Building Fins

Robert H · Post by **Robert H** » 27 Oct 2005, 06:00

I am new to R/C sailing, and am just learning the ins and outs of boat building. I have built a coulpe of US1 meter fins. Both were built with balsa cores, uni-directional carbon, bidirectional 5.7 oz carbon on the bias and then 1.5 oz glass cloth. I didn't vacuum bag either one, but they turned out fairly light and stiff.
I am now building a IOM Triple Crown and would like some advice on building the fin for that. I want it to be as light and as strong as I can get it. So I guess vacuum bagging or some sort of preasure mold is what I need to do? How do you guys build your fins?
Rob

Steve Landeau · Post by **Steve Landeau** » 27 Oct 2005, 19:36

Vacuum bagging is not the best method that I have found. A pressure mold is the preferred method for me, but if you are only looking to make one, it is a bunch of work. There have been successful fins made simply by using 2 metal plates, "wrapping" it around your fin layup, but I have not done this and will leave the intructions open to someone else.
My personal opinion... if you can afford it, buy one from someone that has done the design testing. I think the singlemost important factor in IOM speed is the fin and bulb.

Robert H · Post by **Robert H** » 27 Oct 2005, 20:28

Thanks Steve, Half the fun for me is building my own parts and the other half of course, is trying them out( sailing). I am not going to build any thing to sell I just want to learn the best way to build my own fins.
Can you give me any more info on your methods of building and using a preasure mold or direct me to a site that shows the same? I would appreciate anything. I have not been able to fin anything. Is it a big secret among boat builders?
Rob

spaldi01 · Post by **spaldi01** » 30 Oct 2005, 11:22

Hi Robert

I have built fins in a similar manner to yourself so I am not sure if I can give you much advise. I have tried vacuum bagging the carbon onto my fins. This has the benefit of removing any excess resin and improving the surface finish. However I have recently tried making a rudder in two halves gluing them together and filling the inner void with an epoxy micro balloon mix. This has produced my best fin to date although it could be a bit lighter.

Last year I visited a full size boat builder who was happy to show me all his production techniques apart from those used to make the fins. So perhaps there is a big secret out there.

Regards

Chris

Andrew Baak · Post by **Andrew Baak** » 30 Oct 2005, 15:10

I built a fin and rudder using fairly dense foam as the presure mould. What I did was glass up the wood core, rapped it in plastic then sandwiched it between to pieces of foam sandwiched that between two pieces of plywood then clamped them together over night. There was a lot of excess resign with a little filler after and paint, not bad. I have nothing to compare it two but I like to try building things for my self as well so i am happy. ( the foam and plywood were cut 2" bigger than the fin)