I have just finished a 20cm 47r fin for dezzas new red falcon 49, I haven't used it but I used the plug for the mould yesterday on my naish sp 80 and 5/8 n/p rsr, I was way over finned and a tad over powered with the sail , I was trying to sail off the wind to get to primbee too get the same fin but thinner but was to bugged by the time I got back to head out again
I have 4 versions of this fin, a thick and a thin forward boxed and the same normal boxed , I haven't used the others but arky posted close to a 37knts the last time he sailed with the thinner normal box
theres no weed at primbee this year so there for more chop, so last years 17 & 18 cm fins are on the back burner until the weed comes back
so the ideal fin depth for primbee this year is 20cm+ at 47deg to 45deg , a 20cm fin at 47deg will still get you into some shallow water but much safer in chop
I didn't have any great speeds (32.08 ) mainly because of the power of this fin , the fin has the power of 20 wind turbines and a similar foil ,

While the flying fins board is getting repaired the ground effect thingoe is on the back burner, so I've been concentrating on fins.
Basil has come up with some end grain balsa and I've lashed out $50 on a 5mm x 50mm stainless bar.
So I'm trying something a bit different, but have had in mind for a while, and Basil is the guinea pig.

Basil has cut the balsa to 6mm thick, I'll laminate 2 of them together with glass to make 12mm. This will allow me to shape it without it falling apart at the edges.

I started experimenting with cutting/shaping the stainless today.




I'll get 3 15mm wide pieces out of the 50mm. I'm copying the fin above, as it works well for me with my 5.8 and Basil is about the same weight as me, and wants it for his 5.8.
So I've marked the 5mm thick line on the leading edge of my fin, and copied that onto the stainless. The next trick was to make a 1mm rebate just behind this line. This will allow the carbon/glass to butt up against the stainless at full thickness. So the extremely thin layer that otherwise would be there doesn't flake away.
A mate has given me some milling machine tools to try in the router, good idea but I couldn't get it to work. The tool got too hot and didn't cut very well, so I tried the good old right angle grinder, with much more success. Used a 5mm thick disc to make the rebate and a 1mm thick disc to cut to shape. I'm leaving it attached to the main rod so I can clamp it easily for shaping the leading edge. That's tomorrows experiment.