to bond or not

[Elessar]

Having had an outdrive log block this year, and having had to link the engines with sanitary pipe to draw coolant for both from 1 leg to get me home, I decided on a better solution.

So I've added a seacock, the outlet of which Ts to give a feed to each engine, and each of these feeds is Td into the leg coolant feed before the strainers.

Thus I now have a seacock and 3 DZR Ts that are electrically isolated. The strainers themselves are earthed.

The question therefore is, should I electrically bond them or not?

 

[Deleted member 36384]

I understand that your DZR components are about as neutral as it gets wrt galvanic corrossion and as such there is no need to bond them. If the valve is also DZR then that too does not need to be bonded.

 

[vyv_cox]

No, bonding is likely to produce more problems than it can solve and is quite unnecessary thanks to their DZR construction.

I'm no authority on outdrives but you may need to be careful about connecting them electrically to the earth of the boat, as with sterndrives. Plastic hose is OK but no metal.

 

[Talbot]

If you had used marelon (like I will be doing) then there would have been no need for this question!!!

 

[Bosun Higgs]

I understand that your DZR components are about as neutral as it gets wrt galvanic corrossion and as such there is no need to bond them. If the valve is also DZR then that too does not need to be bonded.

This isnt really the full story. Electrolysis requires two dissimilar metals, a circuit between them and an electrolyte. You may remember the scoolboy experiment where you had a tan k of acid with two electrodes some distance apart and a wire connecting them via a light bulb - which then lit up.

So if you bond the seacocks you will create that sort of circuit, and it then becomes an issue of how close the compnents are ( ie the resistance between them) and the material they are made of.

I would not bond but I would keep a very careful eye on things. I assume, incidentally, that there are electrodes on the legs anyway.

 

[Deleted member 36384]

This isnt really the full story.....

Thanks for the good example and reminder. I guess where I was coming from is that DZR and its ilk are not likely to waste away in a normal set up as they are low down on the Galvanic Table, hence the risk is low of them being an anode to another metal further down the table. By connecting them, as you state, you could actually be increasing the risk of wastage occurring.

http://www.eaa1000.av.org/technicl/corrosion/galvanic.htm

 

[Elessar]

thanks all outdrives (sterndrives) are not earthed except (i think) via the mercathode electric anode. They have loads of anodes on that seem to be made out of alka seltza, except pricier.

 

[fireball]

They have loads of anodes on that seem to be made out of alka seltza, except pricier.

Ah - that explains why the wake of a mobo always has a frothy bit .... probably there to disperse the oil!