Bigger engine

[eyespy999]

Hi I have a 15hp on my 3.11 Avon rib. The transom states 15hp. I could do with slightly more power because of the tide where I live. Could I put a 20 - 25hp on it safely?

Cheers

[spartacus]

You can put anything you like on it but it's likely to invalidate your insurance. Transom weight is tested and if it says 15hp, then thats what you need to stay within. If you need more power, upsize boat, etc.

[lightning]

Be careful with fitting a larger engine than recommended.

I have a Zodiac 2.85m SIB and it is rated to an 8hp. I fitted a Tohatsu 9.8 (weight the same as a 6hp only 26kg)
Your boat will probably have a maximum hull speed rating. Mine is rated at a maximum of 17mph.
This is on the sticker on the transom where it also states the maximum engine power.

The boat performs very well with the Tohatsu, planing very easily and achieving close to 20mph.
However at over 17mph the boat becomes harder to steer and generally feels less stable.
But at lower speeds it is much less noisy and relaxed than with my old 6hp, which was absolutely flat out at 14mph.
I don't drive the boat flat out for this reason, so care does need to be taken when your boat is over-engined.

[eyespy999]

Thanks both for your info. Good advice I will keep things as they are. Regards