New Design TMS-20 Racing Trimaran

[Samnz]

Originally Posted by themanshed

In question of AMA / hull volume percentage how is the volume calculated?

I'm also looking for suggestions on Carbon Tube contruction.

calculate weight of boat sailing including crew vs the volume in kgs of the float.

i.e 500kg boat with 1000kg floats equals 200% boyancy in floats.

less than 150% floats will make it almost impossible to fly the main hull, less then 200% and you still will barely see the floats when flying the main hull, 300%+ is required if your planning on sailing around with the main hull out (i.e seacart 30)

[themanshed]

Thanks Samnz,

Very rough calculations put me at 300% - 350% if I leave the grog on shore. Looks like I'm flying.
Boat and crew less then 1000lbs that allows for 500lbs of designed weight (before carbon and foam design change), and 500lbs of crew.
AMA's had 1400 lbs displacement each before 3 inches of additional freeboard and 1 inch of additional beam was added in with design change.
I was told by Kurt that it will easily fly the main hull.

Carbon tubes anyone? I've read several article on Shrink-Wraps, "Chinese Finger Tubes", and the stand-by of vacuum bagging.

[themanshed]

Ok starting to feel a bit better shoulder is working now so I'm back at it....slowly. The Farrier guys will have a go with this post. Starting to bog out the outside of the hull. The foam and glue sand at different rates so I gave it a basic shape with an in-line air sander. Now a coat of bog and it will all sand evenly.

[redreuben]

I would have to disagree with your sequence here, I would be glassing the foam first before screeding with bog. If you have a few rough areas/edges after shaping the foam bog and then glass over wet on wet.
I think this sequence has the potential to get very ugly not to mention heavy.
When using foam like this the filler/ adhesive used when joining the foam only needs to be as strong/dense as the foam itself, same with woodstrip too actually. Good luck!!

[themanshed]

Well taken but it is easier to sand bog and foam then carbon fiber. The key is to have it very fare before vacuum bagging on the carbon skins. Once the skins are on you do not want to sand them. It will only have two layers of 200gram carbon not much to fare out without cutting into the skin. I spoke to my NA about this process this is the proper way. Most of the bog will be sanded down in the faring process. You want a smooth void free surface when vacuuming skins.

In the ideal world you are correct I wish my mold was that fare. The attached pic is the inner hull before carbon as you can see there is not much bog after the faring process.

[redreuben]

Fair enough! I would never advocate sanding into carbon it costs too much to turn it into dust! Can you apply the outside skin without overlapping joins or do you rebate them into the foam?

[themanshed]

I will rebate the overlap into the foam. Once I have this side fare and my shoulder heals a tad more I'll start the other side. I need to foam it still. Then when both sides are foamed out and carbon on the inside I need to fit the bulkheads and fore spare then join the hulls. Once the hulls are joined I will laminate the outside. I want to lay-up the deck on both hull half’s as one with one run of carbon. So then I’ll cut my rebate when I can actually fit the cloth. On the deck the carbon is from 2 –4 layers. On the hull sides it is 2 layers except for where the beams mount. There will be one layer of 4oz E-glass over the outside to protect the carbon. Between the carbon and E-glass there can be some slight faring if needed at the rebates and seams.

Carbon is costly but I shopped it on the Internet and found a good supplier and purchased a roll at $18 a yard US delivered. I have my contact listed on my website www.themanshed.net The roll was 160 yards so it was costly but not too bad of a deal. I get the Divinecell foam at 50% discount, and 30% off of the West Systems Epoxy. I also picked up a Carbon Tornado Spar , like new - never rigged for $1,300. So all in all for what I have in the boat including NA design fees not that bad. Well my time it keeps me out of the pub.

[themanshed]

Nice article thanks Joe!

http://smalltrimarans.com/blog/

[ThomD]

I like my tube and stays beam on my KHSD 24. Normally beam wall doubles when you go stayless. Carbon is light, but you will also have higher loads on the main hull. The pick-up of using better materials is not always there

[themanshed]

ThomD did you build your boat?