It's time to get a new prop

[walleye1968]

Hi guys
Im looking to get a little more speed and RPMS out of my boat
Its a 2001 16 foot sylvan explore sc
About 850#
2001 40hp merc elpto
It has a black diamond aluminum 10.5x13
By GPS it runs about 26 mph at about 5100 RPM
RPM Range is 5000-5500
20 gallons of fuel
Four batteries two in back two in front
One person about 220
I was thinking of going to the solas new Saturn 11-1/8x13 ss
Or should I go with a 12 pitch to get RPMS up


Thanks for any help
ken

 

[tpenfield]

Re: It's time to get a new prop

Sorry to burst your bubble, but since your engine is already running in the specified WOT range, you are not likely to see any speed improvement with changing propellers. The 12 pitch will get you to the high end of the RPM range, but probably no significant change in speed. I'm thinking the 11.125 x 13 may actually slow things down a bit. . .

 

[steelespike]

Re: It's time to get a new prop

That boat is a real load.Slip is a little high at 17%
I'd like to see if we can get a little more from your present setup?
Why 4 batteries? The antivent(cavitation) plate just above the prop should be even with or slightly above the bottom.
Are you sure the throttle opens all the way?Is the bottom clean and smooth?
Have you adjusted the trim for best speed?

 

[walleye1968]

Re: It's time to get a new prop

Yes the throttles open all the way
2 of The batteries are four a 24 volt trolling motor
1start and 1 four electronics and lights. the speed listed above is at that Max trim

 

[steelespike]

Re: It's time to get a new prop

Is the antiventplate even with or slightly above the bottom of the transom?
Its difficult to tell what the changes will be when going to a ss prop.
Its my feeling that the Saturn in a 12" should get the rpm up and the slip down.
should improve hole shot maybe add a touch of speed.
I do wonder if maybe your using some horsepower to get the bow up
by having to run full trim. A 40 isn't like a 100 or 150 that can get the whole boat up.
I had a big 15 foot kit boat with a huge front deck , as a kid, and had to run the 18hp in the 4th notch to get the bow up a little.
Im sure I could have done better if the bow was lighter with less trim.
Maybe you could do a test run with the front batteries closer to the mid section of the boat.

 

[walleye1968]

Re: It's time to get a new prop

The plate looks to be about 2 inches up from the bottom of the boat
the bow of this boat sits lowin the water with or with out the batters
i will try to move them all the way to the back
cant do a test run lakes still have ice 0n ramps

 

[steelespike]

Re: It's time to get a new prop

Wow 2" up is exceptional. Are you looking at the plate just above the prop?
Probably no place to put the batteries in the midsection somerwhere?
Seems like all the batteries in the stern would turn the boat into a dog.
Maybe try both locations when you get to test.Don't install just set up for the test.

 

[walleye1968]

Re: It's time to get a new prop

Yes 2 inches up to the bottom plate
going to try to get on the lake tomorrow After work
We've had some pretty good northwest wind the last couple days should Below the ice out
Will move batteries around To see what happens
Will post results tomorrow night if I can get on lake

 

[walleye1968]

Re: It's time to get a new prop

was able to get on a lake for a test
air temp 43 water temp 36 wind sw 5
test 1 batteries in the middle of boat 28mph by gps at 5400rpm at max trim
test 2 batteries in the back of the boat 27 mph at 5400rpm at max trim boat bounced reel bad

 

[steelespike]

Re: It's time to get a new prop

Great job.I think 28 is respectable. And rpm is close.
I think the gross weight is almost 1600 lbs.
Slip is a little high but to be expected with that load.
Can't predict the results with a ss prop but I think I would try a 13.
Sometimes you can find a dealer that will exchange for a small fee.