I know that boats are planned for H&H in the future, but what are these plans? I have a few theories about what we might see, and of course I understand that boats are most likely a distant goal. At the very least, we know that they will only appear once deeper water is present.
Still, it's fun to imagine what we'll get, so here's what I'm thinking.
First off, we'll get at least three depths of water: Shallow, where you can walk much like now, Deep, which you must swim* in, and Sea, which is just as impassible as deep, but has other effects.
*Swimming has a constant stamina drain and may limit your actions. At very least, you can't carry things while swimming. If you have no stamina, you start to drown.
Boats can then be defined by the shallowest water they can pass.
Raft:
Moves at a crawl when rowed, but can be polled at a walking pace- though this can only be done in shallows. Holds goods like a cart, or can have a person in a slot. Takes X Blocks, probably no more than two log's worth.
Rowboat:
Moves at a crawl with one rower, at a run with two. Has five slots, only two of which can hold someone. Takes X boards and X Blocks.
Galley?:
Has a sail, allowing it to move at up to a run with the wind, though it's usually a walk. May also seat from two to four rowers. Having two increases the speed by one step, and four decreases the stamina cost of rowing. Can carry up to eight total passengers, each one taking up one of 16 cargo slots. Cannot pass through small areas or shallow water. To build it would take 4 X blocks and 3 X boards, large amounts of flax cloth for the sail. And probably some kind of material for caulking.
Now, all those are doable with the current system; in fact, they'd basically be modified carts (given the ability to lock characters in place on the boat). Now, here's where things get a little more complex- large, walkable boats. That is, a boat surface that you can stand on, and walk around on while the boat is moving. These large boats would almost certainly be limited only to Sea, and would require resources on par to several cabins to build. Further, they would need to be wind-powered, but luckily would be more efficient at sailing into the wind.
A few last notes: Traditionally, it is possible to put a "Boat" onto a "Ship" without sinking either. This is not the case in the reverse. This gives us two items to note; loading life-rafts onto big boats, and a rule of thumb for naming these vessels.
Despite what one may think, it is possible to sail into the wind; by setting the sail right, one can create a suction effect much like the way a plane's wing produces lift, which pulls the boat to one side. Skilled sailors can use this to move at a 45 degree angle into the wind, then swap sides and continue, eventually ending up straight upwind of the origin.