Your best bet is to just make a small dock. If you don't want to spend time making one just jump off whenever you are close to land.

Without a dock you will have to swim and use the ladder to get back on. Either way, the ship will stay put in the exact location you jump off of it from.

Making a dock will save you a lot of time in the long run. Just line it up to the dock and jump off and on to load/unload cargo. Plus you have the extra benefit of being able to just take off when you want to sail again, vs pushing it back out to sea or rebuilding it, then swimming to it.