Foils on Stern Drives?

Question

Has anybody attached foils to Stern Drive legs to give extra lift. Or is this only something you do on outboards?

Answer 1

are you talkin about the things referred to as dol fins. they mount horizontally on the lower unit and are advertised to give quicker plane time. my father had them on his 21 ft vip cuddy cabin. they actually slowed the boat down and did not improve the handling. he opted for trim tabs which you have more control over and can adjust according to weight displacement in the boat side to side and bow up or down.

Answer 2

I have seen quite a few attached to stern drive units.

Generally speaking, Hydrofoil stabilizers are used to correct: mounting, under-power, or miss-loading issues with outboard powered boats. Basically they are a cheep way to fix a symptom without having to address the problem.

Stern Drives are less susceptible to mounting issues and more forgiving of underpower and loading problems.  While I have seen people mount hydrofoil on stern drive “legs” I’ve yet to come across one that actually had a positive effect on the performance. The only exception to this would be an older Volvo or OMC unit, which didn’t have trim. In that application it does seem to help lift the stern slightly out of the water. If you have a unit that already has trim and tilt however; it’s a waste of time.

Answer 3

Not done it but it seams reasonable that you would receive the same benefits...cheaper than installing trim plates on your hull and drilling holes.

It'll be interesting to see if anyone has done it.

Answer 4

I was a captain and marine mechanic for the USNPS. We tried the foils on a portion of our fleet of boats and we found no appreciable difference. We stopped the testing after one year.