With a Fin about 1.5 metres (yes 150cm) and an above water length of less than 15 metres it is probally about effective as a submarine as my narrow boat 16 metres by 2 metes that I patrolled the Lee and Stort Navigation in.
Just compare the man against the boat it more diddy that an x-craft.
I am sure it wil still make the planners think twice about committing a unit without sanitising the area well first.The crew I am sure will be on a one way mission wearing lots of underpants and desperate to do a serious amount of damage!!
There will a delay in sea trials as they are waiting for the arrival of special Mercury outboad motors. It was discovered that there wasn't enough room to place engines inside after they had not allowed for the number of crew required to man the boat