Re: just bough this "mini boat" (addison addictor)
If possible, post a couple of side view photos showing the lower unit and bottom of the transom. From the angle of the current photos and the set-back of the engine, it looks like it is sitting too low. Click on the photo. If you look closely, you will see how high I have set the engine on this 10 foot tunnel hull.
If your engine has multiple pitch props (and most do) for sale, start by choosing a higher pitch. That is: If, for example iboats offers a 12, 13, 14, and 15 pitch, try a 14 or 15 first. If at all possible buy a used one because there is a slim possibility that you will hit the correct prop on the first try. Again, in the photo, that 10 footer uses a 10 1/2 diam. X 14 pitch cupped prop on a 50 HP engine.
As far as prop selection, you really need to ask on the prop forum. However, I don't see any instruments on the dash. At a minimum, install a tachometer then a speedometer. On the prop forum, they will need to know engine RPM, boat length and weight, load, etc. before recommending a prop.
Also, are you looking to just have a fun ride or do you want to maximise speed?