Trimaran Yacht

So I've been doing WRC Canoes for about 10 years now. And I've been wondering what it would take to build a 40m Trimaran. Not one of them with the skinny outer hulls but one with full hulls. I'm not one looking for speed. It will be slow and steady. 8knots to say 15knots with sail. Maybe top end around 20knots on motors. This will be both sail and motor. Hull will be made of WRC 1/2" thick strips, All bulkheads will be done in foam sandwich core and all interior decking will be honeycomb core. I do have 99% if not more of the WRC to complete the exterior of this endevor. I'm just needing help with below the WL of the hulls. I can't seem to be able to figure it out the way I'm wanting it to be. I've tried the free 3D programs for boat building but at my age I just don't want to learn a program that I would only use once.

As for motors I have been looking into jet drives coupled with dual 250Kw electric motors on the outer hulls and a dual Diesel motors on center hull. With the size I'm wanting it to be I know 1 sail will be way to tall, would it be posible to do a double sail with it being 40m?

As for my sailing life it's only been small monos maxing out about 30ft.

Center Hull 40m loa x 4m beam
Outer Hulls 24m loa x 3.25m beam
Over all beam 20m

I was looking at the Bruce Rober's catamaran 2400 when I got the idea for the trimaran I want to build.

Yes I'm pretty set on size and like I said speed isn't something I'm worried about. I just want to get the hull right and not have just a big tank trying to go through the water.

 

Welcome to the Forum Van.

In a nutshell, it will take millions of $$'s, and years of your life.
How many millions do you have available for this project?
How many layers of 1/2" thick WRC will you use for building the hull - have you done the calculations to determine this?

The Bruce Roberts 2400 cat would be a more realistic project, but you are still looking a cost of 7 figures.

 

Thank you for the welcome. And I've been talking with a few of my Canoe buddies and one has already built a 20m Catamaran with only 1 layer of 1/2" WRC. I would be able to do 2 layers if I had to. The cost of the WRC is Zero so that don't matter. And I'm pretty sure I have access to enought WRC to do the hull 3 to 4 times if I wanted to. Several of my buddies have mills and we do all our own lumber for the Canoes we build. This will be a group build so between like 6 of us I'm sure we have almost everything to build this. I've also seen several 40ft catamarans built with 3/16" WRC strips.

Yes I know it will take years to complete and I was counting no less than 5. I first emailed Bruce about the 2400 and they only suggested 1 layer of 1/2" WRC would be needed for a 24m cat. As long as the lamanation where done right and the right weight glass was used 1 layer would be good enough. As long as I'm picky on which WRC strips I use, I should be just fine using 1 layer of WRC.

 

So be it, but the cost of the glass and epoxy required to build the vessel is still going to be significant, and the final cost is still going to be in 7 figures for a boat this size, no matter how much you do yourself, and how much free WRC you can lay your hands on.
Have you got at least a million dollars to start this project?

 

The scantlings are way too light. You can't simply decide what the scantlings will be without a design first. Caveat: a drawing is not a design, but a representatio of it. Also, a 40 meter trimaran should be about 20 meter wide at least. You have a hodgepodge of engines, etc. which make no sense. To start with, at your target speed a monohull would be fine. Also, the hulls are normally about 10-15 % of the total build in materials, and less in the build time. How many millions do you have?

 

I don't understand why y'all are talking about money. I'm just looking for help with the design of the lower hulls, below the water line. And yes Gonzo if you read my post it's 40m loa x 20m beam the lenght of the outer hulls can be made longer which I don't care. That is if they need to be. I'm set on the WRC, I could probably do the whole thing in it. I take it y'all think others dreams are just that. If ya don't think you can help then why comment? I have questions asked and most of what y'all are talking about I have already covered. Don't worry about what people's bank account's look like. Easly answer the questions that are asked. I'm not here to be talked out of it. Yes the epoxy is expensive and Like I said between the 6 of us we probably have everything needed to build this.

I'm just on here asking if anyone is able to help with the lower hull design. That is it.

 

Because this is really the most important factor in building a boat - you cannot build the boat if you do not have enough money to design the vessel and then to buy all the materials, labour and outfit equipment required to build it.
If you have millions handy to build this boat, then sure, go for it!

How much 'help' are you looking for?
If you are just looking for help with the lines plan of the hulls, then there is not much point in drawing this until you have come up with a General Arrangement drawing, and then using this drawing to carry out an initial weight estimate that is as detailed as possible - as you need to have enough buoyancy in the hulls to support the complete weight at the intended design waterline.

And just doing the above weight estimate and initial general arrangement is a LOT of work - even before you do this you first need to establish a very detailed Statement of Requirements outlining exactly what you want this vessel to do - the more detailed you can make this, the better, as it will help a lot with the whole design process.
your best bet is to look for a naval architect who has experience of large multihull vessels.
A custom design for a vessel this size cannot be drawn on bits of paper - it will involve a very detailed specification and perhaps a hundred (or more) detailed drawings - are you happy to shell out perhaps US$ 200k (or more) for this up front?

 

Because you are looking at the cheapest part of the build and don't seem to understand the whole project will be at least 10 times more.

The materials may not be appropriate. You need to first have a design and then the material options are derived from it.

Critique is help. Otherwise, if your attitude is that you are right on everything and need no help, a forum is the wrong place for you.

That is the crux of our advise. Epoxy is a tiny amount of the cost.

 

Again that is our concern to deal with. We have as much time as we need to get past all of that. We are not looking to finish this thing in a year. We know it's going to take time and money. In our case not as much money as others but we do know it will still be up there.

Was emailing Bruce before I even made an account here and I have already cleared it can be built in 1/2" WRC strips as a core materal. We have even been talking about bumping it up to 5/8's or even 3/4 depending on which lower hull we go with. But as for WRC being the choice core materal it's already been cleared that it will work perfectly for the build we are wanting to do.

Critique is one thing. And never said I was right on anything. Coming here to this forum and asking for help from people with more experince, thinking it would be more than just MONEY answers.

Just the fact that the only thing WE are missing for this build will be the Mast's, Sails, and the 48v system that is going to cost a bit yes but that is our concern.

Yes I was looking for help in a forum for advice on the lower hull, to get more of an idea on which way to go with it. We already have the bulkhead lamination order, hull lamination order and many other things. What we are having an issue with is what hull should be put on this. I just figured with the experince I've seen on this forum that it would be a great place to ask about lower hulls. My bad If I was wrong.

I came here to this forum cause I thought I would actually get advice on what hulls would work and which one's wouldn't. I'm not here to worry or talk about my finances. Or anyone else's finances that is pitching in to build this massive thing. This started out with 3 small WRC builders and as of today it is now 8 of us.

Look I'm sorry that I came off the way I did. I'm only here cause we are standing still till we figure out the hull shape. And once we figure that out, we will all be busy.

Yes I understand there is a lot of work that goes into desiging a Yacht this large. But at the same time a lot of it is already on paper and in our heads. We know everything has to be balanced. We know that it's going to cost when we get into a lot of the work. But at the same time We also know that with most of our skill sets that we won't have to spend an arm and a leg to do 99% of the work.

We know that just the WRC alone will be in the ballpark of 14.93tons to 15.44tons. Then adding in the weight of the motors, 48v system and all the other electronics will add a lot more weight. We do understand that. But coming here asking about hull design. I figured I would get more answers on hull design not on how much is in our accounts.

 

Vandorine, bajansailor already told you the facts but their importance seem to have saild right by you. Underwater hull shape is heavily dictated by SOR, GA and weight distribution. All modern multihulls have what is called a canoe underbody, meaning a rounded U shape. The exact volume distribution is influenced by the weight distribution, you want the boat to sit level in the water. Where is the engine, where are the tanks and whatever other weight concentrations there are on your hull?
SOR dictates if you want an immersed transom or not, you need to decide how much sailing vs. how much motoring and under what wind conditions. SOR also dictates how big your fuel tanks are.
Rocker depends on the volume distribution, if you have an immersed transom, envisioned speed under motor and sail, etc.
In short, without knowing any of that we can only discuss the theoretical merits of immersed transoms, more or less rocker, softer or harder chines etc. If that's what interests you this forum already has plenty of discussions about such factors in older threads. The theory is the same be it mono or multihull.

If you have scantlings you already have this info. I don't understand why you have chosen 1/2" as the general core thickness but that's not my problem, just as how much money you will spend. Maybe you have determined that's the optimal core thickness or maybe you are just putting the cart before the horse. Anyway if you want a discussion about your underwater hull shape you better start with telling us a more detailed SOR.

 

Vandorine,

Welcome again to the Forum.
It's solid advice you're getting.
Listen to it, especially the parts you don't like hearing.

Best of luck with your project.

 

If you have a general arrangement drawing of the proposed vessel (rather than it still being in your heads) can you post a copy on this thread please?
What else have you established on paper so far?

 

Do you already have boom vangs, travellers, guardrails, clutches, gooseneck, rudder bearings, jib tracks, windows, propeller strut, cushions and all the rest for a 60' trimaran sitting around?

The hull is not "99% of the work". It's normally roughly one third.

It's no use asking for "below the WL of the hulls" since that has to match the above-waterline shape of the hulls.

 

It is not 60 feet, but 40 meters. That is 131 feet; about 8 times the volume of what you are thinking.

 

@Vandorine I just saw this latest project mentioned on Schooner Ruth's Facebook page, re a 42 metre sailing trimaran to be built locally in Barbados, and I thought it might be of interest to you?
Schooner Ruth is a Tom Colvin design - she is a 100' steel gaff schooner which was built on the beach in Barbados over about 15 years, and launched about 12 years ago.
Log into Facebook https://www.facebook.com/photo?fbid=2755646027957127&set=a.101378020050621

Home | Schooner Ruth - Barbados' Sailing Ambassador https://www.schoonerruth.com/

The Facebook post with the description is for friends only, so I will copy and paste it below, along with a few sketches of the trimaran :
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Perfect time to celebrate a fresh New Year and announce 2025 lift off of our new Caribbean Sail Cargo Initiative ZEROe RoPax ( zero emissions, roll on roll off with 12 passengers ) fast sail cargo schooner trimaran to be built owned and operated by Barbadian and CARICOM nationals - our plan is to have all in place to start construction in Barbados in 2025 for first delivery January 2028. Pre-eminent multi hull designer Kurt Hughes and long time visitor to Barbados has brought our concept to life in these stunning 3D renderings of his unique 42 meter ultra modern vessel specially designed for inter island trade, fast passenger and cargo transits, solar powered refrigerated and intermodal cargo bay and even disaster rescue and evacuation relief capabilities and much much more ! Listen to an amazing discussion here !
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Dropbox https://www.dropbox.com/scl/fi/4tjw9okeriq8nmzzgsdtw/Proposal-for-Zero-Emissions-Sail-Cargo-Vessels-in-Barbados.wav?e=2