White powder on my thruhulls

[arch007]

I have seeing white powder on my thruhulls.
I clean it off and it comes back.

I installed a galvanic isolator.

No difference.

Thinking of removing the bonding wire linking all the thruhulls.

The wire seems to be solid copper not stranded wire
And very stiff.

Any problems removing the wire or and other suggestions ?

No fridge and bilge pump replaced.

AC socket and panel checked.

[Dick Villamil]

Are the plugs the same metal as the housing? One of my thruhulls gave way while at anchor and I couldn't leave it (finger in the dike syndrome). Finally got it plugged and had to replace it. Also it looks like the screw clamp is getting rusty - meaning that it is not a totally stainless clamp and is rusty. I would definitely replace the screw clamp with a stainless one (make sure the screw is also stainless). As for the white powder I can only think there are dissimilar metals in contact but it could be some galvanic action from elsewhere.

[arch007]

have changed the hose and the clamps.

Disconnected the bonding wires. Going to see if that makes a difference.

Also going look at the bonding wire link to the propeller shaft and cutlass bearing.

Has anyone looked at the link ? Any problems disconnecting it ?

The bonding wire seems to be SOLID COPPER not stranded. Maybe for lightening protection ?

Bonding wire goes to dynaplate from chainplates. The from dynaplate to engine thru hull. The engine thru hull to sink thru hull. Sink thru hull to ?????? Scupper thru hull ??????

Can I replace the bonding wire with stranded wire ?

Thanks

[Steve Laume]

Why are you disconnecting your bonding system and what is the reason for wanting to replace the solid wire with stranded? If you don't have a though understanding of a system it might not be a good idea to mess with it. If you did know exactly what you are doing, and all the pros and cons, I suspect you wouldn't be asking questions here. How do you know that the white powder is a result of a bonding or galvanic issue? How long are you going to leave the bonding wires off to determine if they are a problem? Do you keep the boat in an area that is prone to thunderstorms?

I have a lot of questions. I know there is some controversy over whether things should all be bonded and tied to the engine along with the DC ground but I would do a LOT of research before I disconnected the system. I don't think switching to stranded wire is going to hurt anything except your wallet. I know that solid wire is never recommended for marine use except that this stuff is heavy enough that it is unlikely to flex and break.

If you do away with the above water bonding then you lose you lightning protection. This all seems like a lot of effort to "see if it makes a difference". This maybe a cast of tossing out the baby, Steve.

[moctrams]

I suggest taking a digital volt ohm meter and put one side at the Dyna plate and going to each location and check for continuity. I'll bet there are places where there is so much corrosion, you will see high resistance.

[Steve Laume]

Cleaning all the contacts is always a good first step, Steve.

[arch007]

Disconnecting bonding wire to clean contact. The wire is very stiff.

Also going remove and clean bonding wire contact on shaft.

Has anyone done this ? Have a cape dory 28.

Dont know what the white powder is. Any ideas ? But no problems then just started
3 months ago.

I am in California and there is very little lightening here.

Thanks

[wikakaru]

Can I replace the bonding wire with stranded wire ?

You certainly can. The ABYC standard for lightning protection calls for stranded copper wire, as does the Dynaplate installation instructions (https://www.marinco.com/en/~/media/inri ... -31798.pdf) .

[Keith]

Just looked at Figure 1 on page 3 of the dynaplate link and find it interesting that they show the caulking on the inside of the hull between the the backing plate and not on the outside of the hull. Hmmmmm

Keith

[sgbernd]

Taste the "white powder". I suspect it is just salt. A bit of water is seeping in and evaporating leaving the salt residue. Bronze turns green (CuCl) with the salt corrosion, unlike Aluminium which will turn to white powder. If it is salt, remove the screw, repack the threads with water-proof grease and screw it back in. Easiest repair you will ever do.

I would not recommend removing the bonding wire although for bronze thru-hulls and seacocks, you can get away with it. The grounding wire allows all the thruhulls to be protected by the single prop zinc and provides a ground to the dyna-plate in case of lightning strikes. The hope is that the lightning will not jump to the single thru-hull exit, run all it's current thru that one, blow it out of the hull and sinking the boat.

-steve

[SPIBob]

Those look pretty good to me. I agree with sgbernd that the white stuff most likely is salt. Maybe the tapered plugs are a bit loose and are ready for cleaning, greasing and refitting.

[arch007]

I considered salt BUT

All the thruhulls started showing the white power a the same time.

Highly unlikely they all got loose at the same time.

Some power boats came in a few slips away.

I suspect someone's electrical system is leaking and causing stray current corrosion.

I had the propeller zinc replaced and it was still 30 percent there. So zinc was not completely used.

Removing battery positive connections and seeing this makes a difference.

ALso purchased a hanging zinc and connecting directly to a thruhull and see if while powder comes back after I brushed all the white powder off.