How to make a smooth-sailing boat using constraints?

I am looking into making a boat system using constraints, that would function similar to what is seen here.

The issue I am having is, trying to replicate this. In the video above, I use BodyMovers’ BodyPosition, which is long since depreciated, and some of the boats seen in the game where I recorded in, they spazz out due to using the ancient BodyMovers.

I tried replicating BodyPosition with a boat model I have, and this is what happens:

Spazzes out still, but at least it doesn’t fall into oblivion.

I use AlignPosition, the recommended replacement for BodyPosition, and it’s useless, as seen below:

What should I do?