Multihull Structure Thoughts

I noticed the latest issue of Professional Boatbuilder Magazine has an article by John Marples about folding multihulls so I thought I would do an item about SYZYGY.

SYZYGY is a day trimaran designed and built by John Marples for his personal use. She is 21 x 16 and weighs 850 lbs with all gear aboard. The arched aka folding system reduces beam to 8’5″ wide for trailering. (Due to the folding system John will not be offering plans since this boat is very complicated to build.) The rig is a Hobie 16 with additional swept back spreaders to strengthen the mast. The jib is on a furler. The main hull is 14 to 1 length to beam. There is a daggerboard and kickup rudder.

The cockpit is large and open with room for up to 6 persons. The initial design of this tri was to provide comfortable day sailor where the crew can sit comfortably and not have to move as the tri went upwind etc. To take advantage of differing sailing sites the tri also needed to be really trailable and easy to launch and recover as John is in his 60’s.

The folding system with arched akas did present a design challenge but it works very nicely and easily folds on the trailer. The akas have a dihedral angle of 8 degrees to ensure the floats wash out or tilt downward as akas fold aft to fit bow under main hull flange. The hulls have narrow flats on the sides and bottom with cedar strip planking in the bilges and deck edges. Hulls were molded on a table, split on the vertical centerline, one side at a time and then joined along the keels later. The hulls are strip plank with 2 layers of 200 gsm (6 oz) in epoxy inside and out. There are 4 main bulk heads in main hull. Where aka attachment to the main hull, the 6 mm plywood bulkheads are curved with a fir flange on either face of the bulkhead top and bottom. The akas (crossbeam halves) are 3 ply 9 mm plywood top and bottom with a 25 mm balsa core. Each curved beam is 4.5 foot long and weigh 30 lbs. Each float weighs 100 lbs. (Remember John Marples is the co designer of the Seaclipper 16, 20, 14 and DC3 which all have flat timber swing arm cross beams)

The tri sails very well reaching speeds of up to 15 knots so far. SYZYGY sails at 10 to 15 knots in moderate wind and water. With additional sails John thinks the tri will go faster. The ama arrangement makes the boat very stable, even on the mooring.

The jpegs give an idea of a very good trailable tri. The last jpeg is a Seaclipper 20 for comparison. John, I hope you release the plans as this boat is no more difficult to build than a Farrier.

 

SolGato made a comment that he had a folding catamaran idea. I did a little search and found his proposal, it is good. SolGato built a small model of the idea and wrote an item describing the idea.

“Here’s a small model I made to demonstrate the articulation of the swing/folding system. The idea is to make the beams of the platform from U channel or square with a side removed which would accept the short tubular Akas of the hulls which pivot outboard of the beam ends allowing the hulls to swing and lock in a tucked closed position swung out into an open position. When open, the round tube Akas run inside the platform beams and are thru bolted in place. When closed, the short fore and aft aka sections swing into alignment and are joined by a sliding outer section of tube to become one long ridged member. The folding and unfolding would be actuated by lines. When unfolded, the Akas would be pressing against the inside forward face of the platforms beams locking them against the channel acting as a stop when underway. I realize the most vulnerable position structurally is during swinging/folding so some half round guide plates might be needed at the pivot points for the tubular akas to swing around/against.”

SolGato’s idea has many characteristics of Frank Smoot Slingshot 19 folding crossbeam system which work well in reality. A PDF contains detailed information about the Slingshot folding system and would be a good guide as to how to do SolGato’s folding approach on a small cat. The PDF is a little hard to google but look for it in the images pages, “Portrait SP Construction Manuals RGB_Combined.pdf” under a google search for “Frank Smoot trimarans” . The first jpeg shows the image you are looking for (it is not linked to the document).

SolGato approach again depends on hinge strength in the fold and unfold but when its in the sailing position the hinge pins become a secondary item as the beam is supported in the U channel. Solgato, as stated in an earlier item, is thinking of a sliding tube method to narrow the beam of his cat now but I think either approach (swing wing or sliding tubes) with a little development will work.

The first jpegs show the Portrait SP Construction Manuals RGB_Combined.pdf image. The next 7 jpegs show SolGato’s idea. The next 2 jpegs are of the Bernd Kohler design KD800 which you can buy the plans for($US 220). The KD800 compresses to 7.9 foot from 14.4 foot. The next jpeg is of Strings a 40 foot cat designed, built and raced by the Gougeon Brothers. The hulls swing aft with the crossbeams. The final jpegs are of Frank Smoot’s Slingshot trimaran with a similar fold aft folding system. Good work SolGato.

 

There was also another proposal for a folding cat by the designer of Slider, Ray Aldridge catamaran. His Slinger cat had a proposal that connected a central beam with the aft folding cross arms. I have seen the concept but I cannot find it again as Ray no longer has his web site up. Pity.

 

Polar diagrams give you a lot of information about the projected performance of your multihull. A polar diagram shows how fast a sailboat could potentially travel at different wind speeds (TWS=True Wind Speed) and various angles to the wind (TWA=True Wind Angle). Every sailboat model has a unique polar diagram, which displays the results obtained using a velocity prediction program (VPP) based on the craft’s weight, hull shape, rigging and sail setup.

Most manufacturers of boats will provide a polar diagram today if you ask, but many buyers don’t. Many a salesman will say “the cat will top 15 knots” but when you look at the polar diagram this will only occur if you are carrying full sail at 110 degrees in 25 knots of wind. Most of the time you will be doing 10 knots in the same 25 knot wind.

Polars appear to be confusing but are relatively simple to follow. A polar consists of three data indicators — straight lines, circles and curves. The straight lines that radiate out from the center represent the True Wind Angle (TWA). The circles, which also spread from the center, represent boat speed through the water (STW).

The coloured curves (can be black curves) overlaid on the grid created by the straight lines and circles, plot the boat’s predicted speed at various combinations of TWS and TWA. If there are multiple different coloured curves they often represent different sail plans. The diagrams are usually divided into upwind and downwind sections.

EG The first jpeg is a Lagoon 380 that in 10 knots of wind will go upwind and downwind at about 4 knots, reaching at 120 degrees it will go at 6.7 knots (assuming good sails and a lightly loaded boat). In 20 knots of wind, it will go 6 knots upwind, 8 knots down wind and 13 knots at 120 degrees.

A Helia 44 in 10 knots of wind will go upwind at 5.4 knots and downwind at about 5.4 knots, reaching at 100 degrees it will go at 8.8 knots (assuming good sails and a lightly loaded boat). In 20 knots of wind, it will go 8 knots upwind, 8.8 knots down wind and 14.3 knots at 100 degrees.

A Leopard 45 in 10 knots of wind will go upwind at 5.7 knots and downwind at about 4 knots, reaching at 90 degrees it will go at 7 knots (assuming good sails and a lightly loaded boat). In 20 knots of wind, it will go 8.8 knots upwind, 8 knots down wind and 11 knots at 90 degrees.

The Outremer 4X, a known performance cat, in 10 knots of wind will go upwind at 9 knots and downwind at about 6 knots, reaching at 90 degrees it will go at 11 knots (assuming good sails and a lightly loaded boat). In 20 knots of wind, it will go 13 knots upwind, 9 knots down wind and 24 knots at 110 degrees.

Translation of the above looking at polars will give you an idea of what your cat is capable of if you have good sails, a good crew and the boat is not overloaded. The second clear message is if you buy an accommodation first cat you will travel at 50 to 70% of windspeed. If you buy a real performance cruiser cat you will travel at 60% to 120% of wind speed.

In accommodation cats you don’t start to get performance until you own 50 foot or above and in real terms a Lagoon 380 will cruise as well as a Leopard 45. In performance terms a 32 foot performance cruising cat will outperform many 45 foot accommodation cats.

The jpegs give an idea.

 

The following cat is a design by Vincent Lebailly Architecture Naval. Vincent has also designed cats like Adelaide 50 and Insula 52. The cat could be built by a home builder if you have the odd 10 years of spare time. The Zephyr 55 is 55 x 26.7 foot with a displacement of about 44,000 lbs. Sail area is unknown but the Adelaide 50 and Insula 52 have about 1300 square foot. Draft unknown. The hull length to beam is about 9 to 1.

The accommodation is large with 3 double berth cabins and 2 toilets/bathrooms per hull. 6 sleeping cabins in total and each cabin has generous space. The bridgedeck cabin has a very large galley/bar and several seating/tables to seat 12 people at a time. In the lower cockpit there is another external table that connects to the cabin via a large doorway. The flybridge over the lower cockpit is where all the sail controls and helming happens. This cat will probably require electric winches or several crew to cruise. The design has sensible access stairs to the flybridge which I hope will have strong hand rails.

Now we get to the interesting part. The Zephyr is a multichine plywood epoxy build which could be built by amateurs. The x ray shots show the 21 plywood and timber frames per hull and the 13 cross beam structures required to build this cat. The plywood and timber required to do the basic “frame” of this cat is substantial. The shell is about 9 mm or 12 mm plywood. All soaked in epoxy and covered externally in biaxial e-glass. We are talking several 220 litre drums of epoxy and several hundred sheets of high quality plywood. To join all these structures together will require hours of filleting and epoxy glass taping. This would be a 10 year project for a home builder. (PS A foam glass version of this cat would take a similar time but would likely have a greater resale value). Projects this big require determination or a lot of very good friends.

One person who was considering this cat changed his mind after he did some cost and time estimates. He started to build a 45 foot ply cat with 4 double berth cabins instead, he said it was going to built for 65% of the time and money. I hope he was right.

No performance figures but my rough calculator says about 200 mile a day averages with peaks near 20 knots.

The jpegs give the idea.

 

Long time listener, first time caller. Love the thread and the wealth of knowledge Oldmulti has presented here. I've been reading for months and really enjoying it. In the spirit of the thread I'd like to bring up a design feature I haven't seen mentioned (though I could have missed it) but I find very interesting: flexible mounting of a nacelle on a performance cruising catamaran, to enable a very light nacelle structure. This requires a bit of history to get to the main point.

This is a very specific feature of cruising "tube cats" (and tube-cat adjacent designs) which I've only seen on a few modern boats by Christophe Barreau. It may be applicable to more designs, and I think may be especially interesting to the home builder. Barreau is famous for designing some of the most popular Outremers, as well as the TS42 and TS5. These are all very performance oriented 'cruisers'. The designs that interest me specifically are the TS3, MG5, and H2 which we will get to at the end.

When I say "tube cat" I refer to catamarans where the main structure between the hulls is that of strong tubes. This is a very common structure on beach cats - but it can be scaled up to much larger designs. Sometimes, it's literally aluminum or carbon fiber cylindrical 'tubes' but similar structures can be made with box shaped beams, etc. This structure is differentiated from modern accommodation-cats where the entire hull/nacelle is one solid composite component.

A 'typical' tube cat doesn't have a nacelle, see the Kurt Huges 30 or almost any of the Grainger racing designs. These designs can be very light due to the lack of central structure, and are easier to build as there is less to build. The tubes are also very predictable in their performance compared to the curved shapes of a structural nacelle, theoretically lowering design time.

What I'd call a 'classic' version of an accommodation-focused tube cat is the first generation of 'Edel Cats' from the late 1980s early 1990s (also of note, the KD105 from Bernd Kohler). These cats have 3 'tubes' holding the hulls together, one at the aft, one at the bow, and one under the mast. They have a nacelle which spans from the central to aft tube, while leaving a gap between the nacelles and the hulls. This gap allows the whole structure to flex a bit without damaging the nacelle. The nacelle is not structural - it just houses some accommodation - so it can be quite light. An Edel 35 weighs only 7,000 lbs while a modern Aventura 34 weighs 9,900 lbs, and a Gemini 35 9,800 lbs. Of course, you won't get as much interior space in the Edel, but you save weight.

Edel reinvented themselves in the early 2000s, in a bid to get more interior volume while remaining light. The Edel 4xcat 33 was an interesting twist - it rotated the nacelle 90 degrees and replaced the central tube under the mast with the nacelle. It was still demountable - but offered much larger births while getting even lighter (around 5000 lbs from what I can see). There weren't many of these made, and I cannot find any information about the connections between the nacelle and the hull - it must have been quite intense to take the loads placed on the nacelle, and the nacelle itself would need to be well thought out as it is a structurally critical component. But the rotated nacelle is the interesting part - it stays within transportable dimensions while offering more internal space. The original Edel, and the KD105, put the external cockpit as part of the nacelle - limiting internal volume (due to max-width limits for fitting in a container). The 4Xcat used all the volume of the nacelle for internal space - the cockpit was just a separate deck component.

As we look forward again, we can hop to the Christophe Barreau designed TS3 - the TS3 is a smaller version of the TS42 and TS5 - at 36 feet long and 4,200 lbs but boasting two large double births, kitchen, chart table, and eating-table inside the nacelle. The style is similar to that of the 4xcat, but the hulls have very limited internal space (it seems just a head). It's rustic, the entire cockpit is a trampoline. The interesting part when looking at the TS3 vs the Edel 4xCat 33 is the notable addition of the tube in front of the nacelle, where the mast rests, and the large gap around the nacelle where it mates into the hulls. I again cannot find information on how this is attached, but we can look to other Christophe Barreau designs for a clue. There appears to have only been one TS3 made, and there aren't a lot of photos of it. My guess was the nacelle was connected via a flexible connection, but I couldn't be sure until I found the next design.

All the above catamarans have been discussed on previous pages, but the newer MG5, also by Chrisophe Barreau (and Neuman), doesn't seem to have been. It was recently reviewed in Multihulls Magazine #186 and you can watch the video on the cat here, which actually shows a great closeup of how the nacelle is mounted at 1:15s. The MG5 is basically a 51 foot 'tube cat'... although the 'tubes' are more like hollow square carbon fiber beams, the idea is very similar. The nacelle is specifically not a structural member, and is mounted with large rubber isolators - allowing the hulls to flex a bit without stressing the nacelle. The nacelle can be extremely light while all the forces of the rig are translated through the optimized cross beams. The nacelle can be removed if desired for racing. The interior of the nacelle is enormous, as one would expect on a 50 foot yacht - while maintaining a weight of 16,500 lbs for a 51 foot boat - a TS5 for reference is 24,250 lbs and is considered an extremely fast boat. These boats are both from the same designer, both on the cutting edge of construction, both very performance oriented cruisers with debatably comparable internal accommodations - but with a vast difference in weight. I attribute this at least partially to the construction - the beams can be easily optimized for strength, more easily than a complex nacelle structure, while the nacelle only needs to be strong enough to hold itself up and can remain extremely light. The downside is you cannot get direct access to the hulls from the nacelle, which limits the layout. But the weight benefits are potentially extreme - are nacelles overbuilt/sub-optimal shapes vs beams/tubes?

In the article in Multihulls Magazine, Christophe Barreau discusses working on a 'personal project' called the H2, a 28 foot demountable catamaran of similar design (no photos) using windsurfer mast feet as the mounts to isolate the nacelle from the hulls - apparently the nacelle is already made and weighs only 120 lbs! Very cool idea (I wonder if he'll sell plans...).

I started looking into this because I like the idea of building a 30-ish foot performance cruiser. The issue is there is no way I can build a boat anywhere near the water - it needs to be demountable and transportable for final assembly at the water. Tube cats are great, but lack much internal accommodation space. I stumbled upon the KD104, and then realized perhaps the TS3 arrangement could offer more space - but realized the nacelle would become a structural component and probably break if I just bolted it to the hulls. I was wondering how the TS3 did it, and I finally found the article/video in Multihulls world explaining how these nacelles were isolated from the hulls, and thought others may find it as interesting as I did. For what it's worth, I messaged Bernd Kohler about this new isolated-nacelle idea and he was less than enthused about it, haha.

I have a long way to go before I can seriously consider building anything, let alone trying to modify a design, but I found this rubber-isolator idea, particularly the windsurfer mast foot version, worthy of note. Hopefully others find this as interesting as I did, and I hope I didn't get any of my specifics incorrect. Thanks for such a great thread Oldmulti!

 

Thanks OldMulti. Cool to see a very similar folding concept built to scale and working in the wild. If I ever get my hands on a pair of Prindle 19 or Hobie 20 hulls I may have a go at the swinging concept. My telescoping design for the Viva hulls is less complicated and better suited for the hulls, and I like that the system is self-contained with all moving parts protected inside the beam housings.

SYZYGY looks like a great boat/design. The big open cockpit reminds me of the Farrier Tramp, perfect for day sailing. And the execution of the folding system is impressive.

 

Spearmintier. Keep writing stuff of this quality and you may become a co writer of this thread. Well done. A few initial thoughts from me.

I understand what you are asking but my answer comes from a different direction. All multihulls flex to some degree, full bridgedeck cats flex less than tube cats which flex less than Wharram cats. There are 2 differing approaches. Create a very stiff central cabin then attach cross beams and hulls EG Richard Woods Sango and Wizard. Create a central pod as an integrated part of the structure as in Woods Gypsy, Hughes 38 and 45 pod cats, Crowther 32 and 56 foot racing cats or as you have seen in some designs put a "pod" on a tube beam cat.

The difference is how much "flexibility" there is in the cat and cross beams and the central pod. Wharram cats are flexible and have pods that are fixed to crossbeams that move out of alignment. The pods are built to withstand some flexing. In the Wizard, Sango and Crowther pod racing cats the central pod is a stiff build as it is an integral part of the structure.

The cats you are talking about appear to have a relatively stiff pod attached to a flexible cat which requires a joining interface. Not hard to design or implement. Boat engine mounts are all about absorbing movement whilst keeping the engine in position, maybe a reasonable starting point.

But also look at Richard Woods 22 to 27 foot trailable tube cats that can have a "pod cabin" added or taken off for racing. The pod cabin and cockpit basically attaches to the mid beam and rear beam. The pods flexibility around the cockpit area takes care of any beam alignment issues.

 

The Squalt CK 72 is designed and built by Squalt Marine International. It is 72.8 x 33.6 foot with a weight of 84,000 lbs. The mast is 85 foot high and carries a sloop rig. The length to beam on the hulls is about 9.5 to 1. The draft is 4.9 foot over the low aspect ratio keels. The engines are 2 x 150 HP VOLVO.

There are 6 of these boats built to do charter work and under the Squalt brand a CK 70 model of very similar dimensions has been sold to private clients. The accommodation is very large with either 4 or 6 double cabins in the hulls along with 4 toilet/bathrooms. The main saloon has a large U shaped galley and many seats with a large table. The saloon is connected through a large door to a lower cockpit that has many seats again. The helming and sail control are on an upstairs flybridge. Two comfortable crew cabins in the forward peaks have independent access. The cat has massive deck space and lots of room for toys.

These cats are promoted as go anywhere global cruisers, a claim I don’t doubt as the cat is robust and with aluminium construction is suitable for cold water cruising if required. The construction jpegs give an idea of the chine hull shape and internal room. Being designed for charter work with big engines, the most refinement round bilge hull shape was not required. Cost effective, fast building was. Aluminium is very good as a fast build material with simple shapes. In a cat this big it will still sail reasonably fast anyway and in light airs I am sure the engines will be running.

The only major downside to aluminium is corrosion control. Get that right and your boat will be around for years. The secondary issues are insulation and noise mitigation. Both are easy to control but still require sensible work done at the build stage. The great joy of aluminium is its ease of build of ancillary items like masts, fore beams, chainplates, stanchions etc and modifications or repairs. These are just an extension of the build process not an entirely separate sub contracted items.

The jpegs give the idea of a floating home for a few million dollars.

 

Squalt CK 72 cruising catamaran interior jpegs.

 

This is an update on the Outcut 29.5 catamaran that appeared on page 110 on this thread. The Outcut 29.5 is a folding and transportable motor sailing catamaran. The Outcut is 29.5 x 11.5 foot and can compress to 8.2 foot in 60 seconds by the press of a button. The weight is 3,135 lbs. The approximately 37 foot mast carries a headsail only rig with a jib and gennaker. The rig can increase the cats speed by about 30% under good conditions. The hulls length to beam ratio is 18 to 1. The cat draws 1 foot without its rudders. With two 20 HP outboard engines, it has a maximum speed of 15 knots and a cruising speed of 13 knots. There are two 70 litre fuel tanks.

The Outcut 29.5 is from the Italian shipyard Outcut. After four years of research, the DHR (Dynamic Hull Range) folding system allows variable width beam for easy transport. The folding system has electronic and hydraulic components. When the floats are folded, the living space does not change, maintaining the same interior layout.

The simple and uncluttered layout has 4 berths. A cabin at the front with a large double bed (5 x 7 foot) and a saloon with table for six guests which converts into a double bed (4.5 x 6 foot). A bathroom with shower completes the set and the saloon can also be fitted with a fitted kitchen with sink and two-burner stove. The headroom is 5.7 foot. The hulls house the tanks for fresh water, fuel, batteries and two large storage areas.

The hulls are entirely made in vacuum carbon and epoxy resin composite with a 15 mm foam core to maximize the weight/performance ratio and are equipped with water-tight compartments and a bow crash box that make them unsinkable. The cabin construction and cockpit are in carbon and epoxy resin composite with15 mm and 25 mm foam cores. Lateral windows are 8 mm anti-UV lexan. Access to deck through two 40×40 cm hatches. Two internal 20 cm portholes for air circulation. The cross beams are carbon fibre boxes that slide within each other for compression of the hull structure underneath the edge of the main cabin pod.

The jpegs give further detail. An expensive, but very innovate design that is really trailable (about the same as a F 31) and will expand and contract on the water.

 

Folks I have to update the boat Index again as I am unsure if I have done this one, either way treat it as an update. The Excess is a brand that is progressively taking over from the Lagoon brand. The Excess 11 and 15 were based on the Lagoon 380 and Lagoon 50 hull moulds with differing shapes above the waterline. The Excess 14 is a completely new build and aims to be a sportier cruising catamaran than the Lagoons but without the expense of the really high performance cruising cats.

The Excess 14 is 43.8 x 25.8 foot but depending on options (prodders etc) can be up to 52 foot long. The weight starts at 25,700 lbs and the maximum displacement is 40,400 lbs. There are 2 rigs. Standard has an 893 square foot mainsail, a 320 square foot genoa and a 775 square foot Code 0. The Pulse rig has a 6 foot higher mast and upwind sail area of 1435 square foot with a 926 square foot Code 0. The draft is 4.9 foot over modified low aspect ratio keels. When VPLP did the design of the Excess 14 they consulted owners of production cruising catamarans and found the owners preferred fixed keels and were willing to have greater draft. Result, the fixed keels became deeper, shorter in length and more aerofoil in shape improving the upwind performance of the cat. VPLP found the increase in draught would give the keels 15% better efficiency. This also allowed deeper rudders for better steering. The engines are 2 x 45 HP or 2 x 57 HP (optional).

The accommodation is either 3 or 4 double berth cabins in the hulls with 3 or 4 bathroom/toilets. The bridgedeck contains the galley, seating, navigation and connects to the large cockpit with additional seating. The helming is done on the aft quarters of the cockpit with the helmsman having an excellent view of the rig but has to look through the main cabin windows to look forward for 40% of the horizon. Luck the main cabin windows are vertical to minimise heat gain, no closed curtains allowed.

The main structure of this cat is the reason this thread is getting harder to generate. VPLP’s design achieved a few things. The lines of the Excess 14 benefited from VPLP racing experience allowing a forward-set rig, a square-top mainsail, large overlapping genoa and an optimize the sail area to displacement ratio. Also, an increased bridge deck clearance, asymmetrically designed hulls to reduce interference drag, new longitudinal volume distribution and a low centre of gravity.

But the real gain was the use of cutting-edge FEA software by VPLP design to modify the structure to reduce weight by about 4500 lbs. The optimized structure (foam sandwich, carbon reinforcements, etc.), was specifically designed in each area for the optimum layup and fibre direction to take the loads required. Excess did not want to go to a full carbon fibre build to reduce weight due to its expense. VPLP found that by using e-glass, varying layers of stitched fabrics, unidirectionals and varying densities of foam and balsa cores they could lighten the structure considerably. The weight of furniture also came under scrutiny EG the galley is 25% lighter without resorting to expensive foam cores. Also things like EG Dyeema ropes are used in the steering system to help save weight. Carbon reinforcements are used in EG cross beams or some rigging components as required. Result of all this design work is a lighter, more cost effective build. The structures are mainly done in vinylester resin infusion.

So what is the end result? The price is OK and the performance is according to tests “We’re sailing upwind in 12-14 knots of true wind, with boat speed hovering between 7.4 and 8.0 knots. The helm feels positive and responsive, the boat tacks easily and responds readily to accurate sail trim.” With the larger rig “The boat performed well on my first sail in 8-12 knots of breeze, reaching at speeds of up to 7.3 knots under Code 0, and maintaining six knots with a true wind angle of 58 degrees. However, it falls off quickly if you try to point too high in appreciably less than 10 knots true wind. Turning downwind and setting an asymmetric spinnaker we maintained 7-7.5 knots at a true wind angle of 145 degrees, increasing to 8.5 knots after heading up to 110 degrees.” In true winds of 17-18 knots with choppy waves led to some wave tops gently slapping underneath the bridgedeck. This short, steep sea meant speed was quickly lost if you pointed too high when sailing close hauled. Bearing off to a true wind angle just over 50° (around 33-34° apparent) saw speeds occasionally topping 8.5 knots. Bearing away with the Code 0 saw boat speed climb up to a maximum 10.3 knots. A delivery crew reported a top speed of 16.5 knots.

This means this is a cruising cat capable of about 60 to 80% of wind speed, better than many production cats 50 to 70% of wind speed. The reduced weight, better hull shape and improved rig help here whilst the Excess 14 maintains the large internal accommodation for its length.

The jpegs give the idea of a good design.

 

Hi Spearmintier. I have the same problem, trying to find a design that coud be build up to finished components in one location and after short transport, assembled in another.
In my case it does not have to be demounted again, and could even be longer up to 40+ feet.
Any sugestion that could help me?

Great post and i can see you did your research. That`s why i am asking.

BIGUP !! to Oldmulti for this thread. I just started reading, but there is a wealth of information to find. Love it, keep up the good work please !

Thank you Spearminter.

 

Voodoo Child. A few questions to help people. Do you want a cruiser, a cruiser racer or a racer. Several designers can provide a design that can be built in component parts then joined together next to the sea. What would be your preferred material? There are some kit boats that can be delivered to a sea side location and you can hire a team to put it together in a month then fit it out on the water (EG Fusion 40 foot cruising catamaran). There are occasionally near finished cats that are being sold etc. A bit more detail may help people give some good advice.

 

Great thread , long time reader but I have never posted. Due to my very poor funds,I am interested more in low cost - small multis. I don't know how I came across this video , that is a confirmation you don't need mega $$ or huge sizes to go places. Unfortunately the guy speaks german and french in his videos, and he doesn't really go into too much detail about boat structure or at least its size, I am guessing around 6m main hull . I really like the fact that being strip planked, it has almost no internal framing that steals precious space. Anybody got more info on this boat?