Fins/foils, do they work?.........
..............and I'm back in the room.
Well well well that was fun. The new fins worked better than expected!
With 2 crew and a full fuel load in the stern (2 x 30lt) not to mention the packed lunches (Beer/crisps/toffo's), we got on the plane almost instantly at 6-7 knots. The fins remain approx. 8" below at this speed, but from 10ish they surface and we are flying along.
We had a total of two weeks of play in various conditions, but in each case we rose above it (pun intended).
5.2m deep V Base Marine RIB
Piranha Fins (composite, two part bolt through port/stbd).
Shaft tucked well under on a stock 'Tohatsu 50' 2-stroke.
Bristol Channel, from F2-4 most of the time to F7 on two occasions.
The basic positive results are:
Nose stays much lower at very slow speeds and stays lower on take off.
Acceleration from just on the plane is much improved.
Gets up on the plane much much faster (almost instantly).
Ride quality is noticeably smoother.
Handling is twice as responsive with extremely hair raising turns.
My 12 year old nephew thinks they look rad.
Get too tight on the turn and the amount of air getting to the prop seems to be double the norm which stops you dead with much wailing and gnashing of teeth.
Although the fuel burn seemed to be about the same, I take the point that anything that potentially drags is gonna cost more. This said the fins seemed to be riding at 'water level' at speed, our need to make distance at 8-10 knots (fins just submerged) might be the real burner. We were having too much fun flat out to try distance at slower speeds!
Hope this helps others, I'll update as the year progresses. Thanks to everyone who has inputted, it just goes to show each experience is different, luckily mines a goodun!!