[Boards: 3 / a / aco / adv / an / asp / b / biz / c / cgl / ck / cm / co / d / diy / e / fa / fit / g / gd / gif / h / hc / his / hm / hr / i / ic / int / jp / k / lgbt / lit / m / mlp / mu / n / news / o / out / p / po / pol / qa / qst / r / r9k / s / s4s / sci / soc / sp / t / tg / toy / trash / trv / tv / u / v / vg / vp / vr / w / wg / wsg / wsr / x / y ] [Search | Home]
4Archive logo
Images are sometimes not shown due to bandwidth/network limitations. Refreshing the page usually helps.

You are currently reading a thread in /diy/ - Do It yourself

Thread replies: 75
Thread images: 37
ITT- the ultimate trailerable catamaran!

Please help me with suggestions, drawings, etc.

I live in a landlocked state, but the sea calls to me. So I figured I'd try to design a catamaran.

I'd like help, pls!

My biggest question right now, is can it be a flat bottom? All the designs for trailerable catamarans I've seen have rounded, contoured bottoms.

I've got plenty questions, I'll get into those later.
Here are towing regulations in all 50 states.

You'll notice in my OP picture, the rectangle at the bottom is 40 squares long and 13 squares high. That represents the maximum side profile I have to work with. The square at the top left is the maximum frontal profile. Each square is one foot.

At the bottom left is a line 13 high beside an L shaped line that's 7 high and 3 across the bottom. That's how big my doors are to the backyard and I put those there for scale.
File: cf2catinterior (1).gif (196 KB, 3995x3012) Image search: [iqdb] [SauceNao] [Google]
cf2catinterior (1).gif
196 KB, 3995x3012
Here's one of the better trailerable catamaran layouts I've seen. I've got a couple I use for inspiration.

The main problems to me are the hulls are too short. I'd want standing headroom for almost the entire length of the hulls.
File: m17show.jpg (100 KB, 804x538) Image search: [iqdb] [SauceNao] [Google]
100 KB, 804x538
I believe this is a picture of the catamaran from here >>924985
Why the hell do you want a catamaran and why not start with lakes and rivers first before deciding to kill yourself?

How hard can it be, calculate the displacement via some modeling software and figure out how much draft you have to play with.
Uhh what? That cat is about the size of a small house, how are you going to put that on a trailer?
Here's a video of a folding trailerable catamaran. I want contributors to see.


I would like a lot of help here, I can't understand how the folding crossbeams would provide enough strength for full sailing in open ocean.

I'd like to design this with a full central mast. If materials allow, a telescopic mast or two piece mast would be nice.

I'd like to have a small "crows nest" around 3/4ths the way up, like pic related. Nothing much more than a single seat deer stand.

I like this design a lot BTW, but no way can I, or the average catamaran builder, turn THAT into something trailerable.
File: trailable4-big.jpg (124 KB, 765x510) Image search: [iqdb] [SauceNao] [Google]
124 KB, 765x510

Catamarans are a very stable design. The only way you're going to capsize a cruising cat is gross negligence or deliberately doing it. Racing cats have a HUGE amount of sail up for their size and weight, which is why they capsize easily. However, they are incredibly easy to right. You can go on youtube and see people capsizing their catamarans, then righting them to demonstrate how for newer sailors.

If I'm ever going to take up sailing, a cat is by far the safest and most stable platform.


Like THIS! Pic related. I like this design because of the removable central cubby. I'd like to incorporate something like it into what I'm designing.

There are 30 foot trailerable catamarans that cars can carry, no truck necessary.
File: wizardlaunch2.jpg (13 KB, 450x299) Image search: [iqdb] [SauceNao] [Google]
13 KB, 450x299
Here is a site with plans and photos I'm getting some inspiration from. The hulls aren't nearly as high as I'd want, and I'd like the central cubby to be higher off the water, but it's just inspiration.


They don't have plans for a trailerable cat over 30 feet, though. The one I'd like to design would be closer to 40, and probably require a truck to tow. Weight should be no more than 3000 pounds, ideally.
File: Gypsygaea1[1].jpg (9 KB, 287x400) Image search: [iqdb] [SauceNao] [Google]
9 KB, 287x400
I see you are going the HARD and HUGE way. There is no money saving in building a boat over buying one, and there's thousands (literally) of hours of work for a project that size.

In any case, i think you might want to start a few steps further back:
Why a catamaran? Why that size? Why trailereable?

It doesn't really makes much sense to have a huge boat, with living space, and trailer it around.
I know you might not want to move to the coast or live in the boat for now, but there are moors, and that might be more convenient than trailering such a big boat (im insisting on the word big, because it is, you are having a whole damn house in there, plus it needs to be seaworthy, so think how much cost to maintain a house with the same commodities and multiply by 5)

In this kind of situation it's a VERY good advice to start small, and second hand. By no means stop dreaming, but if you start walking towards the dream you'll learn SO much on the way, and will already start enjoying and living a bit on the dream.

Im a civil constructor, and studying naval engineering (im just two years away from my degree!) I also love to sail and am looking to buy my first ship.
So i'd gladly answer any more questions on the topic.

If you insist on the catamaran designing and building topic, i fucking love Richard wood's desings, he's got some trailerable things


And come back to discuss more!

PD: the two pics you posted dont look like the same cat.
File: wizardlaunch6.jpg (14 KB, 450x255) Image search: [iqdb] [SauceNao] [Google]
14 KB, 450x255
Here it is on the water.

And here's a video of that model :) it's about 10-16 feet shorter than I want to design, though.


Again, I don't want to incorporate the method they use to fold hulls, rather more like the picture in >>925000 to allow for higher headroom.
I was thinking smaller than you, 40ft and trailereable? and oceanworthy? if you manage to get all those things on the same design, and make it work, you would be a genious. It can still be done, but again, i dont see the point on trailering a house wich can already sail around, give up and live on the fucking thing!.

I still recommend checking wood's designs, he's got some 40+ft

Actually, you've got no idea the shit I'm thinking about doing to that boat. I want the planking below the waterline to be lignum vitae that's been vacuum impregnated with resin, so the wood will be rotproof and waterproof for thousands of years, and if I hit rocks it'll have a better chance of survival. Lignum Vitae is supposed to be the strongest wood that's frequently traded, stronger than the planks on old ironsides hull.

I've actually put some thought in this. I'd have to build a vacuum chamber that's like 6 feet long and 2 feet tall or something. I'd need help with that part definitely.

I've already mentioned why I want a catamaran. Even if it capsizes, which is difficult, it'll still be nigh impossible to actually sink. I want the size because I want it to have some room. Plenty of storage space. A trailerable cat you could actually live on.

And, no, I've researched enough to see boats being sold for $80,000 that cost $10,000 to build.

No fucking way am I ever going to have enough cash to buy one. And if I did, NO FUCKING WAY I'd be able to sell it for anything close to what I got it for.

Yea the pictures I'm posting aren't always in order. Sorry.

I'm not sure I actually want a 40 footer... max legal length of the towing vehicle and it's trailer is 60 feet I think. If I'm using a 40 foot boat, I'd be scared of jack knifing.

Maybe 38 feet, 37, 36?

I've checked and I don't see any designs for a trailerable cat longer than around 26 feet.

And no, I wouldn't live in it if it's out of the water.

I'm thinking of incorporating ideas from pop up campers to certain areas BTW. That's a little much, I know, but I'm not building a boat anytime soon.

I just want to see what it would look like on paper.

Here's a pic of a cat I love. I really want to find a way to attach the hulls to the center cubbys.... it would all have to be detachable, though.


Oh, about what you said...

Yes. I want to draw a plan for the ultimate seaworthy trailerable catamaran.

Nobody else has done this yet!!

Look my picture in the OP. That is a lot of space and most plans for trailer cats are 1/2 to 2/3rds of the allowed size.

Granted they are designed to be trailered by lighter vehicles, too.
None of these come close to the size you are talking about which is like a mini yacht.

What is your budget? Can you even afford the amount of fiberglass and resin this requires?
Im not very sure that you can build for $10k the same thing you buy (used) for 80k. But, i wont deny that building a boat is a romantic and beautiful endeavor. Just keep in mind the work, tools, resources, space and time you need.

As for the actual use of your boat/house i really don't get it, you want something where you can live comfortably for long a prolonged time or store god knows what, you want it very safe and oceanworthy, but still want to move it over land. Im not saying it can or sould'nt be done, but really i dont see the point. Why not moor it? or is it that you want to "cross" land as if it was "all terrain"?

Back on your design ideas, strong wood is heavy wood, that not only means hard to trailer or take in/out of water, but also reduced performance when sailing (this is speed, but also maneuverability) .
I see you worry about capsizing and hitting rocks. Another way to stop that from happening is avoiding unnecesary danger. If you are reckless, no ship ever built is safe.

Another thing to consider is the beams, you need them to be strong enough, yet be foldable or removable, this is a challenge. Consider when you scale up an existing design , you fight the Square-cube law. This is especially problematic on a boat because of the weight distribution. You need to check where the metacenter will end. This is what will say the position in wich your boat floats.

If i may reccomend a book, Larson's "Principles of yatch design" is a great one

All the links to boat plans I posted are actually Woods designs. Check the links to boatplans.cc! The trailerable cats are all Woods.

The largest trailerable cat I've seen from that site are 30 feet.

LOOK AT THIS PICTURE. I guessed 30 feet long, 6-7 foot hull height... that's a LOT of unused potential.

I'm wanting to plan a much bigger cat than that.

I'm thinking 8.5 foot tall hulls, maybe 9 or 10.


There's room for so much more!
Ok, we are talkin many, many hours of paper, calculator and thinking. Then im in.
I thought you were more like "i want to build the thing right now, i'll just tamper with some designs to make a frankeinstein that suits me perfecly".

DUH lol of course it would be a mini yacht. A mini yacht you can take on the road by yourself.

My budget? I'm not sure. It's not like I'm gonna build this thing anytime soon. If I was going to build a boat it'd be in a decade or two.

Right now, I want to put ideas on paper, that's pretty much it.

Hopefully they will evolve until I have a book or two full of plans for an actual boat that would really work.

Look at the pictures I've posted of graph paper, this isn't even in the concept phase yet. It's just a visual representation of the maximum space I have to work with.
File: trim[1].jpg (22 KB, 442x383) Image search: [iqdb] [SauceNao] [Google]
22 KB, 442x383
You know, there's carefully thinked placement of each kilo in a boat, that's because of the metacentre principle i mentioned earlier. It means if you put weight on the wrong place, you boat wont float straight. Also need to consider the hydrodynamics: For the boat to be able to take a wave, steer, self right, and move with as least energy as possible you need certain shapes and weight distributions.
I don't know how technical do you want me to get. Do you feel like talking about the physics or just discuss size and layout?
I don't think you can go far from any proved design without doing at least some rough math and geometric analysis as in pic related

People think their homemade plan boats are worth more than they actually are. Some might have special circumstances.

Check out this link.


The dude wanted 100 thousand for it!!! I'm not kidding.

Strong wood isn't always heavy wood. Epoxy impregnated balsa wood is like a piece of steel.

And nobody plans on hitting rocks, but shit happens. It's why I wanted lignum vitae at least on the bottom, and I want to design it with a flat bottom for maximum clearance in shallow waters.

I didn't just go "LOL I WANT MAEK BAOT" I've actually researched this shit as much as I could in the last month without spending 2 thousand bucks to buy someone's plans.
File: Cat_06.jpg (60 KB, 1000x290) Image search: [iqdb] [SauceNao] [Google]
60 KB, 1000x290

I'm not gonna lie, I thought about just lengthening and heightening one of Woods designs. But I want it to be unique, seaworthy, and with a few little tricks up its sleeve to set it apart. Yea that's what every boatbuilder says, but if the bottom of the boat is one of the strongest woods on the market and vacuum impregnated with epoxy... it would set it apart. It'd be stronger and more resistant to holing if it hit a rock. Which would be unlikely because I want a flat bottom.

I really need advice about the flat bottom. No cat I've seen has a flat bottom.

If you really wanna talk about making a Frankenstein boat, I've got this batshit insane idea about fold down hydrofoils for high speed in reasonable conditions. I'm NOWHERE near the point where I can see that happening, but I figured if I was making a plan for the largest trailerable catamaran ever made, it should at least have the potential to race. It's obviously total pipe dream though but it'd be absolutely insane or absolutely awesome.

Here's a pic from a cat I like. My thing is, I want standing headroom from the bunk to the kitchen to the bathroom. The design I'm thinking of would only have one head, of course.

The hulls can only be like 4'3" or something like that.

D-did I use apostrophes right? 4'3" is 4 foot 3 inches? That's the maximum hull width at the top of the hull, assuming the connection beams can be tucked away somewhere else.

Again, I just want realistic advice for what I can draw.

This is a paper only concept to see what's possible.
File: maxresdefault (3).jpg (96 KB, 1280x720) Image search: [iqdb] [SauceNao] [Google]
maxresdefault (3).jpg
96 KB, 1280x720
Size, layout, weight.

I know both hulls gotta have the same weight distribution.

I figured I could use lead weights as ballast to even it out after I've got weight distribution close enough.

And weight distribution is so complex! I've considered it!

I want the extra room because the pipe dream is, to make it seaworthy enough to cross an ocean. And you need space to store food and whatnot.

I read that Seawind 24s have crossed oceans fine. Here's a link, neat read.


But the question is, can you cross oceans in it COMFORTABLY? That's why I want walking headspace. Stretching room.

Look at the pic, it's kinda the general hull shape I'm thinking of. Tall. Maybe profile the front a little, adjust the shape of the frontal hull profile for better seaworthiness... hey! What about a tumblehome? That's unique on catamarans, it's a relatively flat bottom....

It's only been used on monohulls, though.

But because the tumblehome would be wider at the bottom and thinner at the top, it would ride shallower and the thinner top hulls would allow room for folding crossbeams.
File: Cat_05.jpg (65 KB, 1000x319) Image search: [iqdb] [SauceNao] [Google]
65 KB, 1000x319

I've been on lakes and rivers. I've paddled and motored. I've jumped off 25 foot cliffs into lakes.

The next step is the ocean shallows near shore. Which is what I'm planning and designing for.

The problem, is.... I want a relatively flat bottomed hull and I haven't seen any cats with one.
File: tandem.jpg (35 KB, 550x393) Image search: [iqdb] [SauceNao] [Google]
35 KB, 550x393

Hmm... go ahead, educate me.

I'll admit I don't know as much as I should. I've got plenty of time to learn, though.

I've considered using fuel and water stores to adjust the ballast. Other things can work too, like if I need more weight to push down the front of one hull I could have a heavier chain for the anchor. Or anchors, if I'm planning to moor it. If I need less weight, I could use a rope. I could design the interior to have compartments in the bottom for ballast, and move the ballast from hull to hull as conditions change. I'd need to mark measurement lines around the waterline on the front and back of both hulls, though.
I like where we are going. I still see it as a pie dream, like you said, but since we are dreaming...
The thing with the flat bottom is that it's tricky to make the thing go in one direction. You want both hulls to move forward or backwards, wile they stay always parallel to each other and moving in the same line. That's easier with some kind of keel or V shape on the hulls.
If you dont mind me being technical, the problem here is the inertial momentum you have. It depends on geometry and it roughly means "how hard it is to spin something in a given axis". What you want is the hulls to be super hard to move sideways. You get that by making them slim. Also if they have more surface underwater that helps. If im not wrong or oversimplifying that's one of the main reasons for the V shape. Here's one thing you can try to get it more clear. Grab a knife and a bucket of water, then "slice" trough the water while trying to bend the knife sideways, if you do it fast you'll find the knife kind of wants to stay in the same angle (I don't know if that's clear at all).

Another reason for the V shape it's that it can adjust gradually for more displacement, in a square, every inch you submerge gives the same amount of displacement, in a V shape, every inch gives more, so if you double the weight aboard a square ship, it will float at half the height, where in a V shape you can add weight and see the ship go down less drastically. This matters because you design the ship to have a certain shape and surface underwater, that's "just right". Adding or removing weight on a square hull will affect dramatically the draft, that doesn't matter much in ships designed to go slow and use whatever energy, but cats are supposed to be "fast", and sailing boats need every drop of wind to count, so efficiency matters, a lot.

Height limit is 12 feet. Combined hull width limit 8.5 feet. Length limit is still 40 feet, but 38 is better. I could design a flip up rudder 2 feet long just to say it's the maximum legal length for towing, but still have 2 feet as a safety net in case of a jack knife during towing.

The graph has been updated!

The problem is, individually the hull width is 4 feet 3 inches. Inside a complete hull will be less. This is why I wanted walking headroom. Because it's a tight fit.

I drew a guy inside the box on the upper left, which has been separated into two rectangles to represent the maximum frontal hull profile.

This leaves a maximum of 1 foot 6 inches for towing on a trailer. I want the maximum height on a trailer no more than 12 feet 6 inches. I've seen those bridges with 13.5 foot clearances before lol
I don't really know about lignum vitae, we don't have that kind of wood around where i live (southern hemisphere!), so i assumed it was heavy, but if you think you can get more strength with about the same weight, absolutely go for it.

The thing about using tanks and storage to distribute the weight is not bad, but you cant relay just in that, you need to be close to ideal, or have enough space already destinated to that. The main problem with that is, if you are adding more weight on one part, you either had space that weren't using or you are occupying space that has another purpose. Neither are good options. The ideal situation is that the ship "as designed" is perfectly trimmed in most (or all) conditions. In real life you will be moving weight from here to there all the time anyways, but just for smaller corrections, not to make up for a design flaw.

btw captcha asked me to select images with boats! :P
File: 420px-GNfiguur.png (41 KB, 420x600) Image search: [iqdb] [SauceNao] [Google]
41 KB, 420x600
The metacenter is about the righting of the hull. What it means is this: you have a center of gravity, as with everything. But a boat also has a center of buoyancy, witch is kind of "where the water is pushing up".
So in one hand you have a center of gravity, that depends on how the weight is distributed.
In the other you have the center of buoyancy that only depends on the geometry of the boat. In simple words, the part that has more volume submerged will float more (duh!).
I dont think i can explain the metacenter in simple words, but the trick is that the two centers try to align themselves. If your design is ok, the ship will align right side up. After heelling a certain angle, it's easier to realign wrong side up than right. That's why monohulls capsize.
With a cat it's really hard to capsize, but you do stress the beams. So, you want to imagine each hull separately and have them stable. Also there you have another reason for the hull being V shaped, just draw a V and a square, then heel them (in naval engineering we usually draw the hull, then draw diferent lines for the water in diferent situations. What's under the line, would be underwater)
So, back to your drawing, draw the square and the V, draw a line angled to the horizon (hull would be heeled) see how the area and shape underwater changes for each one? there's something to think about. You need to think this on every axis! Then compare the center of gravity with the center of buoyancy and you can tell the "rightening force" you have. Of course you have a diferent situation on each hull, so there you have the diferent forces on each end of your beams. Your beams are not only bending but twisting, too.
That's why i don't like your towing idea, it's the limiting factor on every way, and i still don't see the need to bring the boat somewhere you wont use it, just to store!
Plus, it's a real pain to take it out of the water, disasemble, get it on the truck, and all the same the other way around when you wanna sail again. You are talking about crossing oceans comfortably, for god's sake, you wont be near your truck in quite a wile!

Well the thing is, weight distribution on this scale hasn't been considered on trailerable cruising catamarans yet to my knowledge; except by individual builders. I think if I have lead bars I can shift around from 4 points, it will correct any ballast lost from water/fuel usage, consumables, passenger items, etc. I'll have to paint a yardstick on the hull near those 4 places though. That should suffice for ballast, right? If I plan the interior accordingly, of course.

You mentioned one of the biggest concerns I have, the beams. Did you see the you this link I posted?


That catamaran has almost everything I want in my design. Central mast, collapsible beams, etc but I want my design to be longer, taller, and have some kind of central cubby- possibly a pop-up design inspired by towable campers.

I don't know how to incorporate reinforcements for the beams, either. They are literally going to be pushing the ship along because I want a central mast. I don't know how to reinforce the wood, epoxy, and fiberglass around where the beams connect, either. I've recognized it's a problem in the design. Check out the pic. Would the red box be enough space for all that? The wood, epoxy, and fiberglass would be a little thicker where the beams attach. I've also gotta provide a space for them to fold, though.

I've got no idea how to do this ;_;

In the pic I made the hull 7.5 feet tall. Not as tall as I want but I was rushing. You can see how cramped it is though, right?

The pic shows you why I want it to be taller. Most cats I've seen only have that kind of hull height for a few feet.


That picture was supposed to represent the maximum length and width of the hulls from above. I was short a foot. I fixed it on my graph paper.

I bought a brand new graph pad so I could try to sketch out this idea.

It's late and I'm getting tired though, I've had a half pint of whisky too.

This is just a concept, guys. I don't plan to build a boat anytime soon. I just want to get some rough sketches, ideas, and input.

Thanks so much, everyone.
>I'm thinking of incorporating ideas from pop up campers to certain areas
thanks anon

I'm being serious.

Look at this camper.

Solid walls, but it folds up incredibly compact.

Google "Skíðblaðnir". I kinda want to incorporate the ideas of that ship into what I'm drawing.

Something that can be folded down and very compact, but very large when unfolded.

Because I want the two hulls to be like 9 feet tall, that leaves 3 feet for the central cubby for me to work with. Which means it will have to be like pic related.
OP here again.

I want you guys to watch this video.


It's the same boat I mentioned in >>925058 where the guy wanted 100 grand for it. I wish them the best, he ran into medical problems which is why they were selling it.

Look at the way the deck unfolds! It's an amazing design.
Just to note the higher your boat will be the shittier it will sail. If you look at racing boats/ship/yachts their sails starts from low, close to the sea. You want to build one that is high. With a triangular sail the majority of the sail is low as it is widest there. Lifting this pulling power higher will make the hull twist more if you want to sail really fast. Which you won't.

Also a flat bottom doesn't take the waves nicely. A sharp V cuts the water as the bow falls down, a flat bottom will bang (hard!) when it goes down a wave. They are called butterboxes here and are frowned upon over here as they can't handle both weather and speed, unlike a V-bottom.

I've seen a mast that was all wrinkly in the bottom because of hard banging and this was a aluminium mast in a proper (meaning not DIY) ship.

Back in the day as a sailing bum down in Andalucia I saw some ships I can tell you... I was supposed to sail to Thailand with one that was DIY but even after extensive fixings (for eight months!) she wasn't seaworthy.
To skip the rookie errors I suggest you should help on someone others project first, or somehow get a feel for (maybe by sailing) what it means and how boats feel on the sea!

And by the way. THIS boat crossed the Atlantic!
That is some serious fucked up stuff man. Been boating with marinos as they are made just where I was growing up, good shit.

Thanks for the advice.

THAT tiny boat with no sail crossed the Atlantic?

How much gas does it carry?

I guess I'm stuck using the V hull, other anons agree it's the best.

I still want the bottom 12-16 inches of the hull to be vacuum epoxy impregnated hardwood.

I've seen what happens when a boat scrapes a rock. Not pretty.
The original wood you wanted is more for like planning to hit rocks... might want to try out different types of hardwood during you planning process. Epoxy impregnation idea is good though....

Captcha: all images with trees


I quite like the idea of it, too. Just the wood that would be below the waterline would be epoxy impregnated hardwood. I'd prefer the hardest I can find but availability and price would be a concern. Lignum Vitae is 3 times harder than oak!

The goal is to make the boat as idiot proof as possible. Because I am an idiot.
Also, would it be a good idea to use brass hardware? Brass screws would last longer than steel ones, right?

I know they have found broze that was thousands of years old and in perfect condition. I do not know if bronze screws would work, or if they even make bronze screws.

Is it a good idea?

Also, I only want to vacuum impregnate the outside planking below the waterline. Would it be a good idea to vacuum impregnate anything else? I was thinking of designing the boat with aluminum crossbeams, but would it be a better idea to use something else? The Foldcat used carbon fiber beams and it worked well, the Wizard uses wood, I think.. I'm not certain.


Check this out, the alcohol soaks into the wood very well.


In this video, he mixes epoxy with alcohol and he says it turns that piece of balsa wood into a piece of steel.

Would that work well on hardwoods?

There might be an easier way to get the results I want besides vacuum impregnation?
File: Capture.png (2 MB, 1915x981) Image search: [iqdb] [SauceNao] [Google]
2 MB, 1915x981
So I work the summers on the sea, driving around doing mostly biological surveys. I work mostly in pic related but in other parts of the coast also. I have ONCE hit a rock and this was after smartphones came, you can guess why, stupid came aboard. Speed was a few knots thankfully...
So instead of building a boat that can withstand hitting rocks instead learn to navigate and don't hit rocks! Other parts of the world's oceans are so childishly easy to drive in compared to the Baltic. And yes, been in other seas also.
And yes, we drove around in the middle of the night in total darkness before plotters were a thing. I still don't think they are but a radar, that surely is a thing

OP here.

I watched this video during my research.


The guy was an experienced sailor and navigator, and there was a rock in the shallows nobody knew about or mapped.

Experience is irrelevant sometimes.

Which is why I want the bottom half of the hull to be like steel.

Plan for the worst, dude! Building a boat is a huge investment of time and money.

Epoxy is cheaper than building a new boat, and a decent vacuum chamber can probably be built cheap enough.
Hey guys, anyone interested in contributing ideas for the central cubby should check this out.


It's a great design. I like it. I want to expand off that idea.

Because I want the hulls to be 7-9 feet tall, it only leaves a few feet for the central cubby up top so it'll have to be collapsible and pop up. Furnishings on the central cubby will also have to be foldable depending on things.

Trailerable cats are mostly a way to go camping at sea but if I can put this idea on paper right and everything checks out, it would basically be a yacht you could take anywhere.

I like the concept.

I'm kinda worried about seaworthiness though. Usually catamarans don't have ballast, because monohulls need ballast for stability but on cats the double hulls give it stability.

I'm wanting to draw a feasible towing catamaran because I live in a landlocked state. That's why. That's why the limits of a trailerable design. Necessity.

And because the thing is a pipe dream, it might as well be a GRAND pipe dream!

It might as well be a little grandiose, because all I'm doing at the moment is drawing on graph paper.
Here's a photo from this link.


I'm curious, how thick does fiberglass have to be so it's strong enough to sit on, walk on, etc?
File: shipproto.jpg (124 KB, 1310x724) Image search: [iqdb] [SauceNao] [Google]
124 KB, 1310x724
Alright OP heres a good way of attaching fiberglass to a steel belly. Another way would be rivets but youd have problems with rivets over time leaking even if you used the ones with little rubber washers... Studs welded onto the sheet steel and then pressing the studs through the fiberglass roving/mat.

Neat! Thanks, but that wasn't at all what I meant.

I mean that when you impregnate wood with epoxy, it basically becomes a piece of steel.

>studying naval engineering

I might have pissed you off a few times in /k/ navy threads lol
File: s-l1000.jpg (100 KB, 1000x709) Image search: [iqdb] [SauceNao] [Google]
100 KB, 1000x709
OP here. I have another idea I want to implement in my catamaran design.

A way to right it if it capsizes. Another part of being prepared for the worst, like the super strong hull planking on the bottom.

I know it's a fringe idea, but there has to be way, right?

I was thinking if it capsizes, you could use straps and a dolly wrench to flip it back over if you could find something heavy and stationary to attach it to.

For example, you could deliberately get your anchor stuck on the sea floor, attach straps to the anchor chain, wrap the straps around the hull, and slowly tighten until the boat flipped.

I'm not sure if you can understand what I'm saying, I might have worded it in a weird way.

Any ideas for making a self righting system?
the heaviest part of your catameran is going to be the keel/keels... you work with those and your body weight to right it... perhaps instead of something depending on an anchor look at using something to help push the other side up while you apply weight on the opposite side... some kind of inflatable lifting bag system connected to co2 shots, or hell.. maybe mount an inflatable aircraft style liferaft on either side.. if your boat flips trigger the liferaft then get your ass to the other side to help flip the boat back up properly... if you fail utterly then you have a liferaft handy...

I like you op... but this thread needs more waterworld trimeran....
You are building a yacht. If it will have some living space on the central piece, whatever it is called, and the mast sticking up from it then the sail area can't be all too big. It'll be a slow sailor and hard to capsize.
As you are planning on building a boat that is modular then the joints might break before the boat capsizes.
Basically at that point one of the hulls is hanging from the other! With some gusts making the impulse bigger.

But basically you don't use ratchet straps to right a sailing boat. It has these things called winches...
>when you impregnate wood with epoxy, it basically becomes a piece of steel.
No, it doesn't. Not even remotely. Soft aluminum is much harder and stronger than any wood, epoxy, or wood/epoxy composite. Structural aluminum alloys are several times stronger still, but only the strongest approach even weak steel alloys. Strong steel alloys can be a hundred times as strong as wood while being homogenous and defect free (read: effective strength is a higher percentage of ideal strength). If you want a strong boat with no regard to cost, make it out of Monel, fully welded. For the weight of that impregnated lignum vitae, you can have a bottom better-armored than a Sherman tank. Which is entirely unreasonable, but the point is that if you want strength over other properties, wood is not a good choice. There's a reason warships aren't made of wood any more.

Here ya go. I can't recall what the catamaran is or who made it, but it was a racing cat.
File: js52fp.jpg (527 KB, 1606x1106) Image search: [iqdb] [SauceNao] [Google]
527 KB, 1606x1106

I'm not planning a yacht.... look at this deck layout. That's a yacht. Now look the layout here >>924985 that is not a yacht.

Mini-yacht, sure... but the hulls are going to be so thin, and the space in the central cubby so small, that I'm not gonna say it's yacht territory.


I meant that as a euphemism, dude. I meant it makes the wood stronger, more resistant to damage, waterproof, shrink/expansion proof, etc.

I'm already taking huge leaps in realism by thinking an idiot like me could build a boat. I don't wanna get into welding or forming sheet metal. That would be out of my league by miles.

The catamaran I'm planning is anywhere from 36-38 feet long, I don't think my body weight will right it.
File: tahiti_75_10.jpg (54 KB, 450x308) Image search: [iqdb] [SauceNao] [Google]
54 KB, 450x308
Here's another unusual idea I want to incorporate. I have no idea how it would work, though.

See the beaching ladder in this pic? I want a beaching ladder in my design. It wouldn't be too hard to find a way to stow it, but I want the ladder steps to appear flat when is raised, so it's no different from hull planking to the naked eye. When you lower the ladder, the steps would change pitch. Does that make sense? I've seen that been done before I'm pretty sure, just never with a ladder.
I don't know how high the trailer should be... if I'm going to draw a towing catamaran I need to take that into account.

Here's a dude with pretty much the same idea as me, I just want to design one a few feet shorter and with a collapsible central cubby and folding decks like the Foldcat 36
Just a crappy sketch but here is a WIP idea for a decking to stairway mechanism/design. More to follow.
*Top down cross cut*
The idea is that a C-beam with partition in the top and bottom of the C holds a catch-pin and wheel assembly. The mechanism is simple. a piece of wood, that is part of the stair... it is the same height of the stair and perpendicular. The C has teeth in it that have gaps in between them and are positioned to let the stair rest flat if the beam is at a 45degree angle. The gaps allow the catch-pins to move up and flat to deck mode.. the teeth lock the catch-pins into stair mode. Wheels in the other side of the C-beam partition allow the stairs to move from positions. And high tensile wire at the front (longer portion) and back of the stair (shorter portion) are used to change the stair to deck mode and vice versa. The front wire is also a support wire to take tension off the catch-pin... the specifics are hard for me to do without making it... and I don't have the capabilities.
Last sticky for now, various ideas and angles to help you understand better... possibly.

Holy shit, thanks man.

I have no idea what that's called, so I can't search for it on the internet.

Would it be easier to make a mechanism that turns the stairs without interruption? Like, as you lower the ladder the planks constantly stay facing upright? I like your idea that the planks are supported when in the "upright" position... I hadn't thought of that. That might be a necessity.

Do you know what that would be called, some kind of term I can use to search Google for ideas?
Thinking up some things... sorry for the slow response. I have an idea for deployment of either design but the ladder style is proving harder to show on paper. As far as web searching... idk... I thought that first design up by scratch.... I'll link anything I find online back here for you but also having bad luck so far

I know, right?

It's like, you know EXACTLY what it is, but don't know what it's called... annoying.

Mostly in this thread I'm looking for input, advice, etc.

I really don't know shit about boat building.. but I know enough to know I don't know, which is important.

I'm trying to think about how high the center will need to be, how to strengthen the attachments between hulls, how to get the sail low enough to make it a decently fast cruiser but not interfere with headroom, storm sails, what the mast should be made of, how to reinforce the central mast, etc.

It's VERY complicated.

But I'm kinda in love with the idea.
Here's a nice catamaran :)

I like the colors.
Shit, it's a really nice cat.

I was wondering if I should put windows in between the hulls.. I guess it's not such a stupid idea. Ventilation is always nice, and the extra view might be worth more than I thought.

What are boat windows usually made from?
Here's a nice idea about making the hull entrances open to the central cubby.

I'm still unsure about if I should plan it using fabric like a tent or collapsible solid panels.

Solid panels would definitely be more difficult, I think.
boatbuilding forums exist and have experienced designers posting.

I know.

I'm looking for input, advice, etc from people that know more than I do. I'm not quite ready to take any questions to a dedicated forum.

Like I said, if I actually build a boat, it'll be in decades probably.

There's so much to think about... Like desalination, cooking, plumbing, etc.

I only want one bathroom though. I see a lot of catamaran layouts with two heads and I just don't understand why. I think it would be better to have more storage for food, water, fuel, booze, beer, liquor, etc.
Coolest thing about cats is when they put hard wooden runner boards on the keels on them so they can be completely beached and get into really remote beaches,
HEY GUYS I've got a question.

Instead of using epoxy resin to impregnate the wood, what about using styromfoam?

I could saturate acetone with styrofoam and use that...? The polystyrene would saturate the wood and the acetone would evaporate off.

It might be cheaper than using resin.

I heard that in the Amazon people found out they could dissolve styrofoam in gasoline, and use that to fill holes in their boats. There's a youtube video showing you how to use gasoline and styrofoam as a glue.

Would this work well?
Deployment idea. Just a simple slider rail on a pivot... think pivoting kitchen drawer. Pull it from front or push from back. Needs a lock of some kind as mentioned in pic.
File: Rung Step.jpg (39 KB, 768x1024) Image search: [iqdb] [SauceNao] [Google]
Rung Step.jpg
39 KB, 768x1024
Side view of Rung or step. Free floating bar design with counterbalance to make it stay upright when the ladder is deployed. I still have to think up a good locking mechanism...

I have one in mind but I want to make one that you can lock/unlock all the rungs at once

and not individually as this ^ would be easier to use.

Keep in mind that the width of the step needs to be longer than the decking (probably) because the rungs are as far apart step wise as the front and back of two rungs are from their respective bars...... a better explination is short rung in decking mode means less height between rungs in ladder mode.

A way to make this blend in better would be to make the ladder rungs out of aluminum or some other lightweight sturdy material and make them wider than the decking is.. then add a paneling on top of each rung to make it blend with the decking of the ship. Sink in the ladder just a bit and viola "hidden".

Will answer any questions soon, I work a lot though so again sorry for any late responses... I'm slow even by /diy/ standards.

I was thinking I'd need to connect all the steps to the same mechanism, so they would all pivot the same.

You know... that's actually a good idea, making the ladder from metal and paneling the top.

This is why I made this thread! Having a few minds throw their opinion out is a good thing sometimes :)

OP here

Anyone got any opinions on using polystyrene instead of resin? Once the air is out of the styrofoam and the acetone evaporates, it would dry like glue or resin.
Thread replies: 75
Thread images: 37
Thread DB ID: 402625

[Boards: 3 / a / aco / adv / an / asp / b / biz / c / cgl / ck / cm / co / d / diy / e / fa / fit / g / gd / gif / h / hc / his / hm / hr / i / ic / int / jp / k / lgbt / lit / m / mlp / mu / n / news / o / out / p / po / pol / qa / qst / r / r9k / s / s4s / sci / soc / sp / t / tg / toy / trash / trv / tv / u / v / vg / vp / vr / w / wg / wsg / wsr / x / y] [Search | Home]

[Boards: 3 / a / aco / adv / an / asp / b / biz / c / cgl / ck / cm / co / d / diy / e / fa / fit / g / gd / gif / h / hc / his / hm / hr / i / ic / int / jp / k / lgbt / lit / m / mlp / mu / n / news / o / out / p / po / pol / qa / qst / r / r9k / s / s4s / sci / soc / sp / t / tg / toy / trash / trv / tv / u / v / vg / vp / vr / w / wg / wsg / wsr / x / y] [Search | Home]

All trademarks and copyrights on this page are owned by their respective parties. Images uploaded are the responsibility of the Poster. Comments are owned by the Poster.
This is a 4chan archive - all of the shown content originated from that site. This means that 4Archive shows their content, archived. If you need information for a Poster - contact them.
If a post contains personal/copyrighted/illegal content, then use the post's [Report] link! If a post is not removed within 24h contact me at wtabusse@gmail.com with the post's information.