Prop shopping... Need advice

[EJ3]

So I am trying to figure out what prop to get for my 1997 60hp Merc 2-stroke. It is on a 15' VIP Seasquirt CC.

Here's the story...

Bought the boat.

Didn't change anything and on the water it ran WOT at exactly 5500 rpm and 31 mph (gps).

Thanks to tubing and weeds I spun the prop it came with. It was a Michigan 10 1/2 x 13. But something makes me think it was already spun a little bit prior to this.

I bought a Quicksilver 10 3/8 x 13 prop and on the water WOT is only 5000 rpm. Unfortunatly I did not have the gps with me to get the mph.

Does anyone think the same as I do? That the original prop's hub was slipping a bit getting me 5500 rpm and I should drop the pitch to 11? Or that there is such a difference between the 2 manufaturers and that is whats causing the rpm drop?

I use aluminum props if that helps!

 

[K.P.]

Re: Prop shopping... Need advice

Props are not all created equal, even within the same manufacturer. You said you bought a Quicksilver aluminum prop, but was it the Black Diamond or Black Diamond XT? The physical blade size of the XT version is larger than the regular Diamond. That would definitely cause reduced RPM. The Hustler Aluminum props I tried for awhile turned at a lower RPM than the same size OEM Suzuki prop. But the Hustler made up for it's lack of RPM by being slower, having poorer hole shot and was far less durable.

It is possible the Michigan had a worn hub but I'm guessing 13 pitch would be about the right size for your rig. Maybe 12 at the lowest. Verify if the Quicksilver was the XT or not and see if you can exchange that prop for either a regular Black Diamond or some other brand.

 

[rndn]

Re: Prop shopping... Need advice

Once a hub starts slipping, it doesn't last long and will not slip to give you a higher rpm at WOT. As stated above all props are not created equal, so it is very possible and probable to get different performance numbers from different prop mfg's.

 

[steelespike]

Re: Prop shopping... Need advice

It seems to me 5,500 rpm and 31 mph is kind of slow.Also seems a a 60 on a 15ft would produce something closer to 35-40.

 

[EJ3]

Re: Prop shopping... Need advice

It seems to me 5,500 rpm and 31 mph is kind of slow.Also seems a a 60 on a 15ft would produce something closer to 35-40.

I would like it to do 35-40!!! I have not had it that long and still playing with "the setup". I recently lowered the motor on the transom and that did several things, such as raise the back end out of the water a bit more and corrected the leaning the boat did while underway. I usually only have 2-3 people on the boat, including me, and some fishing stuff.

Any ideas on increasing the mph? Any advice would be great!