23 w/225 four stroke - Prop issue

[schooner]

Just repowered my 23 sceptre with a Johnson / Suzuki 225. Mechanic installed a 4 blade 14.5x17. with a 2.3 reduction, this is way underpropped. Numbers are 9 mph @3000 - 15mph @3500 - 19.5 mph @ 4000 - 28 mph @5000 - 31 mph @ 6000

My target was 28 mph @ 4000. Can anyone who is running a 225 four stroke on a 23 share their prop size and speed numbers so that I can see if I'm on target. Trying a 16x17 this weekend. Not sure what to expect.

Thanks

increase pitch to increase top speed and lower rpm. I would try a 19 but a 21 might be better depending on the load in the boat

[FELLOW-SHIP]

A 3 bladed prop is more efficient prop to use as well.

FellowShip

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My motto: Just for the Grins

[gss036]

I would think you should be able to get 40+ with the right prop. Your speeds VS RPM seems awfully low, but I run a 2 stroker on my 23WA and get 42/43 mph trimmed out at WOT.
http://www.rbbi.com/folders/prop/propcalc.htm This will give you a prop calculator site. Maybe that will help.

[schooner]

Tried a 15.5x19 three blade this weekend. 5,500 WOT gave 36 MPH. 4,000 gave 25 mph and 3500 gave 19 mph. Numbers looking better but still a little shy of expectation. Wondering if anyone running a four stroke 200-225-250 on a 23 can share their numbers? Thanks

[Briguy]

Check with trever hicks on this board or look up his old posts.

[ocuyler]

Schooner,

Your motor should WOT at 6000 RPM with a light load, indicating that you still need another 500 RPM or roughly 2 more inches of pitch. The 21" recommendation was a good one.

[schooner]

Otto,
Thanks for the reply. Do you mean 2 inches "less" of pitch or 17" to get the revs up...? More pitch would mean less revs I think. I do see 21 inches on the Suzuki on some performance tests on 22-24 foot boats. Wondering why the Seacraft does not want the 21 pitch. Don't think that the SeaCraft is extraordinarily heavy or has a radical deadrise. I am stumped.

[eggsuckindog]

Somewhat both, they are a pretty heavy and the deadrise needs more horsepower to push. You are correct a 17" will get the RPM up, those Zuke props are funky on the sizes because of the gear ratio I think.

Pitch is the distance the prop would move foward in one revolution. So if you have a 21 pitch prop one rev. would push the prop 21 inches foward minus some slight slip. Changing the prop pitch is like changing the gear ratio or tire size on a car. A smaller pitch prop would traditionally be used when a better/faster holeshot is desired but should be used with caution due to the potential for over revving the motor and the larger the pitch the higher top end speeds. There as far as I know is no real science to finding the right combo. Try and find the prop that will give you a good hole shot and good topend speed without over revving go find a 21 and give it a try.