Turkey isn't going to do that. They would lose most of those 20 ships then where would they be? With practically no Navy! NATO isn't going to back them up since they would be the aggressor. Also they may make Israel think twice about boarding in international waters. But once those ships leave international waters. Turkey can't do anything without openly declaring war on Israel.
According to Wikipedia this is the composition of the Turkish navy.
Turkish Navy - Wikipedia, the free encyclopedia
19 Frigates
7 Corvettes
14 Submarines
108 Fast Attack Craft