Keytouch hi and welcome to the forums. My dive club has exactly this setup. Takes 5 divers (6 at a push) travels at 18 - 20 knots with the small prop and all the diving kit on board. Ours is late 80's and an ex dive school boat that had never been looked after in its life! A weekend sorting it out and it has given us 9 years trouble free service.
Thankfully like this one we have a full cover, which probably saved the tubes and boat from the worst of the weather and sunlight over the years.
View it if you can to hear the engine run up and check condition etc.