RPM of XP150 too low?

[walleyehed]

Re: RPM of XP150 too low?

Unless there is something I am unaware of, your gear ratio is 1.87:1

 

[farginicehole]

Re: RPM of XP150 too low?

Okay, so that still puts me roughly in the 21-23% slip range, right?

 

[walleyehed]

Re: RPM of XP150 too low?

I see 3 possibilities..#1, Tach is reading 500 high.<br />#2, Prop is "really" a 15 pitch.<br />#3, speedo is off sending us on a goose chase....<br />IF you 17 is a flat prop (no cup) those figures are still a tad high.<br />Too many variables to contend with...we need at least 2 known variables to complete the puzzle.

 

[farginicehole]

Re: RPM of XP150 too low?

I'll try and work on it - thanks for the response. The prop is a factory OMC 15x17 aluminum, with a few nice dings but I've seen a lot worse. Speedo always used to be very close to gps, and I'll try and re-confirm that tonight. Not sure how I'm going to confirm the tach. Any options other than spending a couple hundred (are they that much?) for a troubleshooting tach of some sort?

 

[walleyehed]

Re: RPM of XP150 too low?

Well, the best thing (as I have learned the hard way) is to just buy a good OMC/BRP tach..it IS the most informative and important gauge you can have....yea, they cost a few bucks, but it "may" save you other more costly troubles in the future.<br />It is in no way a waste of money to buy the OEM tach as I have found out..I've owned teleflex and OMC...I just bought a new BRP tach and found my 6 month old teleflex to be about 100 off at the top and about 50-75 at the bottom.

 

[Basscat 1]

Re: RPM of XP150 too low?

I agree, pay now or pay later. By the way, I like your pictures of your jack plate set up. Did you build it yourself?<br />I am going to add an aluminum plate to the inside of my transom like you did for more stability. Just one of those things I havent got around to yet.

 

[Seasport]

Re: RPM of XP150 too low?

You should be able to get the Tach checked at an instrument shop. Otherwise, if you know a friendly electronics technician, you shoud be able to check it out using a square wave signal generator.

 

[walleyehed]

Re: RPM of XP150 too low?

Basscat1. yea, for 20 bucks, I built it myself.<br />It's quite functional for no more than I have into it.<br />About 230 hours of use in 2 years so far with no problems.<br />I have a piece of alum angle inside that can't really be seen in the pics that REALLY added the strength to it and allows pressure to be directed at the transom gussets.<br />The handling of my boat improved 300% when I added that...it really made a difference.

 

[farginicehole]

Re: RPM of XP150 too low?

Thanks guys. So do they sell these OMC/BRP tachs on Iboats, or do I have to order one from a local dealer? I had the boat out last night, and according to the Teleflex tach, hit around 5900 (maybe a hair more) rpm. Boat speedometer said around 39-40, and my gps said around 40.5-40.8 mph. This was with my fishing buddy and I (each of us in the 190-200 lb range), fishing gear and quite a bit of weight in beer. I was able to trim it all the way up with no noticeable ventilation while going straight ahead. Again, this is the 15x17 aluminum in I guess what I would consider "fair" condition, and the motor raised to the 2nd highest position on the transom with no jackplate.