I always thought the Forstner bits were for drill presses -- certainly other than small sizes. The beauty of the bit was that it cuts a precise, flat-bottomed hole (if held and applied properly).

John, I'd try it with a borrowed bit or two using your intended portable drill. I you do so, try the tests in a manner similar to how you'd envision using it on the boat. You'll likely be on your knees or up against a bulkhead ect.