Grounding Plates

[Finster]

Anyone have any thoughts on this? My Alpha I outdrive seems to have a lot of electrolysis, the zinc's melt quick. Would a bronze grounding plate help this? Or should the boat be grounded already though the outdrive?

[Water Rat]

Finster,

I'm no marine electrician but have a '78 I/O Sceptre 23 (7.4L Bravo One) with a lot of metal in the water (beside the outdrive, have Kiekhafer tabs, transducers, etc.). I mounted a large transom-mounted zinc plate and have all underwater hardware bonded together with #6 wire and to the zinc plate itself. I also have a Guest Dynaplate (sintered bronze ground plate) that was used as a ground for my old Furuno loran, but the ground plate itself is not going to help reduce your electrolysis; if anything, it would probably help make it worse with more noble metal underwater.

I also keep up with my outdrive and tab mounted zincs carefully and so far have had no real problems with a now 20+ year old outdrive and my tabs still look like new (I am sure I just jinxed myself by typing this). Sorry I cannot upload any pictures just now.

[Finster]

Thanks. Ya I should probably recheck all my ground again. It's no biggy replacing the caviltation plate zinc once a month if I can't find anything.

[Blue_Heron]

Originally Posted by Finster

...It's no biggy replacing the caviltation plate zinc once a month if I can't find anything.

If you're going through zinks at that rate, there's probably something wrong. Water Rat's right about the bronze. If it's in the water, it's only going to make things worse.

If there are other boats moored close by, one or more of them may be introducing stray current into the water. I'm not sure how you would check that. Maybe if you put on Capt. Chuck's zinc plated undies, stick a toe in the water and lick the negative battery terminal. If it tingles there's probably stray current.

An alternative is to use an induced current system (to fix the galvanic corrosion, not to find the stray current). Merc makes one for the Bravo drives called Mercathode. It seems to have fixed the corrosion problems they were having. I don't know if it will fit an Alpha, but it probably won't. There might be a way to rig it, though.

Dave

[pelican]

Originally Posted by Blue_Heron

If you're going through zinks at that rate, there's probably something wrong. Water Rat's right about the bronze. If it's in the water, it's only going to make things worse.

If there are other boats moored close by, one or more of them may be introducing stray current into the water. I'm not sure how you would check that. Maybe if you put on Capt. Chuck's zinc plated undies, stick a toe in the water and lick the negative battery terminal. If it tingles there's probably stray current.

An alternative is to use an induced current system (to fix the galvanic corrosion, not to find the stray current). Merc makes one for the Bravo drives called Mercathode. It seems to have fixed the corrosion problems they were having. I don't know if it will fit an Alpha, but it probably won't. There might be a way to rig it, though.

Dave

alpha drives have the mercathode system as well...that system,it didn't "fix" anything on the early bravo III drives - that system was allready there,the repair on the BIII drives was an update on the drive itself.



dissapearing zincs:

a common cause is the trim sender - wires are broken...

another common cause is wet wiring in the boat itself...

dumb question: you're stating the cavitation zinc - what about the trim cyclinder zincs ? the zinc on the transom assembly ? these zincs burning up quickly ?

trim tabs ? zincs on them ? stainless steel prop ?

when the boat's in the water,drive tilted up - are ther any small white powdery deposits apparent on the drive ?


the true test is with a special plug in metal - on end of a DVOM is connected to the metal,it's dropped on the side in the water,the other lead on the DVOM is connected to ground - voltage is read...
not sure about the zinc coated bannana hammock ?
"electrolysis" - it's hair removal...

[Capt Chuck]

Yo Scupper Lips

Why don''t you just wear these Zic plated underwear and hang your big toe over the side while your trolling

[Water Rat]

Originally Posted by Capt Chuck

Yo Scupper Lips

Why don''t you just wear these Zic plated underwear and hang your big toe over the side while your trolling

Or that, that should work too.

[Finster]

Damn Chuck, I'm so glad I don't know what that is, but questioning the fact that you do...:P

[Finster]

Ya I'm thinking dead short somewhere, though I couldn't find anything last year. Shutting the batteries off doesn't seem to help either. I'll just go through everything again and or try Chucks undies. Thankfully I won't need to use my toe

[BigLew]

Com'on Finney, use the toe. You were the first to admit there was probably a "dead short!"