Could a Stainless P:ropeller cause galvanic corrosion of an Alloy power head.

[shaungonemad]

interesting you never mentioned your boat was moored in your other thread!

Pretty sure he is talking about the accumulative time that the boat was in the water during various trips.


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[Noelm]

Scientifically there is a huge difference to dissimilar metal sitting in an electrolyte to dissimilar metals connected together electrically sitting in the same electrolyte.

[Lovey80]

I am wondering if in 13 years when the new engine corrodes out if he’s going to have all the other stainless parts removed from his next engine. Could be difficult getting a prop shaft galvanised then lapped perfectly so a prop will fit nicely.

[Bobpen]

Great thread

I cost me $16,000.
I hope Karma hits your engine. AH

[Bobpen]

I am wondering if in 13 years when the new engine corrodes out if he’s going to have all the other stainless parts removed from his next engine. Could be difficult getting a prop shaft galvanised then lapped perfectly so a prop will fit nicely.

If I had never had a Stainless prop it would have saved me $16,000.
Hope Karma hits your motor AH
I don't have a stainless prop now and never will.
I am capable of LEARNING.

[Bobpen]

Scientifically there is a huge difference to dissimilar metal sitting in an electrolyte to dissimilar metals connected together electrically sitting in the same electrolyte.

The Prop and the power head are connected by the drive shaft and the power head and the prop are connected by hot sea water.
Try it in a glass of sea water. How do you think zinc anodes work? They sit in sea water. The anode dissolves. It is fact.
It isn't rocket science.
Any time you put a stainless prop in seawater you are gradually destroying your alloy power head.
It might take 13 years.
Try it.

[Bobpen]

This has me totally flummoxed, how?

The propeller is bolted to the drive shaft which is attached to the power head.
Like a large wire.

[Bobpen]

Pretty sure he is talking about the accumulative time that the boat was in the water during various trips.


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To Noelm: Boat was anchored while fishing.
I should use smaller words. Sorry.

[DATCOL]

I think my motor is pretty safe as the hot water coms out of the motor past the stainless prop & disappears into the ocean dose not suck back in past the prop

[Steeler]

I cost me $16,000.
I hope Karma hits your engine. AH

You have a good day too champion.

[stevej]

I cost me $16,000.

you got that right you cost yourself 16,000 because you have no idea what your doing with your home servicing and maintenance

and really calling everyone a holes now
your more likely to convince people the earths flat then the rubbish theory you have to why your engine died

[billfisher]

The hot sea water from the alloy power head exhausts through the stainless propeller.
A direct connection.
I worked out my boat was in seawater for about 1,600 hours before there was enough corrosion to destroy the engine mounts.
Most of those hours the boat was at anchor but the motor was still full of sea water probably still warm.
Anyone else out there?

The seawater exits through the prop as you said - then it goes out into the ocean. So there is no electrolyte connecting the powerhead to the prop, That means a galvanic cell is not formed. Also it has already been pointed out that the cooling water drains out of the powerhead as soon as the motor is switched off.

[Bobpen]

Ha ha, Gazza, I think in this case Disorderly would be laughing alongside with you. I suspect this is a Troll post, especially when he queries whether Scottar who works and spends his off time on the water whether he has been on a boat is laughable.
I actually sent the copy of all these posts to a scientist mate who specialises in metallurgy and has spent 2 seasons in the Antarctic so no fool and he just laughed and did say some rather harsh things and said I was being had, so I'll stop commenting now.

Edit: I see Scottar got in before me.

On another offshore marine project (not a mariculture pond) we had some 6 inch plumbing fittings made from Gun Metal.
The Nuts, Bolts and Couplings were all made from the same metal pour to prevent galvanic corrosion from slightly dissimilar mixes of the gun metal.
There are a lot of know nothings on this forum.
Boring but you try to help them .
Some people can't even understand galvanic corrosion is caused by connecting dissimilar metals with an electrolyte.
How many times can you say it?
Let's try again. I am used to dealing with toddlers. Constant repetition.
Some people can't even understand galvanic corrosion is caused by connecting dissimilar metals with an electrolyte.

[Bobpen]

The seawater exits through the prop as you said - then it goes out into the ocean. So there is no electrolyte connecting the powerhead to the prop, That means a galvanic cell is not formed. Also it has already been pointed out that the cooling water drains out of the powerhead as soon as the motor is switched off.

Do you seriously think there is not enough film of seawater left in the powerhead to conduct electricity?
So why flush motors at all then. How stupid are you? When I drain my kitchen sink the water leaves a film I don't use Rainex on it.
On another offshore marine project we had some 6 inch plumbing fittings made from Gun Metal.
The Nuts, Bolts and Couplings were all made from the same metal pour to prevent galvanic corrosion from slightly dissimilar mixes of the gun metal.
There are a lot of know nothings on this forum.
Boring but you try to help them .

[billfisher]

Do you seriously think there is not enough film of seawater left in the powerhead to conduct electricity?
So why flush motors at all then. How stupid are you?
On another offshore marine project we had some 6 inch plumbing fittings made from Gun Metal.
The Nuts, Bolts and Couplings were all made from the same metal pour to prevent galvanic corrosion from slightly dissimilar mixes of the gun metal.
There are a lot of know nothings on this forum.
Boring but you try to help them .

I'm not stupid at all - in fact I'm a qualified chemist. Check what happens when you drain the bath or sink next time. Water has a low viscosity and has the property of surface tension. It we bead into droplets rather than form a continuous film.