Vibration at WOT

[Rickysa]

New shafts about a year ago, had a diver under the boat last week to clean, first time we have had this happen...vibration at WOT. Back it down a bit and the vibration goes away.

Haven't hit anything either...

Suggestions welcome.

Rick
'85 45C

 

[Passages]

Was the problem there before the diver cleaned Props & Shafts?

Fishing line chew up the Cutlass Bearing?

Engine Alignment OK?

Last resort - don't go WOT...

 

[Trojan]

What engines are you running and how is your speed? Do you get the same speed and RPM as before the vibes? Was the vibes there before the cleaning? Need a little more info.

BILL

 

[Rickysa]

nope, problem not there before the cleaning, and the boat hasn't been out to get anything around the shaft, and can't imagine anything that would have thrown the alignment off???

Thanks for the response!

New Capt on board trying to get a feel for the boat and pushed it to WOT...just curious why it would only show up there.

Rick

 

[MikeP]

Are the engines in synch at WOT? A synchronizer will disconnect at WOT if the engines aren't properly set up for the synchronizer ( the slave engine governor must be set for a higher WOT RPM limit than the lead engine).

If the engs are not in synch either because the synchronizer disconnected OR if doing it manually, you don't have the engines at the same RPM - you may get a vibration that is NOT a result of an actual out of balance condition at all, but just from the harmonic of the two engines beating against each other.

 

[Rickysa]

6V92s....we have been having issues with boat speed and WOT rpm not hitting 2350 (maybe 50-100 off) before the vibration was noted this past weekend.

Phototach shows our stb. engine guage to be 100 rpm off from 2000 and up, and to be honest, I'm not sure where the Glendenning sync. gets its info from...the tachs on the bridge are even, but the engines aren't...I'm not sure if the sync was on when they felt the vibration...they just backed her down and left it there.

Thanks again for the input,

Rick

 

[Mike36c]

Maybe the diver left one prop blade with some growth, a dinged blade, small rope tangled? Hate to say it but its time to get wet and have a peek, then go from there.

 

[Rickysa]

Maybe the diver left one prop blade with some growth, a dinged blade, small rope tangled? Hate to say it but its time to get wet and have a peek, then go from there.

Mike, that is the plan...I've not been around the boat through all of this, but I'm thinking the diver didn't do much of a job on the running gear...we had something painted on the running gear of our old Bertram that worked miracles, but I think it's been banned by the EPA nowadays...bummer

Rick

 

[Mike36c]

Mike, that is the plan...I've not been around the boat through all of this, but I'm thinking the diver didn't do much of a job on the running gear...we had something painted on the running gear of our old Bertram that worked miracles, but I think it's been banned by the EPA nowadays...bummer

Rick

I'm have four months on my first application of propspeed applied to my running gear, so far its working nicely but still too early for conclusions. I need to change shaft zincs next time I see the boat, I'll forward a current report.
Mike

 

[Genesis]

Sounds like you got some stuff on one of the blades of the wheels or a half-azz job done cleaning..... time to do a bit of diving.

 

[MikeP]

"Never trust anyone else to do anything" has, unfortunately, been my motto for many years. It's why I got my SCUBA certification a couple years ago - so I can do all the underwater work myself.

If you do it yourself you know it's been done right and if you cut a corner at least you KNOW you cut a corner. That way subsequent problems that might occur because of it won't be a surprise.

 

[Rickysa]

Mike,

Same reason I got mine...and I agree with the do it yourself...the only problem is that we have such growth so quick, and I only have limited time to enjoy the boat (oh, to be retired or near the boat) that doing the bottom myself just took up to much time and effort, when so many other things were demanding attention also.

Thanks all,

Rick

 

[mstailey]

Mike P,
Not disputing your post on setting the slave engine WOT governor higher just trying to understand it.

My Glen-d has 2 adjustable collars on the shafts that traverse in-out of the unit and can be adjusted to hit a button on high-limit switch (WOT) and a button on low-limit switch(Idle) that will disengage the sync if activated.

Based on that why would you want to mess with your WOT governor on the slave? Are you not inviting a run-away? Again, you know a lot more than I do and I'm just trying to understand...

 

[MikeP]

For the synchronizer to maintain the engs in synch at idle and at WOT requires opposite settings which are done individually at the engines. Let's say you want the engines to Idle at 550 and the WOT setting to be 2500 (no load).

For idle you set up the LEAD engine at the idle you want - 550, and the slave engine at say, 530. For no load WOT you adjust the lead engs governor to produce 2500 and the slave eng governor at say, 2520 (or maybe drop the lead to 2480 and put the slave at 2500 - whatever).

The reason you do this is because the Glen is trying to always match the slave to the lead. If at idle the slave engine is set to idle at 600 while the lead is set to idle at 550, the Glen cannot bring the slave down to the lead's idle speed and it will disengage. Same is true at WOT. If the lead is set at 2500 and the slave at 2480, it can't increase the slave's speed to match the lead and it will disconnect.

So if you want the engs to be able to be synched at idle and wot - lots of folks don't care - then the appropriate idle speeds must be set on the engines as well as the appropriate gov adjustments for WOT.