Of the same era as the Caribean Coaster, I made one of those back in the late '50s. There was one for sale last year and there was quite a competition to buy her on ebay. My one is long gone.
I remember the motor I was using, a Kako 4 on 6 volts (dry battery). I have still got it and several other of the numbers including the Kako 5. Ripmax, in Camden Town, was local for me, and carried many of the Japanese motors.
Can't say the Titan tug impressed me very much. Having the kit, if untouched, is best left as a museum piece Just my opinion. I had already made a Vic Smeed tug Bustler which was a much better example.
While at school I also recall buying a kit by Feltra, a torpedo boat, I still have the plans. It came from Gamages in London. Anyone remember the Feltra Banana boat?
In my torpedo boat I had a Taycol Star, which is a permanent magnet motor, but running on 9 volts and my boat planed! Both motor and the 4.5 v flat dry batteries were hot, didn't last long either.
Roy