Shaft crevice corrosion

[Keith]

Ouch! Worst case I've ever seen.

 

[Phil Fill]

The shaft could be flamed sprayed and machined like new. We do hundred of shafts.

 

[Capn Chuck]

Oh, I think ours has that beat by quite a bit, The Trawler Beach House: Repairs, Failures, And The Domino Affect . Chuck

 

[Hendo78]

Oh, I think ours has that beat by quite a bit, The Trawler Beach House: Repairs, Failures, And The Domino Affect . Chuck

Lol bugger!

iPad Forum Runner

 

[psneeld]

The shaft could be flamed sprayed and machined like new. We do hundred of shafts.

Agreed...had mine done last year with new split coupling for around $400.

Maybe another good argument for running your engine in gear as often as possible to keep oxygenated waster all along your shaft.

 

[FF]

Aquamet , or other more suitable replacement at haul time.

Life is too short to use SS underwater.For anything.

 

[RickB]

Aquamet is stainless, the percentage of chrome varies with the "model" between 17 and 22 percent but it is still stainless steel. Compare the composition of 316L and Aquamet 19.

Unless you want to keep your boat tied to the dock unused in an area with low oxygen, hot, brackish, contaminated water for decades, there isn't all that much advantage for the recreational trawler owner to go with the high priced bar stock.

 

[psneeld]

Aquamet is stainless, the percentage of chrome varies with the "model" between 17 and 22 percent but it is still stainless steel. Compare the composition of 316L and Aquamet 19.

Unless you want to keep your boat tied to the dock unused in an area with low oxygen, hot, brackish, contaminated water for decades, there isn't all that much advantage for the recreational trawler owner to go with the high priced bar stock.

I've heard of some larger vessels that plumb the water injection into a continuous pumping system (I think the example was the a/c system) to keep water flow through there. Not sure I like the extra complication but see the point.

In my case I think it was ancient packing from the PO and little use that did my shaft in.

 

[RickB]

I've heard of some larger vessels that plumb the water injection into a continuous pumping system (I think the example was the a/c system) to keep water flow through there. Not sure I like the extra complication but see the point.

I've never seen or heard of it but if the boat lives in bad water I guess it can't hurt except for the added plumbing complication.

This thread is a good example of why class says you need to pull the shaft every 5 years. It is a bit much to hope that anything not made of quartz can go unattended for 35 years without some corrosion problems.

 

[Blue Heron]

My shaft have corrosion. But it is 28 years old. Should I be concerned ? Anyone have corrosion and still running?

 

[Keith]

Not unless it's causing problems. It can eat up your packing in no time if it's bad, so if you're continually re-packing and adding rings, that could be the issue. Mine had some issues when I first bought the boat, so we replaced the shaft, packing gland hose, and put rings of Gore's GFO packing in. After the initial run-in, I think I've tightened the packing gland nut 1/8 turn maybe 2 or 3 times in 11 years.

 

[boatpoker]

I would get rid of a shaft with pits like that. The first photo below is of a shaft that broke. Note that the exterior shows miniscule pits while the inside of the shaft is a mass of corrosion.

The second photo is an x-ray of a shaft showing the one small pit on the surface that leads to a cavern of pits under the surface.

 

[FF]

A too rapid shift to reverse can loose the prop too.

Priced a prop lately?

 

[fstbttms]

What do you make of this? (Sorry for the poor focus)

 

[fstbttms]

Priced a prop lately?

Pulled these two 18" beauties off a Sea Ray 34 last week.

About $1K each to replace in bronze. Considerably more in Nibral.

 

[Keith]

Sweet.

 

[Marin]

The best way to avoid crevice corrosion in a shaft is obviously to run the boat in gear periodically. I've been told that even turning the shaft by hand a bunch of times will help a lot. Anything that changes the water sitting around the shaft.

If your boat has a cooling/lube water feed to the shaft log, even better as that forces new water into the log and along the shaft. Not a great idea to start the engine just to push new raw water into the log for a few minutes, though. Better to go ahead and put the thing(s) in gear and run it (them) up to put a load on and run at operating temperature for awhile.

 

[charles]

Keith,
As you know I put many thousands of hours on my boat and had some crevice corrosion on occasion but also lots of plain old wear. A local machine shop redid the worn or corroded areas on each shaft and they were like new. Had that done several times in 25 yrs. Once in NY the guy really tried to sell new shafts no deal. When I sold the boat the ORIGINAL shafts were in place.
Just my experience.
Oh, several over the decades have held that I was wrong or crazy to do so, but it works and for REAL SHAFTS as well not the Tinke Toys that we use, you know shafts one foot in diameter.