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Prop

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jak0253:
I am very happy with my 2006 tracker 170, 40hp four stroke other than it takes forever to get on plane. There is a tag that says 13 x 26 pitch (for the prop). Is there another prop / different pitch that I could install to help my hole shot but not affect top end? Thanks

frugalangler:
possibly, 13X26 seems way tall for a 40HP, is that the original rigging prop? or, did someone swap to a taller one to try to get more top end?? I'd have expected to see maybe a 23" on that motor.

if that is original, there are some possiblities:

something that is common is the motor on smaller boats is frequently mounted too low on the transom, or the boat is loaded heavier than typical causing more of the lower unit to be submerged than necessary. some experimentation there might improve, but without a water pressure gauge you need to be cautious of going too high.

that said, generally it's a ratio - like the transmission in a car, you get more starting power in lower gears,  but to get speed you need higher gears, which makes starting difficult.

when you say it takes forever, describe better the behavior, does the bow rise to the sky for a long period of time, that may be a sign of not trimming the engine at launch correctly (if it's a power trim, make sure it's trimmed ALL the way down, the prop will actually be pointed slightly upward toward the front of the boat when correctly set for takeoff), or not having correct bow to stern balance, some experimentation there might reveal things.

Curt:
Frugal got it right. 26 seems way too tall for your boat.

Just to clear things up a bit, having a higher number, such as 26, vs. a lower number, like 21 or 23, will give you better top end speed, but your holeshot will suffer.

Changing the prop to improve your holeshot will always result in a lower top-end speed, unless some other possible adjustments are made, such as raising the motor height. But  raising the motor should be done carefully, as @frugalangler also mentioned, to make sure there is no drop in water pressure on plane.

frugalangler:

--- Quote from: Curt on November 28, 2016, 01:34:55 PM ---Changing the prop to improve your holeshot will always result in a lower top-end speed, unless some other possible adjustments are made, such as raising the motor height. But  raising the motor should be done carefully, as @frugalangler also mentioned, to make sure there is no drop in water pressure on plane.

--- End quote ---

That's true, unless the prop is so too big that the motor is lugging and not able to achieve it's WOT recommended RPM, therefore not really getting more top speed. I see this frequently on bigger boats, guys want to go faster and then complain about not really going faster, taking longer to launch, and burning way more fuel and oil because the computer thinks it's WOT but not achieving proper RPM, so adds in fuel (and oil) to try to achieve the target RPM! Been there many times, guys can't believe going down in pitch raises top end - it does happen in some cases!!

RJP44:
Like posted above, what is your RPM at wide open throttle?  26p is too much prop.  What is your top speed as well?  On my previous tracker with a mariner 40hp I was running a 14p with max speed of 32mph all within the recommended rpm range.  Although a different hull i still think you should see similar numbers

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