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PSA - Sometimes it's the simple solution

bsangs

E35-3 - New Jersey
We haven't been out since late June, because, well, life. But we were finally set to go this past weekend, so I decided to run the engine at the dock for a bit, just to make sure all the routine work I'd done the past 1-1/2 months was completed properly. Spun her up to operating temp, all was well, and while tied up decided to put her into gear - which I never normally do. While in idle, shifted into forward and was greeted with the most hellacious vibrating I've ever experienced. Dropped back down to neutral, then in reverse and it was fine. Forward again, the vibrating immediately returned. Upped the RPMs and it ceased. Back to idle - teeth-chattering. Needless to say we weren't going out, so I set about diagnosing what could be happening.

It exhibited all the signs of a slipping transmission cone clutch, which is easy enough for a pro to fix, but would have meant a late-season hauling out, and God knows how long for someone to be able to get to it, as my yard is pretty busy right now. Before heading down that path, I asked my dock neighbor friend - who happens to be the marina's diver - if he'd take a look at the feathering prop, shaft, zincs and cutlass bearing, so I could eliminate them as potential causes. When he was done, he told me everything was fine, however he had to clear off a lot of growth from the prop. Now, we're not usually in the slip during August, that's normally when we'd be somewhere up the Long Island Sound, in Block Island, or out to Martha's Vineyard. And August is THE month for copious amounts of growth in my marina. Still, I didn't expect it was the solution, since when in reverse, there was no issue with vibrating. I couldn't have been more wrong.

Fired her up, moved the transmission into forward, and wouldn't you know it, all was well. Kept at it for about 15 minutes just to be certain, and the vibration never returned. It was clearly the prop growth causing the issue. So yeah, just another reminder to check the simple things first, before heading down a costly rabbit hole that wouldn't have been necessary. Finally will get back on the water this weekend, hopefully.
 

Nick J

Contributing Partner
Moderator
Blogs Author
We had the exact same experience during our sea trial / survey in 2019. We spent the trip form the slip to the yard discussing the cost and complexity of replacing a transmission or at least renewing/lapping the drive cones. The broker even asked if the transmission would be a deal breaker and if we wanted to turn around, a tempting proposition given we were only able to make 2 knots for the whole trip along with the heavy vibration. Thankfully we found the same issue you did and went ahead with the purchase. Replacing the original chipped 2 blade prop with a new 3 blade Campbell Sailor prop shortly after purchase solved the last bit of vibrations, but wasn't 100% necessary.
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AdventurousAnton

Member III
Chiming in with a recent, very similar incident for my neighbor yesterday.

I helped them cast off and maneuver backwards out of the slip.

Everything A-OK. Good reverse movement. Heard him engage forward, and expected to see his Valiant's nose to come around.

He was still going backward....

Oh shit time!

There was a lot of yelling back and forth, and I almost went out to bring them back in by RIB, but they backed down close enough to throw me a line.

He has reverse, but no forward, and his boat has a three-bladed folding prop.

His boat had just been scrubbed and new zincs put on...and I dove his boat and found his shaft zinc was literally a hair's breadth too large, and only allowed the prop to unfold in reverse, and not in FWD. I was free diving, so they called our bottom diver (we all use the same cat), to come remedy the situation. He'll be there in the morning.

NOTE: As part of my checklist before ever leaving the dock (ever!), I have "Run motor for 10 minutes at low throttle; run motor at half throttle for 5 minutes; engage FWD and REV to check prop and drive train; back down throttle and prepare lines to cast off." I told Peter he needs to do the same...and he's meticulous, so it's now in his LOG Book and a note next to the companionway hatch.

Details matter, eh?
 

peaman

Contributing Partner
He has reverse, but no forward, and his boat has a three-bladed folding prop.
That's an issue which anyone with a Max-prop type propeller should be aware of. That's a design by which the blades rotate on their individual axes to transition from forward to reverse, while feathering when no power is applied. Any fouling which prevents full movement of the blades can lead to trouble. Not long ago, I recounted one particular incident which I witnessed.
 

southofvictor

Member III
Blogs Author
Just rebuilt our Maxprop yesterday and realized firsthand the potential @peaman describes. The prop blades need to move through the last 10 or 15 percent of their range of motion when switching from reverse to forward or you’ll stay in reverse. We thought we had it rebuilt correctly but nope - when I put it in forward I was definitely moving in reverse.

A quick call to PYI and Fred’s kind suggestion to watch their Youtube video (duh, why didn’t I think of that first) and the problem was solved.
 
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