Originally Posted by Kraden313
it actually just sounds like the water is just too cold and our unit just can't keep up.
That may be in part be true but it is not the problem that you are having. If that were the cause of your problem, the unit would be running continuously and you would have a continuous flow of water at your through hulls. The clue to what is wrong is that you do not have water flowing.
But even if your system were running it may not be able to keep up since boats are insulated and water to fiberglass is a pretty efficient heat exchanger. But even so, a water media heat pump should work reasonably well even when the water is close to freezing.
You should shut that system down until you determine whether the circulator pump is working right, and whether you have a burst hose or through hull. You also should check your bilge for rising water.