corsair f31 trimaran

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• Sailboat Reviews

Corsair F-31

Ian farrier's latest fold-up trimaran is bigger and fasterthan the popular f-27. construction is generally good, though there havebeen some problems, and the wiring could be neater..

Like the blips on a heart monitor, Corsair Marine has experienced several peaks and valleys since our review of the Corsair F-27 (September, 1990), including the sale of the company by its founder, and the introduction of two new boats, the F-24 and F-31. With that in mind, and considering the increasing interest of sailors in multihulls, we’ve taken another look at the company, its designs, construction methods, and its most recent entry in the marketplace.

The company was founded in 1983 by John Walton (of the Wal-Mart family), who recruited naval architect Ian Farrier to abandon a thriving practice in Australia and move to California to design boats and oversee production.

Farrier conceptualized the development of a foldable, trailerable, performance-cruising boat that would attract new sailors to the sport, and would appeal to those seeking a user-friendly yacht. By 1985, the F-27 trimaran was coming off the line at a steady pace; more than 450 F-27’s have been produced to date.

In 1991, Farrier designed the F-24, a scaled-down version of the 27, which went into production that year. Walton left his management role at Corsair to return to the family business. He also bought into TPI of Warren, Rhode Island, the plan being that at least some Corsairs would be built on the East Coast. Farrier and the new Corsair management disagreed about changes to his design, which ultimately led to his unplanned, though amicable, departure from the company. The conflict over design issues eventually resulted in his disavowing design responsibility for the boat, with the exception of the hull lines and beam structure.

After he left Corsair, Farrier designed the F-31, a stretch version of the F-27 with more headroom, and oversaw its initial production by OSTAC, Ltd., a boat building company in Australia. In 1992, the boat won the Multihull Offshore Championship, and was named Australian Sailboat of the Year.

In 1994, Corsair purchased American production rights to the new boat, then produced six of them under a construction agreement with TPI.

Farrier, however, says he was chagrined that the prototype weighed 5,600 pounds, compared to the 3,800-pound standard, and the next five produced also were heavyweights. In a somewhat surprising turn of events, Paul Koch, the managing director of OSTAC, purchased Walton’s interest in Corsair. He subsequently moved the F-31 molds to the company’s Chula Vista, California, production facility, where 50 F-31s have since been built and where a backlog of orders exists.

Farrier rejoined the firm in a part-time design consulting capacity in 1994.

Despite its internal turmoil, the company has produced more than 750 boats in its first 10 years, so we must conclude they are doing something right, especially considering that the F-series is priced at the high end of the new boat marketplace.

In his multihull designs, Farrier seeks to develop boats that are stable, sailed flat, and are comfortable, having lots of deck space and a shallow draft.

However, every conversation with the designer centers around the issue of sinkability.

“The ultimate point of stability for a monohull is sitting on its bottom, even if that is an ocean bottom,” he begins. “The F-31, by comparison, is unsinkable. It has nine watertight compartments so even if it pitchpoles or turtles, the crew can crawl inside the capsized hull and have air to breathe and protection from the elements while awaiting rescue of both crew and boat.” In a monohull, he says, the crew will more likely be adrift in a life raft. Though his argument provides interesting fireside chatter, it doesn’t end the debate. In a sense, it isn’t all that relevant, considering the small percentage of sailors who make ocean passages.

In any case, his designs meet the objectives set forth: the F-31 presents an aesthetically pleasing design with its fine entry; low, 27-inch freeboard; and fine lines. A flat aft section prevents the stern from burying when the bow rises in heavier breezes. Even when sailed on a broad reach with the windward ama out of the water, Farrier believes that his multis are more comfortable than a monohull sailed at a comparable angle of heel.

Owners agree that being able to launch from a beach, or sail into a shallow anchorage, adds to the boat’s overall utility and their enjoyment of the sport. These all are positions long put forth by multihull advocates.

The usual trimaran compromise is in the gbujnt of interior volume in the main hull, which serves as the boat’s only indoor living quarters. Though headroom is 6’ 1″, the beam of the boat is 8′ 6″ when folded. However, interior space in the main cabin is just 7 feet, narrow when compared to a typical 32- foot monohull.

The company initially produced two aft-cabin versions of the boat, then added an aft-cockpit model that became so popular that aft-cabin models were discontinued. A redesigned aft-cabin version with the same cabin area as the aft cockpit model is scheduled to resume production.

The main cabin is sort of a multi-purpose area that serves as sitting area, galley and sleeping quarters. Dimensions are 7′ 10″ wide at the hull-deck joint by 6′ 10″ long. On a cruise, it will feel tight. A 6′ 3″ settee to port converts to a double berth when a platform stored beneath the cockpit slides forward to create the second half of the berth. Alternately, the same platform rests on a mount and provides a dining or chart table.

To starboard, a 24″-wide settee aft of the galley provides a second berth for a slender 6-footer. The forepeak has similar dimensions: 6′ long, 4′ 7″ narrow. All cushions are covered with Sunbrella in patterns selected by owners. Interior surfaces are covered with Frontrunner fabric, as are chainplates and beam connectors, so the area is tidy. Fortunately, spaces are well lit and ventilated. Gray polycarbonate windows run the length of the cabin, and a 16″ square hatch is located in the forepeak, as are 8″ square hatches over the galley and in the head. Bomar and Lewmar hatches are factory specs, but the boat we tested was outfitted with a Weaver hatch manufactured in New Zealand.

The galley is a rather utilitarian affair, being equipped only with an Origo two-burner alcohol stove, small single stainless sink, and hand pump.

Stowage is beneath the forepeak and settees, behind the stove, and on narrow shelves situated along the hull. Additional stowage beneath the cockpit is wide open and not particularly well finished, and will best be utilized with the addition of bins and hanging nets.

The enclosed head is located to port. It is furnished with a small stainless sink and toilet, and handheld shower that drains into a sump equipped with a pump. The head is equipped with a 22-gallon holding tank and Y-valve for overboard disposal.

An electric panel is unobtrusively located in the companionway to starboard; it houses eight switches and a voltmeter and battery tester. Wiring runs from the mast aft are exposed along the overhead, a poor arrangement that could have been concealed, we think. Wiring for running lights runs along the hull and under the galley, so is accessible, but does not have drip loops. Wiring from the panel aft for a loran antenna was loosely installed. In general, we think the entire wiring scheme could stand improvement.

Deck Layout

Standard rigging for the F-31 is a 40-foot tall, fractionally rigged Sparcraft mast with sweptback double spreaders, 1 x 19 stainless steel standing rigging, three shrouds and two cap shrouds. In the absence of a permanent backstay, the cap shrouds are led outboard to the amas. However, except in heavy conditions, they will seldom be adjusted with the attached tackle. In this configuration, the boat carries 599 square feet of sail in a fully-battened, large-roach mainsail and jib. A racing rig is offered.

Running rigging includes a main halyard, two jib halyards, and a spinnaker halyard, all of which are internal and led aft through Harken turning blocks to Lewmar sheet stoppers. In our opinion, halyards exit the mast too close to the deck to facilitate easy hoisting of sails, especially in racing conditions.

Though a pricey option, we suspect that most owners will develop a fond appreciation for the Harken roller furler.

The cockpit is equipped with two Harken B40.2A winches for jib sheets, and a Harken B 32.2STA for the main halyard. The boat we tested had three additional winches in the cockpit for spinnaker handling—more than necessary and poorly located, we think. For more efficient spinnaker trimming, the deck layout would benefit from a careful analysis of winch location to facilitate more efficient cross sheeting when trimming from the weather ama.

Standard equipment includes a stern pulpit that intrudes into the cockpit, which will be adequate for casual sailors. However, the pulpit on the boat we tested had been shortened 24″, so the cockpit was less cluttered and with reduced opportunities to bang elbows.

The traveler system is a Harken.

Moving about the boat is easy once one adjusts to walking on the unstable mesh (or tramps) that fills spaces between the main hull and amas. The primary mesh amidships is sturdy; the mesh used forward of the beams will deflect spray but will not support the weight of an average sized crew person. Corsair says it is looking at alternative materials.

An optional 42′ tall rig increases working sail area by five percent, but increases the size of the bowsprit- mounted asymmetrical spinnaker from 1,004 to 1,112 square feet. In our experience, the additional rig height is unnecessary unless sailors find themselves sailing almost always in winds of less than 5 knots.

Compared to monohulls, the F-31 has a paucity of stowage above decks. Space for fenders and spare lines is available in the amas, though an excess of cargo may affect performance. Aside from that, there are two small stowage areas in the cockpit, one designated for a 5-gallon fuel tank, so cruisers must adjust to traveling light.

Construction

Corsair boasts of a low turnover rate among its production workers, which they feel contributes to a high quality product. For the most part, we agree, though the company has suffered from its share of gremlins.

Initially, Corsair was producing its own water tanks, but after experiencing leaks it now purchases roto-molded plastic tanks from Ronco Manufacturing. Some of the aka (connecting) beams of F-27 hull numbers 225-300 had oil-canning voids caused by foam failure; under the company’s five-year warranty program, many that cracked or fractured were replaced.

The F-31 has suffered from minor problems. For example, trailing edges on the rudder, which are purchased from Foss Foam, have required fairing because they were too wide.

The tiller is mounted in a pivot box in the cockpit. Because bearing failures have been experienced by several owners, and water spouts tend to appear in the cockpit at high speeds, the company is considering mounting the tiller on the transom.

At least one owner has experienced fore and aft movement of his daggerboard at speed, a problem of too much play in the trunk. Farrier agrees that the close tolerances required for a snug fit are not always achieved so individual fixes are occasionally required.

Most importantly, Farrier says, none of the owners have reported a failure of the folding system.

The aka beams are carbon fiber filled with foam, supported by aluminum struts with fiberglass-reinforced acetal bushings and stainless steel alloy pivot points.

All hull-deck joints use a method Farrier refers to as a “top hat,” rather than a conventional shoe box. Decks are precisely fitted to the main hull, and ama tops to bottoms, then bonded with a putty slurry that includes a combination of vinylester resins, chop fiber and Cabosil filler. The company reports no leaks, nor have the owners with whom we talked. However, some report that water enters amas through hatches or fittings following extended heavy air sailing at speeds in excess of 15 knots. Because the amas have a hatch and three inspection ports, examination of the areas is simplified, though wet gear in a storage area will present a problem.

Hulls are hand laid in a foam sandwich. We managed to secure a copy of the lay-up schedule and would conclude that the boats should be strong and seaworthy. The lamination schedule calls for a layer of NPG gelcoat, over which is laid a skin of .75-ounce chop strand mat bonded with vinylester resin to prevent blistering; the company warrants the hull against blisters for five years. Next, five to eight layers of uni- and bi-directional fiberglass with Kevlar reinforcement are laid in stress areas on the bottom, at the daggerboard trunk, and at bulkheads, all bonded with polyester isophthalic resin. Last are layers of .75-ounce chop strand mat and 18-ounce mat sandwiching a .75″ Divinycell foam core. Vacuum bagging is employed to assure a proper mix of resins and catalysts, eliminate residual chemicals, eliminate voids and to enhance the curing process.

Special foam inserts are glassed throughout the hull where shrouds, bulkheads and hardware are installed. Though winches and hardware are all backed with aluminum plates, we noticed deck movement under a jib winch under normal loads in15-knots of wind, so would recommend a double check of those areas.

The amas follow a similar construction scheme, though 5″ PVC tapered stringers run a distance of 11′ 6″ along both sides to add strength. Bulkheads inside the amas are constructed of marine plywood, and are tabbed to the hull in as many as seven places; in addition, there are gussets taped to stringers and bulkheads. The final product of the construction process is a smooth, nicely finished surface.

Performance

Having tested Corsairs since 1990, we believe that the F-31 measures up to earlier models in terms of performance, price, construction, accommodations and comfort, and is noticeably faster than smaller models.

As with the F-24 and F-27, we were surprised at the ease with which the boat is trailered, rigged and sailed within its performance predictions, even by casual day sailors.

We sailed in steady 10-15 knot winds during a five-day regatta, so had an excellent opportunity to put the boat through its paces. We were impressed by its acceleration and overall speed, hitting 18 knots on a tight reach in only 12 knots of wind. Sailing is simplified by a Harken roller furling unit that allowed changes in sail size as we beat to weather. Changing from a jib to a ‘screacher’ (a 180-percent genoa) increased speeds on a tight reach by 30 percent.

With only a quick introduction to sail handling, we quickly launched the asymmetrical spinnaker and had it drawing. Jibing is a simple matter as long as the skipper and trimmer coordinate efforts, and the trimmer quickly releases the sheet and the grinder brings the sail across the boat

We raced in a fleet that started each race five minutes behind the J/35 fleet and typically rounded the first leeward mark in the middle of that fleet, so overcame the time we owed them under PHRF handicapping. Though we were unable to point as high to windward as the J-boats, Farrier says that with training the F-31 will point as high as a good monohull. In our situation, we footed off, took an extra tack, and still rounded the next mark ahead of the others.

Of equal importance is the fact that everyday sailors, who are more focused on having fun than on getting the last one-tenth knot of potential speed, are taking advantage of the ease with which the boat is sailed. Even the most casual Corsair owner, after learning how easy it is to get an extra knot, seems to have developed an affinity for speed.

Conclusions

Perhaps the greatest obstacle for many boat buyers will be the high entry price of the F-31—$97,500 base. That’s before sails, trailer and motor. The construction of a fold-up trimaran is extremely labor intensive, which drives up the cost. And, of course, there are many moldings that make up the akas and amas

From an investment standpoint, the flip side of that coin has been an equally high resale value, resulting in a moderate long-term cost. Compared to similar new multihulls, it is very competitive. (For the adventurous, Farrier offers a kit version of the boat, the F9A, which he estimates can save you 50 percent. Be warned, however, that the job can take a lot of time.)

As a consequence, a buyer must consider the boat within the context of Corsair and Farrier’s objectives: It is fast and easy to sail. The boat will reach its performance potential, even by sailors who concentrate on casual sailing rather than on technical sailing. At the launch ramp, rigging is easily achieved within 15 minutes by two moderately experienced persons.

Perhaps more importantly, the trailerability of the boat opens new horizons. After all, the F-27 caught on big on the West Coast, where ports are limited, because you could trailer it down to Baja.

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Corsair F-31

With 300 units built over more than 20 years, the F-31 is undoubtedly one of the most remarkable 30-foot (9 m) trimarans on the market. For a long time seen as overpriced, this foldable and transportable little rocket is now much more accessible.

Practical info

• Builder : Corsair Marine
• Finance your Corsair F 31
• Available in issue # 173

Boat Test price 3.00 € Inc. tax

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and get an extra discount!

This is a trimaran that hasn’t aged: her design is still in tune with the times, with an elegant coachroof and fine, racy hulls. This model is an adaptation of the F-9, intended for amateur construction. “Home-building” small trimarans has always been very popular in Australia – and it still is today. Like many models that have enjoyed a long career, the F-31 is available in a variety of versions. The best known are the C for Cruising, and the R for Racing. Between the two, a difference in sail area provides extra horsepower in light airs. When Ian Farrier and Corsair went their separate ways, this model continued her career under the name of the Corsair 31. The C model became the CR and the R version adopted the name RS. A carbon rig was offered, then later there was a one-design series (1D or One Design). Corsair also developed a central cockpit with an aft cabin: the CC model.

For speed enthusiasts

As soon as the sails are hoisted and trimmed, it’ll only take you a moment to figure out the character of the F-31: this is indeed an excellent boat, above all built for performance. For the appendages, there ...

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• Sailboat Guide

Corsair 31/F-31

Corsair 31/F-31 is a 30 ′ 10 ″ / 9.4 m trimaran sailboat designed by Ian Farrier and built by Corsair Marine between 1991 and 2012.

Rig and Sails

Auxilary power, accomodations, calculations.

The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more.

Classic hull speed formula:

Hull Speed = 1.34 x √LWL

Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio .311 Hull Speed = Max Speed/Length ratio x √LWL

Sail Area / Displacement Ratio

A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more.

SA/D = SA ÷ (D ÷ 64) 2/3

• SA : Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay).
• D : Displacement in pounds.

Ballast / Displacement Ratio

A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize.

Ballast / Displacement * 100

Displacement / Length Ratio

A measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more.

D/L = (D ÷ 2240) ÷ (0.01 x LWL)³

• D: Displacement of the boat in pounds.
• LWL: Waterline length in feet

Comfort Ratio

This ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more.

Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam 1.33 )

• D: Displacement of the boat in pounds
• LOA: Length overall in feet
• Beam: Width of boat at the widest point in feet

Capsize Screening Formula

This formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more.

CSV = Beam ÷ ³√(D / 64)

Beam folded: 8.16’. Available in aft cockpit (AC) and center cockpit (CC) models. Each available with ‘R’ (racing option) with bowsprit and carbon spar. This design, of one variant or another, has proved to be one of the most popular of all the Farrier/Cosair designs. (Evolved from the F-9A, which was offered as a stock plan.)

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