He says he'll teach you to take his boards and make a raft of them; but, seeing that you know how to do this pretty well already, the offer, though doubtless kindly meant, seems a superfluous one on his part, and you are reluctant to put him to any trouble by accepting it.
Egli dice che v’insegnerà lui a prender le sue tavole e a farne una zattera; ma, giacchè sapete già abbastanza bene come si fa, l’offerta, benchè senza dubbio gentile, sembra superflua da parte sua, e voi non avete intenzione di disturbarlo, accettandola.