Ask SAIL: Zincs Emergency

Author:
Updated:
Original:

ZINCS EMERGENCY

Q: I need advice. All of a sudden I’m burning through zincs while at dock. My gut instinct says that there is a stray current somewhere. Is it most likely from outside my boat (dock or nearby boat) or inside my boat? What kinds of checks can I make with my voltmeter and how do I do it?

George Blakeslee, New Haven, CT

NIGEL CALDER REPLIES

If you are plugged into shorepower then most likely this is galvanic corrosion brought on board by the shorepower cord. You need a galvanic isolator or isolation transformer to block this. (If you already have one, it is not working properly.) If you are not plugged in, then this could be stray current corrosion emanating from either your boat or elsewhere. However, I doubt this. Stray current corrosion is agnostic regarding what metals it corrodes. Regardless of metal composition, any metal that is discharging a DC current into the water will corrode. For your zinc to be the metal that was effected, it would have to be the discharge point, as opposed to a through-hull, the propeller or some other underwater metal. Zinc loss is generally associated with galvanic corrosion. There are tests you can carry out to determine what is going on, but these are rather more involved than I can spell out here. They are, however, covered in detail in my book Boatowner’s Mechanical and Electrical Manual.

Got a question for our experts? Send it to sailmail@sailmagazine.com

June 2016

Related

Youth_AC

The Kids Will Also Get a New Cup Boat

Turns out the AC75 full-foiling monohull isn’t the only new boat that will be tearing things up this America’s Cup cycle. Earlier this week, organizers of the Youth America’s Cup, which runs parallel to the regular 36th America’s Cup, announced that a brand-new foiling monohull ...read more

Where-to-Go-Garmin-chartplotter

Gear: GPSMAP 8612 Chartplotter

Knowing Where to Go The easy-to-use GPSMAP 8612 chartplotter, one of three new smaller variants of Garmin’s celebrated 8600 series, comes standard with such premium features as BlueChart g3 coastal cartography and a 12in HD IPS touchscreen display that’s refreshingly easy on the ...read more

01-LEAD-lagoon46-ncz4503-a3

Learning New Sailing Skills

The other day I was thinking about the very first time I sailed a multihull. It was in New Zealand, of all places, on the Bay of Islands, midway through Christmas break at the school where I was then teaching as a Peace Corps volunteer in Western Samoa. Stranger still, I was ...read more

Gale-Force-Watt-and-Sea-wind-generator

Gear: Watt&Sea’s Hydro-generator

Gale-force Electricity Watt&Sea’s award-winning hydro-generators have long been popular with both racers (for whom its products were first created) and cruisers. But what to do if you are, say, François Gabart aboard the maxi-tri Macif, a boat in which the main hull spends much ...read more

Beneyteau-Excess12

Boat Review: Excess 12

Groupe Beneteau, builder of Lagoon catamarans, has introduced a new multihull line called Excess. The first of the boats to reach U.S. shores at the Annapolis boat show was the Excess 12, a 38ft 6in design based on the popular Lagoon 40. The thought process behind this new boat ...read more

Spindriftracing

Extreme Sailing: No Piece of Cake

It can be easy to take for granted the incredible performance of today’s most cutting-edge grand prix racing boats. The latest crop of full-foiling 75ft America’s Cup monohulls, for example, were all up on their foils and even successfully tacking within hours of their first ...read more