Is my prop too small?

[imported_Captain Morgan]

Re: Is my prop too small?

I'm taking it out tomorrow for the 1st time. This time with only one other fat guy instead of two. Just couldn't make the 3 130lb girls thing happen. I'll have some better numbers tomorrow. I charged and installed the battery today and fired it up briefly with the water suction-cup things on the drive. The rpm gauge at idle read 3000 rpm. I know this isn't correct. Shortly after it dropped down around 1000rpm. Hopefully I can get a somewhat accurate rpm reading at wot. I'm going to try to get my hands on a gps for the next time I go out so I can accurately measure speed.

 

[imported_Captain Morgan]

Re: Is my prop too small?

Okay, I took the boat out today. I replaced the speedometer pitot tube unit just in case before we hit the water. With only 1 other guy aboard, we still topped out at 27 mph. I adjusted the trim to bring the bow up and woila! The speed increased to a maximum of 38mph and 3900 rpm. My wot range is suppose to be 4200-4600 rpm. My prop again is aluminum and it's 13.75 diameter and 21 pitch. I'm thinking of picking up a replacement prop and keeping this slightly bent one as a emergency spare.

Should I consider going with a 19 pitch prop with the same diameter? Wouldn't that get my rpm's up a little higher and possibly increase the top end as well as the hole shot, or will the top speed drop a bit?

* Note * While cruising at wot at the conditions described above, I hit a cross wake kinda hard. I backed off the throttle immediately and then atttempted to take off again, but bogged down due to the prop not being trimmed down enough. I lowered the drive all the way down with the trim button and applied wot. After trimming up slowly, I found that the rpm's were now reading within my rated range. I was able to control the rpm a bit by trimming up and down, but now I was not able to reach the same speed even thoght my rpm's read higher. Any thoughts on why there was a change?

 

[dodge1971340]

Re: Is my prop too small?

Hid if your tach is doing that when you hit a good wake i would look at it or the wiring It might not be reading right (faulty tach or wiring) did you look at the idle speed after that was it higher if so you probably got a faulty tach. I would look into that before you go spending your $$$ and if you are getting that 3900 rpm's that 19 pitch should get you around 4300 or 4400 rpm's. and that is a common size that could be picked up on eBay really cheep.
Good luck Dodge