Welcome to the forum. The 11-footer makes a nice tender or small boat. It is certainly a suitable boat for your young son to grow with and be able to use, potentially by himself once he shows the necessary skills. The 20-HP engine should push the hull onto plane, but with tiller steering you may be exceeding the 10-HP maximum power limit. Typically a 20-HP rating would imply remote steering and throttle controls.
Cf:
https://continuouswave.com/whaler/refer ... tions.htmlBe sure to get a short-shaft engine. I am assuming the SUZUKI 20-HP engine will be a pull-start model.
Q2: can the SUZUKI 20-HP engine run without needing a battery?
Also, the hull looks like it needs to be moved forward on the trailer so the aft part of the hull is not left hanging beyond the trailer frame. Once an engine is mounted, you can then assess the balance on the axle, looking for proper tongue weight.
I am concerned about your plan to paint the interior. There appears to be some non-skid sections in the cockpit that are molded into the gel coat. When painting the gel coat you will probably have a tendency for the paint to fill in the low spots in the non-skid pattern, which will reduce the traction they will provide. Also, with use of the boat, the paint will tend to wear off on the high spots of the gel coat.
You might consider the alternative: leave the gel coat in the cockpit as is, but just clean it, remove oxidation, polish to a lustre, and apply wax (which will prevent dirt from attaching), but don't wax the non-skid areas.