Multihull Structure Thoughts

Russell, trimaran float ?

Oh, I thought this boat might interest you.
The Wavelength 780 Trimaran – Breaking New Ground with Plywood Construction | Small Trimarans http://smalltrimarans.com/blog/the-wavelength-780-trimaran-breaking-new-ground-with-plywood-construction/

 

I am the current owner of Crazy Train. The boat hulls were built by Greg Martell back in 2006 and the rest of the boat was assembled by Auckland sailmaker Tony Harold in consultation with John Tetzlaff and others. The boat was originally known as FusionX and has had several successful Coastal Classic campaigns. I purchased the boat in May 2020 and it had not been actively raced in a while, although it came with a very nice set of sails that were all built by Tony Harold. So far, I have only replaced the overlapping Genoa. We did the Coastal Classic in 2020 and were the second smallest boat to finish the race in only 27.5 hours. I believe Tony had a very good result back in 2007, but I am struggling to find the results. In better winds, we have definitely achieved oat least 23 kts gps speed and I’m told the boat has hit a few knots faster under a professional skipper that used to sail it.

I’ve attached a better photo of the interior - let me know if you are interested in any other details. The hulls themselves are actually 10m in length and the rudders and cassettes add about .4m beyond that. The boat is about 6.1m at it’s widest point and the mast is 15m. Tim Clissold will appreciate the metric, but it’s a few feet bigger in every dimension than the description above.

 

Crazytrain you are very welcome. Thankyou for your correction on the dimensions of Crazytrain rig and beam. I was guessing at the weight do you have any idea? One further question, many on the thread interest is the boats structure, has there been any issues with the cats hull structure beyond normal maintenance? When a cat can approach 25 knots, I am sure it is a lot of fun.

Russell. In a book “Sailing Boats” authored by Uffa Fox in 1959, on Page 43 is a design called Pegasus. Pegasus is a powerful and fast two person racing and cruising dinghy designed by Uffa Fox in 1957/8. It was notable for being a boat capable of being built at home using marine ply but still with an efficient and aesthetically pleasing round bilged hull form. The boat has a narrow bow entry and a planning hull. Stability is achieved with a trapeze allowing this relatively narrow boat by modern standards to carry a large sail plan. Approximately 250 Pegasus's were constructed. Pegasus kits were built by the Bell Woodworking Kit Sets whose boss was Dusty Pollock. Dusty Pollock talked Uffa into designing a compound plywood dingy that could be built by a home builder in half the time of a chine dingy. It took about 5 builds to full develop the approach and a special plywood made to the BSS 1088 specifications introduced in 1957. Pegasus used only 4 sheets of plywood to build the hull which had 4 external "mould frames then the plywood sheets were forced into shape and additional joining strips were added. The resulting round bilge shape had many compound curves like tortured plywood cats.
Pegasus Index Frameset http://www.cvrda.org/pegasus/index.htm

 

Yes, trimaran floats. The main hull will be strip Cedar underbody and flat panel ply above. Still working on the design, but I'll post it here soon. It's kind of an old guy's cruising boat, but will be lightly built. We don't really have natural harbors and a slip is out of my income bracket, so I have to be able to set the boat up (unfold and rig up) easily and quickly.

Thanks for the interior shot Crazytrain. I'll see if I can contact Greg Martell.

 

Rafael and Heidi Francke names may be known as the creators of the Cat2Fold catamaran, a trailable 36 catamaran that folded and unfolded on water. The cat had limited commercial success so they choose to develop another trailable multihull. This time it was a proa that fitted US trailing standards in some areas. The pacific proa “Hocu Pocus” was developed and is 39.5 x 22 foot which “disassembles” to 8.5 foot for trailing. The weight of the proa is 3000 lbs without cruising gear on board. The initial rig is a small schooner rig with free standing carbon fibre masts and self tacking booms. The sails can be reefed by rotating around the mast. The float is 24 foot long. The lee pod is an inflatable tube to help prevent capsize if caught aback. The proa takes about 90 minutes to get from the trailer to the water.

The proa has limited but effective accommodation for 4 people with berths, small galley, toilet and some seating. The central cockpit effectively has all controls leading to it to allow tacking, raising and lowering of rudder/boards and changing of steering controls. The small size tempory rig is very easy to handle. The proa can be sailed without rudder steering by adjusting the centre of effort on the rigs and varying the board depths. Yes its easier to use the rudders but its nice to have backups.

The prototype is wood and fiberglass construction with aluminium cross beams. The initial performance video’s in light winds show Hocus Pocus can sail very well in light airs and appears to be easily controllable. There are no performance claims or heavy air videos to my knowledge.

Sorry about the limited jpegs. The youtube video is at:

 

Oldmulti
Is this proa maybe the up-cycling of Macgregor 36 hulls cut and joined with bow mods from Rafaels Cat2fold2 in attached video?

 

redreuben
FYIW Kurt Hughes has female mould from ply as you mention with good results from what I've seen.

 

Cool!I wasn’t aware of this boat.

Been a fan of the final version, especially the continuous hinged deck that folds up and over the hulls when collapsed, then drops into place when expanded. I may end up doing something similar on my current build.

Thanks for posting.

 

Summer sailing season preparations have begun on my Skip Johnson designed Seawing trimaran. The first order of business was testing a few hull assembly assist designs I had worked on during the winter. As Oldmulti had mentioned in his feature post about this Trimaran, the outer hulls are a bit of a handful for two people to remove, walk out, and lift to slide up and over the curved beam arm ends. To make matters worse, I launch into a river with an up-paved field for prep, so no rolling hoists, etc..

I had come up with a variety of ideas on how to make the process easier with an ultimate goal of eventually being able to assemble and disassemble single hand since I’m coming from a folding boat.

The first step was to find out what worked best for two, and in the end that was simply having a place to rest the hull on its side just outside of the beam arm ends off the ground about waist high to allow for a break prior to rotating the hull vertical and as close to alignment as possible, then lifting it up the last few inches and hooking it over and onto the ends and installing the outer bolts.

As you can see, I accomplished this by mounting two cross supports (galvanized sign posts) to the main trailer supports to act as a backbone, then used a few pairs of roller brackets and pivot bolts to support additional 10’ square tube posts that angle out and up to meet the beam ends, leaving it all completely adjustable in angle and length for trial assembly. There are also a pair of adjustable RV jacks for additional support.

With the geometry of the hanging brackets being longer in drop inside and shorter on the outside, the long support tubes are able to pivot from a flat (perp to trailer) position up to angled either by lifting/jacking their outer ends, or using a bottle jack at the inner end attached to the upper pivot point of the brackets, and this is how I hope to eventually accomplish my goal of making it a single hand process.

Anyway, I thought I would share this as assembling seems to be one of the last/least things designers spend time thinking about (unless you are Ian Farrier), and I’ve looked at a lot of demountable multihull designs over the years and spoken to many owners, and assembly/disassembly was always one of their biggest gripes, even though some had elaborate ways of dealing with the process.

 

That's a really good-looking trimaran!

 

Thanks Russell!

You can say it was love at first “site”.

We met online of course.

On Craigslist of all places

But seriously, I know you have a eye for designing and building and can truly appreciate what Skip created.

I feel lucky and honored to be able to share his design with others, and am really looking forward to introducing her to our Hawaiian waters this Summer.

 

SolGato. Can I just confirm something. You own this great Skip Johnson 24 foot tri and you have just purchased a Viva 27 catamaran? You are going to have serious fun but how are you going to decide which one to sail on a day. Oh, I wish I had your problem. Good work.

 

Yes, you are quite correct Oldmulti and that’s a very good question!

The answer is easy though, I will sail the Seawing because the Viva hulls will be used to build a scaled up version of my Solar Electric Catamaran.

As you’ve mentioned in past posts, more than a few older larger trailerable catamarans have been converted to powered cruisers, and the Viva is one of those.

Many years ago Mike from MultiMarine converted this particular example (formerly Tyger Tyger as seen in my earlier Viva post) by increasing its water line length to 30’ by adding transom scoops and reverse bow extensions.

In its final configuration, the boat was fixed to a 10’ overall beam width and ran twin Tohatsu 20HP motors with a custom built cabin.

It was named Momentum and was said to be highly fuel efficient.

I spent the last year trying to acquire the hulls because they are perfect for my application being efficient, lightweight, tall and trailerable, with a good amount of volume in the stern where other popular designs (Stiletto, Conser, MacGreggor, etc..) tend to be lacking which causes the sterns to drag once you add weight.

Here are a few photos including the way it was last configured as a functioning power cat. The beam was wider when these photos were taken, later narrowed and fixed to max towing width as Mike got tired of assembling it at the ramp.

I basically purchased just the hulls and shortened beams on trailer.

 

Old multi, I just watched this (long) video about a single-handed voyage to Hawaii on a 25 foot trimaran.


The boat looks very interesting and seems to date from the 1980s, but there doesn't seem to be too many details on the own-design. Googling, it appears that the boat is for sale now in Hawaii 1981 Trimaran Custom 25 Trimaran for sale - YachtWorld https://www.yachtworld.com/yacht/1981-trimaran-custom-25-7200074/

Some things I noted from the video: interior space is very limited even for one person when loaded up for a journey of that length. A problem with the backstay led to most of the voyage being done with only the headsail and occasionally the outboard. The leakiness of the companionway and fore hatch let lots of water in during storm conditions.

I'm not sure what else there is to say, but I'd be curious on your thoughts about such an apparently seaworthy own-design tri from 40-plus years ago.

-Neil

(Thanks, I love this thread so much, your generosity sharing this information here is a tremendous gift to the world.)

 

Looks like a Crowther Bucaneer !