do I need a different prop?

[Tail_Gunner]

Re: do I need a different prop?

Again check your tach and verify speed with gps

 

[Leardriver]

Re: do I need a different prop?

People that don't live at altitude sometimes are in disbelief at what it takes to make engines run well up here.

The 17 pitch 4 blade that you bought will spin like a 18 pitch 3 blade. You need a 17 pitch 3 blade to even get to 4500 rpm, and a 15 pitch to ski and haul around a full boat. I've been in a boat that hit it's max rpm at sea level with a 21, and a 15 pitch in Denver barely got there.

 

[pheasanthunter]

Re: do I need a different prop?

I know my speedo is accurate because I checked it with the gps on my fish finder. I'll check my tach and see if it is accurate. Thanks for the info on the prop Leardriver. Going from 21 to 17 only changed WOT RPM about half what I need so it seems a 15 should be what i need.

 

[Tail_Gunner]

Re: do I need a different prop?

I know my speed is accurate because I checked it with the gps on my fish finder. I'll check my teach and see if it is accurate. Thanks for the info on the prop Leardriver. Going from 21 to 17 only changed WOT RPM about half what I need so it seems a 15 should be what i need.

Hence the need to substantiate all of your numbers

 

[pheasanthunter]

Re: do I need a different prop?

Thanks for all your help guys. I checked my tach, It's accurate. I got out yesterday with a new 15 four blade, and the boat performed like it should. Pops out of the water great and gets up to 5000 rpm. Could have probably pushed it above 5000 by trimming it but didn't have as many people as I will normally have in the boat, so I think a 15 is the right one.

 

[pheasanthunter]

Re: do I need a different prop?

O.K. gentlemen. I am bringing this back up because my boat has been performing pretty well ecxept for the fact that it doesn't pull me up very well when I am deep water starting on a slalom ski. It drags me through the water and I end up drinking alot. My wife is new at driving a boat but I don't think she is the problem. I have moved the three trolling motor batteries to under the drivers console and that has helped the boat plane out a little. but not enough. I can get the engine above 5000 rpms (WOT 4600-5000) so here is what I am thinking of doing, please give me some insight as to what my results might be.

A correction from previous posts my engine is a 260 h.p. 5.0 MPI

Iboats has a 5 blade stainless 17 pitch that is 14" diameter(currently have a 4 blade aluminum 15 pitch that is 14-3/4" dia). If I go to the steeper smaller diameter 5 blade will I get a better hole shot and bring my rpm. down just a bit?? FYI -The very first prop I tried I went from a 21p 14" 3 blade stainless that was on the boat to a 17p 14-3/4" 4 blade stainless and it hardly made a difference at all.

I'm also considering smart tabs that are about $120 from Iboats. The prop is $520. I don't mind spending the $600 some odd dollars if it gives me the hole shot I'm looking for, but not if it doesn't work. Should I start with the smart tabs first??

Thanks for any insight.