Electrolysis nealy sank me! Why?

[rob1066]

I pulled my 28' regal with twin mercruiser outdrives up yesterday and saw my brass drain plug was severely eaten away. When I went to unscrew the plug the whole thing fell off. You can imagine how lucky I was that it didn't fall off whilst in the water, one more month and I think that would definately have happened. <br /><br />My zinc bolts and sharks were also eaten away. I looked at the ground and it is all going to the battery. I have noticed one thing though that if I am wet or I have a small cut I get a small electrical shock from my Stainless steering wheel and windscreen frame. The bay that I was morred at is notorious for electrolysis and maybe thats all it is, I have since moved. Could I have a leak somewhere and how, any ideas anyone? I will have to pull my boat every six months otherwise to replace the drain plug.

 

[FlyBoyMark]

Re: Electrolysis nealy sank me! Why?

Recheck ALL wiring and you may need MORE zinc plates in the water and they all have to be connected with a wire...use one of the new all NYLON/RUBBER drain plugs.

 

[rob1066]

Re: Electrolysis nealy sank me! Why?

So do I have to connect all the zinc plates with a wire and then attach that wire to the ground.

 

[Franki]

Re: Electrolysis nealy sank me! Why?

Its just a small thing, but rather difficult for all that..<br /><br />except for the zinc plates, try to have the fewest disimiliar metals in contact with the water as possible.. as the weaker metals will always be eaten.. if you have only one type of metal and your zinc plates, then the plates will get 95+% of the effect.. <br /><br />but yes, I believe having all of them connected to a cental point will stop stronger metals bleeding electrons out of the weaker ones. since the easer path is through the wire you hook up.<br />and current always takes the easiest route..<br /><br />rgds<br /><br />Frank

 

[FlyBoyMark]

Re: Electrolysis nealy sank me! Why?

The weekly TV show " Ship Shape" had a very good segment about electrolisis about a year ago. If ya look them up on the web you can order the video. Extremely well detailed info on how to cure this problem.......<br />This episode video if ya want to buy it:<br /> Episode 5-101 <br /> Projects: Bonding Systems and Sacrificial Metals

 

[EGalvTex]

Re: Electrolysis nealy sank me! Why?

We had a similar but more severe situation at the A&M Galveston Terminal a few years ago. An alluminum hulled 45' sport fisherman had a pencil width hole eaten through its 3/8" plating and nearly sank. We discovered the problem one morning when the "Romin' Empire" was listing badly and had 1500 gallons of water in her bilge.<br />No matter how hard we searched, we could not find an electrical leak inside the vessel and when old Zincs were replaced, they were quickly eaten away. Part of the problem was diagnosed as a possible shore power leak, electrifying the water around the terminal docks.

 

[FlyBoyMark]

Re: Electrolysis nealy sank me! Why?

In that segment of Ship Shape TV they coverd that with some instumentation....I don't remember if it was special equip. or a quickie setup of a VOM. They explained in detail how to find all the problems.

 

[DJ]

Re: Electrolysis nealy sank me! Why?

rob1066,<br /><br />Your Regal is fiberglass (I assume) so you do not have to worry about the hull. You also do not have to worry about anything grounded to the hull.<br /><br />What you must do however is make sure all electrical grounds are clean and tight; such as;<br /><br />1. engine grounds.<br />2. aux. power grounds.<br />3. house electrical systems. This one can be particularly leaky.<br />4. battery connections are good.<br /><br />You may, as you mentioned, just be in an area with "hot" water surrounding you. The only defense against this is more zincs.<br /><br />In the past, Mercruiser used to offer a system called: MerCathode. I do not know if it is still around. A Mercruiser dealer could tell you. This system will do a good job of protecting your drives.<br /><br />The tape that FlyBoyMark mentioned might be worth your while in your hunt for potential problem areas.

 

[jocko_nc]

Re: Electrolysis nealy sank me! Why?

Many marinas are notorious for having sloppy electrical service. Even if all the service is properly grounded. you are still at the mercy of the boat next to you. Any difference in electric potential (voltage) at the dock makes a giant battery, with the vatious metals present as anodes and cathodes. The sea water completes the circuit of a wet cell much like your car battery.<br /><br />With so much going on in a confined space, be wary of marinas.<br /><br />jocko