Anyone have experience useing a Solas Saturn SS on Mercury 05 15 hp 4 stroke?

[Star]

Hi Guys,
I have a 61 14' starcraft and a 15hp mercury 4 stroke with 2 batteries, floor and carpet. It is heaver than most boats this size. I have a Mich 9x10.5 aluminum prop. I weigh 215#. In cool weather at sea level I turn 21.6 mph gps @5600 rpm. If I add my wife 150#, snacks, and a cooler my speed drops to 12.5 mph gps @5300rpm. If I change to a 9x9.5 I can get to 13.5 mph @5450rpm. The motor trim is set right and cav plate is about 1" below the bottom of the transom. I talked to a salesman about a solas 9.25 x 11 SS he claims that the better dezigned prop will be more efficent and will not deflect like the aluminum doesHe says I should pick up 300 rpm prop for prop. He will exchange the 11 for a 10 if it will not get back to 5600 rpm. Don't tell me to get a bigger motor. I love the 2 gallons of gas I use over a 3 day weekend. When fishing alone it is the perfect setup for me. One more mile an hour and it starts to plane out and my efficeny improves greatly. Anyone with experience with Solas on small motors would be very much appreciated.

 

[Monterey10]

Re: Anyone have experience useing a Solas Saturn SS on Mercury 05 15 hp 4 stroke?

The stainless propellers are thinner. They offer a LITTLE more performance. Personally, I stick with aluminum and have different props for the different loads you may encounter.

 

[Star]

Re: Anyone have experience useing a Solas Saturn SS on Mercury 05 15 hp 4 stroke?

Wow! Monterey10,
That was a quick sensible answer to my problem, thank you. I do that most of the time now but the judder that occures as the rev limiter cuts in bothers me. I guess I just have to back it off a bit, I have always run my 9.5 rude WOT, doesn't that pulse cause engine wear. I guess that the aluminum prop is more forgiving to the drivetrain if you smack somthing.

 

[steelespike]

Re: Anyone have experience useing a Solas Saturn SS on Mercury 05 15 hp 4 stroke?

Your pushing a pretty good load and your slip numbers are really high ,about 22%.
The Solas Amita 10" 4 blade might help improve slip and it should plane easier and maintain plane better.
Also will allow raising the motor higher.If you could get the antivent plate slightly above trhe bottom it should help.
Have you tried trimming in a notch with the added weight,moving the batteries or gas tank up behind the front seat?

 

[Star]

Re: Anyone have experience useing a Solas Saturn SS on Mercury 05 15 hp 4 stroke?

Hey Steelspike,
I have tried raising the motor but I ran into cavition problems. I have had trim all over with no improvement. Bottom is polished.
what would be a normal amount of slip. What is the formula to compute slip. Thank you for your trouble

 

[steelespike]

Re: Anyone have experience useing a Solas Saturn SS on Mercury 05 15 hp 4 stroke?

Pushing a load that is heavy for the horsepower can cause higher slip numbers. 6% would be a really nice number
on a motor that is well matched for the weight. Sometimes you might see as low as about 3%.I think
you might feel pretty good at 10%.
You can find slip using a prop calculator.You do need 4 out of 5 performance specs.
rpm,prop size,gear ratio,slip and speed.You had all the "accurate " info needed to get a pretty accurate slip number.
Figuring slip is the most illusive. Lots of times I will use a reasonable slip number to try to see if a setup seems to work.
But you need to keep in mind that any best guess could throw off a calculation.