Multihull Structure Thoughts

Dustman. I will answer your question tomorrow but if you look on the web at things like the OMAR wingsail you will find the modern version of the Taulua approach.

 

Dustman. Flexible wing sails are being developed by many organisations. Several of them are fully reefable. They all share the same issues. If they are trimmed correctly they will generate up to twice the power of a normal sail but the downside is if they are trimmed incorrectly they can easily stall and generate far less power. The advantage of a normal rig is you can get it to “self adjust”. Normal rigs can depower with a flexible top mast allowing an EG fat head main to “blow off a bit”. A headsail can help a lot in steading the airflow onto a main etc.

Result overall the theoretical advantage of a wing can be exploited on a race course with a crew constantly adjusting things, but in a cruising situation they don’t have such a great advantage when a yacht is self steering and there is no crew on deck. Below are a few sample web sites of the concept.

https://www.pinterest.com.au/joelnsmith/wingsail/

https://www.omerwingsail.com/

https://www.accwingsail.com/en/home/

 

Exile S is a fast cruising catamaran designed by Nicolas Purnu of 3 Lignes. The catamaran is the next step up from the Palma 30 also done by 3 Lignes. The Exile is 37 x 21 foot with a weight of 13,440 lbs and a displacement of 16,500 lbs. The aluminium or carbon mast carries a 630 square foot mainsail, a 400 square foot self tacking jib and a 789 square foot gennaker. The length to beam is a guess, but looks about 8 to 1. The draft over the fixed low aspect ratio keels is 3.9 foot. The engine options are either a single diesel engine of 20 hp or a single diesel in one hull with an assisting electric motor of 10 kW in the other hull. The batteries can be recharged at the quay by connection or at sea by the 660 W of solar panels installed as well as by the diesel engine if necessary. The electric motor can run for 1 hour independently.

The accommodation layout is simple to minimise costs. 3 double berth cabins with 1 very large common use toilet/bathroom. The starboard passageway houses the very large kitchen whose communication with the saloon is not is not neglected due to the large openings in the structural partitions. The nacelle is therefore entirely dedicated to the saloon, two long and deep bench seats, library, numerous storage spaces, bar. The cockpit has good seating with outboard steering tiller positions. This cat is either is a good daysailor or has a good self steering setup for cruising, as being exposed for days tiller steering would be a pain.

The design was intended to built as a series product cat from full moulds. Resin infusion (vinylester) in molds with e-glass and foam forms most of the structure. There is limited carbon fibre is load areas. No performance figures.

The jpegs give the idea of a nice fast simple cruiser with a very practical cruising layout.

 

Windpearl Yachts are the manufacturers of the Palma 30 cats but actually produced many high quality monohulls. Back 2011 they also had a design done to attract some of those clients to multihulls. Windpearl produced the Windpearl 60, a very high performance cruising design with a semi open bridgedeck. The 60 was 60 x 32.3 foot with a light weight of 38,000 lbs and a displacement of 51,500 lbs. No rig dimensions were given for the fractional sloop. From the limited drawings the hull length to beam appears to be about 12 to 1. The design had daggerboards and is intended to be sailed.

The accommodation is large for a semi open bridge deck design with 5 double berth cabins each with their own attached bathrooms, a large galley and seating area in the port hull and wingdeck extension. The owner’s cabin in the centre of the starboard hull would do justice to any luxury cat with its own seating area, entertainment etc. This cat had comfort to spare. The cockpit area is vast with a well-protected central seating area and room to do all sail handling.

As there are no rig details, I cannot even guess what the performance would be, but I suggest fast, if it has an EG 80 foot mast and a cloud of sail. Windpearl at this stage was building in high strength foam glass mono’s usiing vacuum bagging, some resin infusion and carbon so this cat if it had been built have probably would have been done in these materials.

The limited jpegs give the idea of a very interesting design that I don’t think was build.

 

The following is a style of cat that I hope will be built. The design is done by Nicolas Purnu of 3 Lignes. A day sailor/short term camp cruiser. As beach cats become more performance orientated, they are less capable of camp cruising due to reduced displacement and a lack of storage space. “Unplugged” is 23.8 x 13.2 foot (can be disassembled to 6 foot wide) that weights 2,480 lbs and displaces 3,830 lbs. The Carbon fibre mast carries a 252 square foot mainsail, 183 square foot jib and a 455 square foot gennaker. The length to beam is about 12 to 1. The draft ranges from 1.5foot to 5.85 foot over the swing up centre boards. Power is either a sculling oar or a small outboard.

There is no accommodation but the hulls accommodate numerous lockers which house the kitchen modules. Forward there are storage areas in each hull for water, food, clothes, deck tent and porta potti. When overnighting the deck tent can be established and cushions set up to form beds.

The build of the symmetrical hulls calls for composite construction (sandwich side and solid glass bottoms) in only 2 moulds with an internal plywood structure. Just like the rudders, the daggerboards are pivoting reinforced by an internal aluminium structure, they deliberately protrude from the hull to protect it from running aground. The crossbeams are composite and partially integrated with the wing deck panels. The composite frame that makes up the cockpit is made of 2 articulated and removable parts for handling on land. Its shape guarantees good stiffness at sea and during assembly on land.

No mention of performance but I suspect it will peak at around 18 knots and get near windspeed in moderate conditions. A F25 will probably be faster.

The jpegs give the idea of the concept.

 

It's hard to picture a boat that size weighing that much. Is there a mistake?

 

I was thinking the same thing.

The way they designed the bridge deck in two pieces and how it integrates with the beams is an interesting feature.

Seems like it is one of the challenges with larger trailerable/demountable Cats of this size as a one piece would be difficult to manage and limit trailer ability.

On that note, I always thought Cat2Fold’s 2-piece piano hinged hard deck with each half flipping up and folding over each hull was a clever way to keep a large hard deck attached to the hulls for easy assembly and striking for trailering.

 

Hi. The exact quote on the web site is:
CE light displacement: approximately 1110 kg
Load capacity: approx. 600 kg
When I did an estimate of displacement of the hulls based on a 2 foot wide waterline, 1.1 foot hull depth and 23.8 foot waterline with a PC of .65 it calculates out at 1742 lbs displacement per hull. As I don't have the hull lines to verify the exact shape this seems close enough. Also having a solid glass hull bottom and a solid bridge deck with high freeboard would add weight. Finally the statement of plywood internals and an aluminium frame for the centreboard cases is not the lightest way to do things. When you look at well done F24 and F25 they start at about 1600 to 1700 lbs weight. I agree it appears heavy but it is possible.

 

Merlin Eagle or Janus would offer actual accommodations at half the quoted weight

Sailing Catamarans - Merlin - 7.65m a compromise between Gwahir and Strider

There was a boat built in Australia called the Windrush 600. 20' long 8' wide. Sails like an aggressive beachcat, barely enough room to sleep and sit up in the hulls with your head sticking out. And LEEBOARDS!!!

I have said many times how much I loved my caper cat and the rare larger 18' versions are most collectable, but those sorts of boats are really limited in a lot of camp cruising situations. Having a cubby hole you can crawl into makes a big difference.

Edit: I recall one or more of the small Woods boats can be built with a 2 or 3 piece bridgedeck. I want to say Eagle but I expect any of them could be thus modified...Hull weight matters, a lot, if you want to wheel it onto and off a trailer...

And I get just a tiny bit cranky every time I see reverse rake bows....They are the 80's giant shoulderpads of the boat world..

 

The Purnu cat reminds me of the Nawiatr N700K. Both are similar sized with hard floor camping area and skipper seat "flap" that sticks out.

I like the idea of a "big cockpit" catamaran daysailer of this size. But I think I would rather use the hull top as a long seating surface, and have a bunk inside. Of course, that means having build a bunk and having to finish the inside of the boat to some degree, which I'm guessing Purnu was aiming to avoid.


Nawiatr N700K
Hulls Length 7.00 m
Beam 4.70 m
Draft 0.25/ 1.25 m
Boat weight 450-600kg
Displacement 1050 kg Design Cat.
CE C Crew 4/5
Sails - Mainsail 22 m 2 - Jib 8 m2 - Schreecher 18 m 2
Designer Piotr Kopczynski

 

This is a story about an Argentina design and initial build of a fun power catamaran that was sold to the USA in about 2011 and then had an improved build. According to its designer, the “Helicat 22” is great for 'stable and safe, fun, fast, economical and practical water travel, island transport, resort adventure tours (with 4 side facing jump seats with seat belts) or day charter/rental'. Seat belts required at speed and if you look at the jpegs the quality of seats is amazing. This is going to be interesting.

The “Hellcat 22” is 21.5 x 8.5 or 10 foot. The weight is 1,600 lbs without engines, with 2 x 60 HP outboards it weighs 2,200 lbs. The draft is 1.5 foot. The engine options range from 2 x 60 HP to 2 x 90 hp 4-strokes or a 115/125 Mercury Optimax. The maximum weight of each outboard is 400 lbs. The top speed is 38 mph with 60-hp motors. 30 mph in white cap waves. With 2 x 90 HP outboards is 43 mph. The range is over 100 miles [160km] with standard twin 12 gallon [45 l.] tanks. At speeds from 20-45 mph, she burns only 4-13 gph, getting 5 to 3.5 miles per gallon.

The accommodation is in the standard form is 2 very comfortable seats and comes equipped with a VHF and navigation lights, plus a stereo. The seats will support you as the cat goes 30 mph in white cap water. Some of the available video’s indicate it can handle limited rough water at speed. This is a case of a good fun machine but it is not an ocean racer in spite of the advertising. The “charter” version can sit 4 with a 2 people seated outside the main pod. Again, a lot of fun and some windburn.

The construction varied. In Argentina the structure appeared to have solid glass skins. When production moved to America, the U.S.-built HeliCats were manufactured by Sunbacker Fiberglass of Monroe, Washington. Sandy Williamson (the new company owner) changed the structure to some foam glass with watertight compartments and foam flotation in each hull. The overall weight was reduced by 400 lbs which allowed an increased payload. The tail on the pod has a use for those who like wakeboarding or waterskiing, that’s where you attach the tow rope. HeliCat can come with graphics and a variety of colours (white, red, blue, and yellow).

In about 2014/15 Sandy Williams was advertising the Helicat moulds, company etc for sale as he was intending to retire. I do not know its history since but the Helicat web site is still up. There were several built and as I said there are a few interesting video’s of its performance in smooth and rough water.

The jpegs are only the start of the story. The yellow boat is the original version.

 

Unlimited racing canoes in Hawaii are 42 to 45 foot long and carry 6 people when racing. The concept is to paddle very hard over a short course but some racing is done over a longer distance. The result is each canoe is conceptually similar. They are 32 to 45 foot long with a beam of the main hull of about 1.5 foot resulting in a length to beam of over 26 to 1. The overall beam is from 15 to 20 foot with a short balancing out rigger. The “professional” manufactured racing canoes weight range from 160 lbs to over 400 lbs depend on the materials and how traditional you want the design to be. The lighter weight helps but you are going to be paddling in the open ocean in wave conditions. The surfing ability of the canoe is also important as is the skill of the crew to achieve and a racing outcome. Light weight is important but not the most important issue.

Professional canoes can cost over $20,000 so some local put together home build versions for far less money. This is about one home built version.

The guy and a friend wanted to have fun. He had some old Western red cedar from the side of his house so he choose to build the canoe from strip plank. After discussion they choose carbon fibre in WEST SYSTEM® 105-C Epoxy Resin with 207-SC Special Clear Hardener epoxy on either side with the outside covered 275 gsm e-glass cloth covering the outside for abrasion resistance. The cross arms are Ikoa covered with carbon fibre covering. The deck and seats are 50 mm blue Styrofoam cover with glass and epoxy for weight reduction and buoyancy. There is a “keel” inside the main hull to help provide fore and aft stiffness. The mould support frames on a strong back were 18 mm plywood to get the shape they wanted. The mould was removed after the strip planks were glassed outside.

The total weight of the Unlimited racing canoe is 320 lbs. The canoe can care a limited rig to help in down wind courses on non racing days.

This is one way of getting a lot of exercise with friends in a beautiful environment. The jpegs give part of the build for the boat.

 

Harryproa’s keep on having minor improvements of the existing designs as Rob Denny fits in boat design amongst his finalizing his 80 ft Cargo proa, waste recycling work he is doing for the Fijian people, education work etc. The Harryproa we will discuss is the C60 cruiser. The C60 is 60 x 40 foot (the mast hull is 60 foot and the accommodation hull is 40 foot long) with a weight of 8800 lbs and a displacement of 15400 lbs.. The 2 free standing carbon fibre 65 foot masts each carry a 540 square foot mainsail with a wishbone boom. The sails can rotate through 360 degrees (within the limits of the sheets). The length to beam on the mast hull is 24 to 1. The accommodation hull length to beam 12.5 to 1. The draft ranges between 1.5 foot and 6.8 foot with the daggerboard/rudders located near the fore and aft crossbeams. The power in this set of jpegs is an outboard which we will discuss later.

The hull shape is a flat bottom dory symmetrical end to end shape. This shape is done to simplify the build and compromises performance marginally (guess less than 5%). To offset the chine hull is the very low displacement for its length, the very thin sailing hull and the simple powerful rig that can be reefed/depowered easily. This boat can be sailed at near maximum power in a variety of sea conditions longer than many cats with the perfect hull shape. This boat is very capable of being a fast cruiser over long distances. I read various performance claims of Harryproa’s but I am yet to find a serious long distance sailing log to confirm the performance numbers my simple calculator indicates. All I will say is wind speed should be possible in light to moderate winds.

The accommodation has 2 master cabins with queen size berths and ensuite toilets/showers. In the leeward (mast hull) there are 2 x singles berths. The main saloon has a large galley with 2 x saloon tables. The attached cockpit can have many options done to provide shelter and storage. The cockpit also contains a very innovative storage of a tender that is pivoted on the bow temporarily attached to the cockpit floor, the stern with outboard is dropped down to water level that then acts as the power for the C60 for in port power. The tender can be disconnected from the cockpit then used as a separate tender. Good idea.

The build of the C60 is using intelligent infusion and flat panel foam glass. The majority is light e-glass biaxials/triaxials in vinylester or epoxy (your choice) with some carbon fibre in beams and masts. If built to plan this is a very fast build process as the “moulds” are simple MDF (chip board) panels that can be put together in days. When you infuse parts of a hull it can be done in hours after a few days of preparation etc. The major time is consumed in assembling the parts, finishing, painting. Then starts the real pains of the fitout of equipment and systems. But because the build uses less materials in a simpler build process the total build time can be half the time of an equivalent size cat or tri.

These are interesting, can be very fast boats cruising boats that can be home built in larger sizes. The jpegs give the idea.

 

Today we will talk about the Harryproa C50 Air, which has an open layout which will appeal to those sailing in warmer waters, day sailing or sailing with a crowd onboard. With the option of easily rolled down plastic clears around the open cabin for wet, cool or mosquito conditions, the Air configuration provides the best of both worlds for sailors whose use does not include long term cruising in harsh conditions. The C50 is 50 x 25 foot with an accommodation hull of 33.3 foot length. The weight is 4,480 lbs and displacement is 8960 lbs. The 2 x 51 foot above deck carbon fibre freestanding masts carry a 475 square foot wishbone mainsail each. The length to beam on the mast hull is 19 to 1 and on the accommodation hull is 12 to 1. The draft over the daggerboard/rudders ranges from 1 foot to 5 foot. Power can be an outboard attached to a tender which is temporarily attached to the C50.

The accommodation has 2 master cabins with queen size berths and ensuite toilets/showers. In the leeward (mast hull) there are 2 x singles berths. The main saloon has a galley and open air and undercover seating. The “cabin” area can be enclosed by a PVC cover with a zip doorway. The attached cockpit can have many options done to provide shelter and storage.

The build of this Harryproa follows the now standard approach of foam glass vinylester or epoxy in cheap simple moulds using resin infusion. This is a fast build method and you can complete a boat like this in about half the time of a similar sized cat or tri. The materials list for the C50 air is as follows.

400 gsm double bias fibreglass: 180 sq m; 600 gsm double bias fibreglass: 780 sq m 400 Uni glass:

40 sq m 300 gsm standard modulus carbon uni: 560 sq m Zoltek 70k carbon tow: 1 x 6 kg spool

15mm H80 foam: 40 sq m. Perforated if infusion mesh is used, perforated and scored if not.

20mm H80 foam: 215 sq m. Perforated if infusion mesh is used, perforated and scored if not.

25mm H80 foam: 12 sq m. Perforated if infusion mesh is used, perforated and scored if not.

Infusion Resin: 550 kgs, incl 35kgs for glue which will require 2 kgs of colloidal silica. Peel ply: 650 sq m

This build depends upon the thick foam, thin skin model to obtain its stiffness and “strength”. It saves a lot of ribs and stringers and saves a lot of work, especially if it is done as an infusion in a mould.

The performance of this boat is windspeed up to 15 knots. Beyond that I suspect fast but have not seen any serious performance reports.

An interesting design that can be “converted” into a C50 cruiser at a later stage. The limited jpegs give the idea but the PDF from the Harryproa site give some excellent drawings of the design.

 

Folks this one confuses me. The cat featured here is from Multihulls Direct which is company set up by Mike Mallory and Ian Farrier to produce Farrier designs. It has a web presence ( FMX 50 http://www.multihullsdirect.com/fmx-50.html ) and claims it can build F22, F33, F45 and the new FMX 50 cruise cat. To my knowledge the rights to the F22 etc belongs to a company in the USA called Deadalus who control Farrier International and are no longer supporting the F22 etc. Can others please inform us of the situation. The CMX 50 is a high performance cruising catamaran that is 50 x 26.5 foot with a full load displacement of 19,700 lbs. The 60 foot rotating aluminium mast carries 980 square foot of sail area with a self tacking jib. The length to beam is about 12 to 1. The draft is 2 foot to 7.7 foot over the daggerboards. The underwing clearance is 3.1 foot. the power is 2x Yanmar 40hp with sail drive/folding props. There are 2 x 160ah house bank batteries, 2 x 55ah engine batteries and 2 x 2.5kw Inverter/chargers with associated solar panels.

The accommodation 3 cabins with double beds with attached toilets. The main cabin has a large central dinette area, a large galley and entertainment and navigation area. The attached cockpit provides additional seating. This is a conventional layout that is practical and effective.

The estimated performance numbers suggest a 8 to 10 knot average cat with peaks of over 20 knots. Its build is claimed to be fully vacuum bagged fibreglass laminate with epoxy resin and foam core with a 2 pack primer and top coat paint – the toughest and lightest exterior finish and polycarbonate windows. I presume this is done in moulds and flat panels.

Now I do not know if this is a completely new design or an stretched version of the Farrier F 41 (later extended to F 44) catamaran. I have included a F41 jpeg which shows a different shape bit there are similarities of gunnel line but a different main cabin shape. No mention of the designer after the passing of Ian Farrier.

The limited jpegs give the idea. I hope this cat is produced as it should be a worthwhile addition to the fast cruising cat fleet. The last jpeg is the F 41 cross section and F 41 sail plan.