Kallen,
Boy this is a headscratcher. Here is a recap to help me understand what I think is your situation followed by a recommendation.
Issue: performance of the boat from last season to this is horrible, hole shot is sluggish and top end not what it used to be. Never mind what the gauges are saying, you know it and feel it, its different like a badly slipping clutch on a manual car. Only change from last year is the prop was same Dia and Pitch. And based on suggestions, the following have been checked:
- Engine: compression and all else good. Runs smoothly up to WOT. In fact, the engine starts, idles and behaves as it always did. It purrs like a kitten, all seems good. Check.
- Extra Weight, due to possible waterlogged. While possible it’s not probable due to radical difference over the off season and it’s on a trailer. But checked the weight anyway and in line with spec. Check.
- Extra Drag, due to hull fouling. Again, while possible it’s not probable due to radical difference over the off season and it’s on a trailer. So checked the underside and all is good, no delaminating materials, etc. Check.
- Prop Flo-torque Hub. Prop hub checked good. Check.
- Drive Coupler. While you raised this as a potential, I was only aware of their function but have no experience with them, so started doing some research. As you suspect its is a coupling device that has a metal tube in the middle to accept the drive shaft spline, which in turn is molded to a ball of rubber, which in turn is surrounded by and bonded to a metal ‘cup and plate’ that bolts to the flywheel. All this adds up to a device to account for miniscule misalignments (nothing is perfect) and engine vibrations. Can they fail? You bet. But their failure is normally accompanied by smell of burning rubber and lots of smoke. Additionally, while I do not have any experience in this, I would bet that once it started failing it would rapidly fail completely under any significant load. Back to the slipping clutch analogy > you may be able to idle your way down the street but try to get on the freeway and you’ll sit there. But you had no smoke or smell, and you can still get around. Hmmm.
Logically it seems as if all is exhausted, so I am going to suggest a different logical approach: your new prop. From last season to this season the only thing that changed was the prop. While you intended to put on the same D & P perhaps its not due to mispackaging or some such.
Thus, my suggestion is to switch back to your old prop with a brand new Flo-torque Hub (I understand the current one is good and normally only do one change at a time for troubleshooting, but humor me and please change it). Also, with white paint, put a line on the outer hub of the prop that lines up with the rounded end of the cotter pin. Idea is to see if there is some slippage issue between the prop and its shaft even if all looks good.
Launch boat, have fun (I hope!) and report back.
Good luck!
