designed in 1997 but she's the current (2016) title holder of the Australian Multihull Chamionships (2 successive years) and the fastest inshore racing boat in Australian waters.

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VPLP´s Trick: Asymmetric Hulls

• February 16th, 2022

It seems that since I´ve mastered my first 1.000 miles aboard a catamaran during the two Excess-deliveries last year (read it here and here ) I kind of became a fan of multihulled boats. Not that I would skip a monohull in favor of two hulls, but I can clearly see the huge advantages a cat has over a mono and that for some circumstances the multihull is absolutely the boat of choice. Last week The Excess brand launched their lates catamaran, not the 13 like I´ve speculated but a fairly big 44 footer, Excess 14 . This alone is not a big deal, but the new boat bears one feature I found particularly interesting: Asymmetric hulls!

Since I am very interested in naval architecture and stories from this part of the business, I immediately called Hervé Piveteau, the “Catamaran Guru” who works for the yard, and persuaded him for another interview on this topic. I am glad and flattered he agreed and here´s what we´ve been talking about…

Hervé Piveteau on conceiving the new Excess 14 with VPLP

Lars Reisberg | NO FRILLS SAILING.com: “Hervé, first of all, congratulations to the Excess 14! How long did the team work on conceiving this brand new boat?”

Hervé Piveteau: “Hi there, Lars. Thanks, we are all excited too! Well, the overall project started approximately eighteen months ago. But interestingly enough, but most of the teamwork and detailed design occurred during calendar year 2021, which is a pretty fast process, I´d say.”

NO FRILLS SAILING.com: “I´ve noticed that the yard undertook a load of extra-efforts for the Excess 14. Why this much? Why going through this sort of trouble of developing a catamaran from scratch, I mean, in the end Excess was and is a “normal” production boat?”

Hervé Piveteau: “Well, we did not see this as trouble but rather as an opportunity. The opportunity to create a boat – as you said – literally from scratch. Within our new, young and open-minded brand it seemed logical. This needed efforts indeed, but they are not that many occasions to investigate, innovate, create. We are a passionate team: We saw this whole process was as a real chance, not an extra effort. Yes, Excess is a production brand, but the hydro-solutions we have found using high-end CFD software hardly affect the manufacturing process or the cost of the boat. So, why do “as usual” if we can offer something superior at a similar cost?”

NO FRILLS SAILING.com: “The one detail I am very much interested in are the asymmetrical hulls. First of all, what is the idea behind having hulls with a not-mirror-inverted hull-cross section?”

Hervé Piveteau: “Well, let´s maybe take one step back. The whole mindset of our team was to really think out of the box. To really try to go unusual ways. So the question was not “why going asymmetrical” but rather the other way round: “Why should it absolutely be symmetrical?” Our partners at VPLP had the feeling that asymmetry could reduce the drag and so we decided to further investigate this idea. That was the beginning of this story.”

NO FRILLS SAILING.com: “In understand. So, compared to a completely mirror-inverted cross section, what is the gain of an asymmetrical hull?”

Hervé Piveteau: “First of all, this choice had no impact at all on the global volume and longitudinal center of buoyancy of our new boat. Also, the wetted surface is very similar. But … the major gain is on the interference drag, we can talk about this later a little bit more in detail. Also, an additional gain is on the, let´s call it “power”, of the boat. Asymmetry lifts the center of buoyancy to the outboard-side of each hull. In this, the boat artificially gains some extra width, hence extra righting moment.”

NO FRILLS SAILING.com: “Let´s talk about drag some more. You mentioned that the concept of having the asymmetrical hulls reduces drag – how is this achieved?”

Hervé Piveteau: “Maybe during your own trips on the Excess 11 you have looked between the two hulls underneath the salon. Have you seen the waves created by the hulls? Well, on a catamaran we see, on top of viscous and pressure drags, an additional drag being created exactly there. It is done by the two hulls’ waves interfering in the middle, below the platform. These interfering waves create drag, slowing down the boat. Now, by making the hulls asymmetric we achieved that the inner waves had been reduced and as such this interference isn´t that strong anymore.”

NO FRILLS SAILING.com: “It seems that the Excess 14 has a lot bigger or at least deeper fins than, for example, the Excess 11. Can you explain the iterations and variants tested on this new hull before the naval architects settled with this configuration?”

Hervé Piveteau: “At first, during the “white sheet of paper”-phase, we started with the idea of lifting daggerboards. We quickly discarded this concept because they had a huge impact of the cruising-aspect and comforts of the boat. Daggerboards imply more maneuvering, deeper draft while sailing, more things to trim, more things that can break, risks of leaks, less living space et cetera. So, still thinking out of the box, we said “Okay: Why not trying to get efficient fixed fins then instead?” Iterations of these newly designed fins were mainly made on their draft, chord length and thickness. In this, we searched for having the best compromise between hydro gain, technical and structural feasibility, and shallow areas access. We did gain a lot with the first centimeters we added and going further showed less gain. In the end, a 1.48 meters draft is the compromise we felt ideal on a boat this size.”

NO FRILLS SAILING.com: “Another interesting detail on the new 14 is the use of inverted bows, negative stems: What are the advantages of having this bow shape on a multihull?”

Hervé Piveteau: “Excess cats are about sailing fun. So, our main objective was to improve the sensitivity on the helm. Deep immersed bows can be seen as a kind of “forward fins”. They do put the boat on tracks but also reduce maneuverability. Another advantage has appeared in the higher speed ranges: By lifting the bow and immersing the transom, the longitudinal center of buoyancy has moved aft, and this has reduced the hulls drag while sailing above 5 knots, which is another nice effect.”

NO FRILLS SAILING.com: “Is it suffice to say that the Excess 14 is the most powerful production catamaran on the market? Which target group in terms of buyers are attracted by the concept of this cat?”

Hervé Piveteau: “I do not know if this is the most powerful production cat, I really don´t know. For sure, it will have a very good sail area/displacement ratio and – more importantly – we expect it to be a boat that gives real sailing sensations, a boat that is fun to sail yet easy to handle. Our targeted clients are people coming from the monohulls, seeking more comfort without losing the pleasure and sensations of sailing. This can be either private owners or people renting the Excess 14 in a charter fleet. You really should try it out, Lars!”

I absolutely will do, Hervé! Thanks for sharing your thoughts on this topic again and sparing some of your precious time! Very much appreciated.

Articles you may like to read as well:

First time on a catamaran

Biscay trap in a multihull: The Race of Alcerney

How to escape a capsized catamaran

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Catamaran Hull Design

• Post author By Rick
• Post date June 29, 2010
• 2 Comments on Catamaran Hull Design

Part 1: Notes from Richard Woods

Since the America’s Cup experimented with going multihull, there’s been a lot of interest in catamaran performance and the catamaran hull designs that define performance. Many guys are investigating whether to buy a catamaran or design and build their dream boat. Let it be said here that building a large catamaran is not for the faint of heart. People begin building 100s of boats a year, yet few are ever completed, as life always seems to have a way of interfering with a good boat build. 

Never the less, since the rest of this website is about selecting and buying a boat , it only seems fair to have at least one webpage that covers catamaran design. This page contains notes on boat hull design goals and an accompanying page from Terho Halme has mathematical formulas used in actual catamaran hull design. It has become a popular research stop and an important reference to the catamaran design community.

The content of this page was reproduced from the maestro of Catamaran designs, renown British naval architect, Richard Woods, who not only designs catamarans, he sails them across oceans…. repeatedly. He has a lot to say on the subject of catamaran hull design.

“…When it’ all said and done, the performance of a sailing catamaran is dependent on three primary specs: length, sail area and weight. If the boat is longer it generally means it’ a faster boat. If she has more sail area, it means she’ a faster boat and if she’ light it means she’ a faster boat.  Of course, there are limits: Too much sail area capsizes the boat in brisk winds. If the boat is designed too light, she will not take any kind of punishment. Too slim a hull design and the boat becomes a large Hobie Cat capable of only carrying your lunch. Of course, too long and large and you’d have to be Bill Gates to afford one. Then there are lot of additional and very important factors like underwater hull shape, aspect ratios of boards and sails, wet deck clearance, rotating or fixed rigging and so on….” Richard Woods

All Catamarans are not equal, but all sailboats have two things in common: They travel on water and they’re wind powered, so the Catamaran design equations in the 2nd part should apply to every catamaran from a heavy cruising Cat to a true ocean racer.

Richard Wood’s comments on catamaran design:

We all know that multihulls can be made faster by making them longer or lighter or by adding more sail. Those factors are the most important and why they are used as the basis of most rating rules. However using just those figures is a bit like determining a cars performance just by its hp and curbside weight. It would also imply that a Tornado would sail as fast forwards as backwards (OK, I know I just wrote that a Catalac went faster backwards than forwards)

So what next?? Weight and length can be combined into the Slenderness Ratio (SLR). But since most multihulls have similar Depth/WL beam ratios you can pretty much say the SLR equates to the LWL/BWL ratio. Typically this will be 8-10:1 for a slow cruising catamaran (or the main hull of most trimarans), 12-14:1 for a performance cruiser and 20:1 for an extreme racer.

So by and large faster boats have finer hulls. But the wetted surface area (WSA) increases proportionately as fineness increases (for a given displacement the half orange shape gives the least WSA) so fine hulls tend to be slower in low wind speeds.

The most important catamaran design hull shape factor, is the Prismatic Coefficient (Cp). This is a measure of the fullness of the ends of the hull. Instinctively you might think that fine ends would be faster as they would “cut through the water better”. But in fact you want a high Cp for high speeds. However everything is interrelated. If you have fine hulls you can use a lower Cp. Most monohulls have a Cp of 0.55- 0.57. And that is about right for displacement speeds.

However the key to Catamaran design is you need a higher Cp if you want to sail fast. So a multihull should be at least 0.61 and a heavy displacement multihull a bit higher still. It is difficult to get much over 0.67 without a very distorted hull shape or one with excessive WSA. So all multihulls should have a Cp between 0.61 and 0.65. None of this is very special or new. It has been well known by naval architects for at least 50 years.

There are various ways of achieving a high Cp. You could fit bulb bows (as Lock Crowther did). Note this bow is a bit different from those seen on ships (which work at very specific hull speeds – which are very low for their LOA). But one problem with them is that these tend to slam in a seaway. 

Another way is to have a very wide planing aft section. But that can increase WSA and leads to other problems I’ll mention in a minute. Finally you can flatten out the hull rocker (the keel shape seen from the side) and add a bustle aft. That is the approach I use, in part because that adds displacement aft, just where it is most needed.

I agree that a high Cp increases drag at low speeds. But at speeds over hull speed drag decreases dramatically on a high Cp boat relative to one with a low Cp. With the correct Cp drag can be reduced by over 10%. In other words you will go 10% faster (and that is a lot!) in the same wind and with the same sails as a boat with a unfavorable Cp. In light winds it is easy to overcome the extra drag because you have lots of stability and so can fly extra light weather sails.

The time you really need a high Cp boat is when beating to windward in a big sea. Then you don’t have the stability and really want to get to your destination fast. At least I do, I don’t mind slowly drifting along in a calm. But I hate “windward bashing”

But when you sail to windward the boat pitches. The sea isn’t like a test tank or a computer program. And here I agree with Evan. Immersed transoms will slow you down (that is why I use a narrower transom than most designers).

I also agree with Evan (and why not, he knows more about Volvo 60 design than nearly anyone else on the planet) in that I don’t think you should compare a catamaran hull to a monohull, even a racing one. Why chose a Volvo 60/Vendee boat with an immersed transom? Why not chose a 60ft Americas Cup boat with a narrow out of the water transom?? 

To be honest I haven’t use Michelet so cannot really comment. But I have tested model catamarans in a big test tank and I know how inaccurate tank test results can be. I cannot believe that a computer program will be better.

It would be easy to prove one way or the other though. A catamaran hull is much like a frigate hull (similar SLR, L/B ratios and Froude numbers) and there is plenty of data available for those. There is also a lot of data for the round bilge narrow non planing motorboats popular in the 1930’-50’s which again are similar to a single multihull hull.

One of the key findings I discovered with my tank test work was just how great the drag was due to wave interference between the hulls. Even a catamaran with a modern wide hull spacing had a drag increase of up to 20 % when compared to hulls at infinite spacing. One reason why just flying a hull is fast (the Cp increases when you do as well, which also helps). So you cannot just double the drag of a single hull and expect to get accurate results. And any speed prediction formula must include a windage factor if it is to give meaningful results.About 25 years ago we sailed two identical 24ft Striders next to each other. They were the same speed. Then we moved the crew of one boat to the bow. That boat IMMEDIATELY went ½ knot faster. That is why I now arrange the deck layout of my racing boats so that the crew can stay in front of the mast at all times, even when tacking or using the spinnaker.

I once raced against a bridge deck cabin catamaran whose skipper kept the 5 crew on the forward netting beam the whole race. He won.

Richard Woods of Woods Designs www.sailingcatamarans.com

• Tags Buying Advice , Catamaran Designers

Owner of a Catalac 8M and Catamaransite webmaster.

2 replies on “Catamaran Hull Design”

I totally agree with what you say. But Uli only talk sailing catamarans.

If only solar power. You need the very best. As limited watts. Hp.

The closer to 1-20 the better.

Closing the hulls to fit in cheaper marina berth. ?

You say not too close. But is that for sailing only.

Any comment is greatly appreciated

Kind regards Jeppe

Superb article

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Start Fresh to Get the Boat You Want

Many different kinds of boats have been around for millennia, so it’s hard to imagine where improvements could be made. While some builders focus on adding more complex systems to their proven hulls, we took another approach and looked at the fundamentals. Change for the sake of change is not what we’re talking about. We discovered a better way.

Proa Hull Design

Setting out with the goal of building the most efficient boats we could, our founder Larry Graf and his designers sought to create earth-friendly cruisers that would inspire a new generation of boaters. And because Larry and his team played a hands-on role in developing some of the world’s best catamarans, they had an idea of what a boat could be in terms of comfort, stability, and fuel economy.

Knowing what we already knew about catamaran hull design and the many inherent benefits of multihulls, we began to explore a dual hull boat that would be different from a traditional catamaran.

What we found is the asymmetrical hull catamaran. This revolutionary hull design is called a proa and it exhibits certain benefits for power catamarans, aside from the obvious stability that is a key advantage of a catamaran over a monohull. The two hulls are identical in profile, but they are actually very different in shape—with one hull being 35 percent thinner.

The Multifunctional Result of Better Design

The patented Aspen proa design with its asymmetrical hulls provides many benefits to those who want to spend time on the water, it’s a natural fit for those looking for a Swiss Army knife of a boat, with many functions easily managed in the same package. It’s no wonder that many consider the proa to be the best combination fishing and cruising boat.

For the designers, the efficiency was the first noticeable aspect of the design, since the smaller of the two hulls has roughly half the drag of the large hull, thanks to fluid dynamics. Stability is another factor that can make or break a day chasing the fish, and our multihull design makes it easy to enjoy fishing in rough conditions with a consistent, predictable hull movement. Speed is a factor in everyone’s enjoyment of a boat, whether it’s the thrill of a fast run up the coast or a quick jaunt offshore.

Aspen Thinks About Engines Differently Than All Other Builders

Aspens run on a single diesel engine or two mismatched outboards, depending on the model chosen. Both configurations have their advantages, depending on the boating experience you’re after. A single diesel engine design saves dramatically on machinery weight, which in turn saves on the required structure component sizes, plus additional necessary fuel and the corresponding weight of that load. As outboards have continuously improved—and grown in popularity—we saw an opportunity to incorporate outboard power to create even more of an advantage for Aspen owners.

Spacious Decks Make a Big Difference

Whether you choose a cruising model with a full interior and accommodations or an open-deck, center-console-type catamaran with loads of seating and open space, Aspen designs make a lot of sense for boaters looking for a certain type of experience. Having the space to move around means that even a large group of friends won’t feel crowded. No matter what choice you make, we know you’ll find our designs make the best use of that broad, stable platform for a dayboating adventure or longer, overnight excursions.

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Asymmetric hulls

Discussion in ' Multihulls ' started by Trevlyns , Oct 15, 2006 .

Trevlyns Senior Citizen/Member

Looking at the P95 plan view at http://www.ikarus342000.com/P95page.htm , - which seems to have quite radically asymmetric hulls - I got to thinking what hydrodynamic effect (if any) would be present because of the Bernoulli Principle. Any thoughts?  

Raggi_Thor Nav.arch/Designer/Builder

It could add some lift to minimize leeway, but I think it also adds more resistance than lift generated from keels or centerboards.  

Thanks for the quick reply! Looking at the larger picture between the hulls, you also have the "pinched tube" effect where pressure would be greater at the bows, but suction greater at the stern. Would that have a performace effect do you think? Regards Trevor  

yipster designer

In 1986 we integrated what we call the "Chamfer panel" into the design work for a 10.6m (35') LOA open bridge deck cat which we were designing at the time and which was to become the Alfresco 1060. The chamfer is quite simply a 45û bevel between the bridge deck and the inboard hull side and our original intention was to create a more uniformly stressed structure by minimising the loadings on the hull to bridge join but it had a surprisingly beneficial effect on the motion of the boat in a seaway and significantly improved access into the hulls when applied to bridge deck catamarans. At the time there were two of the Alfresco 1060's building side by side and one of the owners elected to employ the straight bevel (chamfer) as designed while the other rounded it out, effectively creating a large diameter radius between the hull and the bridge. When the two boats were sailing side by side it was possible to detect a distinct difference in the motion of the two boats in short lumpy conditions, with the boat which employed the chamfer as designed demonstrating a more even motion as it encountered wave action. The chamfer panel effectively has a dampening effect on the motion of the boat and this is especially noticeable in quartering and beam seas. When the rising wave encounters the chamfer, the wave acts to lift the boat slightly and if the wave is large or steep enough to strike the underwing it will eventually do so with less force and create a minimum of vertical acceleration to the boat. A steep beam sea is potentially the most uncomfortable sailing environment for a catamaran, with wave forces at 90û to the hull side often creating a sharp jerky motion. The inboard hull side causes most of the problem here as waves are effectively trapped in the corner created by the hull side and the bridge. In this situation the horizontal accelerations are dampened in a similar fashion to the vertical accelerations with the chamfer panel lifting the hull and easing the wave under the leeward hull. The structural form created by the use of the chamfer panel was ideally suited to the integration of composite technology to produce an evenly stressed structure which was also simple and economical to build. Unidirectional glass fibres are laid across the bride deck and splay out down the inboard hull side, thereby removing the highly stressed corner join which is otherwise formed, and effectively distributing the loads from the main bulkhead into the adjoining structure. In 1989 we were commissioned to design the Azure 37 production catamaran (also known as the G37) and in this case the chamfer was a major attribute to the design quite apart from it's structural and sea keeping advantages. The chamfer panel allows the steps into the hull to be moved closer to the hull centreline, thereby making access from the hull into the bridge a reality without having to stoop and without having the upper coach house extend too far across the boat thereby stealing valuable deck space and limiting access to the foredeck. Click to expand...

cleblanc Junior Member

Trevlyns said: Looking at the P95 plan view at http://www.ikarus342000.com/P95page.htm , - which seems to have quite radically asymmetric hulls - I got to thinking what hydrodynamic effect (if any) would be present because of the Bernoulli Principle. Any thoughts? Click to expand...

Thanks to all for your valuable input. I enjoyed your website, Yipster and have picked up on a few more ideas from the articles. Gotta rush back to the drawingboard and make some changes! Cheers guys  

fhrussell Boatbuilder

99% of the CSK cats were asymetric. The very first ones did not even have daggerboards. Most of the big beachcats you see in vintage Wiakiki photos were designed and built by Woody Brown and Rudy Choy and they all had asymetric hulls, were very fasy, and had shallow draft. There is no Bernoulli effect taking place. The effect is more about the high pressure on the outboard side of the leeward hull creating lateral resistance. The windward hull is slightly lifted, while the leeward hull is slightly depressed, therefore the lift effect is stronger toward windward. Many designers and critics claim the hulls negate each other when sailing flat, but a heel of only 2 degrees changes that. Besides, a cat sails flat only on those offwind tacks where you would lift the boards anyway, reducing wetted surface. Another plus of the asymmetric hull is its resistance to broaching in following seas. You should pick up Chris white's book and the new book by Gregor Tarjan.  

another thought on asymmetric hulls. Talking with Roy Seaman, (son of Warren Seaman (CSK), designer of several Nacra Cats, multiple winner of the Worrell 1000, batten maker, and helmsman on Aikane X5 when they broke the TransPac record) he is not a big fan of asymmetric hulls. His comments were that up to a certain speed they make sense. Aikane X5 was capable of speeds above 30 knots. Roy claims that at about 25 knots the boat would 'shudder'. The Randy Smyth designed rig was very powerful and wanted to push the boat faster than 30 knots, but the hulls, being asymmetric, wouldn't go through the water as efficiently as the rig needed. It was a planing issue...he said the hulls wanted to 'break out', but couldn't because they didn't plane at all, like a D-section hull would ala Tornado, Nacra, etc. Roy did agree that asymmetric hulls are great for cruising, not having to worry about skegs, boards, etc and having a very shallow draft. Although, you can not load up an asymmetric hull as much as a D-section hull. I, for one, am very interested in Bernd Kohler's 'anti-vortex panels'. What a great way to add lateral resistance without the draft! One other plus..... Due to the design of an asymmetric hull, a boat realizes more perceived beam in a given length. The centerline of each hull is moved outboard slightly giving a wider centerline to centerline beam than a symmetric hull with the same overall beam. It's all a trade off. I love the asymmetric design, aesthetically and in practice. In large cruising boats, the interior has a unique hull layout that makes for a very ergonomic hallway in the outboard side; and with the head and all shelving, bunks, etc, occupying the area in the extreme curve of the interior side.  

Hi and thanks for a different point of view. It's always good to see all aspects. The boat I'm designing is a 26 foot conservatively rigged "coast hopper" so it'll definitely be more of a cruiser than a speed machine. Draft is an important consideration and the lack of appendages will make for hassle-free beaching when required.  

Jimbo1490 Senior Member

Asymetric hulls have more wetted surface per unit of buoyancy. They are also much more sluggish in turns, making the handling of the helm much more tricky to avoid ruining a tack. I have found that in a rough quartering sea, I could not tack my Prindle 16 upwind. Repeated retries confirmed that the boat could not tack because it lost too much speed while turning. I was forced to head off and gybe. No such problem with my Prindle 19. It glides through tacks almost like a monohull. Jimbo  

Thanks for your point of view, Jimbo – as with all these responses they are greatly valued. Just putting the matter into perspective though, the yacht I am considering is a 26ft cruising cat which would be vastly different from a performance beach cat like the Prindle 16. My understanding is that the underwater profile and section shape – particularly in the forward sections of the hull - would affect the turning properties. The cruiser would have more rocker and flatter sections compared to the Prindle. Nevertheless, your points and practical observations are totally valid and appreciated.  

It is true that asymmetric hulls are harder to tack than D-sectioned hulls. But, if you're tacking in a heavy sea, it helps to keep the bows down and backwind the headsail until the main fills,..then tack the headsail over. It takes a little getting used to, especially on how you round up. A 'hard over' maneuver usually stalls the boat, so you have to gradually round up, keep the speed, then hard over at the last moment,...and sometimes if the waves are really steep, even reverse rudders if you drift backwards...but that's an extreme. One observation (and opinion) with beachcats (specifically H16, P16) ... It is more difficult to tack a beachcat because the helmsman must stay aft to swing the tiller extension behind the mainsheet blocks. If the crew (if there is one) isn't right up on the forward crossbeam, the bows are going to ride up high and the boat will never tack in a steep oncoming sea....any thoughts on this?  

ron17571 Junior Member

Funny my favorite cat has been the Prindle 16,i never had any problems sailing it any where or way i wanted,my only problem was hull volume(or my weight!)but this was on a lake,i really liked to wait for a front to move in and go out with white caps and hall butt.I guess if it was a problem on a larger boat a bow thruster would help to turn.i mean how often do you actually come about on the ocean.Oh yeah backwinding the jib is how you push the bow over on a prindle 16.  

I really learned to sail on my Prindle 16 on Lake Murray, SC in the early 80's. Thought that boat could do anything until I took it into the ocean THAT'S when you figure out it has some faults! Great all around beach cat, though and miles ahead of the Hobie that it replaced. Jimbo  

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Yes the prindle was much better than the bow burying cartwheeling hobie.Ive never sailed on the ocean,i think the bigger it is the better it would be would hold true for safety on the ocean.my neighbor years ago said he thought 600 foot was about as small as he would go on the open ocean(ex navy man)my parents with much sailing exp. rented a hobie 18 in hawaii and couldnt beleave how rough the water was.I like a lars type keel,i think daggerboards on anything else than a pure race boat are a pain in the butt.i think of going right up to the beach.i think of this stuff,mabe some day ill actually exp.it.  

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Structural, Institutional, and Spatial Factors of Operation of Enterprises in Novosibirsk Oblast

• REGIONAL STUDIES
• Published: 07 April 2024
• Volume 14 , pages 86–90, ( 2024 )

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• E. A. Kolomak 1 , 2  

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The article examines the influence of structural, institutional, and spatial factors on business performance in Novosibirsk oblast, Russia, based on information about enterprises in the region for 2019–2020 available in the SPARK-Interfax database. An empirical analysis was carried out using regression models; an approach based on an extended production function was used, within which, along with assets and wages, the impact on the revenue and profit of enterprises for such factors as industry, age of company, form of ownership, and distance to regional capital was assessed. Assessments found higher productivity and profitability among private enterprises and young businesses, which argues for support of entrepreneurship and new firms in the region. Higher productivity and profitability of businesses in industry and services compared to agriculture indicate the advisability of assistance to the agricultural sector. The results of the analysis showed the significant contribution of agglomeration effects to the results of the operation of firms in Novosibirsk oblast, which is comparable to the average Russian estimates, and this speaks to the request for implementation of transport and infrastructure projects that reduce the costs of business interaction.

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The study was supported by the Russian Science Foundation (agreement no. 23-28-10007, https://rscf.ru/project/23-28-10007/ ) and the Government of Novosibirsk oblast (agreement no. 0000005406995998235120662/Nor-54).

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Kolomak, E.A. Structural, Institutional, and Spatial Factors of Operation of Enterprises in Novosibirsk Oblast. Reg. Res. Russ. 14 , 86–90 (2024). https://doi.org/10.1134/S2079970523600397

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Received : 22 June 2023

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DOI : https://doi.org/10.1134/S2079970523600397

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