Prop Strut Bent or Intentionally Offset?

[reed1v]

Where is your cutlass bearing? Shaft does not look that bent from looking at your video, or do you mean its 20 degree angle from horizontal? Again, check the cutlass bearing for wear.

[Scaramanga F25]

Bent strut!

[Terra Nova]

Originally Posted by fstbttms

The strut on boats with offset shafts are not mounted on the centerline. Your strut is bent.

This. A proper hull survey would have picked up on this.

The Yankee 30 has an offset shaft; it is easily seen inside the boat, with the engine offset to port. But your strut is badly bent.

[techmans]

Mounting flange of the strut forms a Vee to match the hull.How can you possibly mount that offset ?
Go to his site and see his video where he rotates the shaft with his fingers.
I had no idea that a rope in the prop could do such "perfect" damage.

The shaft not centering in the log is immaterial as long as it does not rub

[tdoster]

I agree, on the YY30, you can look from the rudder and see the shaft angle, but the entry into the cutlass, Strut and boat are right on. Slight offset of the engine.

Pull the packing nut back and see if there is any scoring on the shaft.


That is one where when you get it set back up, you will want to find someone who can laser align it initially to get the motor and shaft where they need to be, then make sure the strut is set to that.


since it all has to come out, it is a good time to pull the shaft and have it checked at a prop shop as well as the prop, have a new coupler fit and faced if needed and packing assy. r/r. Strut will need work as well as the cutlass most likely.

Engine mounts need to be looked at closely as well.

[Celestialsailor]

One sure method is to uncouple the prop-shaft flange to the back of the transmission. If there is a horrendous gap...you know for sure,

[reed1v]

Easiest way is the check the cutlass bearing for wear. Uneven wear will tell you the direction of the bend, if there is one.

[Evan Burkosky]

Some great replies here everyone, thank you very much! Your input is much appreciated in trying to solve this one.

GordMay, this boat is S&S design #2098. Same hull as the Northstar 1000, but mine has the low "bubble" cabin almost flush with the deck:
Sparkman & Stephens: Design 2098 - S&S 30
NORTH STAR 1000 sailboat specifications and details on sailboatdata.com

Good points about the strut being mounted right on the centreline with a V-bracket. I gather that the models with an offset strut have it offset to one side of the centreline? Is that correct? Does anyone have a photo?

It also seems possible though that the strut was not meant to be offset at all, but rather simply unbolted from the hull when removing the shaft. The nuts that hold the mounting bracket in place are easily accessed from inside the hull, so it’s not a terribly big job to remove it, then bolt it back in place and epoxy over when done.

Also good points about checking the shaft for scoring and cutlass bearing for wear. However, in this boat the line was wrapped while in her berth (a mooring line I believe), stalling the engine, and she was towed to the marina yard where the line was cut off after lifting her out. Therefore there hasn't been any turning of the shaft that would cause wear.

It seems like the best way to diagnose will be to undo the shaft coupling and see if it's obviously out of line with the engine. I'll do that this weekend and post a pic back here.

[Nicholson58]

Originally Posted by fstbttms

The strut on boats with offset shafts are not mounted on the centerline. Your strut is bent.

I agree with fastbottoms. He has probably had his hands on more of these than any of us. My first reaction was offset and & made that way but the pictures tell another tale.

Here is ours. Deliberately set to starboard and angled. I needed all of the extra space to pull the shaft past the skeg. Blades off the hub is nearly 5" diameter. Angle counters prop walk.

The rope event probably did it. The other end us usually attached to something firm. The wind up will give it a heck of a jerk. Perhaps a hydraulic port-a-power can be applied to bring it back. Watch for cracks.

[Terra Nova]

Originally Posted by Evan Burkosky

...
It also seems possible though that the strut was not meant to be offset at all, but rather simply unbolted from the hull when removing the shaft. The nuts that hold the mounting bracket in place are easily accessed from inside the hull, so it’s not a terribly big job to remove it, then bolt it back in place and epoxy over when done...
It seems like the best way to diagnose will be to undo the shaft coupling and see if it's obviously out of line with the engine. I'll do that this weekend and post a pic back here.

Simply wishful thinking.

It is very obvious from your photos that the strut is bent and the shaft pushed all the way to one side of the tunnel.

[Evan Burkosky]

Originally Posted by Terra Nova

Simply wishful thinking.

It is very obvious from your photos that the strut is bent and the shaft pushed all the way to one side of the tunnel.

Er, which part exactly do you consider wishful thinking?

[fstbttms]

Originally Posted by Evan Burkosky

Er, which part exactly do you consider wishful thinking?

Look, there are no curved struts. Yours is bent and any other postulation about what is going on is wishful thinking.

[Evan Burkosky]

Agreed. All evidence points to it being bent through damage, not by design. I plan to proceed as I posted above by unfastening the coupler to confirm that it's out of alignment, and if so removing the strut and straightening it. No wishful thinking there.

This brings up my next question: with the strut straightened the shaft will not clear the rudder skeg when removing or reinstalling shaft. Does the original design therefore intend for the strut to be removed and re-glassed each time the shaft is removed? Is thinking that the strut can be removed and re-glassed fairly easily the wishful thinking part?

[Orion Jim]

S&S wouldn't have designed a shaft which couldn't be removed (or installed) so I'm betting you have sufficient clearance once uncoupled and the prop is removed. If the skeg was an add-on then all bets are off. Your strut is definitely bent.

[tinkrman69]

when an offset is designed in to the boat the shaft log is also offset and the strut is not bent to achieve this. your strut is bent. bending a strut will weaken it.

when you repair this make sure the shaft is true...straight...and also check the bearing on the output shaft of the reverse gear for excessive wear, as a misaligned shaft will wreak havoc on it.

the strut appears to be bent pretty far and straightening it might weaken it. you might consider replacing it. it's not all that hard to do, I've replaced a few. bed it with epoxy and just tighten the bolts just to the point of alignment. once the epoxy is cured tork the bolts and glass it in.