She was injured badly (killed?) and he didn't want to get in trouble for spousal abuse. If she was still alive, he told her he would drive her to the hospital, but instead, he took her to his warehouse and killed her and prepared to dispose of her body.
He took the truck and dumped her weighted body in some isolated watery area.
He then put his boat in the water at the marina and went to the isolated area to tow the body to where he finally left it.
No body in the boat. No evidence in the boat for the cadaver dogs.