Car Toppable Trimaran Pocket Cruiser

Dear Readers

This is the beginning of a idea for a car toppable trimaran. It probably goes without saying, but that this is a design meant for protected waters. I envision using it either on inland lakes, or in protected bays. I have not finished balancing the boat, so the rudder and dagger board are not yet in the design. The main hull and the ammas will be made with tortured plywood sheathed in glass.

The thing that is unique about this boat is the option of using it as a high performance day sailor or a pocket crusier. The boat will have two sets of trampolines. One set will have sleeping nacelles embedded in them. If I plan on spending the night on some pristine alpine lake in the Adirondacks, I can use the trampolines with the sleeping nacelles. If I plan on tooling around Sodus Bay or visiting the bluffs, I can use the normal trampolines.

The three hulls and two akas and mast can be disassembled and car topped, since the length of the trimaran is 18 feet. She displaces 900 lbs, but will certainly weigh far less. No component will weigh more than a canoe or extend too far past the front or back of an SUV to be legally cartopped with a flag hanging of the bow and stern .

I would need two cars or to make two trips to bring the sleeping nacelles along. Of course the boat sleeps two, so that would be convenient. The nacelles hinge open and contain a foam mattress and bedding. A built in cooler in the main hull, along with a camp stove, a privacy screen and a portable head (read bucket with waste bag) complete the requirements for a weekend of cruising.

I would love to hear any suggestions or ideas to improve the design.

Thank you very much in advance for any comments.

David

 

Neat-O!

Have you considered making these soft and using fiberglass tent poles for support? They would setup like an expedition tent, no extra car needed.

 

That is a great idea. I love boat and tent setup.

 

Have you considered a catamaran ?

Years ago I had a caper cat. A family sailed one from Brisbane to cape york, about 1000 miles. They slept ashore but it's both easy and comfortable to pitch an off the shelf tent on the trampoline. Very soft to sleep on. The caper cat had huge lockers in the hulls, one insulated to use as an ice box. They made a few 18' boats but they are rare. There is a book about the trip written by the son.

Anyway it would be easy enough to design a boat like that and demount it to cartop. You can also carry one of those camping shower enclosures and pitch it on the bow net for a private bathroom.

Usually the trouble with camping on trimaran side nets is the floats sag more than the main hull so your bed ends up on a slant.

Either way good luck.

 

Thank you so very much for the introduction to a unique and interesting boat I have never heard of or seen before. I am sure that your little caper cat must have served you well.

A thousand mile journey in a 12 foot boat is quite an accomplishment. The family you referenced must have been quite the adventurers.

It is hard to say the caper cat is a pretty boat. It does look like it is probably a great boat to camp on though.


It has tremendous volume and storage for its diminutive size, which is an unmistakeable advantage. It is also super compact which is also a great advantage.

Personally, I was hoping for something that was a bit sportier, even if it does take a bit more work to assemble and transport.

I just started doing expansions for the tortured ply on my trimaran. I am going to build a scale model first to see how the hulls form when pushed through the deck mold. Tortured ply always has at least a few surprises as the three dimensional shape pops into being. I hope to be posting pictures of the model hulls soon.

Thank you again for the reference to a great boat.

 

I wasn't suggesting you copy the caper cat slavishly.

If you built a cat, say 20' long in TP and built some lockers into the hulls, rig a tent on the soft bridgedeck and made it easily demountable you could make it pretty, fast, light, cartoppable. The big advantage is a horizontal deck to sleep on. You could accommodate boards, fast hulls, big rig.

The capercat was never designed to be the fastest. It was conservateivly rigged and intended for learners, families, fishermen campers. There was an optional outboard bracket. The 18 was a BIG boat and it could probably carry and sleep 4 adults. With faster hulls, boards, modern rig a 20' cat can be fast and offer the accomodations you desire.

Either way I hope you enjoy building and sailing your boat.

 

I use to trailer a Hobie 18 up and down the East coast for years while my wife worked as a traveling nurse. It was a great boat and two couples could easily sleep aboard, although our camping happened on the beach. A very accommodating boat, especially with the wing seats. With those, you could add another two people to sleeping accommodations.

 

Dear Guzzis,

I didn't think you were. As soon as I read your post, I looked the boat up, because your post was really inspiring. The idea of a 1000 mile journey in a 12 foot open boat is truly awesome. Thank you very much for commenting.

 

Hi David
I like your project.
I own a 16ft car toppable trimaran. It weighs around 100kg fully rigged, empty. Main hull perhaps 35kg. I'd be cautious about the car topping; I used to carry it on a swb transit, and it was a great deal of struggle and fiddle to load and unload, and affected the driving even of a relatively large vehicle. I bought a christmas tree style canoe trailer, and built a gear box in the bottom storey, and found this much easier. If you are able to use and store a trailer, I would consider it. Generally too, I'm cautious about the sleeping on board a small boat; if I possibly can, I will beach the boat (the lightweight is important in being able to pull it up a beach easily) and camp ashore. Camping at anchor in a small boat, I find, is uncomfortable and restrictive, and anxiety over the anchor dragging is also an issue. Having voiced those caveats, you are absolutely talking my sort of boat. I use a jetboil style stove in a large cup holder. I'm considering a build of a Harryproa E25 or similar, but probably in ply, with a bucket toilet in the lee hull, and a hiking bench on the windward hull that can be used as a bunk. Pram hood over the hiking bench and ww hull for accommodation, and a small hood over the lee bucket toilet for privacy. My tri does'nt have trampolines - its pretty conservative, but they should form a comfortable bed with a simple tent.

 

Dear Tiny,
I understand your concerns about draggin' anchors, but the places I am going to be camping are so sheltered, I actually probably don't even need to anchor. They are mountain lakes in the Adirondacks. The Lakes can be windy in center, but there are tons of sheltered inlets where there is scarcely a ripple, and simply tying off to an overhanging tree is more than enough to keep safe. I have spent more than a few nights asleep in a canoe, a mosquito net draped over the gunwales (100% need a mosquito net), surrounded by trees a few feet from shore. Even if I broke loose, there is little danger. The nice thing about boating there, is the fact that you can blast for miles at speed, in a rough windy lake and then be in a silent cove just by dropping sail and paddling around a corner. Unless you have boated there, it is hard to believe how much the water can change on the same lake.

There is little better than sleeping under the stars as the loons laugh into a mountain night. You had might as well be a hundred miles from the nearest motor. You have to get moving before the black flies swarm in the morning though. Those little black flies are a plague. A biblical plague. You think it is fog, but no, it is little black flies. Little black blood sucking flies. The welts they leave behind aren't little though. Chiggers and black flies. Two things I never want to be bit by again. Netting doesn't keep them out.

The main reason I am trying to stay away from a trailer is the primitive nature of the roads. If I can get away with car topping it would simplify things. In many places it is barely possible to turn a vehicle around much less get a trailer jockied around. If I can't get away with cartopping, then perhaps I will need to build a trailer as well. I was hoping to car top the boat in, take it off and get it launched, then turn the car around so I can pull out after boating for a weekend.

 

Okay, so I tried to make the model of my first amma today. The process is simple. Cut out two sides and make sure they are identical to each other. Glue the bottom of the two sides together with a fillet. Pull the bow together and glue. Force the whole thing through a form shaped like the deck. Glue the deck on. Instant amma.

I had Delft Ship run expansions on the tortured ply design for the ammas. Then I exported the expansions to illustrator and cleaned them up. I cut the expansions out of card stock. I glued the two halves of the hull together along the bottom, then I glued the bow together. As a result the model forms a shape that looks a little like a banana. At this point I looked at the hull and wondered to myself how this would look like the graceful amma I had drawn. Then I cut out the deck expansion and glued the card stock around the deck cutout to several more peices of card stock. Then I cut the shape of the deck out the additional piece of cardstock to produce the mold through which the ama needed to be forced. If things went to plan the shape of the hull would magically appear when I pushed the hull through the form. As expected it did not work, but it was close. My first model has a shape very similar to my drawings but there was not enough material in the forward sections, when the area between the bow and the midesction tried to spring into shape, a hollow appeared where the two sides joined. The Joint along the bottom also failed at several points. In the model, I just used elmers glue which wasn't strong enough. On a full scale version I would use an epoxy fillet with fiberglass tape. I redrew the expansions in illustrator and added a bit more material to the joint where the hollow was. In order to make the joint in the model stronger I am adding a peice of cardstock shaped to help the joint hold together. I then made the amma a little taller to help distribute the stress.

In addition, I have to add a curve from front to back to the form in order to mach the reverse sheer of the amma. Once I get a new amma built, using the new expansions, I hope to provide a photographic explanation of the process.

 

Sounds typical. Can you get cheap ply in the thickness you intend to use ? Make full size "models" and you will get a good idea of what's working and what isn't.

 

I have built a 16' rowing/sailing trimaran and I can tell you from my experience that you have to consider weight: you will always end up with more weight than you expected. From your initial drawing it seems your vaka hull is too thin; it would ok for a solo racer, but for camp cruising for 2 people you will add up kg like there's no tomorrow. If I were to build another hull I would certainly make it wider, specially near the bow (my boat was initially built as a stabilized paddle machine, so floats and mast are all up front, leaving the aft part free for a double paddle).

 

Funny you should ask that. I went to my local marina to price some 3mm ply and found out, that since covid hit, wood prices have tripled. I was a bit in shock. The fellow I talked to suggested not doing any marine projects this year because material costs are through the roof. I still intend to finish the model stage, and continue posting. I may push ahaed despite the costs.

 

You could build your model out of non-marine exterior grade luan. I'll bet Covid has improved the business of home improvement companies. All those people working at home with extra time to work on that DIY project. Prices will still be up, because covid is a good excuse to rationalize higher prices, but not like the specialty wood supplies.