30hp on a 25 rated boat

[JFISHER]

Hi all,
Just wondering if anyone has or uses a bigger engine than there transom is rated to ?
I have a 4.3m quicksilver with inflatable keel. Transom is rated for 8 people and a 25 hp, I usually only have 4 on maximum but the 25 mariner I’ve got is old and dosent go as fast as I would like. Any help appreciated.

[ChrisParish]

Couple of questions:

How fast is not fast enough. That type of hull won’t do much more than 20 knots.

What’s the weight limit for the transom? When you go over 20hp the weights start shooting up.

Is the engine revving correctly / is it propped right? If you are using high revs and still at a low speed then maybe you need a bigger prop.

Personally, I wouldn’t do it. The extra 5hp is not going to make a huge difference.

[JFISHER]

Hi, thanks for the reply , it’s doing about 22nots a few more would be nice that’s all, if it’s not going to make much difference maby I need to think about getting a proper rib with a 40 or 50. If the transom is rated to slightly heavier weight it should be fine for a light weight 30 shouldn’t it ? As long as the 30 is within the limit ?
Cheers again. It could do with a new prop as it’s pretty pitted and bashed up I guess getting a better prop will benefit. It’s just an old mariner that I don’t really want to pour to much cash into.

[ChrisParish]

If you are getting 22 knots then you are knocking on the max speed for the hull, so extra power would not result in much more speed without effecting the handling to a dangerous degree.
If you want to go faster then you need a different hull.