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homerl

Regular Contributor
I changed prop size/pitch from a 13 3/4x21 to a 19.They tell me it gives me better low end,which means?,moves more water on take off or less?but I may lose a bit on top end?I would of thought less pitch moves less water and slower take off but I'm told it works the other way by increasing rpm's more in the power range,giving you better take off.Can anyone explain this better?
thanks homerl.:confused:
 
homerl said:
I changed prop size/pitch from a 13 3/4x21 to a 19.They tell me it gives me better low end,which means?,moves more water on take off or less?but I may lose a bit on top end?I would of thought less pitch moves less water and slower take off but I'm told it works the other way by increasing rpm's more in the power range,giving you better take off.Can anyone explain this better?
thanks homerl.:confused:
Click to expand...

less pitch give you more power to get up faster. with heavy load or pulling water ski you need this extra quick hole shot..

if you are going out with no passengers the 21inch might work out with no problems..

it is better to run with less pitch slightly , than too much .too much puts extra wear on the engine and drive...
 
Thanks jcat always had problems getting on plane and we would have to get to the front for about10-20 secs and than she would plane and go like hell.
 
Well the new drive is on,and the 19 pitch prop.Took the boat out today for a couple hours and what a difference a 19 from a 21.this boat hit almost 3400 rpm's on take off and usually it was about 3000.
Did not have a chance to try wot as the waves were close to 2'-3'.Things looking good and thanks to all that helped.
homerl
 
homerl...

Prop pitch is similar to thread pitch on a bolt. Its refers to how far the prop will screw itself through the water in one revolution. In this case it will go either 19 or 21 inches, depending on which prop you have on at the time. This is theoretical although because of slipping of the blades in the water. It would be better to say how far it would screw itself thorough a solid in one revolution (if it could). You need to spin the 19 or 17 or 15 faster to go the same distance as the 21, or a 23 or 25. This means that engine RPM has to go up to spin the prop faster. So using a smaller pitch, you can pop a skier out of the water easier because the engine gets into its power band faster. However, top speed suffers because the engine runs out of RPM and the boat may still be going slow.

There are all different types of props that try to make the best of both worlds. Variable pitch, cups, props that are designed to run about 1 inch beneath the surface.....

Aluminum props tend to flatten out slightly under the heavy stress of acceleration compared to stainless props that hold their shape better. Stainless are less forgiving if they hit something under water.

Multiple blades, larger diameters, counter rotating on the same shaft... ugh.

Wrench
 
try some trim tabs. the ones i use is smart tabs on my 21' baja had same prob they get u on plane quick. i got mine from iboat they work good luck
 
Before I changed the lower drive,I had the 21pitch prop with those two piece "dolphin tabs",the ones you drill two holes for each one.That didn't seem to help with that prop,or I would hate to think it did help and what if I didn't have them on.
I have not reinstalled them as of yet as I am quite pleased with the take off with the 19pitch prop.Do you still think it could make a better difference if I installed them?
 
the dolphin tabs dont work i had one not good for ur outdrive and gimble try the smart tabs they work! to answer ur ?? yes help a 100% boat also trails alot better. they cost like 129.00 plus ship let me know good luck
 
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