Multihull Structure Thoughts

Jan Andersen of Denmark, designs and builds some interesting trimarans. He started a series of tris with a home built 30 foot race winning light WRC glass tri, Barracuda. The 32 foot Black Marlin was next with several design improvements in construction, a 3 foot taller mast, more sail area, more width, better foils, taller and narrower floats. The floats allow Black Marlin to sail better in heavy weather but heels slightly more, but the floats also allow the tri to push into light airs better compared to Barracuda. Black Marlin can cruise at 12 to 13 knots and has peaked at 26 knots. Black Marlin can go upwind at 40 degrees. Result other people wanted a copy of the swing wing “Black Marlin” as Black Marlin is a very successful racer in the Baltic Sea.

This leads us to Marlin the production version of “Black Marlin”. Marlin is slightly longer, all carbon fibre and probably fastest trailerable and foldable sailing racer-cruiser trimaran in Europe. “Marlin” is 33 x 25.5 foot (main hull length 31.5 foot, folded length 37.7 foot, folded beam 11.6 foot) with a weight ready to sail of 3,360 lbs in the racing version, to 4,300 lbs in the full cruise version. The carbon fibre wing mast is 44.3 foot for the cruise version and 49.2 foot for the race version. The racing rig mainsail 495 square foot, jib is 215 square foot, Code 0 420 square foot and a Gennaker of 915 square foot. The
cruising rig has a mainsail of 450 square foot, jib of 193 square foot, Code 0 of 376 square foot and a Gennaker of 828 square foot. The draft is 1.3 foot to 6.9 foot when the kickup centreboard is down. The rudders are kickup on the floats. The Marlin trimaran is self-sufficient in energy with a 450 W solar panel on the roof of the deckhouse, supplying power for its e-engine by Torqeedo, light and other equipment on board.

The accommodation has standing headroom of 192 cm in the salon and space for 8 at the table. There are 6 berths (2 of 6 in the main cabin).

The hulls are built in molds and are carbon fibre infused epoxy on foam with PRO-SET epoxy, which belongs to the professional part of West-System. It is made with biaxial carbon fiber to produce high stiffness and lower weight. The carbon fiber mast uses UD - Uni Directional (fiber in one direction only) and limited biax carbon fibre. Even the main cabin table and parts of the interior is built in Carbon Fibre with veneers to provide a finish.

This is a fast racer cruiser trimaran that has been developed over 3 interations. It has a cruisable interior but, if the weight is minimized with a racing rig you will have a 25 knot capable boat that can average 300 mile days. The jpegs will give the idea of the build of marlin, the sailing jpegs are mainly of the previous Black Marlin.

 

The following is a design study of a solar and wind powered swath. It has a few interesting ideas but like all design studies there are some items that will require a lot of engineering.

The design is called Elizabeth Swann and floats on a submerged central hull, with outriggers just skimming the water surface, to provide stability. The 'Elizabeth Swann' is an in-progress design study, under development, in the hope of defining a technical/cost compromise that will allow the vessel to beat the present water speed record for solar powered vessels. For this we need minimum frontal areas in and out of the water, and superior hydro and aerodynamics.

The power is coming from solar panels on a swing wing system and wind turbine boom which were developed on a land vehicle. The idea is to combine a rotary sail generator with solar panels to allow faster blue water transits, allied to advanced computer navigation for the best routes.

The Elzabeth Swann is 139 x 53.5 foot with 52 x 4.3 foot floats. The displacement is between 67,200 lbs and 78,400 lbs. The length to beam on the main hull is 18 to 1. The float length to beam is 12 to 1 when in displacement mode. There is a foiling option being contemplated which will reduce the resistance of the floats if the swath can go fast enough. The main energy system is the solar array that can harvest 70 kw during bright light and 10 kw at night including the assumed power of a 19.8 wind turbine. There are 29 x 106 KWH batteries for energy storage. There is also a proposed hydrogen storage system to provide auxiliary hybrid power if required. The sun tracking solar panel wings moves independently of the other, to face the incoming solar radiation (insolation) head on, as far as is possible. EG the port wing only lowers to 33 degrees, to allow clearance for the port sponson. An increase in apparent daylight hours of around 4 hours is possible for the wing area.

The proposed cruising speed 8 to 10 knots on renewable power. The vessel should do 10 to 12 knots under hybrid hydrogen power. The maximum speed is anticipated to be 15 to 18 knots using all options.

The accommodation in the build will sleep 4 people in the rear cabin. The forward cabin contains the helming controlling infrastructure and the galley.

The construction is mostly 5083 marine alloy for the hulls and cabins. The alloy tube infrastructure is triangular in shape with 304 mm fore aft tubes and smaller tubes used in the cross frame support structure.

I think this design study has some merit but you would be a brave investor to fund such a large structure with a lot of engineering issues to resolve during the build and initial testing. The jpegs give an idea.

 

This is about a 55 foot carbon fibre sport fisherman that has been developed to go fast. 55 knots of fast. The hull required to handle this needs to be light and strong, capable of handling designed for 5-g acceleration loads. The structure is using known products but the detail is important.

The “Skinny Witch” is a 55.3 x 16.3 foot deep V monohull of 55,400 lbs displacement. The draft is 3.9 foot overall. The boat is powered by 2 x 1,940 hp MTU12V2000M96L Diesel engines.

The builder Martin Hardy reached out to Lou Codega, a naval architect in Virginia who had designed rapid-response military craft and subsequently worked with naval architect Donald Blount on cutting-edge boats. Codeaga says. “It’s not just about more power and light weight. Once you get over 40 knots, weird things start happening—props cavitate, rudders cavitate—you just start boiling water instead of producing thrust. You have to pay huge attention to all that stuff.”

Codega’s design called for a bit of tumblehome, deadrise of 48° forward and 17° at the stern, 7° prop shaft angles, rudders nestled in shallow pockets, and extreme attention to saving weight at every turn.

The structure is basically foam core and carbon fiber, but requires a very good fabric-to-resin ratio. According to the builders the solution would lie with the choice of the resin and the process. “Infusion is the current buzz, but wet-bagging with plenty of working time is a better way to manage fabric consolidation and weight. It’s the king of resin handling to optimize confidence and results.” Working with the Composite Yacht team they developed a custom formulation of Crestapol 1250, a vinylester/urethane/acrylate resin from composites supplier Scott Bader. “We worked with the chemists to develop a very low, 150° to 180°F [65° to 82°C], temperature cure to allow working time, fabric consolidation, resin flow, vacuum pressure adjustment, heat, and weight savings,” Benkelman says. “We had done practical and instrumented testing with the Scott Bader folks while developing race car body parts,” Horsmon recalls. “This resin proved to be very tough and creates a tenacious bond to fibers—especially carbon.”

Benkelman: “Horsmon spec’d the fabrics and core densities to meet the loads, and we worked together with various suppliers to find material with malleability we needed. The problem with a lot of the fabric is that it’s stitched so tightly and doesn’t have good conformability.”

The structural material for the boat is 12-, 18-, and 22-oz [404-, 600-, 756-g/m2] unidirectional, ±45° and 0–90° carbon fiber with stitched carbon fabric in high-load and complex sections. The outer skin has a layer of fiberglass mat to avoid print-through and a double layer of 17-oz biaxial Kevlar for damage resistance, extra thickness, and sound abatement. The hull bottom core material is 1⅜” (35mm), 8-lb (140-kg/m3) density Corecell from Gurit. Topside Corecell is 1¼” (32mm), 5-lb (85-kg/m3) vacuum-bonded to the skins with Crestomer 1196PA adhesive. The builders thermoformed the Corecell on male molds in a high-temperature oven to match the hull and deck profiles to avoid any gaps and unnecessary filler weight.

The result of the above is a strong light structure that was hand laid and vacuum bagged to form the structure. All possible in a home build. But the difference is the choice of resins and fabrics. Getting the correct combination of materials to suit your design and build method is the important part here.

Finally if you are interested:

The revisionist mythology of Wharram https://www.boatdesign.net/threads/the-revisionist-mythology-of-wharram.68600/unread

Page 6 has some interesting comments about resin strength. EG polyester resins can be “stronger” than epoxy. The jpegs are of the 55 foot sport fisherman.

 

The intention of this trimaran power boat was to provide a fast economical day boat with some accommodation for overnighting. The Tri60 comes in either the Tri60 Saloon, which comes with a near full-beam deck cabin and the Tri60 Cabriolet, which is the more open design version more for outside living and day trips.

The Tri60 is 60 x 21.9 foot of an unknown displacement. Draft is 2.7 foot over the hull. Twin 475hp diesel engines drive through Jet drives on the main hull. The intended peak speed is 32 knots with the narrow main hull giving a comfortable passage in head seas and fuel efficiency compared to a monohull of the same length – an estimated 30 per cent less power will be needed. At low speeds, the twin water jets will give fingertip control for manoeuvring in marinas.

The accommodation varies according to the model. The Tri60 Saloon has a main deck cabin with 3 separate table seating areas, a large galley and a forward triple seat helming area. Down below forward is a toilet area and a double berth cabin. In the Tri60 Cabriolet The main deck saloon has 1 table seating area and another bench seat, a smaller galley area and a double helm seating area. The forward area is the same on both models, as is the cockpit and storage for a 10 foot tender in the stern. The float hulls are used for storage and “toy” storage. The real story here is the advertising line “Large sliding doors and windows, plus flexible furniture configuration allows the owner to rapidly and easily tailor the yacht to best suit swimming, lounging or entertaining and dining”. This is not a long term cruising design.

The build is from McConaghy Boats who have built many high-performance ocean racing multihulls and monohulls in collaboration with BMT Asia pacific. The structure is mainly foam composite.

The limited jpegs give the idea but as far as I know the boat was not put into production. The development by EG Neel of production power tris came very soon after the 2013 Tri60 design and may have effected its market potential.

 

The following tri was a very good starting point for many, with a VPLP design and production in a China factory (Torpen) for a relatively cheap racing day sailing trimaran. There were about 70 produced in the 2007 to 2017 production run. There was (and in some areas) class racing done but like all vessels there was a mark 2 version that had improved performance which limited the class racing.

The Multi 23 is 22 x 15.66 foot with a Mark 1 weight of 784 lbs. The 32.5 foot aluminium mast (with carbon fibre spreaders) carry a 237 square foot mainsail, a 91 square foot jib, a 237 square foot Code 0 and a 484 square foot Gennaker. Spinnakers are optional. The floats have 200% buoyancy. The length to beam on the main hull is 11 to 1. The float length to beam is 13 to 1 when driven hard. The draft over the kickup centreboard is from 1.3 foot to 4.5 foot when down. The single rudder is a kick up on the stern of the main hull. The outboard can be from 5 to 10 HP.

The tri is a racer day sailor and has a large open cockpit. There are some storage spaces if you want to camp cruise. The tri is trailable when disassembled. It takes about 2 hours to assemble the tri for sailing.

The construction of the Mark 1 in the main hull above the waterline, decks, topsides and amas is infused vinylester resin over e-fibreglass and Corecell foam. Below the waterline is solid e-fibreglass vinylester resin. Beams are Infused vinylester over fibreglass with carbon fibre reinforcement and Corecell. The mast is aluminium with all Dyneema rigging except wire forestay. There are Dyneema backstays.

Now we get to performance. This tri can sail up to its rating in light airs and flat water, but as with all small tris as the wind increases and waves start you are dealing with a small boat. Translation small boats are weight (payload) and wave sensitive and the more difficult the conditions the less likely smaller multihulls are to beat their EG OMR rating. Good sailors can get good performance from these boats but larger multihulls find it easier to meet their OMR ratings in heavier weather or with slight payload overloads.

Next performance issue with the Multi23 was the kickup centreboard slot which caused a lot of drag. Several owners converted their Multi23 to daggerboards in the main hull that improved speed due to less drag. Some owners also added extra buoyancy to the stern which improved speed.

The manufacture in about 2015 produced a Mark 2 version and made this comment on a web forum: “The boats from your club are Multi23 first version, now we propose the Multi23 MK2 version, still very light, with more carbon parts including beams (80%), rudder, blade, centreboard... Concerning the centreboard (some boards broke), we have now 4 times more carbon reinforcements that before, and we haven't receive any reports of problem concerning the centreboards. The Multi23 is originally built to reach 20 knots speed, this is also the limit of our Manufacturer's Warranty, But in fact, this is difficult sometime not to go over this limit because the Multi23 can easily run over 20 knots, which is also the reason why we have added more carbon reinforcements”

In the jpegs there is a Multi23 speed versus wind speed and direction chart created by VPLP at the design stage. It shows this tri when reaching, can sail at faster than windspeed up to about16 knots in the right sea state. Eventually slightly larger tris like the Diamond 24 and Seacart 26 came into production which took over from the Multi23 but the Multi23 still is a good fun machine.

The jpegs give an idea.

 

This is about where we have come from and the reason for choosing modern designs. We will use the Simpson “Liahona” cruising trimaran as an example. The “Liahona” tri is 42.6 x 26.6 foot with a weight of 8,750 lbs (if foam glass bare shell) and a displacement of about 13,000 lbs to 14,500 lbs depending on build. The original 45 foot fixed aluminium mast carries a mast head rig with 880 square foot of sail area in the main and fore triangle. The length to beam on the main hull is 8 to 1. The draft over the minikeel and rudder was 3 foot and if it has a centre board 6.5 foot. The engine is a 30 HP Yanmar diesel. Fuel consumption was 1.5 - 2.5L PH at about 5 knots cruising with a peak of 6.5 knots. The original Liahona had post installed 300AH lithium batteries, 800w of new solar, 400w wind turbine and an 80 amp alternator. There is a Victron 1200w inverter and a 1 x 100/50 Victron solar charge.

The Liahona is an older design done in the early 80’s and the accommodation is very good for a tri. There are 4 double berths separate head, large galley and dinette. The cockpit is large and has relatively easy access to the rig.

The Liahona structure is of the early 80’s. There was a choice between strip plank cedar/glass or Foam glass with a lot of plywood. Hulls are of fiberglass foam sandwich construction. The core material is 15 mm Klegecell PVC foam except for the bow section of the main hull, which is 15 mm Airex PVC foam. The outer skin is 300 gram chopped strand mat, 800 gsm woven roving and 300 gram chopped strand mat. The inner skin is 300 gram chopped strand mat and 800 gsm woven roving. Resin is 1027 waxless slow cure polyester. Total hull thickness is about 19 mm. The stem of the main hull is constructed of 14 layers of 6 mm Douglas Fir, laminated with epoxy.

Main hull decks are of fiberglass foam sandwich construction. The core material is 12 mm Klegecell PVC foam. The outer skin is 300 gram chopped strand mat, 300 gsm woven roving and 300 gram chopped strand mat. The inner skin is 300 gram chopped strand mat and 300 gsm woven roving. Resin is 1027 waxless slow cure polyester. Total thickness is about 15 mm. The deck over the galley and navigation station is constructed of 9 mm Bruynzeel mahogany marine plywood to facilitate deck hardware attachment. Deck beams are Douglas Fir. Deck stringers and hardware backing blocks are Ash timber. Ama decks are constructed of 9 mm Bruynzeel mahogany marine plywood covered with 300 gram chopped strand mat/epoxy.

Crossbeams are Douglas Fir and 9 mm Bruynzeel mahogany marine plywood box beams bonded and coated with cold cure epoxy. Crossbeam fairings are built of cored fiberglass using 12 mm Airex core with reinforcing ribs. Bulkheads are 12 mm and 9 mm Bruynzeel mahogany marine plywood. The centerboard is constructed of Western Red Cedar sheathed with copper where it turns within the trunk. The rudder and skeg are laminated layers of 12mm Bruynzeel mahogany marine plywood. Interior furniture is constructed of 6mm Bruynzeel mahogany marine plywood. Floors and furniture are framed with Douglas Fir and Spruce.

Today structure for the same boat would have EG 2 layers of 600 gsm e-glass biax outside of 15 mm PVC foam with 800 gsm e-glass biax inside in vinylester resin. The result would be lighter, less subject to degradation and tougher. It would also be easier to build.

Now we get to performance. Liahona has a nice sea motion, her sails are strong with a Genoa, jib and main, setup as a masthead sloop with cutter forestay, she sails to windward well, moving along at 6-8 knots in 10-12 knots on a beam reach and up to 12 knots when the wind hits 15 knots. One a broad reach with the spinnaker and main up she is a delight to sail and will sail at apparent wind speed, sailing at 8-12 knots in 10-15 knots, not the fastest boat but comfortable and easy handle. One person who sailed onboard her commented “ The Liahona 43 was not amazing. It was a heavy boat that was interesting in its way. The fat main hull does a very abrupt turn in waterline shape, from the cockpit aft, to go to the fine stern. I do know of one 43 that was stretched to 48ft. It may have been to do something about the water flow here. There was a lot of turbulence in the area on the one I sailed.” And another former owner Jeff Bush who owned her for 3 years said: “She was a comfortable yacht - not terribly fast - but very comfortable.” The best indicator is a nonstop coastal trip of 650nm in 5 days averaging 6.5 knots.

From the above we can see there is a design issue with the hull shape which has produced a comfortable boat that is limited by its stern shape. At least 2 of these tris have been made wider in the main hull stern extended aft to 45 and 48 foot. Both boats performance improved. The weight is also an issue and a lighter build using modern fabrics and resins would reduce weight. Less plywood and foam glass cross beams would help also. Modern designs of similar length by EG Grainger would be much faster and an easier build. If you want accommodation a NEEL 43 would be faster and have more accommodation. Design has moved a long way over 40 years.

The jpegs give an idea of Liahona.

 

“Rustic (or Sandpiper)” has been featured before but this is an update on its hull construction. The Nigel Irens design (the racing multihull designer) was his version of a Wharram type cat. Sandpiper is a plywood cat of 65 x 28 foot with a 50 foot waterline that weighs 28,000 lbs and displaces 38,500 lbs. It carries two 240 mm diameter 63 foot tube aluminium masts (when carbon fibre top gaff up 67 foot high) in a schooner rigged with a total sail area in the Mainsail, Foresail and Jib is1,755 square foot. The mainsail is 883 square foot, foresail of 578 square foot and jib of 296 square foot. The fore mast carbon fibre gaff is 13.4 foot and the boom is 15.5 foot. The aft mast carbon fibre gaff is 20.6 foot and the boom is 24.5 foot. The hulls length to beam is 11.75 to 1. The draft is 4 foot but can include daggerboards. There are two 105 hp Yanmar inboard engines. The cat is designed so the propellers and rudders are protected to allow the cat to be beached at any time. The numbers indicate a good performance cruiser.

The entire structure is basically plywood with timber stringers and chines. The hull is plywood sandwich construction; 19 mm 12 ply Okume Marine Grade Plywood (lloyds Approved) above the waterline with the exterior covered with fiberglass, below the water line 25 mm16 Ply Okume plywood over frames and stringers There are 19 mm Okume plywood frames or bulkhead every 3 foot. Decks are 19 mm Okume Marine Grade plywood with the exterior covered with fiberglass over deck frames and stringers. The build is done in a WEST type epoxy saturation technique. The daggerboard and rudders are timber construction.

Rustic has 3 crossbeams. The beams are 510 x 533 mm boxes with top and bottom flanges of 4 layers of 19 mm timber for a thickness of each flange of 76 mm x 470 mm wide. The box has fore and aft plywood faces of 2 layers of ply cut at 45 degrees. The 3 crossbeams are locked into position by carbon fibre straps. The cat is basically designed as one solid unit.

For those who would like one professionally built according to the builders think about $1 million plus. This is a big cat with 3 very comfortable sleeping cabins. The galley and dinette area are also comfortable. The downside is this boat is a warm climate vessel as you can get cold shifting from one hull to another.

The jpegs give the idea. Sandpiper is currently available for sale at $270,000 US. Mulkari this is a 50 foot waterline cat built for charter work and would have to conform to structural rules for charter work. I do not know under what rules but the structure is strong and could possible be built lighter.

 

It really seems quite heavy structure. I'm watching a Salt and Light youtube channel
https://www.youtube.com/@saltlightdix4704/videos
showing build of Dix 470 cat and guy building it mentioned hull is 12 mm marine plywood then comes 50 mm insulation foam placed between the stringers and it is closed of on the inside with 3 mm plywood. Bigger version of it Dix 550 is made similarly. Interestingly there is no fiberglass on the outside, just several coats of epoxy and paint. Not sure if it is good idea.
Crossbeam structure from Sandpiper should be pretty close to what I need.

 

Alain Thébault and his team unveiled the drawings of l’Hydroptère.ch and I’Hydroptère Maxi in about 2009. Who is Alain Thébault? He is the man who has spent years raising money for and developing the 60 foot foiling trimaran l’Hydroptère that eventually reach 61 knots over a measured 500 meter course.

After the 60 foot foiling tri reached 60 knots Alain did research as to how he could either reach higher speeds or go global in less than 40 days with a foiling boat. The design process started in about 2010 and came up with the idea of a foiling catamaran. Alain built 3 test trimarans before he built the 60 foot foiling trimaran and he built a 35 foot test catamaran to prove the concept before Alain would start on a 100 foot Maxi catamaran.

Alain eventually built the 35 foot test catamaran but during the development the Americas Cup cats appeared which took a slightly different approach and had more development money behind them. The l’Hydroptère.ch, the 35 foot cat was 35 x 34 foot and weighed 3,350 lbs. The peak speed of this cat was 40 to 45 knots in flat water with moderate to strong winds. The structure needed development but the cat worked well but was not ocean capable. The intention was to next build an ocean capable foiling cat capable of circling the globe in less than 40 days.

The proposed l’Hydroptère Maxi was going to be 100 x 90 foot displacing 45,000 lbs. The 130 foot rotating wing mast carrying up to 9000 square foot of sail area in the mainsail and Gennaker. The aim was to “take off” in less than 15 knots of wind speed and have a peak speed of 50 knots. The Maxi cat was proposed to fly the hulls up to 30 foot off the water. The draft with the adjustable foils can be between 4 and 30 foot. The anticipated crew was 10 people.

I suspect the private banker (managing partner of a major French bank) who privately funded most of the 60 foot tri and 35 foot cat saw the America Cup cats, started to understand the costs and technology developments required and rethought any support for the Maxi cat.

Pity it was not actually built as it would have been fun to see if it could foil around the world. The first jpeg is the 60 foot l’Hydroptère followed by the 35 foot cat then some drawings of the Maxi.

 

l’Hydroptère hit about 61mph, not knots. 52ish knots. That was still an amazing speed for the time.

 

The following 30 foot power cat is probably the largest practical trailable cat I am aware off. The Bond MC30 was manufactured by Bond Yachts. There were many produced and some were trailed by big SUV’s (EG Toyota Landcruisers) where the laws allow 9.5 to 10 foot wide loads.

The Bond MC30 is 29.9 x 9.5 foot with a weight of 4980 lbs. The draft is 1.5 foot with outboards. The outboards can range from two 50 HP to two 120 HP engines. The 50 HP engines will give 20 knots the 12 0 HP engines will peak at 28 knots (depends on brand of engine and good propeller matching to engines). The fuel tanks add up to 255 litres.

The accommodation is good for its size with 1 Queen double berth forward, seating for 6 partially on the wing deck and a single berth starboard aft in the hull under the Cockpit. In the port hull is a head and shower unit forward, a full galley and a single berth aft. There is full headroom in the hulls. This is a layout that will suit a couple for a near shore of coastal trip for a week or so. The main limitation will be the need for refuelling and additional water supplies.

The construction is listed as fiberglass. I suspect there is some foam sandwich construction in there due to the relatively light weight.

The jpegs show several different MC30 boats. A nice simple power cat that can be trailed.

 

That's a really nice hullform, efficient, low wetted surface forward and midsection transitioning back to a flatter planing surface at the stern.

 

The kettle does not match the color of the interior.

 

Roger Mann. He’s 50 years old, lives in Taylors, South Carolina, and works as an aircraft mechanic. He likes sailing adventures and entered the 2015 Race to Alaska, which starts in Port Townsend, Washington and finished in Ketchikan, Alaska. That’s 750 unsupported miles through the notorious Inside Passage — 50-degree water, double-digit currents, storm-force winds, snorting whales and a lot of stark, lonely scenery. Propulsion by wind and/or muscle only. It took Mann nearly two weeks to be the first single-hander home. What fine craft did he compete in? A Hobie Mirage Adventure Island trimaran sailing kayak.

Hobie Mirage Adventure Island tri is 16.6 x 9.5 foot, folded 3.7 foot with a sail rigged weight 185 lbs and a carrying capacity of 400 lbs. the total maximum displacement is 585 lbs. The 16.5 foot mast carries a 65 square foot roller furling mainsail. Draft is 2.3 foot over rudder/peddle drive. The drive is a MD 180 Turbo w/ Kick-Up Fins + ARC Cranks. The hulls are Rotomolded Polyethylene with aluminium cross arms that swing.

So how was the Race to Alaska? Roger hoped he could do 80 miles/day and complete the course in less than 10 days. As with all great plans reality got in the way. Roger loaded the boat with 42 pounds of dehydrated food, “a soup of rice, sausage, eggs, veggies and mashed potatoes,” says Mann. He calculated 6,000 calories a day, even with this intake he still dropped 15 lbs during the race (mainly due to peddling much of the way). Also, he needed water, additional protective clothing, safety gear, items like an anchor and electronics EG phone, limited nav gear, compass etc.

The conditions that can be meet in the race can be ferocious storms can be followed by maddening calms. EG to quote Roger: “Queen Charlotte Strait. Nice day, no wind, 12 hours of pedalling to make 40 miles toward the finish, which was still about a week away. It was the perfect setup for the next calamity. “I pulled into a cove near Cape Caution to spend the night, but there were big swells,” Mann says. “Heard them but couldn’t see because it was getting dark. Landed nose first and flipped. A bolt sheared off, and the starboard ama folded back while the mast hit the sand.”

Roger with the help of another competitor got the boat upright. Roger then did some repairs and continued on after a night sleep. Roger took 14 days to complete the course. He was the first single hander home.

Hobie Mirage Adventure Island tris are tough little boats but the people who are willing to sail them 750 miles in open ocean in parts of the journey are tougher. A not recommended adventure unless you are tough and experienced.

The jpegs give the idea.

 

This is about a traditional canoe designed by Sam Devlin, built by his son Mackensie Devlin from an okoume plywood kit that was cut by Brandon Davis at Turn Point Design in Port Townsend, Washington. Brandon also did most of the CAD modelling and was responsible for capturing the flared bow shape by incorporating tortured plywood shaping. A impressive group of people for a canoe. Why? Local tribes regard canoes as more than conveyances for transporting goods and people across water. They consider them as living beings and members of the community that fill important roles in a healing process aiming to reconnect with cultural and spiritual traditions.

The canoe is 26 x 3.95 foot with a 21 foot waterline length. The basic weight is 250 lbs with a displacement of around 2000 lbs when fully loaded. The length to beam is 7.5 to 1. The motive power is 6 paddlers and a skipper.

The point of this item is the construction. A 250 lbs 26 foot long canoe is impressive. Sam Devlin is a specialist in stich and glue plywood and the clients wanted an economical build. Result is stich and glue semi tortured plywood structure. The build is the hull panels are 10mm plywood but the bottom is 19mm thick with 3 mm marine ply skins and a balsa core sandwiched between. The gunnels are 12 mm x 100 mm plywood to add stiffness to the hull. The bow has the tortured plywood shape with what appears to be small darts to assist the shaping but Devlin says it was done by just torturing 10 mm ply. I have tried to torture 10 mm ply, it is hard very. The entire external was sanded smooth before sheathing it with Dynel fabric in epoxy and taping hull joints with 340-g/m2 fiberglass.

A light weight approach to a long thin hull that could be used as a structural model for a tri or a cat.

The limited jpegs give the idea.