IOM Fin material

Maurice · Post by **Maurice** » 13 Apr 2005, 08:02

Perhaps someone may be able to settle a discusion that is current in our club at the moment, are alluminium finns allowed in the rules ?? and if so is any one using them in competitions' ?

edmorales · Post by **edmorales** » 13 Apr 2005, 08:31

having aluminum as a keel fin and lead as ballast in the presence of water can cause the aluminum to corrode due to galvanic process. disimilar metals are not recommended to sit next to each other unless either is coated with dacromet.
ed

spaldi01 · Post by **spaldi01** » 13 Apr 2005, 09:32

Aluminium fins are allowed there is a boat at our club with one

Steve Landeau · Post by **Steve Landeau** » 14 Apr 2005, 05:06

edmorales wrote:having aluminum as a keel fin and lead as ballast in the presence of water can cause the aluminum to corrode due to galvanic process. disimilar metals are not recommended to sit next to each other unless either is coated with dacromet.
ed

True, but in reality our boats spend very little time overall in the water. Aluminum fins are used commonly here in SoCal, and I've not seen any negative issues.

edmorales · Post by **edmorales** » 14 Apr 2005, 07:58

how can the desired thickness/chord/foil shape be achieved on an aluminum billet? cnc milling? casting? drop forged? will a flat plate be effective? what about torsional stiffness?
ed

Maurice · Post by **Maurice** » 14 Apr 2005, 10:06

ED i WOULD COVER THE ALLY PLATE WITH FIBRE GLASS AND RESIN . THUS BEING ABLE TO GIVE SHAPE , STIFNES, AND PROTECTION FROM THE ELEMENTS. THANKS TO EVERY ONE FOR THERE COMMENTS.

Steve Landeau · Post by **Steve Landeau** » 14 Apr 2005, 16:44

The ones I've seen are milled.

Post by **Chairman** » 14 Apr 2005, 20:55

edmorales wrote:will a flat plate be effective?

A flat plate as a fin can be remarkably effective, especially if you do your best to round the leading edge, and chamfer the trailing edge. It'll never be as good as a "proper" foil with a "proper" aerofoil section, because it will stall rather early, its maximum lift will be modest, and it will give generally higher drag throughout. Apart from that, no problem!