I would use 2/0 but....
you might be able to get away with 1/0 depending upon the exact total round-trip distance (battery to windlass back to battery). Given the current draw that should be in the windlass spec, common wire tables will specify the wire size required for an allowable voltage drop. In the absence of any current spec, I would assume a max current of 150A. I also prefer a voltage drop of no more than 5%, but some sources feel that 10% is acceptable for motors.FWIW, Hunter had prewired my 40.5 from the bow to the engine compartment with 2/0 cable.The most economic source of quality cable that Ihave found is Jamestown Distributors in Rhode Island.