Zinc Anodes Being 'Eaten' by Neighbour?

Solitude · 29-09-2009, 15:13

Hi
My shaft zincs are disappearing at double or triple the rate they used to in my old marina. I don’t have my boat plugged in and have concluded that this is being caused by one of the many poor, home built dock cables at the marina or maybe the marina wiring itself. I have surfed around and found that using a grouper anode (hang it over the side ) should help. I couldn’t find anything on this site about this?

Does anyone use these successfully? I understand they need to be hung close to my prop but should the other end be connected close to the stuffing box on the shaft or is it enough to connect it to the engine ground. The prop is not easy to get close to by hanging over the side, is it worth hanging two or so out on either side? Would this be effective?

Any suggestions?

Next haul out I’ll put 3 donut zincs on the shaft instead of two.

Captmable · 30-09-2009, 16:56

Unfortunately your boat is suffering from stray current corrosion... a very, very common problem. There are 4 things you can do to protect your boat.

1) Install a galvanic isolator (if you do plug in to shore power)

2) The Grouper anode is a great idea as it adds much more anode surface area to your boat but a temporary solution only. The anode is simply an extension of your existing cathodic protection. You need to connect the click of the Grouper anode to a metal part which electricalyl conductive to what you want to protect. For example: the prop is electrically connected to the outdrive/outboard, connect the grouper clip to an non-coated surface such as the engine mount bolts. Or if your boat is bonded, connect to the bonding strip (best). Do not connect to your battery.

3) Continue to inspect your other anodes. The Grouper size and mass will definitley help but the smaller engine anodes will waste much faster. Do not mix anode alloy types. OEM anodes are typically aluminum allloy. A Grouper found at your local store is typically zinc alloy. Each alloy has different properties so one will waste before the other. An aluminum Grouper is available from the manufacturer but may be a special order.

4) Complain to the marina. It is their responsibility to correct the problem.

Good Luck!

Capt Mable

29-09-2009, 15:13	#1
Solitude Registered User Join Date: Nov 2008 Location: West Coast, BC , Canada Boat: Cascade Posts: 545	Zinc Anodes Being 'Eaten' by Neighbour? Hi My shaft zincs are disappearing at double or triple the rate they used to in my old marina. I don’t have my boat plugged in and have concluded that this is being caused by one of the many poor, home built dock cables at the marina or maybe the marina wiring itself. I have surfed around and found that using a grouper anode (hang it over the side ) should help. I couldn’t find anything on this site about this? Does anyone use these successfully? I understand they need to be hung close to my prop but should the other end be connected close to the stuffing box on the shaft or is it enough to connect it to the engine ground. The prop is not easy to get close to by hanging over the side, is it worth hanging two or so out on either side? Would this be effective? Any suggestions? Next haul out I’ll put 3 donut zincs on the shaft instead of two.

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30-09-2009, 16:56	#2
Captmable Registered User Join Date: Sep 2009 Posts: 1	Unfortunately your boat is suffering from stray current corrosion... a very, very common problem. There are 4 things you can do to protect your boat. 1) Install a galvanic isolator (if you do plug in to shore power) 2) The Grouper anode is a great idea as it adds much more anode surface area to your boat but a temporary solution only. The anode is simply an extension of your existing cathodic protection. You need to connect the click of the Grouper anode to a metal part which electricalyl conductive to what you want to protect. For example: the prop is electrically connected to the outdrive/outboard, connect the grouper clip to an non-coated surface such as the engine mount bolts. Or if your boat is bonded, connect to the bonding strip (best). Do not connect to your battery. 3) Continue to inspect your other anodes. The Grouper size and mass will definitley help but the smaller engine anodes will waste much faster. Do not mix anode alloy types. OEM anodes are typically aluminum allloy. A Grouper found at your local store is typically zinc alloy. Each alloy has different properties so one will waste before the other. An aluminum Grouper is available from the manufacturer but may be a special order. 4) Complain to the marina. It is their responsibility to correct the problem. Good Luck! Capt Mable