Should be the same depreciation percentage on a 2019 Beneteau 38.1 or a 2019 Beneteau 41.1 given that the boats are in similar condition and both are five years old. So, using Beneteau's depreciation estimates, both boats should depreciate approximately 33%. But, sales prices on used boats are predicated on a number of variables including geographic region, reputation of builder, price range, market conditions, condition of boat, popularity of model, and motivation of seller. Probably the best indicator of recent sales prices are from "Sold Boats" publication; you may be able to acquire that data from a broker or surveyor.