Ask Sail: Seeing Green

One of the stainless steel chainplates on my Olson 911S is tinted green both above and below deck. The fasteners that bolt the plate to the internal bulkhead do not show the same condition.
Author:
Publish date:
Chainplate-water

Mono D'Angelo of Grosse Ile, Michigan, asks:

One of the stainless steel chainplates on my Olson 911S is tinted green both above and below deck. The fasteners that bolt the plate to the internal bulkhead do not show the same condition. From time to time, the green substance must be mixing with water, as I find small drips coming from one of the through-deck bolts inside the boat. There is no water discoloration on the wooden bulkhead belowdecks, and a tap test does not suggest any weak spots or rot. I sail on the Great Lakes, so salt is not a factor. I don’t know what is causing this condition, but I’m concerned about the integrity of the chainplate. 

Don Casey replies:

DonCasey

The condition you describe is unusual, so it may be that the tinting you see is not really green. One male in twelve is red/green colorblind, so first have a woman confirm the color for you. If the discoloration really is green, there are three possibilities I can think of.

The most likely explanation is that the source of the tinting is some copper-based component. Perhaps the attached toggle or turnbuckle is bronze and is leaching copper oxide down the chainplate. Perhaps the chainplate is fastened with bronze bolts or a brass washer or nut. Could the chainplate itself be plated bronze rather than stainless steel? The second possibility is acid attack, which in some circumstances can result in a greenish discoloration of stainless steel. The likely source would be a two-part teak cleaner or muriatic acid. A third possible source would be organic matter, perhaps mold living in wet deck core, but I do not see how this would cause discoloration above the deck.

In any case, if you have water trickling down the chainplate it may be wet and oxygen-deprived where it passes through the deck. This could lead to destructive corrosion. I would extract the chainplate and examine it for corrosion. You should also check the deck for core exposure and damage, and examine all the components to see what metals are involved.

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

Related

shutterstock_543237994

The Slow Route to Cabo

Each November, cruising boats start leaving California for “a winter of fun in the sun down Mexico way.” And having spent the summer and autumn on a leisurely passage down the West Coast on board Distant Drummer, our Liberty 458 sloop, my husband, Neil, and I were now in San ...read more

MHS-GMR_3549

New Multihulls 2018

Farrier F-22 New Zealander Ian Farrier ushered in a new genre of sailing with his folding-ama trailerable trimarans, the best-known of which are the Corsair designs. Farrier’s last project before he passed away last year was this sweet little tri. Available in three versions, ...read more

shutterstock_373701682

Cruising: Island Comeback

The U.S. Virgins Islands have surged back from the devastation of the 2017 hurricanes, with new infrastructure plans that will benefit charterers and cruisers alike. After hurricanes Irma and Maria roared through the Leeward Islands in September 2017, it was impossible to ...read more

albintoilet

Gear: Albin Pump Marine Toilet

Head Start Is there room for a new marine toilet? Albin Pump Marine thinks so, having just introduced its line of Swedish-built heads—ranging from compact to full-size models—to the American market. The toilets feature vitreous porcelain bowls and either wooden or thermoplastic ...read more

07n_45R2699

Multihull Sailor: Classic Cats

If you’re looking for a decent sub-40ft cruising cat, you have few choices when it comes to new-boat offerings. It is a well-known fact that the multihull market has taken off in a way very few could have predicted. Despite Hurricane Irma’s recent destruction of a large part of ...read more

TOTW_PromoSite

SAIL's Tip of the Week

Presented by Vetus-Maxwell. Got a tip? Send it to sailmail@sailmagazine.com Thanks a bunch  This scene is very calm and seamanlike. No frantic rope throwing or shouting. As he passes the line to the gent on the dock, the crew on the boat says, quietly and clearly, “Would you ...read more