PDA

View Full Version : Question about props....



GeordyBass
03-03-2008, 07:38 PM
i need help because my propeller on my mercury is broken...What does pitch mean?And why does more pitch equal higher price?Thanks for the help!

vanillagurilla
03-03-2008, 08:51 PM
pitch is the angle of the blades. steeper pitch = more acceleration i think or higher speeds.

seahonk
03-04-2008, 02:08 AM
All about pitch ,,,,,,,,,> http://www.marinedepo.com/proschool101.html

GeordyBass
03-04-2008, 08:41 AM
alright this is useful for what prop i want...thanks for the help.

Tail Chaser
03-10-2008, 10:40 AM
Basically the number of pitch is how many inchs the boat moves forward.
A 17" pitch moves a boat 17" forward in the water with each revolution
20" pitch moves it 20" forward etc,
Every 1 inch of pitch changes your RPMs by 200rpms. More pitch lowers engine RPMs and Vice Versa

The diameter of the prop also changes the engine RPMs
Every 1 inch of prop diameter changes engine RPMs by 100 RPMs. Bigger props lower RPMs and Vice Versa

Your engine has a Wide Open Throttle RPM spec.
You run your boat at full throttle on plane.
You pick a prop with the Right pitch/Diameter so your engine is at the proper WFO RPM specs

GeordyBass
03-10-2008, 11:51 AM
thanks....

crappie stalker
03-10-2008, 08:26 PM
alright this is useful for what prop i want...thanks for the help.

Remember that you should be at about 4000-4500 RPMs at full throttle.. If you go with another prop know what you are wanting from it.. Faster take offs or greater top end.. Most will move you towards one of those extremes.. you sacrifice fuel economy with some of them and may not get the higher top speeds with the hole shot props bbut you will snap out quickly..

Hope it helps.

Crappie stalker

sansou
03-10-2008, 08:31 PM
At the extremes, you have to be concerned with overspinning with a low pitch, and stalling at startup with a high pitch. Either scenario wrecks your engine over the long term.

Consult your tech manual!

XFACTOR
04-07-2008, 10:08 PM
Remember that you should be at about 4000-4500 RPMs at full throttle.. If you go with another prop know what you are wanting from it.. Faster take offs or greater top end.. Most will move you towards one of those extremes.. you sacrifice fuel economy with some of them and may not get the higher top speeds with the hole shot props bbut you will snap out quickly..

Hope it helps.

Crappie stalker

I know I would be very disapointed if my top end was only 4000-4500 rpm. That rpm is a good cruising rpm but to low for full throttle. It should be between 5250-6000 depending on your motor. You should allways prop your rig to reach the max rpm for your motor at wide open throttle. Never lug a 2 stroke with a prop that has to much pitch - let it rev.

GeordyBass
04-09-2008, 09:08 PM
I know I would be very disapointed if my top end was only 4000-4500 rpm. That rpm is a good cruising rpm but to low for full throttle. It should be between 5250-6000 depending on your motor. You should allways prop your rig to reach the max rpm for your motor at wide open throttle. Never lug a 2 stroke with a prop that has to much pitch - let it rev.
Damn!I forgot to mention it was a 4-STROKE!LOL

Tail Chaser
04-10-2008, 12:25 AM
Two stroke or Four doesn't matter. Big engine or small.
They all have there wide open throttle RPM range that the engine must be able to reach.

You could call a service shop. They could look up what the WFO throttle rpm is for your engine.
A prop shop has all the info also.
If you buy from them. They will usually swap props if your not happy with what they sell you.

So your dad really made the boat ramp?

GeordyBass
04-10-2008, 01:18 PM
Y
Two stroke or Four doesn't matter. Big engine or small.
They all have there wide open throttle RPM range that the engine must be able to reach.

You could call a service shop. They could look up what the WFO throttle rpm is for your engine.
A prop shop has all the info also.
If you buy from them. They will usually swap props if your not happy with what they sell you.

So your dad really made the boat ramp?
Yeah...they upgraded the docks,They fixed the RV lot,and they fixed the parking lot...

thanks for the advice....I called Boats.net and they told me that the recommended prop costs $120!LOL!