Small Inflatable + Outboard - Fin or not to Fin

[Fire99]

Hi All,

Not a life n death issue but I've a 3.15m Avon rolly-uppy with the inflatable keel tube, running a Mercury 9.9hp 2-stroke. I bought a hydrofoil (fin) for it but haven't fitted yet.
I know there's different trains of thought but what are your experiences on small inflatables + hydrofoils (fins)? I have to admit even as is the little Avon rockets along.

cheers,

Nick

 

[SC35]

Fins can work when underpowered, struggling to plane, as you'll be planing earlier.
But if you are already "rocketing along" I don't think you'll see much benefit, if anything, you might lose a couple of knots at the top end.
A 9.9 on a 3.15m inflatable is a handy combination.

 

[CliveF]

test without first.
Sit yourself in your normal / preferred position and run at normal speed does the boat ride bow high all the time?
If yes fit fins to lift the rear end , if not don't.

Other minor consideration if it does plane already is it really slow to get up on the plane ? if yes the fins may? help.

when i used to have a 16' Strikeliner with only a 25 on the back it did help lift its bum out of the hole.

Regards Clive

 

[chillee]

I used to have a 3m Zodiac SIB with a 2troke Tohatsu 15HP. Bought 2nd hand and came with a fin already on it.
Never took it off, but it went like a rocket, got up on the plane easy as chips with 2 adults and 3 kids, and handled like a go kart.
No idea though what it would have been like with the fin.

 

[Fire99]

Thanks guys.. I bought the Avon as a cheap (ish) tender to potter to shore but it's a handy little thing at speed. I'll see how it planes at medium speed and then maybe try the fin (since I already bought it). I've not had a 2-stroke motor for a while and I'd forgotten how gruff and rorty the little thing is. Quite a bit of fun.. (and light).

 

[rafiki_]

I had a 2.6 Ribeye with a 6hp Yammy. The fin was a significant benefit.

 

[Davy_S]

I fitted an Attwood fin to an Argo hellas 14ft stepped hull fishing boat, it had a Honda 25 and tiller steering, because it was heavy on the stern and lazy to get on the plane, the fin totally transformed it, the handling was improved and getting onto the plane was easy, also it then kept on the plane at a lower speed, it was well worth doing.

 

[Fire99]

Thanks guys... I think I'll have a little experiment with the fin. First do some runs minus fin and then see how the fin performs. 4 little holes in a 1991 outboard plate shouldn't cause too many issues.