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Old 02-02-2010
landmarine landmarine is offline
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Smile 25 foot trailer yacht - Rudder Questions

I have a GRP 25 foot trailer yacht that I'm wanting to improve the rudder on. Basically the foam GRP one I have weighs almost 10kg and is not optimised in shape and its leading edge is 40mm aft of the gudgeon pivot line - It feels like I'm dragging 2 buffalos!!

I intend to construct a new one out of Divinycell (HD) / e-glass / epoxy resin (resin infusion) - and wanted a few tips if possible on the following subjects?:

1) Is the green code Divinycell suitable? blade is approx 1300mm x 360mm - and will need two 20mm thick sheets laminated together with e-glass in between for datum line and strength at the edges
2) What would you recommend in terms of laminate cloths? Someone suggested two layers of uni-glass or carbon followed by a single tri-axial sheet??
3) What additional thickness allowance do I need to make for the 3? skins (what cloth weight should I use)
4) I'm getting assistance from a boat builder but just wanted a 2nd opinion on things - The trailing edge is the difficult one as we need to have a thickness of no more than 1-2mm here. We are using a modified NACA 0012 section with hollowed out trailing edges (concave on exit straights)
5) any other pointers you think might be helpful please??

Any assistance appreciated thanks
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