Sizzling Summer Zincs - Sail Magazine

Sizzling Summer Zincs

Stuart Goldman of Shelter Island, New York, asks:"For the last two years the zincs on the shaft and MaxProp on my Hinckley SW 42 have started to really dissolve in early July—after the boat has been in the water for about a month. The boat is on a mooring that’s at least 500 yards away from any other boat except a 50ft powerboat, which is also on a mooring about 50 yards
Author:
Publish date:
Social count:
0

Stuart Goldman of Shelter Island, New York, asks:

"For the last two years the zincs on the shaft and MaxProp on my Hinckley SW 42 have started to really dissolve in early July—after the boat has been in the water for about a month. The boat is on a mooring that’s at least 500 yards away from any other boat except a 50ft powerboat, which is also on a mooring about 50 yards away, and a 40 footer that is moored at about the same distance at a dock. I’ve asked both these owners whether they are having similar problems and they say that they are fine. This tells me, although I could be wrong, that stray electrical current in the water is not bombarding the boat.

When I leave the boat to go ashore I turn off both the house and starting batteries at the main breakers and the only device that remains activated is the emergency bilge pump, and it operates with a float switch. Am I missing anything?"

Nigel Calder replies:

Although your problem could be caused by either galvanic or stray current corrosion, because stray current corrosion will attack whatever metal is feeding the current into the water— and often that is not the zinc— I suspect that you have galvanic corrosion. Because you are not plugged into any shore power, the chances are that it is being generated on board.

The first question you need to answer is whether you have any substantial underwater metal masses that are tied into the bonding systems. These could include such things as bronze through–hulls, a bronze rudder, or an exposed metal keel.

But you should also test whether there is stray current in the water and to do this put two long leads into a millivolt meter and then hang both over the side in the water at different points around the boat. If you get any reading at all, in either an AC or DC mode, there is stray current in the water.

The best way to test for galvanic current is to put a silver/silver chloride half cell on a long lead and use it with your multi-meter (boatzincs.com/corrosion-reference-electrode-specs). There are some other tests that will help you determine whether you have galvanic corrosion and they are explained in more detail in my Boatowner’s Mechanical and Electrical Manual.

Related

180615-01 Lead

A Dramatic Comeback in the Volvo

After winning three of the last four legs in the Volvo Ocean Race (and coming in second in the fourth), Dutch-flagged Brunel is now tied for first overall with Spanish-flagged Mapfre and Chinese-flagged Dongfeng following the completion of Leg 10 from Cardiff, Wales, to ...read more

MFS-5-2018-Propan-SP02

Tohatsu LPG-powered 5hp Propane Motor

Gassing it UpTired of ethanol-induced fuel issues? Say goodbye to gasoline. Japanese outboard maker Tohatsu has introduced an LPG-powered 5hp kicker that hooks up to a propane tank for hours of stress-free running. Available in short-, long- or ultra-long-shaft versions, the ...read more

TOTW_PromoSite

SAIL's Tip of the Week

Presented by Vetus-Maxwell.Got a tip? Send it to sailmail@sailmagazine.comThink Deeply When chartering, I am always maddened to be told that the echo sounder is calibrated “to depth under the keel, plus a bit for safety.” Such operators seem to imagine that the instrument’s sole ...read more

180612-01 Landing lead

Painful Sailing in Volvo Leg 10

It’s looking to be a case of feast or famine for the 2017-18 Volvo Ocean fleet as it continues the epic struggle that has been Leg 10, with it having been all famine thus far. Painful is the only word to describe the light-air start in Cardiff, Wales, on June 10, as the 11-boat ...read more

01-13_07_180304_JRE_03695_4605

Tips From the Boatyard

Within the Volvo Ocean Race Boatyard sits a communal sail loft which provides service and repairs for all seven teams sailing in the 2017-18 edition of the race. The sail loft employs only five sailmakers who look after 56 sails in each stopover. If you’re thinking, “wow, these ...read more

sailCarwBasicsJuly18

Sail Care for Cruisers

Taking care of your canvas doesn’t just save you money, it’s central to good seamanship  Knowing how to take care of your sails and how to repair them while at sea is an important part of overall seamanship. The last thing any sailor needs is to get caught on a lee shore with ...read more

Ship-container-2048

The Danger of a Collision Offshore

This almost happened to me once. I was sailing singlehanded between Bermuda and St. Martin one fall, and one night happened to be on deck looking around at just the right time. The moon was out, the sky was clear and visibility was good. Still, when I thought I saw a large ...read more

New-MHS-Promo

Multihulls on the Horizon

Fountaine Pajot New 42The French cat powerhouse has been on a roll these last few years, cranking out new models that not only replace their older line but take a step forward in design and user-friendliness. The New 42’s “real” name had not been revealed as we went to press, but ...read more