Warning, West Marine Dangerous Cotter Pins

[CSY Man]

This pin was installed 4-5 weeks ago on the prop shaft.
Boat in brackish water.
Today I pulled the pin and it crumbled and appeared hollow inside.

[CSY Man]

[CSY Man]

Above picture shows rust on the white nylon washers and rust dripping on the prop guard.
They were clean when pins was installed 5 weeks ago.
The boat has been on the trailer for 1 week, in the water for 4 weeks after I put on a new prop, new washers and a new cotter pin.

Second time this happened: After the first time I went back to West Marine, brought the same corroded pieces and warned them about horrible quality. They did not pay attention, mumbled something about a bad batch, gave me 5 new pins and said "these are good".
Not so, and since they don't care, at least not on the local level, I got no choice but to warn everybody: Do NOT buy safety or rigging stuff at West Marine: They have gone too far getting cheap stuff, most likely in China..

[Orion Jim]

Hard to tell from the photo. Does it appear to be an inferior "stainless steel"? Looks like plated steel in the photo.

[sailnow2011]

Stray current? Thats my guess. Nothing should dissolve in 5 weeks, even if it is made from tin.

[CSY Man]

Stray current?

Hmm, never thought of that, but this is an electric boat being charged 12 hrs per day.

The shaft is stainless with no signs of corrosion.
The shaft and therefore the cotter pin is isolated from charger and other electronics with a rubber belt, therefore probably not a faulty grounding.

Stray current would burn a sacrificial zink, but a SS cotter pin?
Would stray current cause the brown rust? Looks like low grade steel instead.
Getting a new pin from a different vendor tomorrow and will keep an eye on.

The scary part is that the West Marine cotter pin is hollow on the inside, I could stick a needle in there. (Hollow after being in the water, probably not before)

[Wotname]

Have you tried the magnet test on the remains of the old pin?

[CSY Man]

. Have you tried the magnet test on the remains of the old pin?

Not yet, good idea.

[boatpoker]

Stray current could have eaten the pin but your anodes would have been eaten much faster than the pin. If the anodes are ok there is no chance that stray current is the culprit.

[CSY Man]

No anodes.
The prop is plastic, no underwater through holes.
The factory never installed or recommended anodes.
The only metal in the water is the SS shaft and the cotter pin behind nylon washers to secure the nut and lock-nut holding prop in place.
The nut and lock nut is nylon. (Or marlon)

Correction: the skeg, or prop guard is steel, but isolated from other metals.
It is bolted to the fiberglass keel with SS bolts and SS washers for spacing.

[CSY Man]

Just tested the old/corroded cotter pin and the new WM cotter pin with a magnet: They are not Magnetic.
Which means they are probably stainless steel and if so, stray currents may be the culprit.
OR is there inferior SS products out there that will corrode in short time underwater?

[colemj]

Originally Posted by CSY Man

OR is there inferior SS products out there that will corrode in short time underwater?

On about the 5th operation of our new Maxwell windlass, the SS circlip holding the gypsy shaft into the windlass broke in three pieces and fell out. The pieces were very corroded and looked like that of your cotter pins.

This windlass has never been underwater, just saw a small amount of deck spray and was only a few weeks old.

So I think there is indeed inferior SS products out there.

Mark

[a64pilot]

Originally Posted by CSY Man

Just tested the old/corroded cotter pin and the new WM cotter pin with a magnet: They are not Magnetic.
Which means they are probably stainless steel and if so, stray currents may be the culprit.
OR is there inferior SS products out there that will corrode in short time underwater?

Stainless Steel is just a name, like plastic, just like there are many types of plastic, there are many types of Stainless, a magnet only determines if the steel is Austenitic, Ferritic or Martensitic.

https://en.wikipedia.org/wiki/Austen...tainless_steel

https://en.wikipedia.org/wiki/Marten...tainless_steel


Now we want corrosion resistance in our "stainless steel", but that is only one of many considerations, for most of our uses, I'd say 316 is a good choice, 304 for instance is stronger, but less corrosion resistance.

If possible find 316 cotter pins, I know you can order them.
Monel would probably be a good choice too

[CSY Man]

Yeaj good idea using 316. That could be the problem, 304 is softer, 316 more resistant to corrosion.
(Specified 316 when I replaced all chain plates on my sailboat)

These cotter pins however seems way to fragile to be even 304.
Not sure I will even bother taking them back to WM once more, they already ignored the problem once. Perhaps they monitor "Social Media" and finds this thread then start looking into it...

[George DuBose]

Monel cotter pins? That's an idea. I know that there are bronze cotter pins.