Im assuming that picture is generic, its not your finished boat?
Brushless motors are fine for any application, the choice after the spec is outrunner, or inrunner, the former probably the cheaper and more readily available. Just ensure that you have nothing danging around next to it as the outer can rotates, very fast👍
Water cooling only if it needs it, it probably wont, however you will find that most specific boat brushless escs will have water cooling, if it has it, (hobbyking are best source) then use it, as some of the hobbyking escs rely on this as they don't have cooling plates inside. Its a simple thing to plumb it in, make you own water pickup, and exit if you have the tools, the shop bought ones are cheap, but sometimes look ugly. Simple bit of brass or ally tube, between the prop and rudder, bent to face the water from the prop,epoxy into the hull, some plastic tube (you will have all this from planes!) to the esc, then from esc to an outlet, at transom tends to be the nicest looking!
Consideration is the motor shaft diameter, and the propshaft as you will need a coupling, that's capable also of the higher revving motor.
SHG Marine are a model boat parts dealer, they sell all of the couplingsd etc, propshafts, and usua;lly have a good srtock of plastic two blade "x" props, grab a couple to test with , 45mm, 50mm I woulds suggest
Pics for reference, the HK escs in the pics are bullet proof, I made water cooling plates for the motors on that boat, it didnt need them, and exited the water pickup via the two engine exhausts on the transom, looked cool when the boat was running!, inside the boat, I used alloy rod instead of plastic tube just for ashthetic reasons as it was a four foot boat and a long run from teh pickups to the esc's