Anti-Ventilation Plate Foil Appendages

Optimizing the performance of Boston Whaler boats
bobross
Posts: 15
Joined: Fri Oct 30, 2020 6:32 pm

Anti-Ventilation Plate Foil Appendages

Postby bobross » Sat May 08, 2021 6:38 pm

Is there a benefit to installing a hydrofoil extension onto the anti-ventilation plate of a Yamaha 40-HP engine on a 1977 SPORT 13?

Tell me your experience with installing a hydrofoil extension onto the anti-ventilation plate of a Yamaha 40-HP engine on a 1977 SPORT 13.

BACK STORY: have a 1977 SPORT 14 and bought a used 1988 Yamaha 40-HP that had hydrofoil fins on the anti-ventilation plate. I removed the hydrofoil fins to do some work on the engine. I did not reinstall the hydrofoil fins on the engine when I mounted the engine on the boat. I have no complaints about the performance of the boat. The boat accelerates to planing speed nicely. The boat top speed is 34 to 36-MPH.

User avatar
Phil T
Posts: 1743
Joined: Thu Oct 22, 2015 6:08 pm
Location: Currently Kentucky

Re: Anti-Ventilation Plate Foil Appendages

Postby Phil T » Sat May 08, 2021 7:40 pm

You don't need a foil appendage.

If you mount the engine to the transom in the one-hole-up position with the top bolt in the second hole down from the top, you should be fine.

Any tendency to for the bow to oscillate up and down can be addressed by shifting the fuel tank or battery forward a bit.
1992 Outrage 17
2019 E-TEC 90
Member since 2003

jimh
Posts: 9349
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: Anti-Ventilation Plate Foil Appendages

Postby jimh » Sun May 09, 2021 9:40 am

bobross wrote:Is there a benefit to installing a hydrofoil extension onto the anti-ventilation plate of a Yamaha 40-HP engine on a 1977 SPORT 13?
The benefit is mainly to the manufacturer and the retailer.