what rpm should I plane at.

[bobrugratz]

my skeeter zx300 is going up to 4300 rpms before plane. Does that sound about right? it has mercury 225 efi and it is 22' long.

 

[5150abf]

Re: what rpm should I plane at.

Sounds like you are a prime candidate for tabs or your hull has alot of water in it, I am going wiht the water.

It seems like you should be planing well before that, has it always done this or is the boat new to you?

 

[scoutabout]

Re: what rpm should I plane at.

All kinds of factors can affect time and power required to plane. If the boat is new to you this can be a bit of a challenge as you have no baseline performance with which to compare. Does the engine seem to struggle to hit that rpm and get up on plane or is it more of a feeling that you've got no bite on the water? First condition might argue undue weight or engine issues, while the second could mean you are just propped way wrong and need a different pitch.

Once you get up on plane you should be able to throttle back considerably less than 4300 and stay up there. Can you give us the wide open throttle (WOT) speed that's gps verified? What's your rpm at that speed? Sorry for all the questions, just trying to paint a clearer picture of what's going on.

 

[bobrugratz]

Re: what rpm should I plane at.

All kinds of factors can affect time and power required to plane. If the boat is new to you this can be a bit of a challenge as you have no baseline performance with which to compare. Does the engine seem to struggle to hit that rpm and get up on plane or is it more of a feeling that you've got no bite on the water? First condition might argue undue weight or engine issues, while the second could mean you are just propped way wrong and need a different pitch.

Once you get up on plane you should be able to throttle back considerably less than 4300 and stay up there. Can you give us the wide open throttle (WOT) speed that's gps verified? What's your rpm at that speed? Sorry for all the questions, just trying to paint a clearer picture of what's going on.

wot 71 gps 5400 rpms. running on a 26p 4 blade power tech . boat is new to me. had 24p trophy on it and motor was 4 1/2 inches below pad now 3 1/2 below.

24p produced to many rpms and 26 is producing 5400. trim it up more than that and it slows. you may hit 5500 under great conditions. dont think theres is water in there cause we run with plug out till we get to the ramp.

 

[metriccrescentwrench]

Re: what rpm should I plane at.

wot 71 gps 5400 rpms. running on a 26p 4 blade power tech .....24p produced to many rpms and 26 is producing 5400.....

You say a 24 pitch prop revved too high, how many rpm's are you calling too many?

IMHO - 1) If you're seeing 71 mph you're boat and engine are fine, you've just got some fine tuning to do on the setup. 2) 5400 rpm at wot is kind of low, that's probably why the hole shot is sluggish. You should probably try a 25 pitch prop, or else even go back to the 24. With higher performance boats it can take quite a bit of trial and error with props and engine height to get everything dialed in to your satisfaction.

 

[DuckHunterJon]

Re: what rpm should I plane at.

I'm by no means an expert, but that seems like alot of pitch, and as such, it will take longer to plane. I have a 20.5 foot with a 200 Optimax and run a 23 pitch. I know, it's not apples and apples, that just seems like a big difference. Then again, if top speed is your goal, you may be dialed in and just have to live with a slower holeshot.

 

[Silvertip]

Re: what rpm should I plane at.

I didn't check the gearing on your motor (assumed 1.85:1) but running your numbers through a prop calculator shows 5400 rpm, 71 MPH on a 26P prop at 12% slip. Not too bad but it could be improved on just a tad but it appears your setup is ok for top end but may need a little help on hole shot. Try raising the engine another hole, move some weight up front if you can, and by all means, do your testing with what you consider an average load. One extra passenger can make a significant performance difference on a performance boat. Tabs do help as well but optimize what you have first.

 

[Boatist]

Re: what rpm should I plane at.

Planning is based more on speed than RPMs.
Most boats I have been on plane between 18 to 22 Miles per hour and around 3000 RPMS.
Do you have the motor trimmed in for your hole shot?
Too me it sounds like your boat is very heavy.
Is the live well full of water and 6 big guys on board?
How much gear is stored in the stern?

 

[bobrugratz]

Re: what rpm should I plane at.

ok went out today. and she is actually planing at a little over 3000 rpms. and it takes about 4- 5 seconds. so I think thats pretty good. still have the 26p on it but I am a little concerned with the rpms at wot. Should I be? I know a 25p should bring it up a couple 100. I am kinda stuck with the 4 blade cause mercury didnt leave room for a trim tab above prop, they put a sacrificial plate on it. the one we got had to be trimmed down to miss prop. If we get a 3 blade it will be a larger diameter and we would have to grind it more. And there is not enough left for that. And it does help with torque. So with that , Is the current rpms hurting me in any way like gas mileage? Reason I am asking first is we are planning to buy extra prop and would like to get a opinion on what pitch? the same or lower

 

[metriccrescentwrench]

Re: what rpm should I plane at.

So with that , Is the current rpms hurting me in any way like gas mileage? Reason I am asking first is we are planning to buy extra prop and would like to get a opinion on what pitch? the same or lower

IMHO I'd get a lower pitched prop. That engine should be perfectly happy running 5800 rpms at WOT, it will be less prone to sticking rings, and you'd get a better hole shot as a bonus.