He is lovely. If he is scared of the engine noise, (unlikely to happen if you introduce him to the boat and socialise him before he is 16 weeks old), then get him used to the boat without starting the engine.
Then start the engine for a short while and turn off before gradually increasing the run time. All whilst moored up.
Then try moving the bost.
Keep him safely inside when underway, then move him onto the deck but on a leash until (if) he can bevtrusted not to leap off.
As Jennifer Mc M (sorry I missed you as you cruised past earlier today) says, get him a harness or life jacket with a handle on, so you can get him out when (not if) he falls in.
My mate has a 1 year old Rotty who weighs 50kg already! He fell in and it took both of us to lift him out.