A tragedy for sure. But in terms of any murder mystery scenario, the guy was an absolute fool. Every part of his plan was stupid. According to every murder mystery I have read, you never do it on the Honeymoon. It doesn't work. An that applies both ways, to the bride or the groom. The detectives always figure it out.
Also as a sailor, how could he not know that the catamaran's hull would float. I can only assume that he thought it was going to sink and would never be examined.
What an idiot. Not only is he a murderer, but he is a dumb murderer.