New Gori propeller corroded (pictures)

[Scot McPherson]

Originally Posted by Sailmonkey

That brings up another point. What is the worlds fascination with the stupid submersible bilge pumps?!? Use a diaphragm pump for day to day maintenance and leave the submersible up a little higher for flooding.....stray current from the always wet electrical motor goes away!!

I have a manual bilge pump and an automatic bilge pump. The automatic Bilge Pump is in another bilge compartment that isn't as deep. The manual bilge pump is only powered when I set the circuit breaker AND pull on the activation switch. If I have stray electricity from the manual pump, it's for just a few minutes at a time. I run it once a week, maybe twice if the weather calls for it.

The automatic bilge pump stays dry and is there as a backup, or if the hull starts taking on water faster than I expected.

[gjordan]

If you have a submersible you have 12 volts in the wire that can leak, but if you have a diaphragm pump you still have a hot wire going to the float switch so bad insulation in either case can cause corrosion or is my thinking all wet??? Grant

[carlo de leo]

Originally Posted by gjordan

If you have a submersible you have 12 volts in the wire that can leak, but if you have a diaphragm pump you still have a hot wire going to the float switch so bad insulation in either case can cause corrosion or is my thinking all wet??? Grant

I think DIAPHRAGM PUMP=MANUAL NOT ELECTIRC PUMP.

[carlo de leo]

In my case (thread case), I do not leave my bilge pumps circuits on all the time. I do as Scot McPherson said, just turn on the manual electric pump when needed then turn off. I don't use the automatic mode. So I think I'm immune to this.

[PortClydeMe]

Interesting prop design. Did you contact Gori? What's the warranty read like?
They are used by some heavy-hitter builders. Being originally from Maine, I like "won't snag seaweed or lobster lines".

http://www.gori-propeller.com/index.asp?ID=87

[Sailmonkey]

Originally Posted by carlo de leo

I think DIAPHRAGM PUMP=MANUAL NOT ELECTIRC PUMP.

Diaphragm pump = electric. However by not submerging the whole pump with multiple penetrations through the body, a major source of electrical leakage is eliminated.

[carlo de leo]

Originally Posted by PortClydeMe

Interesting prop design. Did you contact Gori? What's the warranty read like?
They are used by some heavy-hitter builders. Being originally from Maine, I like "won't snag seaweed or lobster lines".

Gori propeller

I think it's not a prop problem, at least I expect that...

[boden36]

If you use an electric diaphragm pump, and actuate it via a switch positioned above bilge water level (ie a switch actuated by a plastic rod with a float on the lower end), then you tick all of the boxes.

Regards,
Richard.

[PortClydeMe]

Originally Posted by carlo de leo

I think it's not a prop problem, at least I expect that...

Got ya! But... my point was different. Squeaky wheels get the grease. Sometimes a phone call can result in a "new free prop" at your doorstep via FedEx. Worth a try.

[EWOL Props]

That is exactly the reason why we only propose High Grade Stainless Steel propellers !

Bronze props resist against galvanic corrosion but only if perfectly protected. In case the anodes are too much used or lost (it happens many times due to vibrations or wear-out), then the resistance to corrosion is bad and as a result you can have big damages to the propeller plus vibrations.
High Grade Stainless Steel instead will have no damage even in case of anode lost.

Originally Posted by Suijin

Looks like electrolysis to me:



That fluid, organic blob shape is a dead giveaway.

[Oceansailor]

Originally Posted by EWOL Props

That is exactly the reason why we only propose High Grade Stainless Steel propellers !



Bronze props resist against galvanic corrosion but only if perfectly protected. In case the anodes are too much used or lost (it happens many times due to vibrations or wear-out), then the resistance to corrosion is bad and as a result you can have big damages to the propeller plus vibrations.

High Grade Stainless Steel instead will have no damage even in case of anode lost.

I think you missed the conclusion. The damage on the propeller was caused by a DC leak from a faulty bilge pump wiring. Stainless or bronze are not not immune to that. No metals are.

Then there is many different bronze qualities as there is from stainless. Some better than others. Flex-o-Fold is using one of the best.

[EWOL Props]

Originally Posted by Suijin

I've posted this before but it's worth it again for this thread.

This is a sail drive what was the victim of stray current. And this is off a cat and the other was just as bad. It took approximately 10 days for this to happen. Stray current off victim boat itself:

WOW !!! Unbelievable !
Interesting to see that the stainless steel parts are just discoloured, not really affected by the corrosion

[Oceansailor]

Hmm.

The picture only shows that aluminum corrodes faster than stainless.

My point is that the problem with the FFF propeller was caused by a faulty wire. Not the material in the propeller.

If you want to learn more about stainless I suggest this as a good read. http://stevedmarineconsulting.com/wp...less-Small.pdf

[EWOL Props]

Originally Posted by Oceansailor

Hmm.

The picture only shows that aluminum corrodes faster than stainless.

My point is that the problem with the FFF propeller was caused by a faulty wire. Not the material in the propeller.

If you want to learn more about stainless I suggest this as a good read. http://stevedmarineconsulting.com/wp...less-Small.pdf

Sure, I understand your point and I agree with you... probably also for that propeller (like in the above case of S-Drive leg), the problem has been caused by stray currents, probably not by a defect in the manufacturing of the propeller itself. Infact I am talking about materials, not brands.
The picture here above demonstrates that even in case of strong stray currents (I think you agree on this point) the super-duplex stainless steel (used for the S-Drive shafts) has not been affected.

That same material (Super-Duplex) is what we use to manufacture EWOL Props.

In the article you attached (thank you for that) you can find the paragraph on duplex steels, and even better on Super-Duplex, which confirms the superior quality of those materials.

By the way... I have an experience of 30+ years on propellers and their materials, many years ago at a well known manufacturer of feathering props, then at EWOL for the rest of my career...I can tell you I have seen many corroded bronze alloys propellers of all brands, some in very bad conditions...but never seen a problem with the Super-Duplex in 20+ years that we manufacture props here, even when we installed on electric powered boats, one making the world tour and having shown considerable stray currents due to incorrect insulation.

[Vaaldam]

I have a similar situation on my sail drive. Where can I get hold of a replacement as I seem to hit a wall looking for one. I have a 1982 18hp OMC motor which runs faultless.