I spent some decent time redoing my old boat and a lot of thought and thinking went in before the doing.
I can tell the polyurea spray is a superior idea from the standpoint of time, personal effort expended and product quality and final results.
With a wooden boat you can coat the outside, but if you do nothing with the inside then the rain will come along and rot
If you took a wood hull and completely exposed the interior
framing with good access, did required structural repairs
, thoroughly cleaned the interior
likely by pressure washing
, scrubbing with detergent, etc..., might need to pull out the machinery and fuel tanks
to expose the spaces.
Let it thoroughly dry out completely.
Then you could EASILY spray the interior hull and exterior hull and expect a fully sealed and rot proof and very strong boat.
You could even using cardboard boxes form up interior flotation spaces on a large wood power boat
and I think make it unsinkable. The wood hull itself floats and mostly the large fuel tanks
will provide lift
(6 lbs fuel per gallon versus 8 lbs per gallon of water means you got 2 lbs flotation. So if you had a 300 gallon full tank of fuel, you have around 600 lbs floatation in a full tank, much more if empty) You need to overcome the weight of the machinery and other metal gear
on the boat, perhaps about 3000 lbs of flotation needed. What I mean is watertight bulkheads, divide the boat up into about 4 or 5 compartments, each compartment will have to have a bilge pump
. Also you can design in closed totally sealed compartments. My boat has a lot of bilge
space between framing that is mostly just air and nothing else is there. All of this could become builtin flotation chambers.
Even a heavy keel
sailboat could benefit from watertight compartments to limit flooding taking the whole boat down.
With that it might be impractical to consider.
But if you can keep the hull from cracking open then it just wont sink. If you pop off hoses or get swamped in a fierce storm well, it might go down.