Scored Shaft

Hi, I was in the process of getting ready to do a stringer job and upon inspection of the shaft at the strut I noticed some fairly obvious scoring, Does the shaft need to be replaced? Another question is What is the main cause of scoring? It is obvious that the po did not worry about his prop condition, The shaft looks striaght but I will check it better once it is out.
If the shaft does indeed need replacing which type of shaft?
The ARE system looks pretty nice.
Mike

Fl Inboards wrote: HMM!!! Not really sure what we are looking at here!

I can't make it out ether!!

Mike,
How about a couple more pictures? Sizing to fit will help as well.

correcto,
I will work on the resizing thing trying to get a picture of shaft now.
If you use the tabs on the right and bottom you can move the pic around. No luck on the resizing

The scoring is loacated at the strut, the different color appears to be more or less different sheen , at the packing area all is still smooth.
Thanks
Mike

Mike the prop took a major hit which threw the alignment out causing the cutlass bearing to score the shaft. You might want to double check the strut and make sure it is not bent. I would imagine that your cutlass bearing shows signs of wear and needs to be replaced as well.

Mike,
The cutlass is easiest to remove by sawing it in half lengthwise through the bore. You can do it with a hack saw by removing the blade from the frame and then back on the frame after you get it into the ID. A sawsall is easier!! Then it will be free.

If you can find a length of 1&1/4" OD tubing that fits the ID of the strut, it's the best way to check the strut alignment. Pushed forward into the hull hole and the log, it should be centered. If you can't find any tubing, then get the new cutlass in the strut and use the actual prop shaft. If you go with a rubber cutlass, this way is by "feel" since the rubber has some give to it. The shaft should turn the easyest when it's centered in th log. If not, then the strut is ether bent or needs alignment.

I have had to drill new holes and tap them for the set screws. Get the cutlass out and some penetrating oil on them and try again.

Mike,
Rudders can be straightened however, your's doesn't look that bad from the view you did post.

What Ive done to measure straightness is to put the strut on a piece of computer paper on a perfectly flat surface (granite countertop, etc). I havent found that all strut bases to be perfectly square or symmetrical, so I mark the bolt holes on the paper. Then I draw a straight line through the centers, and mark a set of straight lines parrallel to those, which are visible when I put the strut back on the piece of paper. I then take a large square and bring it up to the lines on each side and measure to the body of the strut several times along its length. It should be clear if your strut is bent using this method... spotting a slight bend (<1/2") by eye alone is very, very difficult.

I dont have any pictures of this process but Ill try and put a diagram together for you. Ive successfully used this method to verify straightness of tracking fins as well.

Pete's right- the important thing is that the strut lines up with the shaft log. If it doesnt, then you'll need to take it off the boat anyways, as its either mounted improperly or bent. I dont think you need highly accurate measuring tools though- a flat surface, a square, a tapemeasure and a paper and pencil should be enough to give you a decent amount of confidence.

Pete, the reason for drawing the lines parallel to the mounting holes is for the exact reason you mention- Ive seen several bases that werent even close to symmetrical so measuring off them directly would have been a waste of time! The body of the strut *should* be pretty close though- any variances in the casting should be fairly small, and plenty obvious to the eye to compensate for. Measuring at several points along the body (not just the ends) and comparing the measurements on both sides should give you a pretty good idea if the strut is bent and in what manner (side to side, twisted, etc).

Chris, thats a fancy trick! Ive never been able to get a bushing out that cleanly... its usually a mangled mess.

Struts can be straightened, but if yours cant be saved, then N3Boatworks has them for a reasonable price. I believe there is a PN discount as well.

'Correct Parts' is a site sponsor that can get you a shaft. I'd recommend a double taper A.R.E. style - must easier to maintain in the long run.


I was able to straighten a bowed shaft, but it wasn't bent much (about .010).

We just supported it in v-blocks, found the high spot, then bounced our weight on it in opposite direction. Got it straight within .002 - good enough!

picts are not that good but you can see the pipe on the right and the strut on the left. The other pic is of the old shaf inside a pipe and shows how high it is riding
Does the strut need to be moved back or lowered it is in the factory holes.

Would a washer be good or a piece of stainless or aluminum plate? I a lot to do on the boat but trying to get this figured out before moving on to the next thing, by the way the cutlass bearing was only slightly terrible to get out This is a picture of the rear with the original shaft inserted into the pipe in the log acting as a alignment tube . kinda of interesting nothing looks straight at all in the picture.