Multihull Structure Thoughts

Comparing the F22 to the OG Trailer Tri is interesting.

As you stated the F22 was a culmination and a progression of Ian Farrier’s design, and one of the things I remember he disliked (from comments he made in forum posts) that he was always working toward improving and that can be seen in comparison is the height of the arms when folded.

Not only was he able to greatly reduce their height but he was also able to achieve more underwing clearance as shown in the drawings posted of the F22 design.

I really admire his quest to continually refine and challenge himself to solve stuff like this.

It’s unfortunate the F22 program came to the end the way it did.

I think one of the other challenges in addition to cost for its size was/is also that at just about any given time there are usually a number of good used similar sized F/C designs available for sale on the used market because they were well built and had sold in high numbers, and those same sellers/owners were/are the ones looking to move up to something bigger.

In addition to the floats, it’s also interesting to compare the progression of the shape of the bottom of the main hulls.

 

The folks who sail foiling A-Class cats may disagree.

 

Matt Osmond was a design student in 2006 when he designed this power hydrofoil for a competition. No idea of the result of the competition or if the design was carried further.

The power hydrofoil is 32.4 x 13.6 foot of an unknown displacement. The draft is 1.9 foot. The foil is unusual as it only goes full width forward to lift the bow out and helps planning on the aft hull. The designer says the foil becomes a skimming plate. Interesting idea, but how it would work in reality is a little concerning. EG powering into moderate conditions may have the foil work on some waves and other waves may be the right shape for the forward plane to skim over the next waves. Sharp bump on one wave a smooth ride through the next as the foil drives through the wave. The engine power appears to be 2 inboard jet drives which with modern 235 HP jet ski drives could give up to 470 HP total power. This combination would give good speed.

The concept is a day cruiser with some berths forward and other limited accommodation.

An interesting idea. The jpegs tell part of the story.

 

I appreciate the above designer’s attempt to integrate the foil into the hull design versus the typical fragile appendage and afterthought looking approach you typically see.

 

We have spoken about the Excess 13 cruise cat before but now we have some real sailing information from boat tests. The Beneteau Group employed Marc Lombard group to design the Excess 13 (not VPLP) to get a newer lighter cruising cat that has a performance increase while still maintain the accommodation advantages of the Excess range.

The Excess 13 is 42.6 x 23.75 foot (LOA including bow spirit 50 foot) with weight of 23,480 lbs. The 64 foot carbon (aluminium) mast carries a 764 square foot mainsail, a 452 square foot genoa and a 818 square foot Code 0. The draft is 4.9 foot over fixed low aspect ratio keels. The engines are 2 x 40 HP inboard diesels. The Excess 13 is about 2 tons (4,400 lbs) lighter than previous similar sized Excess models.

The accommodation is in the jpegs below.

The build is refined balsa glass hulls, decks and PET foam glass components with some carbon fibre reinforcements in strength areas. Excess’s attention to weight saving is impressive EG the main bulkhead dividing the cockpit and saloon; it also forms the bulkheads for the aft cabins, creating a single, beam-wide frame that saves weight over separate cabin bulkheads. The ring frame sections in the aft cabins are 35mm-thick PET foam sandwich structures. The infused balsa-cored sandwich hulls, Excess uses a new process it calls ‘infujection’ for the deck – a mixture of infusion and injection technologies designed to keep the sandwich deck as light as possible.

The performance comes from 4 test reports. Report1. “In 6 to 10 knots of breeze the catamaran was sailing at 6 knots in such a light breeze with a code 0.”

Report 2. “It consistently maintained high average speeds in the late 7-8 knots at 40° to the apparent wind, through waves which would have stalled other designs. Granted, we were sailing the more powerful Pulse line version, which adds 9m2 upwind sail area, and was equipped with upgraded sails. Powering along upwind, clocking over 8.5 knots when freed a couple of degrees to 45° apparent”.

Report 3. “Underway, the Excess 13 feels alive. The twin aft helms put you close to the water and in direct connection to the rudders. The steering feedback is direct and tactile, with none of the detached, hydraulic numbness you find on heavier cruising cats. From the first tack, she felt connected.

Upwind, the overlapping genoa drives her smartly along, while the balance remained easy and predictable. But it’s when you unfurl the Code 0 from the integrated bowsprit that she really starts to sing. On our test sail, in just over 12 knots of breeze, the Excess 13 powered up to a lively 9.5 knots—effortless acceleration and a satisfying hum through the rig.”

Report 4. “We now had 26 knots over the deck while sailing upwind into 2+m waves with no excessive slamming. Its asymmetric hulls have fine beams below the waterline to slice through waves, yet still swell out from sculpted chines to allow for generous living areas in the hulls above. It was time for the real fun, to turn off the breeze, unleash the Code 0 and start averaging double figures with ease. For all-out speed, a gennaker would have allowed us to run deeper with the wind and waves and surf more, yet the Code 0 sail still enabled us to reach across and then turn onto some waves for short surfs. This was properly engaging early evening sailing, clocking surfing speeds of 13-14 knots.”


In short, the Excess 13 has more performance than a lot of other cruising catamarans and could top 16 to 17 knots. Marc Lombard design works well in light through to heavy conditions.

The jpegs give an idea.

 

One Sails has reinterpreted the classic downwind twin head sail setup. The Integrated Furling Structure (IFS) means that downwind sails have luff strong enough to be pulled tight on the halyard and then furled without damaging the sail, and minus a torsion cable to get in the way and add bulk and weight when stowed in a locker. The Privilege 51 shown in the jpegs give the idea.

The Multi Tradewind Sail is effectively two IFS gennakers set on furlers so that they can be set opposite each other off the wind. There are no poles needed, so if you do need to gybe you can allow one sail to lie against the other and use the outboard sheet to trim both sails, or you could furl one of the sails and use the other by itself. The cut of the sails is designed to be stable dead downwind, with an efficient airflow across and down the sails, while angles of 100° to the true wind can be achieved when reaching. It’s a versatile setup that can also be used partially furled and with no need for spinnaker poles, making it quick and safe to stow in a squall. By using their proprietary Integrated Furling Structure (IFS) into the luff, they’ve created something lighter, cleaner, and far easier to manage - no more wrestling with cables or extra gear.

In downwind mode, unfurl both sides and let them fly wing-on-wing and you have good balance for long tradewind passages, no mainsail required. The boat steadies, steering can be done by hand or autopilot and with less stress and fatigue.

In reaching mode, clip the two clews together and you’ve got a gennaker. Trim it alongside the mainsail and you can reach up to 110° TWA or bear away to 150° TWA, covering the wider angles where classic tradewind sails usually falter.

The cloth used comes from a 100% certified carbon neutral manufacturing process and includes a water-based UV strip, and the sail bag is made from recycled plastic bottles.

An interesting development, the jpegs give the idea.

 

That is very interesting,..and innoviative.

 

This thread on SA has morphed into a bit of a mini discussion about it. https://forums.sailinganarchy.com/t...s-symmetric-spinnakers-real-world-vmg.255657/

 

The Seawind 1170 is the latest version of the Seawind range. Seawind have built over 800 cats since 1983 starting production in Australia then moved to Vietnam. But they found shipping boats to Europe from Vietnam was expensive in spite of the lower labour cost. Now Seawind are producing the 1170 in Türkiye where a Seawind factory opened in Menemen in 2023 in the Izmir free zone. The Seawind 1170 was partially designed by Richard Ward (part owner of Seawind) as a performance cruising catamaran.

The Seawind 1170 is 39 x 21.25 foot with a displacement of 19,840 lbs. The 56.2 foot aluminium (carbon optional) mast carries a 613 square foot mainsail, a 296 square foot solent jib, a 549 square foot Code 0 and an optional 1,195 square foot spinnaker. The draft is 3.9 foot over the fixed keels. The underwing clearance is 2.25 foot. The engines are 2 x 29 hp Yanmars. The cruise speed of the engines is 6 knots and can achieve 8 knots peak. Ther are solar panels and batteries to your specifications.

The accommodation is a 3 cabin layout with the port hull dedicated to the owner. The aft section is occupied by a large bathroom. In the centre, the passageway provides plenty of stowage space and could almost be described as a dressing room, as the owner’s cabin is located just ahead. The transverse bed is quite high up in the nacelle, but it is accessible from both sides. On the starboard side, the guest double berth cabin has its own bathroom forward, while aft there is an extra cabin that can be used for a weekend or for children. In the centre of the starboard hull is the galley in the passageway.

In the bridge deck cabin is a spacious saloon and a proper chart table on the port side. The galley is not isolated, however, as it remains open at the top to the saloon. It has attractive worktops and plenty of stowage space for a 39-footer. For the past 20 years Seawinds have had a ‘magic door’ between the saloon and the cockpit. Divided into three panels that fold into the centre, the whole thing can then be raised up under the bimini with a few turns of the winch. Once locked in the horizontal position by a sturdy stainless-steel bar, the cockpit and saloon become one.

The catamarans are built using PVC foam sandwich and Vinylester resin infusion, resulting in a light displacement of 9,000kg for the 1170. This equates to a performance/comfort compromise similar to that of Excess, Nautitech and even an Outremer (but without daggerboards). The performance across the wind range is good with the cat capable of 80% of wind speed and peaks of 18 to 20 knots. 8 to 10 knot averages are possible.

This is a very good higher performance cruising cat in a 39 foot package. The jpegs give the idea.

 

this Kraut sailmaker has a version where the 2 sails are sewn together at the luff & are rolled together
Das Passatsegel - Segelwerkstatt-Stade https://www.segelwerkstatt-stade.de/das-passatsegel/
& I recall from the 70s, that a dutch sailmaker had the same system in his portfolio

 

A short one from the Farrier boys about F 22 tris when they are pushed hard.

Re: nosediving F22 - Now with Pics.

From: Andrew

Date: Thu, 29 Jan 2026 07:26:56 AEDT

Our last nosedive was on a reach from Wangi to Belmont, Lake Macquarie NSW Australia. I was pushing really hard with the kite, true wind speed 15 to 20 knots and boat speed was constantly 16+ with a peak at 20.3 through the water. I had to keep pulling away in the gusts to keep the main hull in the water, at one point was sailing to Swansea almost 90 degrees from where I needed to go. We got hit by a sharp gust and the lee bow dove and we slowed down to about 14 but she came back out and speed quickly rose to 18 as I pulled away. The first pic is coming into the finish at the LMYC.

The race on the previous day SKNOT stuffed it big time which was caught on camera by the committee (Last Pic) . As you can see from the pic, she is way deep into the coal under Lake Macquarie by this point. This was on a close reach in 15-22 knots true wind. The other shot of 2XS is the same day and location as the third pic but taken when we were approaching, the committee not sailing away like SKNOT was. You can also see the difference in the crew positions, Paul is on the front beam but SKNOT are already in the cockpit, yet they still nosedived.

The most dramatic difference between 2XS and SKNOT is the weight which I believe that this makes a significant difference. 2XS is 673kg (1483lb) and SKNOT is 952kg (2089lb) both are F22R with similar sail areas, both have carbon rigs, but 2XS is all carbon. I always steer from the rear beam and get the crew on the nets back at the beam. I have seen Midnight Rain ( also F22R ) with both crew aft of the main traveler and really sending it.

The jpegs are of the F 22’ sailing in Australia.

 

The NYX 42C is from the SIMONIS VOOGD DESIGN studio and is a 42-foot performance spacious catamaran. The builder and sales are based in Shanghai China. SIMONIS VOOGD DESIGN has done a lot of catamaran designs for many companies including charter firms. These designs have progressed to meet the customer requirements of both space and some performance but SIMONIS VOOGD DESIGN were better than most in optimising the hull shapes to meet the load carrying versus performance versus structural strength requirements. The NYX 42C is a good performance cruiser it is not a racer cruiser.

The NYX 42C is 41 x 22.2 foot (is 28.2 foot with cockpit side extensions lowered). The displacement is not known but a guess is about 25,000 lbs. The 47 foot mast carries a 600 square foot with a 365 square foot jib. Optional genoa, Code 0 etc are available. The hull length to beam is about 8.4 to 1. The draft is 5 foot over the fixed keels. The engine power is 2 x 28 HP Volvo’s.

The accommodation of this design is large for its length. To quote the manufacturer: “The NYX 42C offers a flybridge with 65% more leisure space compared to yachts in the same category.” The NYX 42C comes in 2-cabin, 3-cabin, or 4-cabin configurations, offering flexible accommodation for up to 10 people, once the salon table converts into a double berth. There is a forward cockpit accessible from the main saloon and an aft cockpit which is separated from the saloon by large sliding glass door. The flybridge is a full unit on top of the main cabin roof. Very generous accommodation.

Now we get to an issue of all modern designs like this. These cats will sail well in the right conditions. I have sailed 42 foot cats in 25 foot seas and strong (40 to 50 knot) winds. I have had wave tops land in the cockpit and on the net foredeck in these conditions. Cats with forward cockpits and glass doors between the main saloon and aft cockpit would have had a lot of water flooding into the main saloon in these conditions. If you are a great seaman, have good weather forecasting equipment and have prepared your cat with storm doors etc, you can cross oceans in these designs but nothing is 100% predictable. In short if you are coastal sailing or near shore sailing with good weather knowledge, no problems. Going seriously offshore be prepared in these designs of cats.

Construction is foam fiberglass. The deck structure and hull are made by vacuum infusion molding. This technology ensures weight reduction and improved composite quality, and accurately controls the structural strength with scientific proportioning of aviation-grade materials and numerical control laser cutting, and improves the quality control efficiency through automatic intelligent management. Its production strictly follows the certification of GB/T 19001-2008/ISO 9001:2008 quality management system, and is more actively in line with international high standards.

This is a good design done by SIMONIS VOOGD DESIGN. I will be interested to read a sailing report. The jpegs give the idea.

 

catamaran design sure has come a long way in my lifetime: from MacAlpine-Downie to this...
(the saying "dangerous in any sea" comes to mind...different spelling, but aptly named, the design ...for a Krautophone...)

 

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Just saying,...
Guess which sails are contributing to that bow burying,..

Sail Propulsion - Revisiting a Mast-Aft Sailing Rig https://www.runningtideyachts.com/sail/

On a cruising boat I'd like my forward and biggest sails providing lift to my bows.

 

Mast aft? Piffle!

If we allow that, what is stopping them from doing cabin forward too?



It can never work!