Multihull Structure Thoughts

Hi Oldmulti, I stumbeled accross this thread and was blown away with what a fantastic resource it is and over the past few nights have spent many hours reading and learning. So thank you very much for the clearly massive amount of time given to spread this knowledge. I have somewhat of a selfish request which is by any chance do you have the index on Page 1 in excel format. Thanks once again, Daniel

 

Daniel. Time is my problem. Yes, I agree there should be an excel version but first I have to update the index with the last 30 pages of the thread and when I do the next index update I will drop an excel version as well.

 

Many thanks for reply, I would happily contribute some time towards helping to update the last 30 pages if it helps at all. It's the least I could offer in return for the information I am getting from this thread. A google sheets file might suit as it can be constantly updated and people with the link can be configured for viewing only and not edititing the file.

 

Jeff Schionning and friends produce many multihull designs from sailing to power vessels. The Prowler range of power catamarans were mainly focused on the private owner market but Jeff has been progressively introducing charter options of some of the cruising designs. The Prowler 1100 Water Taxi charter passenger and cargo cat is based on the Prowler 1040 cruising design.

The Prowler 1100 Water Taxi is 36.1 x 15.7 foot with a weight of 14,300 lbs with a payload of 6,940 lbs (32 passengers). The underwing clearance is 2.6 foot. The engine power is 2 x 115 HP outboards provide a cruising speed of 16 to 18 knots with a maximum speed 24 knots. Similar sized Prowlers have fuel economy of about 1.5 litres/ nautical mile at cruising speeds of about 15 knots.

The Prowler 1100 Water taxi is a commercial charter vessel suited to ferrying passenger or goods. The design is based on the Prowler 1100 hulls with a main cabin adapted to passenger seating with full standing headroom. Perfect for use in the resort and leisure industry, the Water Taxi design is simple, easy to build therefore cost effective, and provides safety and a comfortable ride.

The hull shape is a multichine V shape and the structure is built of either foam core e-glass vinylester or Balsa core e-glass vinylester or epoxy. The overall shape is simple and would be a fast build.

An aside. There is a Farrier 31 sailing tri in Hawaii that uses a 115 HP outboard to power it instead of the 20 HP recommended. The extra 200 lbs of weight on the back doesn’t seem to affect its sailing performance but as the Owner said he has no problem getting home in strong wind conditions which can prevail in Hawaii. And yes, he did strengthen up the stern area and motor mounts to handle the additional loads.

The limited jpegs provide the idea.

 

Regarding the F31 with that massive outboard hanging off the back -I find the owners statement about it not affecting sailing performance hard to believe.

I also have to wonder how much extra stress is being placed on the mount/transom not only due to the extra weight, but also the extra thrust considering the outboard mounting spots of Farrier boats have been one of the more failure prone areas since his first production Tramp Trimarans.

Over the years I have seen a number of second hand Farrier/Corsair examples for sale that were either in need of repair due to stress cracks, or had been repaired in some way.

From my experience in similar operating conditions, having a motor with a long enough leg to keep the prop from cavitating when motoring through swell is most important as light multihulls tend to sit atop the water and hobby horse a lot in rough conditions, and I think this needs to be taken into consideration when shopping for outboards. I would rather have the prop further submerged and limiting performance slightly in perfect conditions than a prop sucking air in rough conditions.

Also interestingly, if you study the various outboard leg and mount designs across the HP range, you’ll notice that as you move up from the smaller 4/5/6 legs, the much heavier and bulky cast legs are set further back from the mounting/hanging point, so not only is the extra weight shifted even further back, but there is also more leverage on the mount, whereas the smaller outboards typically have legs that sit just behind the mounting/hanging point. And I won’t even get into the extra stress of having a big motor fully trimmed out of the water and hanging off out the back as you are sailing. Well, you get the idea….

Funny the timing of that post in that I recently removed the 8HP long leg on my Tri in favor of a lighter extra long leg 6HP.

Not only did it save me 40+lbs, but the extra long leg (Tohatsu SailPro) will ensure good forward progress in swell while also reducing stress on the mount and trolley system which had been “improved”, likely in an effort to make lifting the much heavier 8HP, by the addition of an extra sheave for 5:1 which of course had the opposite affect as it complicated the reeving geometry and ultimately limited the max trim height leaving the leg too close to the waterline.

 

Solgato. The F31 info came from the Farrier group site. The guy had problem maneuvering in and out of the unloading ramp on the "windward" side of the Island and upgraded the outboard after strengthening the aft structure and outboard mount. The statement of not effecting sailing performance was said by him using the logic of him saying it was the equivalent of another person in the cockpit aft. He doesn't race often and found the power of the outboard much more useful than the last half a knot of boat speed. I suspect we have a cruiser more than an outright sailor.

 

Hello Oldmulti,

Can you help me out with the trimaran in the pictures in post 3745 ?
It is for sale in the Netherlands, but i can't find much information about the Kellsall 32.
Thanks!

 

Froddo. Kelsall did many designs about the same size. There is the problem I do not know if it is a Tango 32, a Kelsall 32 or a Strider 32 (unlikely) Each had different displacements etc. Result, I would be guessing about the details, structure, sailing qualities etc so I will not be much help. I hope some else may have some knowledge of the tri. Good Luck

 

This catamaran is a 81.7 foot commercial fishing boat D&D which is based in Narooma Australia. It is built for a purpose and when I spoke to a crew of this vessel it is very successful at what it does which is long line fishing catching swordfish, stripped marline and tuna fishing along the Australian East coast and into the Tasman sea. A class 3A (Australian classification for offshore work) design this vessel is designed to operate offshore for extended periods of time without the need for resupply or support. Naval Architects Australia did the design to the requirements of the Abbott family and the cat was launched in 2017. It is a purpose built, high speed wave piercing catamaran longliner that can, that at 3 times the speed of the other boats out there, this vessel able to operate at a significantly higher cycle rate and follow the schools of fast moving tuna up and down our coast more efficiently than most of the other designs.

The fishing cat 81.7 x 34.4 foot with a weight of 156,000 lbs and a displacement of 257,600 lbs. The draft is 6.4 foot. The power is 2 diesels of 650HP @ 2150 RPM driving through gearboxes with a 2.46 to 1 reduction. The cruise speed of the cat is 15 knots. D&D can remain offshore for extended periods (a few weeks) as it has 4 x 10,000 litre fuel tanks.

When I spoke to a crew member, he said it was hard work but it was more comfortable than other boats because the working deck was covered from wind, water and sun. Built in Adelaide the state-of-the-art, long-lining catamaran was built for the Abbott family of Narooma. The three siblings, Ryan, Todd and Hayley, still only in their 20s, commissioned the vessel to take their business the next step, to deliver the fresh seafood that they value add, selling it direct out of the factory, at markets and to restaurants.

The build is aluminum and took 18 months to build. Notice it is well built but not finished with any paint or fairing above the water line. This is a serious working vessel to do a function, and it will be knocked around. Painting or looking pretty is not required as it has a high initial cost and the maintenance of a “pretty” boat would be high. The owners would have saved at least $200,000 in the build cost by not painting and fairing the boat. PS this cat cost a few million to build as it has significant refrigeration, fishing gear and fish processing equipment aboard.

Smaller fishing operations and private fisherman are not happy that boats like D&D are operating as these big purpose catamarans are very successful causing questions about fish sustainability.

A very successful design, the jpegs give the idea.

 

Wayne Barrett is having problems with his website, go to the wayback machine link provided by Oldmulti en use the “contact us” button, Wayne will respond. Very nice man.
https://web.archive.org/web/20210701122819/https://trimarankit.com/

 

On the right uppercase of the screenshot you will find Mr. Barrett’s phonenumber and mailadres.

 

This is a short one about Ultims in the Arkea Ultim Challenge around the world race for Ultims. An Ultim is a 100 x 75 foot with 105 foot mast that carry up to 7500 square foot of sail downwind. They fly on foils, one major lifting foil in each float and a rudder T foil on each stern. The tris also have a central daggerboard. Ultims can average up to 35 knots and can run 800 to 900 mile days under idea conditions. The fastest recorded speed is 50 knots by Armel Le Cléac’h’s Maxi Banque Populaire XI. Ultims can take off in 12 knots of wind and relatively flat seas.

To the Arkea Ultim Challenge. There were a few special rules for the race. The tri are being sailed single handed, safety was very important to the organizers, result they allowed 24 hour “pit stops” to repair damage but any time over 24 hours would count in the race results. The global course has tight limits as to where the tris can sail especially keeping them away from iceberg area etc. A tri is allowed on occasion to go “dark” not showing its position for 24 hours excluding 500 miles to the finish.

The race starts in France, goes around the Cape of Good Hope, goes below Tasmania Australia, around Cape Horn and back to France. The outright crewed record for this course is 40 days by IDEC sport. The outright single handed record is held by François Gabart with the trimaran Macif in 42 days, 16 hours, 40 minutes and 35 seconds.

So how are the 6 Ultims going? The fastest tri prior to the start was SVR – Lazartigue which just made the start after repairing damage in its front cross beam, the next fastest was considered to be Maxi Banque Populaire XI. But the remaining 4 tris are well proven with speed to spare. Actual, Adigo (ex earlier version of Sodebo), Edmond de Rothschild and Sodebo (latest version).

From the start SVR proved to be the fastest past the equator but had a problem with a float foil after hitting something hard, SVR then did a pit stop in South Africa. Maxi Edmond de Rothschild passed the longitude of South Africa’s Cape of Good Hope after completing the 8,399-mile descent of the Atlantic in 12 days, one hour, two minutes and 22 seconds, at an average speed of 28.85 knots based on elapsed time. This is only a day slower than the fastest ever time. The other tris trailed by up to 2 days.

Across the Indian ocean the lead changed occasionally with Actual getting ahead but Edmond de Rothschild lead pass Cape Leeuwin and Tasmania, in fourth Banque Populaire XI and fifth Actual and in sixth Adagio. SVR – Lazartigue again hit an object destroying its centre daggerboard leaving a hole in the main hull a person head could fit into. SVR pulled into NZ for repairs.

At cape Horn Edmond de Rothschild leads and as of today (32 days into the race) has about 6300 miles to go and will take from 7 to 10 days to do the course. If Edmond de Rothschild can finish the course in 7 days the boat will hold the outright fastest around the globe but it is more likely the boat will take 10 days, again it depends on getting through the doldrums. Next to round Cape Horn will be either Banque Populaire XI or Sodebo.

What we have learnt so far is 100 footers can be controlled by one very skilled person, they are very fast machines that can foil for hours, the tris are fragile and need to be sailed carefully and finally there is a lot of floating objects out there that can cause significant damage to foils etc. These tris think 500 mile days are slow, 700 mile days are OK and 900 mile days are good. You and I are thrilled if we get to 20 knots for a minute, these guys think 35 knots for an hour is OK and peaks of 50 knots is getting exciting. Back to the real world.

A few jpegs to give the idea.

 

In the world of sailing hydrofoils the first viable well funded development was Monitor. A 26 foot hydrofoil developed for the Navy that topped 40 knots in 1957 and it only cost $20,000 of 1957 money. Monitor has aluminium ladder foils on a “monohull”. Monitor is on display at the Mariners’ Museum in Newport News, Virginia. Gordon Baker developed and tested Monitor. Monitor could get up on the foils in about 13 knots of wind and sail at about twice the true wind speed. Top speed was reported at over 30 knots, with some reports claiming 40 knots. At 40 knots, cavitation would probably have set in.

Monitor is 26 x 21 foot over the foils with a weight of approximately 800 lbs. The hull beam was about 6 foot. The sloop sail area is 230 square foot. The flying height is about 2.5 foot. The foils are a ladder arrangement with the main support foils forward of midship and the aft V foil at the stern. All foils could be manually adjusted during sailing by up to 5 degrees by a series of levers to optimise the flight characteristics. The font ladder foils lifting elements had a chord of 127 mm the aft lifting foils chord was 101 mm. Monitor was designed, built and tested for a contract price of $20,000 in 1957, you could buy several house for that price in 1957.

I will not go into much detail but there was a second generation Monitor that was being developed with different foils and 2 freestanding solid wing masts for further evaluation. Parts of the second generation Monitor were being built be I assume the cancellation of the program. (The last set of jpegs). Oh, if only the Americas Cup had caught up with development65 years ago image where we would be now. PS the patent for the “automated” foiling system and concept is US patent office 2,856,879 Oct 21 1958

About the sailing performance a quote from Bob Johnston about sailing MONITOR:

My time on Monitor was limited to two half days but what a thrill it was, and again that was 50 years ago. Gordon and I had two great days sailing her. We had 10 to 20 knot winds which let us take the boat off without assistance. In that breeze Monitor sailed most beautiful. We sailed in all wind directions and the boat handled each wind direction. We could tack, gybe, and reach. As I remember the boat pointed higher than I was used to on conventional sailboats. The control system functioned as planned in all these conditions letting us handle the lake waves, the wakes of other boats and inland lake gusts. I had sailed Bakers other V-foil boats in which we could not gybe without having to take off again and had pitch poled. The design had corrected both of these situations. The after foil was basically controlled by the load on the aft stay. On a reach the after foil angle would go negative to prevent pitching.

What we have hear is a genuine revolution that required another 40 years before people started to explore the possibilities of foiling. It was only when the Moth class really showed what is possible did we all benefit to the point we now have 100 footers foiling single handed around the globe.

The jpegs give the idea.

 

The Schionning designed Solitaire 1740 was designed to challenge the heavy cruising catamarans from Europe. Originally intended for production but now available in a kit format for private builds. The result is the Solitaire 1740 will be lighter and stiffer than the heavy European cats. Her primary design feature is an efficient performance sailing catamaran with high bridge deck clearance and angled tunnel panels to minimize slamming. She has a strong beam / length ratio and strong sail area / displacement ratio. Yet the Solitaire has our best interior volume ever allowing multiple versatile layouts and the payload to compliment it. A Carbon rotating rig with park avenue boom. The first build 9is being done in Greece.

The Solitaire 1740 is 60 foot overall including prodder. The cat is 57.6 x 26.8 foot with a dry weight of 22,900 lbs and a displacement of 31,600 lbs. The 75.4 foot aluminium or carbon mast carries a 1248 square foot mainsail and a 565 square foot self tacking jib. You can have other optional headsails. The length to beam on the hulls is 12 to 1. The draft is 1.8 foot over the hulls with daggerboards. The underwing clearance is 3.1 foot. The power is two 30 kW Electric & Single 100 HP Diesel.

The accommodation has 4 double berth cabins with associated toilets in the hulls. There are 2 small forward cabins in the bows for storage or a workshop. The main saloon is large with seating, a table, a large galley and an internal helming position. There is a forward cockpit for access to the bows and social viewing. The aft cockpit has seating and access to the main saloon for extra space. The flying bridge cockpit is where the main sail controls and helming is done from.

The structure is foam glass Duflex with strip plank foam in the hull bottoms and mainly flat panel foam glass above the waterline. There is carbon fibre strengthening as required in bulkheads, forebeams, prodder, daggerboards and rudders.

The claimed performance is under sail a cruising speed of 12 to 15 knots with peak speeds of 25 knots. Under power the cat should cruise at 8 knots and peak at 12 knots.

This is an interesting new design. The jpegs give the idea.

 

Hi Oldmulti, any idea, why the Solitaire 1740 didn't make it to a production boat?