Re: what are the advantages and disadvantages of hydrofoils
I have used Boston Whaler 16/17s both with and without hydrafoils. My hydrafoils were all SE Sport 300s, so I can't tell you what others would do.
One boat had a Merc 90, the others had a JohnnyRude 70 and a Suzuki DF70.
Compared to performance without the foil, the performance with foil was as follows:
Plane at about 15mph vs 20mph. Get on plane noticably faster.
No change, none, in top speed. Would cruise at 30mph at about 4500rpm vs 4900rpm.
Know it all onlookers often told me that the foil would slow the boat down and decrease fuel mileage.
Optimizing rig was different than optimized without the foil. AV plate was abut 3/4" higher, optimum prop on the Suzuki went from 17" to 18".
The Whaler with the Suzuki had a 4" setback plate. The 375# engine made the advantages of the foil very important.
The only real disadvantage I found was the harrassment by KIAs who insisted that none of the advantages existed.