Formula 40 singlehanded trimaran build log

Some progress on this project lately. I've had the cylinder mold segments CNC cut.

 

With all the talk early on in this thread of cost of wood vs foam core, I am curious if you have got a ballpark figure on what this build will actually cost? Thanks.

 

It's about $6400 AUD for the 3mm ply to build the hull shells. I haven't priced out core yet for the hulls but it's considerably more expensive to build a balsa composite hull than stringers. My initial thought is to build the floats with stringer reinforcement and the main hull with balsa core for less interior interruption in the very limited space. Crossbeams are a mixed bag in Australia its less expensive to buy Paulownia for their construction than WRC but the beam scantlings will have to be recalculated for the different material properties.

Hmmm platform cost of materials at a guess somewhere around 40k - 50k. That's excluding rig, sails and electronics.

 

Corley,
Should be interesting to watch, what's your source & species for the 3mm ply?

Regards from Jeff.

 

There are two options I'm looking to use Kokoda 3mm ply which is about $40 a sheet and a little less in bulk. $6400 ~ 140 sheets

The other option is gaboon 3mm ply similar material properties but a bit more expensive. between $7500 - $8400 ~ 140 sheets.

I'm leaning towards the gaboon despite the extra cost because it's properties in the shape developing stage of the CM are more tested. Both options average out to about 4kgs a sheet in weight.

Source is Boatcraft Pacific for the Kokoda and Gaboon.

 

Wow, that's quite a lot of $ for materials on a boat that there isn't much to. I see why so many people try to convince others to not build. It is a lot cheaper to buy a used boat, only seems to be savings of building new vs buying new. I guess I will have to stay focused on Buc. 24 as this would be way to rich for my wallet(especially since there are Condor 40s going for around $60k).

Are the hulls made with a single 3mm ply, then sheathed with fiberglass before vacuum bagging the balsa on the inside? How thick is the balsa and how is it able to bend to match the curves of the plywood.

 

I wonder how your 3mm plywood compares to okoume or hydrotek meranti? Here, I can get 3mm okoume for $46 per sheet or 4mm meranti for $37 those are without bulk discount.
And the balsa, I'm assuming you use a drapable scored scrim type as opposed to solid sheet?

 

There are rumors flying around here that the condor 40s have serious delamination problems in the balsa core and that is coming from a friend of an owner. Boat is/was for sale after it was discovered and repaired at the cost of the company if I remember right. Owner said they are very susceptible to this. I would steer clear if I were you.

Also, hydrotek meranti, while being cheaper, isn't harvested as sustainable as possible in many cases. Its like lauan door skins, its tropical clearcut hardwood. Also, its heavier than gaboon by a long shot, which we all know kills performance.

 

I would think boat this big and cold molded , it'd be multiple layers not single skin hence the amount of sheets?


Barry

 

Hmm, 4x8" 4mm Merranti is only 1 pound heavier than 4mm Okoume. And I was under the impression the Merranti is stronger. The only thing that makes it "heavier by a long shot" is the lack of 3mm option.

However, if they really aren't sustainably harvesting the tropical hardwood, that's a pretty big negative.

 

A pound could end up big though! Thats 30 pounds if it was a single sheet little boat, if it's something like this that might be multilayer cold molded its 140 pounds if single 280 more if double, then your adding glass. Suppose that's some of the best reasoning for DIY, you get to make best choice, and best time is right out of the gate on the materials for best boat. Poor sails can be replaced later but poor hull! Haha

Barry

 

"Also, hydrotek meranti, while being cheaper, isn't harvested as sustainable as possible in many cases. Its like lauan door skins, its tropical clearcut hardwood"


That's ok! They make up for it by sustainable harvesting bamboo only to "soak" it in epoxy to make it even usable! Haha

 

The boat is cylinder molded not cold molded. There are 3 layers of ply on the main hull and 2 layers ply on the floats. My observation from watching the secondhand market is that most racing boats are pretty worn out and often in need of a full refit. When you add the cost of the refit they are no longer a bargain.

 

hey Corley, Are you doing the biaxial mold? I had some distortions at the turn of,the bilges near the ends of the panels using the biaxial. if I had to do it again I would have a dedicated man watching those spots at bagging time, and maybe put an extra dose Of thickened epoxy there on the scarfs.

 

As a reference, I have about $50k into my catamaran. Foam core throughout, inc the built in furniture, 35ft bridge deck type with full standing headroom in both hulls and bridgdeck saloon.

The average cost of a DIY bagged foam core panel, 15mm thickness with 600-gsm eglass each side, is just under $100 per square meter, or say $250 for a 2400x1200mm sheet.

As the stiffness of the panel is rather high, stringers are not required, and the frame spacing can be increased. So the extra expense of foam core initially , saves money later on other material and the time to build it, fair it, and paint it. I don't think there is a big difference in cost at the end of the day...

Sure it's not too late to build in foam core Corley?

I would not have built if I could have found what I was looking for second hand. And all the used boats are heavy, and thus not what I was looking for...