I vaguely recall that they did get aboard, but found that the equipment had already been removed. The vessel was being kept tied-up dockside in a very obvious place, amazingly.
They had to boogy out of their real quick, and I remember that there was a little bit of shooting.
The crypto equipment went to Russia so the KGB could exploit the crypto key material they were getting from the spies W/O John Walker and W/O Gerald Whitworth...according to the History Channel.
I put very little faith in any thing Marcinko says about this...