A few good reasons to have your prop looked at . . .

[whichwaysup]

Since the boat is being repaired and will be for awhile longer, I figured it was a good time to have my prop looked at.   I'm running a Stilletto 14x19 and have been extremely pleased with the numbers I'm getting from my 150 Vmax - pushing 54-55 and can't remember the RPM it's been so long, but I know it was approaching the limit.   However, in tight turns, I get a lot of blow out/cavitation and it leads to some exciting moments in the tighter creeks I run.   

I got referred to Coastal Propeller here in Wilmington, so I stopped by to talk to Martin.   Walking into his shop is kind of like "Flintstones meets Jetsons" - he uses lasers and computers to measure/gauge the prop, but then beats it into submission the old fashioned way with a hammer and sheepskin.   He deals with wheels from large ships and pleasure craft alike and was a wealth of info.   

I say all this because I learned a few things I didn't know and I thought I'd pass along to those of you who have never had their prop checked out.   Here's what I learned that might make you want to spend the 150-200 to have your prop reconditioned:

1) Brand new props can be sucky (yes, I just slipped past the banded word problem, Gabe).   According to him, Merc are the worst offenders and he showed me some of the measurements he took of the fin alignment.   WOW, not even close.   You can probably imagine the stress that a prop would generate on the lower unit when the fins aren't balanced and aligned.   Pretty cool to see the before and after.

2)  Not getting to your max RPM leads to early engine death.  I'm pretty handy, but when it comes to mechanical stuff like engines, I'm kind of a moron, so anything I say next is solely based on his comments.   Apparently, when you run a prop that doesn't let you get to your max RPM, it keeps the fuel that is injected into your cylinders from getting fully burned.   That gets past your rings and ultimately leads to compression issues.   Someone who is smarter than me can clean this up and say it better, but it made sense to this moron, so maybe it will to others.   Historically, I've just run whatever prop I had on the boat without worrying to much about it.   This made me think twice.

3) You may not need a different prop, you may need your prop to be different.   He shared with me how a prop that isn't giving you the numbers you want may simply be out of alignment or poorly manufactured.   If you are running a prop that "should" work for your set up, but are not getting the numbers you want, before trying something different, have it checked out.  It could simply be mis-aligned.

 

Anyway, hope this helps - and yes, I do realize that a guy who has a reason for me to believe his work is worthwhile might make all this up, but thought I'd pass it along.   I know there are a lot of prop junkies on here, but a lot of folks like me as well who wouldn't have put much thought into the possibility that their prop isn't right and could lead to much bigger problems down the line.   

[jh141]

Great Info.  Not sure about the RPM thing in regards to the injected four strokes. Does hold true to the two strokes. I have heard the same thing from more than one reputable prop repair guru about alignment and balance.