Engine Alignment

[Sadey]

I got a call from the yard today asking me about aligning my starboard engine. I’m having the cutlass bearings replaced which appear to be very old. After they struggled to get the bearings out the starboard shaft was way out of alignment. They called for approval to which I did to align the motor. In the process they were able to align the shaft up and down but there are no slots in the mounts to allow for lateral alignment. The mounts and risers are original so it has not been in alignment since day one. I have two choices. One, allow them to grind slots in the mounts for lateral alignment or two, live with it in its current state. The current state is far better than the state it has been in to this point. We have had the starboard transmission off and the motor lifted for that reason to replace the main seal which could account for the more recent misalignment. However based on the mounts it would appear the boat’s starboard motor was never in lateral alignment. They did check trueness of the shaft and they are spot on. There is no issue with the port motor. I do have a slight vibration but there was some damage to the props which could account for that which is being corrected by Airmarine of Chicago right now.
Should I live with something that hasn’t been broken for 31 years or spend the money to allow for a perfect alignment 31 years later?

 

[Pascal]

At the risk of stating the obvious, do NOT align anything unless the boat is in the water!

 

[Sadey]

Can you explain why?

 

[Bob Bradley]

Overall shape/geometry of the boat is different when its sitting on a few piles of blocking than when it is supposed uniformly by the water.

 

[jim rosenthal]

I've heard that you can do a rough alignment on land. I don't think I believe it, though. I think Bob is right and that the hull and everything else change shape when the boat is in her natural element. I've always launched the boat and given her a couple of days to settle in, and THEN done the alignment.

In this instance, I would spend the money to go for the best alignment you can get.

 

[Sadey]

That makes sense to me.

 

[jim rosenthal]

A few years ago, I noticed that when my Hatteras is out of the water for a while, like a week, for her winter haulout, the door to the V berth stateroom closes differently. It still opens and closes fine, it just acts differently. The boat is blocked levelly, and the door doesn't swing differently, but it feels different when it closes. I finally figured out, since I'm not the sharpest tool in the shed, that the door frame changes shape a bit and the door still fits the frame, but not quite as well. When she's launched in the spring, it goes back to normal.

We don't think of a boat, which is a fairly large object, as something that could change shape under pressure, but the fact is that they do. Even FRP boats like we have do. And if you want to see something dramatic, drive around old boatyards and see what happens to old wooden boats that are left on the hard for a few years. They hogback something wicked.

 

[rustybucket]

second/third/fourth what others have stated. I'd just button it up as-is, idle to the dock at splash, then let the boat sit for a day or two (longer if it's been on the hard for an extended period of time) then do a proper engine alignment.

On my 52c there was a slight change in alignment from on the hard to the slip that had to be made after we splashed.

 

[SKYCHENEY]

Not sure of your setup, but I have a motor mount on either side of the transmission and one in the center in front of the engine. You may be able to move the front from side to side a little. Not sure and YMMV.

 

[34Hatt]

All mounts I have seen have slots for side movement.
Every time I have done alignment on the hard and have checked in the water it has been exactly the same on my 34 Hatt.

 

[SKYCHENEY]

All mounts I have seen have slots for side movement.
Every time I have done alignment on the hard and have checked in the water it has been exactly the same on my 34 Hatt.

Same here. Have always checked it in the water, but never needed to readjust.

 

[madhatter1]

I'll add a little something. Had a vibration on port. Changed out cutlass and props were reconditioned. All is great. Vibration is gone. But due to checking something on the genny while underway at idle I see port shaft is wobbling. But I have no (ZERO) vibration. I know, WTF? So I think original issue is not from my "polishing props" but maybe I need alignment before it craps out this new bearing. And yes, the ONLY way to do alignment is in water when hull is shaped/settled correctly.

 

[Sadey]

There is definitely no allowance for side adjustments. Just curious, how do you check alignment in the water? Right now this is what we are looking at. This after a few hours of adjustment. The shaft was pinned against the hull before adjustments.

 

[racclarkson@gmail.com]

I'll add a little something. Had a vibration on port. Changed out cutlass and props were reconditioned. All is great. Vibration is gone. But due to checking something on the genny while underway at idle I see port shaft is wobbling. But I have no (ZERO) vibration. I know, WTF? So I think original issue is not from my "polishing props" but maybe I need alignment before it craps out this new bearing. And yes, the ONLY way to do alignment is in water when hull is shaped/settled correctly.

Wobbling vibrates. You said you saw wobble. Any discoloration, dirt, spec of paint, shiny spot, etc. will appear as a wobble when spinning. Put a fingernail or a pencil or something firm but not metallic on the shaft and feel. It can’t be vibration free if it wobbles.

 

[racclarkson@gmail.com]

There is definitely no allowance for side adjustments. Just curious, how do you check alignment in the water? Right now this is what we are looking at. This after a few hours of adjustment. The shaft was pinned against the hull before adjustments.

The lateral adjustment could be loosening the mount to engine bed bolts and barring sideways. That’s the way it is on Aslan’s Ace mounts. Note the pictured bolt head off center. Have you considered strut miss alignment?

 

[dsharp]

As far out of alignment as that shaft is I would think about adjusting the struts. If you move the back of the engine over to center the shaft in the shaft log the front may be out by a mile. You have to look at the wear on the cutlass bearing to see where your mis-alignment is. If you trust the yard let them fix it. The motor mount should be slotted. Sounds like they may want to slot the engine mount that’s bolted to the gear. The alignment isn’t going to move that much when it’s in the water. That was a carry over from wooden boats. That being said, I wouldn’t bolt the coupling up until you’re back in the water. To check alignment in the water you use feeler gauges between the the shaft coupling and the output flange on the reduction gear.

 

[31FlyCruzr]

How was the wear on the cutlass bearing?

Mis alignment should wear a clock position on the fwd end and 180 degrees on the aft end. If the wear is centered on both ends I would leave it alone.

When I bought my boat I had a bent strut. Wear as described above. To assess it I took a laser pointer and some bolts 120 degrees apart inside the old cutlass bearing.
I have a lathe so it was a job but I got it to turn almost true, about 1/8 inch wobble at 5 feet.

When we used the laser it was obvious the strut was out of position. Let me explain, we looked at where the laser was centered at the back of the shaft log and at the front, along with where it hits the engine. You want all three to be in the center. My solution was to elongate the holes thru the hull to get alignment after finding the proper strut location.
Worst hole was off by about a bolt diameter. We glassed in the elongated holes with sleeves over the bolts to get the new position finalized.

Big job, my dad is a naval propulsion engineer, he was about 67 when we did that, 92 today and made it out fishing this year.

 

[Sadey]

They checked the shafts and they are true. There is a slight vibration felt on the fly bridge but that could be the props. The props had some “polishing marks” which might account for the vibration. The struts are glassed in and part of the hull so that’s a none starter. The yard tried to bar the motor sideways but there is no lateral play in the mounts. I’m going to have them true everything as much as they can then check it at splash time.