It's an old Leading Edge, 31 cm.

just check that its not delaminated near the base. If the outer layer of carbon looks cracked 1-2cm from the base its days could be numbered. It looks like one of Brendan Bond's old fins. They were really thick and quite draggy when they were upright. Very stiff. I had a 33cm one that looked the same. You can check by measuring the thickness (side to side) and the length (= chord = front to back) of the blade near the base. The ratio of the thickness to chord is a good indicator of what this fin might be useful for. If its more than 11% (I think mine was 13%) it might be OK as a small raked speed fin if you rebase it. Otherwise if its close to 10% its probably OK as is.

OK, I'll do some of those measurements.
I think I bought this from a guy in a car-park, possibly Robbie Radis, but I'm not sure.

It's 90mm across the chord, and 11mm thick =12.2%
It's in good condition, with no delamination.
It's pretty stiff.

Select to expand quote

slowboat said...

just check that its not delaminated near the base. If the outer layer of carbon looks cracked 1-2cm from the base its days could be numbered. It looks like one of Brendan Bond's old fins. They were really thick and quite draggy when they were upright. Very stiff. I had a 33cm one that looked the same. You can check by measuring the thickness (side to side) and the length (= chord = front to back) of the blade near the base. The ratio of the thickness to chord is a good indicator of what this fin might be useful for. If its more than 11% (I think mine was 13%) it might be OK as a small raked speed fin if you rebase it. Otherwise if its close to 10% its probably OK as is.

just try it then. With that thickness to chord it should be OK up to 40kts. The one I had was a little bit more draggy than some of the other fins I had of that size, but you could really stomp on it and that was a good thing sometimes- eg for fig 8 slalom.

Yup, I'll give it a go.
If I get to 40kts I'll buy a new one.
Some wind would be nice.