December 20, 20223 yr Reading JT’s post, I absolutely agree on his points about weight. 100g is only 2.5% of the minimum IOM weight. It’s hardly worth worrying about for club racing. You can lose more time fluffing a tack, choosing the wrong end of the start or simply not setting the boat up well in the first instance. However my understanding from DavBS’ earlier posts is that the boat he was considering is 25% overweight. If I’ve got that right, that’s 1kg and maybe it really is a bit too much to contemplate for club racing.
December 20, 20223 yr 5 hours ago, Martin Brooking said: Reading JT’s post, I absolutely agree on his points about weight. 100g is only 2.5% of the minimum IOM weight. It’s hardly worth worrying about for club racing. You can lose more time fluffing a tack, choosing the wrong end of the start or simply not setting the boat up well in the first instance. However my understanding from DavBS’ earlier posts is that the boat he was considering is 25% overweight. If I’ve got that right, that’s 1kg and maybe it really is a bit too much to contemplate for club racing. In many one design dinghies the weight of the fastest crews can vary by 10 to 15 kilo. OK that weight can be moved around to advantage but it shows that " all up" weight is not the final decider
December 20, 20223 yr 6 hours ago, Tom Roberts said: Not sure about other classes but i am glad the IOM class rules leave the door open for the home builder. If what you are saying is correct ( and i have doubts about the stiffness ) it means that sailors are in the hands of a very limited number of people with access to complex molding facilities and an autoclave. Surely this means that for these classes it is expensive and is a limiting factor on development and class numbers. The option to turn a design idea into a working model is just not there. Sorry, but i just like wood. Home build carbon fibre isn't that hard using either a male or a female mould. You can make a plug exactly the same way as you make a wooden boat, but most people use foam and then skin it with glass cloth. I used a male mould and a vacuum bag and the shell for my 10R (no internals, no ends) came out at 275gm. Male moulds are easier for vacuum bagging but need a bit of work to get a good surface finish. The weight of the shell has gone up to about 320gm after filling. I'm hoping the complete hull will come under 500gm.
December 20, 20223 yr I would be interested in seeing the construction of the overweight boat. I cannot see how that much material can be added to make up 1kg ??? Have you checked the scales ?
December 20, 20223 yr Author es, that's dead right. I was hoping someone would find me a solution, such as drying out or removing wood, if the boat was made from solid wood. However, it seems that 1kg is several bridges too far. I look forward to building a boat one day. They do look gorgeous.
December 20, 20223 yr john949 You are quite right, i have made glass boats using both male and female molds. My wooden IOMs come out at about 600gms so you have done well to get a 10R out at about 500gms ! As you say the key for IOMs is to make a fair stiff hull to a good design and keep the weight to minimum and in the middle. Like to see a photo of the 10R in build. I tried making a balsa hull to see if i could get one ultra light, by the time it had sucked up my stocks of resin it was almost the same as cedar ! Tom
December 21, 20223 yr Here are a couple of pics of the hull so far. I think I'm going to struggle to make 500gm as I keep remembering bits of structure that need to be added. If I include the rudder and a paint job then 600gm is probably a more reasonable target. As you can see it has both conventional and swing rigs, which adds a bit of weight. The hull is made with two layers of 180gsm carbon/twaron (same as kevlar) and the braces, mast and keel boxes are a carbon sandwich construction. The plug is in the background. This is glass cloth over XPS foam and took about a week of sanding / filling to get correct. If I was charging for my own time it would have been cheaper to get it CNC machined from a lump of aluminium! I did also think of having it 3D printed but it would still have need quite a bit of work to finish it. The mottled finish is the remaining filler after sanding. My partner wants me to leave it like that as she thinks it looks like a U boat.
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