Posts: 3508
Location: Elk River, Minnesota | Hiya,
First question: On that tempest prop, are there holes on the main portion of the hub right at the bottom of the fins? If so, that would explain the high RPMs without anything happening. Chance are you can get different plugs that adjust the hole size to set up your motor the way you would like it.
Next, where is the motor mounted on the boat in relation to the transom? Is it tight to the transom? Up a few holes? Setback plate? All of those things can affect how the boat performs both at top end and at hole shot. If the motor is too high, the prop will just spin easily without grabbing water. Trim angle can come into play with this as well...if the motor is not trimmed down as much as it could, it may essentially allow the prop to break loose.
As was mentioned as well, if the motor is mounted using the designed bolt holes on the motor without a jack plate (setback plate), the potential of having a spun hub is definitely a possibility. A spun hub will usually show up at hole shot, but it will also show up under high load (midrange throttle as well). If you get the boat up on plane, back it off just a touch to where the motor is really working to get the boat up....if it has trouble there and spins higher RPMs, a spun hub is looking more probable.
That tempest prop is a good prop. Lots of cupping so it should grab well at all trim angles. If you have access to a prop shop, bring the prop in and see if they will take a look at it. The pitch you have should be pretty close to what you will need, and if memory serves me correctly, that motor will have normal WOT at 5500 or so.
If you have a buddy who has a similar sized motor, see if you can borrow a prop of the same pitch (even aluminum) and see if the same thing happens. If so, then I'm betting it's not a spun prop...
I'll try and keep in touch if you'd like...I love this kind of "tinkering" to get the most out of the boat. That rig overall is a solid rig too... I've considered looking into a 692...
Steve |
