Specs for a Rinker 186 bowrider

nikos

hi does anyone know where to get factory specs on a Rinker 186 bowrider with a 3.0L mercruiser eg prop size and pitch, wot range, 
under load I can’t get mine over 2900rpm and that’s with me only in the boat

Stodge

You should be able to use one of the propeller picking web sites.  If it's a mercury engine and Alpha outdrive check https://www.mercurymarine.com/en/us/propellers/selector/#!/step-one  

In any event you'll need to know the engine and outdrive manufacturer and model and other information like the drive ratio.  The drive should have a decal with the serial number and or that info on it.