Prop Specs depend on Boat and Motor package to start, then the fine tuning of which design of prop to suit your needs. In the 2004 brochure the standard prop for your boat motor package was 15 inch diameter, and 17P.

I don't believe your 180 with a 3lt will perform well with a 21P prop. I ran my Sea-Ray 180 with the same motor using a 17P Hi Five because I needed more hole shot and less top speed. I had a 4 blade 20P but it was gutless on take off, and reasonable top end.

A 21P I don't believe will work as it is to high. I have a 21P, 3 blade, 14 3/4 inch diameter, Mirage Plus on my boat and it is not good for the boat. Slow to get on the plane, low top end and slow to respond because it is too big.
The recommended prop for the Volvo package on your boat is for a 14 1/4inch diameter and 21p. Going up 1/2 inch in diameter is like going up 1 - 2 inches in Pitch so your 21P with a 14 3/4 inch diameter will be like a 22-23P if the spec for your boat was a 14 1/4 inch.

If that Solas prop is a 14 1/8 diameter and 18P I recon it will be ok, but depends on what you want. A 17P prop will give you better Hole shot, whereas a 19 will give you more top end. Depending on the blade design that 18 might give you an inbetween....

That boat came factory with a 14.5x19 pitch prop in 2006
http://www.fourwinns.com/upload/Documen ... s_2006.pdf

I wouldn't go to a 21p if you came with a 19p stock, especially on a 3.0. It won't take off very well.

Thanks Ric.
From your H180 thread you mention you had the 21p prop Solas Amita.
How was that one?
I'm looking for a better take off performance (load carrying capacity) as I often have 4-5 people and some gear and the boat takes forever to get up on the plane.
I don't care about top end at all.