Stumped

I found this forum while trying to find information about propping my 115 h.p. 4-stroke Merc.

Last fall (yes, a year ago) I tore up the prop that had been working really well for me. It was a Quicksilver 13.75 x 15P, and had given me very satisfactory performance on my 18-1/2-foot fiberglass fishing boat. This spring I replaced it with the same prop, and immediately, at 3,000 rpm, it seemed to lose its grip (spin out?). Rpm's continue to increase as I increase throttle, but boat speed won't go above 10 mph or so.

Before I start switching out props, does anyone have thoughts why this is happening?

And if I do try another prop configuration, what would you recommend with the setup I've described (Ranger 690VS).

Thanks in advance!
eyewinder

Re: Stumped

Is this a new prop? Is it the exact quicksilver replacement?Is it used possibly reworked?
It could be defective with a spun hub. Draw a waterproof line across the underside of the hub and body and do a test run and check the line.

Re: Stumped

How did you tear it up? Could you have bent the prop shaft ? Does it have any vibration. What about the trim settings? Are you trimmed down far enough

Re: Stumped

It's a new propeller ordered from same website using the same numbers as the destroyed prop (both Quicksilvers--should be identical). I also installed a new flo-torque hub assembly, and was told by an alleged motor mechanic (a guy I hadn't consulted previously) that it was installed correctly.

It doesn't seem to have any vibration and I've trimmed it all the way up and down, including optimum trim setting for the old prop. It runs fine up to 3,000 rpm, where power remains the same as rpm's increase to 5,000-plus.

Almost half of the three blades were chewed up when they came in contact with the transom saver which was still hanging from motor when it was placed in gear and run (that was really hard to admit!).

The previously-mentioned motor mechanic drove the boat for 10 minutes and came back and told me that it ran fine, and only spun out on tight turns when not trimmed correctly. At the time I took him at his word--I should have been in the boat with him. I've run it a half dozen times since, both with and without a passenger, and the problem persists.

I know it seems like I'm saying that there's nothing wrong with the motor or prop, but that they just don't work--that's why I've remained stumped.

The obvious question is: "Why haven't you had someone else look at it?"

I hope to get it to another boat repair guy before putting the boat away for the winter, but where I live (Wyoming), most of the mechanics are working in the energy industry.