Dinghy outboard question

[CanuckSailor]

This maybe oughta be in the engines area, but I'm posting here as I think this is where I'm likely to find the answer.
I've just switched from my deflatable to a 10 foot aluminum boat - it's 81 pounds, has a 3.5 yamaha engine. Moves along well, but I know this boat should plane with this engine - someone suggested dolphins (doelfins) for the outboard.
Has anyone tried these, or similar? Any suggestions? Thanks.

 

[Mark Maulden]

Yes.. I had them on my 14' Avon RIB that I towed behind our Gulfstar 44. Put them on the cavitation plate just above the prop and leave the engine down and locked. It towed great and went up on plane faster and slower. I'm not sure I'd definitively say that your combination should plane.......But they do work

 

[Stu Jackson]

Hmm, pretty neat description of your former boat: I'd never heard of one called a "DEflatable!"

What was the weight of your earlier dinghy?

An 81 pound boat, unless it is a flat bottom skiff - and even if it is, just isn't gonna go up on anything with a 3.5 HP engine, as long as somebody is in the boat working the engine.

There just isn't enough thrust/power from that engine, and the boat's characteristics aren't mentioned. Not all aluminum boats are "non-displacement" hulls.

 

[Bill Roosa]

I'm inclined to agree with Stu. It ain't gona plane with 3.5 ponies.
It is a simple matter of thrust to weight ratios. An English swallow simply can't carry a coconut. and coconuts don't migrate.

 

[Tom J]

Go figure. My old 9' Zodiak with inflatable keel would plane easily with one person on board, using a Mercury 3.3. My new dinghy, a Walker Bay 8', doesn't come close to planing with the same engine and 1 POB. Pretty sure they weighed about the same, but are totally different hull types. BTW, the Walker Bay rows nicely, so I'm not complaining.