If the water is halfway up the pump, it should be coming on. Check the fuse to see if it is blown. There is a float switch in the pump itself and when the water gets to a certain level, that switch turns the pump on. I had a Sportster 4tec and the manual switch did not work for the bilge pump, but it came on automatically if the water ever got too high in there. As long as it comes on automatically, you should not have anything to worry about. You can test this by pouring water into bilge enough to get lower third of pump submerged. You can do this while on the trailer. If the pump is left on and not pumping water, it could burn up and it may need to be replaced. Thankfully, they are pretty cheap, and I would probably upgrade it to a little higher GPH rating, but not too much more as the tubing going outboard is only so big.
