Posted by JimM on July 24, 19103 at 06:11:48:
In Reply to: I/O jet vs Prop drive posted by Dave on July 22, 19103 at 18:20:04:
My experience is the jets maneuver like a high-performance roller-coaster. You can turn the wheel hard over at almost any speed and it goes where you point it. May have something to do with the fin and lack of side-forces from a stern drive. IO's (which don't normally have fins) as well as OB's are very fussy in their turns, chine-tripping and requiring very careful control of power. Maybe adding fins would solve that - I don't know.
Being able to turn sharp is a big advantage for ski boats. It's best to drive the boat in a straight line to give the skier time to play. At the end of a leg, the boat should make a very tight jug-handle turn and go back down the line he just came from. This way, the skier never has to cross his own boat's wake except at the turns. Jets are great for this.
As for efficiency, my attitude for a boat like that would be, "Who gives a rip?". I'm not convinced the difference would be that great.
Safety: the obvious choice is the jet, for skier safety and hitting submerged objects. With water-skiing, you tend to always seek out calm water, which is often shallow. The jet is a great advantage. Be careful not to run over your ski rope, thinking there's no prop to foul. We once sucked a rope into the drive and it was a royal pain to get out!
Cost: Jet drive is very simple with 3 moving parts (impeller, steering gate and reverse gate). Maybe only slightly less expensive initially, but very little maintenance down the road (river??).
I'm gonna guess installation is harder for the IO.
One disadvantage: Jets throw a crazy wake. I would never chose one for tournament skiing, especially trick skiing. But for getting out and having fun, they're great.
If you want a good wake AND good maneuvering, go for a straight inboard, like the tournament boats. A fin under the CG, where the engine and ski-tow are, makes for the best ski-boat.
Considering Thunderbolt? That would be the ultimate for me.