Prop diameter...Going smaller?

[Joshua Nichols]

I have a 14 1/2 diameter 19 pitch prop on my rig now. It performs like a demon and would be perfect if we hauled alot of folks and did alot of skiing.. Mostly we cruise.. With the 19 pitch I get too high of rpm.. So I been looking and hunting a good deal on a 21 pitch prop.. I even thought of taking mine down to have the pitch changed..

So today I found a 14 diameter 21 pitch prop for a real fair price and was thinking of picking it up for my rig and keeping the 19 for the days if some friends wanta ski or what not... So will the 14" go good in place of the 14 1/2?

 

[Silly Seville]

Re: Prop diameter...Going smaller?

If you're getting it "for a real fair price", then I would think it wise to buy and try it. If it doesn't perform to your liking...c-list it and profit from your experience!

 

[Joshua Nichols]

Re: Prop diameter...Going smaller?

$75 bucks thats pretty cheap... He said he would give me my money back if it didn't work , but it's a CL ad.. Ya can't trust that..

 

[ziggy]

Re: Prop diameter...Going smaller?

$75 bucks thats pretty cheap... He said he would give me my money back if it didn't work

for that price, for a ss prop. i'd jump pretty fast. around here. ss props on cl seem to fetch 200-250 for a used one. if it don't work for ya and the seller don't want it back sell it for profit... imho..

 

[steelespike]

Re: Prop diameter...Going smaller?

If the prop is intended for your application the diameter is usually not a consideration.
If an inch smaller or larger then it may be a consideration.
Engine rpm,prop pitch and the best cruising rpm/throttle is a tricky problem.
The best cruising speed is not necessarly just barely on plane.
Generally the lower pitch prop will stay on plane with less diddling.the somewhat quicker hole shot could be a fuel saver.Your not likely to be able to tell the savings.Your higher rpm may be attained with less throttle with lower pitch.Then there is the speed. you need the most speed with the least throttle setting.A 21 will lower rpm but will slow hole shot and will likey require more throttle to reach planing speed.Again difficult to see an actual difference in fuel use.
Once on plane it will likely cruise at lower rpm but what throttle setting to reach that rpm
due to the reduction in power. Speaking very basically::
One way to tell if a prop is close to what you need is your max rpm and speed with that prop. If the motor over revs at max speed you need a increase in pitch if it doesn't reach max rpm you need a reduction in pitch.If the motor performs near the top end of its rated rpm your propped right.Your speed in relation to that rpm will tell if the prop is working efficiently.This all assumes the prop is in good condition.If you get us the figures I mentioned we can help you decide what you may need.

 

[PROPer]

Re: Prop diameter...Going smaller?

Do you currently have a spare prop? If not, this is no brain-er. Get the prop! Even if it does not perform the way you would like, it might come in very handy one day if you keep it on the boat...

 

[Joshua Nichols]

Re: Prop diameter...Going smaller?

I got a spare.. But it's a rag muffin I guess better than paddling)... The prop I am running currently has the engine running at around 5300 rpm At 46MPH that gps.. Now ya see why I want a bigger pitch?? I have neck snapping hole shot with the 19... I may just take mine off when I go look at the 21 and see if there is much difference and if not pick it up... Oh yeah BTW it is a stainless... He said no one but me has asked about it... I couldn't believe it

I can't be sure if the tach is perfect right on... I kinda know what a engine sounds like wrapped out.. It is screaming at WOT so I am thinking it is pretty close

 

[steelespike]

Re: Prop diameter...Going smaller?

Assuming tach is accurate you need to make up 700 rpm. If your going from al to ss it might make it.not likely but at the price go for it.I would think with the right prop 50-55 would be easy.

 

[Joshua Nichols]

Re: Prop diameter...Going smaller?

I have a stainless on there now... Other than diameter I can't see why the 21 won't work...
He is going to meet me about halfway Sunday... Here is the new deal... He will sell it to me for $50 no returns.. I figure at this point if it won't work for me.. I can sell it on E bay in a hot minute for $100

 

[Joshua Nichols]

Re: Prop diameter...Going smaller?

Okay this was a awesome CL score.. Went and got the prop today.. Seller was a way cool fella... Sold me the stainless prop for $50.. I took my old prop.. Measured everything all looks good to go.. It looked as if he had the pitch changed to 21, cause the prop place had ground off the previous size and stamped 21 on it.. Looks like they also cupped the fins... So I was wondering about diameter well this one is the same as I am running now he just didn't see the 1/2 after the 14.. pretty cool huh? I am trilled