When you get the mission to find the Block and Tackle from the shipwreck, do it immediately. if you choose to go exploring before hand, you could encounter a bug which halts gameplay and makes obtaining the compound bow impossible (atleast until its patched)
There is a cliff face which should only be accessible with the compound bow, however with a little patience, thinking outside the box, and use of the rope arrow, you can pull the boat over to the cliff face and climb it, triggering this bug. when you get to the top of the rock, the game assumes you have the compound bow and progresses, even though the objective is still to get the block and tackle. when you try to retrieve it from the shipwreck, the mast it is hung from has already fallen, and there is no block and tackle there.