Raisiing Outboard on Fiberglass Transom

[subir]

Folks,

I have a 15Hp short-shaft Suzuki 4-stroke (110lb) on a 3.5m Westmarine (made by Zodiac) RIB. After using the configuration for two successful seasons, I added a hydrofoil (SE Sport 200) in order to cut short the planing time and on-plane cruising speed. While attaching the hydrofoil, I realized that the motor is sitting little low (cavitation plate below the boat bottom by 2 full inch) compared to the Suzuki recommended level (up to 1 inch between boat-bottom and the cavitation plate). Although I never had a water spray problem, I thought I may be losing some speed due to drag created by too much of the motor under water.

I decided to raise the motor by an inch. For an inch it did not quite make sense to add a transom extender or something that elaborate. So, I put a pice of wood (with two steel plates on top and bottom of the block) with 3/4 inch thickness between the motor and the transom. Then made the clamps as tight as I could. I do not bolt the motor since I take it out during the winter.

The raised configuration looks sturdy, but I wanted to run this by the forum to see if any one raises any safety concern about the motor coming off the transom. I also use a chain to secure it with the transom, but obviously would not want the motor to come off in the first place.

I am attaching two pictures (one from front and one from side). One concern is that if the clamp is getting enough material on the transom to bite on.

Any comments would be highly appreciated.

Thanks,

- Subir

[jyasaki]

I've seen boats run with the gap between the transom and saddle unfilled. If the transom is strong enough to support the motor and thrust, it should do so with the motor raised up a bit as well. Especially so if you're using the same bolt holes.

I would, however, think that if that gap was excessive, and you had holes closer to the top of the transom, you would want to structurally raise the transom height (not just fill it, but make it structurally sound.)

FWIW, West Marine does one thing pretty well: post sale support. Might give them a call.
From the US:
Phone: 1 800 Boating (800) 262-8464
Fax: (831) 761-4421
Email: wmCustomerService@westmarine.com

Luck;

jky