Open source 12-15m high performance/semi-cruising catamaran design

That's why I was trying to get a few people together, good discounts when you buy in bulk. When I built my little skiff I was paying close to $90 bucks per gallon for epoxy instead of buying in 1000 kg qty for less than half that. The PVC core, same brand as distributed by Gurit can be had for the same type discounts even more actually. Glass as well but I doubt in Australia which is strange considering China being so close. I may end up having to build two shells just to make it worthwhile lol My friend Mario was looking for a cheap place to build in but without any luck last I heard.

Now I have another possibility if Croatia falls through, Chile. My brother's x wife is from there and well connected. Her boyfriend is one of those canoers that competes internationally. He is from Tahiti and was asking me if I would want to do the charter business there, showed me some pics, beautiful as well. I think would be nice to build there but don't know about materials and other resources.

 

My prices for materials as follows and is what i base my estimtates from;
Epoxy= $12kg
Glass = $5kg
PVC Foam sheets 15mm = $145 20mm = $185


These are good prices here in oz, ill send you the spreadsheet with costs accounted for and also quantities required to infuse all panels. We can go through the entire process again with your design if you send me the file...

 

$12 per kg is much better than I got it but I bought in small qty. Mario was quoted as follows
HP-HE3000GL-200 1000Kg in steel barrel Price: 5,60€/Kg
HP-HTE200GL-200 300Kg in steel barrel Price: 9,89€/Kg

Did you include hardner in that $12?

The PVC foam sounds expensive, maybe that is the linear stuff?? That's almost what I was paying for corecell. I just found the price for the pvc for the 12mm it's 14.4 eu m2 and for the 20mm it's 21.5 m2 so about $65 per sheet for the 20mm ... That is more than half savings on the core and about half on the epoxy. Glass was pretty cheap too, big advantage to buying in qty.

 

Yep sounds about right - Australia is very expensive for most things, the epoxy was made here so import amd currency exchange didnt hammer rhe price... PVC foam must be imported as its always been off the chart here, i used to drool over imternet prices id see in europe etc...
Only gonna get worse for us too, our dollar is down near 0.7usd and 0.5euro... outboard motors here are approx double what you pay in the US... no wonder do many boat builders left here and set up shop elsewhere... were rapidly becomimg tenants in our own country and good for nothing except digging or drilling holes in the ground and sending the product offshore and back to the landlords... thats my rant done for today

 

Ouch! My boat won't cost much more or maybe less than yours if that is the case, that hurts to even think about it, that is what I call true sin.

I was messing around taking dimensions of the interior, it's tighter than the SIG I believe )) ... This is what I think of when I think of a race boat, it should hit 30 knots pretty easy but how long do you plan to be on this boat? One week I can see, after that I think it's tough.

The bulkhead cutouts are a cool timesaver but all the deck levels are going to be a pain, you better do everything you can to avoid fairing! lol. I will continue to play with it and get some renders.

 

Yes i beleive you are correct- this hull is a little tighter than the sig by my dead reckoning and also the published length to beam ratio. The sig is 12 or 13:1 IIRC whereas this boat is a touch under 15:1. The sail plan is almost identical in area except the sig uses a higher aspect plan on a 10ft taller mast.

Id love to see what you can do with the interior area just forward of the companion way. There's shoukd be just enough room for 2 benches down each side using 450mm depth drawers- bench width of 500mm.

I know you dont like the steps in the floor levels, but its a nessesary evil to keep the windage low and still have full standing headroom of min 6ft 6in throughout... otherwise the hull gets too tall.

Its going to be interesting when you compare surface areas from this to your design. I think your going to get a fright when realise how much more surface area your boat has and every sqft of surface area has a $ figure of construction time and money that goes with it

I lived on my previous boat for a month with 4 people and i found it to be perfectly fine. This boat is considerbly bigger than that so its not a problem for my tastes. One thing i really missed on the last boat and living at sea was a washing machine. Next boat will definitely have one
Provided you have good silent energy generation, endless freshwater via a watermaker, and hot water, life is pretty comfortable out there...

 

this is one idea. 1.9m long by 70cm wide cuddy projects out over the bridgedeck and provides seating. On the inside, the other 70cm half of the double bed folds up against the hull and the table folds down. The bench seat provides support the bed and seating for the table. Yes the mattress is split.

 

Looks good, but dagger foils (lifting, leeway and steering) are an accident looking for a place to happen. They add a lot of weight and cost to make them strong enough to hit something and survive at 20+ knots. The cost of 2 curved boards, each capable of carrying 6+ tonnes, plus beefing up the boat to carry them will be significant. I agree that they won't normally carry the full load, but this, plus a healthy safety factor is what they will need to be designed for.
Unless you have a big, expensive rig and the enthusiasm to trim it and hand hold the sheets all the time, I doubt you will go upwind when pitching is a problem, fast and often enough to make much use of the foils.
Pushing hard enough on a reach to need the foils to keep the bows up will end in tears if you hit something. Either something hard like a log or something soft like a plastic bag or weed which stops the foil working.
Inboard foils reduce rm. They make sense on width restricted boats like ORMA's, A cats, C cats, AC and Open 50's. Not so much on other multis, less so on cats than tris.
Safer, easier, cheaper, lighter and probably faster to add 2m to the bows.
All IMRHO

Where are you getting infusion epoxy for $12 per kg? Or is this $US, which would be $AUS16/kg, which, incl gst, is still pretty good.

 

Ill send you an email Rob - i buy epoxy direct from the manufacturer and yes price includes hardener ie mixed system price. Its a di functional system where you have 1 resin and 2 different hardeners. 1 hardener if for infusion and is low visc, the other is a higher visc and use for hand laminating, filleting and tabbing etc... Price is by the 225kg+65kg pack. Mixed for infusion, its not as low visc as many others out there such as ATLs but still low enough to work very well on the usual flat panel infusions using transfer mat or infusion grid scoring. Im not sure it would be low enough for a very thick carbon laminate such as a mast as i beleive you can get fiber lockout unless the resin is very thin...

 

Is the base a seat with the backrest flipped/

A Washing Machine for dishes or clothes. I always take my clothes into the shower with me lol. If you mean for dishes I agree, just a drawer size one is all that is needed.

Yeah sq footage will be more for sure, also you don't have a BD or Roof, but on the hulls, yours are actually 2" taller at the bows and only about 10" narrower. With my costs for materials a little more than 50% less than yours, I should come out way under. I will try to get the materials list to be sure.

By the way I got rid of the glass and the aft salon bulkhead making it much more open and added a simple structural support for the roof for the unstayed mast. I like it better! Will try to get renders tomorrow.

 

The bench is a freestanding object.
The idea is that when the bench (base) is stowed the backrest is dropped down (flipped) so you can sit on the bench (facing outboard) without having to turn the bench around. Does that make sense?

 

Nice idea mate, it would work great on a small hull, however as this is a 50ft hull, theres enough girth to fit a queen bed within the hull without any protrusions.

One thing i learned when building the last boat was to minimize edges. Edges take alot of time, especially the internal cove edges. Fairing them to prepare for paint is very time consuming and takes mamy steps to get them looking perfect as they have to be to accept a gloss paint. I really think its a good idea to minimize the number of intersecting edges in a design if you want to keep the build time down.

To summarise so far;
The design is 100% flat panel (developable) surfaces - save the hull shoes which are all compound curved.
Once the shoes are completed via strip plank foam on frame/batten former, they are turned and rested in cradles. 4 Female cradles support the shoes and define the topsides. The full length topsides are lifted into position and pulled together inside the female frames so the panels themselves act as fairing battens.
Once locked in position the join to the shoes is glassed along the waterline.
Starting from the front, each finished bulkhead and floor panel is dropped in and bonded working backwards as you go for ease of access through the transoms. Furniture added also as you go.
Once conpleted, add the deck and coach house.
Both hulls done simultaneously with the main connective bulkheads done in turn with the others.
Hull to deck join hidden behind chamfer panel with lighting.

I have another construction /engineering idea which im looking into which means no painting inside the boat- at all. All in all , it should go togeather very quickly compared to other 50ft cats...

 

You are right about that, the design is for a 10.5m cat. The two unstayed masts disturb the aft spaces hence the need for the bed in the wall.
Your idea would not be melamine sheeting on the inside? Form the hull with flat developable melamine panels (CNC cut) that have matching square interlocking teeth, say 1 cm deep. The panels are lifted into position and meshed together. carbon tow is then woven on the outside around the teeth to tie the panels together. The bulkheads are installed. The top decks are added. The teeth are partial cut back and the foam sheets are butted together and glued to the back surfaces of the melamine sheets. The foam sheets are faired and glassed over. The color and patterns available with melamine sheets should produce a very comfortable appearance and flat surfaces without painting. Well that is the idea. Too heavy?
This is a developable hull/keel 5 segments before and after the break

 

No thats not it

The idea just removes the traditional tabbing of bulkhead to hull type joints. These need lots and sanding and bogging repeatedly before finally painting. My idea means you can prefinish all panels before installation , then the bulkhead to hull joints added without sanding and pqinting etc. They are simply finished, ready to go...

 

interesting. Preform the bulkhead landings and glue them to the flat panels prior to installation in the mold. The bulkheads then simply slot into place?