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2016-01-27

Unforced mating

As a kid, I built 1/72 scale models of this historic bomber. If you'd told me then that in 2015 I would own a steel sailboat and one of these would have flown over it, I would have laughed. Screencap (c) CBC
I was alerted by a fellow YC member that an episode of the Rick Mercer Report, a CBC comedy show, featured a flight in one of the world's last two flying Lancaster bombers. This World War II stalwart was made here and in Britain in the thousands for the purposes of German urban renewal. Now, I was potty enough about "warbirds" in my callow youth that I recognize the distinctive sound of the four Merlin engines (the same engine that powered the Spitfire) that drag this pristinely restored 100,000 rivets flying in formation through the sky, and as they do their fund-raising flights over my house and my boat, I usually don't miss a chance to look up. This shot captures the moment the Lancaster flew over National Yacht Club in fall of 2015, and yes, I've helpfully pointed to S/V Alchemy, just as metallic, if not...yet...as storied.

Batteries were out on the camera, otherwise I would have zoomed in on the waves splashing the runway. About 25-28 knots, I think.
Back in the bleak midwinter of 2016, the wind was up and a reason to tie off the ladder was clearly evident. The tarp over the pilothouse roof will need replacement, as is the case at least twice each winter, as the wind and the snow tend to shred it. I was aboard because, despite the wind, it was about 4C out, almost balmy for late January, and I wanted to charge the battery and take some measurements. I actually use my electronic calipers (which I bought during a 70% off sale) quite frequently, because of the multiplicity of fasteners and holes and mast measurements I have to take. By the way, the mast slide system from Tides Marine has been ordered and should arrive at the sailmaker's next week.

The aft cabin is not just a radio room, but this is a good start.
Firstly, however, was dealing with my Christmas presents. Mrs. Alchemy finally heeded my long-standing request for a "24 hour clock" and threw in a tide clock as well. They fit nicely and are easily seen from the pilothouse and from the aft cabin. The tide clock, which is admittedly not so useful on the Great Lakes, can nonetheless show "ship's time" or that of the local time zone in which we are sailing, whereas the "ZULUTIME" clock stays on UTC time...all the time. Simple, really! Also, if I ever form a cruiser-based pickup band in the tropics, we're going to be called "ZULUTIME".


Needs a touch-up, definitely.
Now that the engine is (one hopes) reliably situated, I can bolt down the aluminum pilothouse roof to the steel inward flange of the pilothouse itself. The problem is one of dissimilar metals, exacerbated by imperfect painting and the completion of the "circuit". Another reason to do this, of course, is that this roof has a fair number of electrical leads going thorough it of the power and signal variety: fluxgate compass, GPS, overhead lighting, and so on, and while this will be carefully handled, an alu roof electrified and in contact with the steel hull would be A Bad Thing, galvanically speaking. Now, while it's true that the mild steel of the pilothouse and the aluminum are pretty close on the galvanic series, the stainless steel of the fasteners used to hold one to the other are very definitely farther away in said series, and are therefore more likely to trouble the mated metals. So, unmating them is key.

Ignore at your peril if you own a metal boat sailing in a weak electrolyte, such as the ocean is.
I'm doing this mainly through keeping them mechanically separated. One metal will not  touch the other. It starts in the spring with removing the pilothouse roof; now that the mast will be back in place, lifting the pilothouse roof straight up using the boom and the topping lift and a harness should be simple. It's in fact one of the reasons I rigged a Dyneema topping lift: to hoist stuff in and out of the boat easier. The other reason was to use it as an aid, when combined with a tackle, in getting crew overboard back on deck.

The "roof remediation" starts with roof removal. Then the various bolt holes are cleaned out, primed and the whole flange is painted, above and below, with two-part Endura, the current touch-up paint aboard. This takes us to the zero point: there is now paint separating flat steel and aluminum plate. But there's irregularities: the join must be sealed. So here's my idea: Glue three-inch wide strips of quite thin HDPE sheeting (a good insulator) in place over the steel flange. Drill holes from beneath. Insert unthreaded soulder spacers with flanges in the holes; these are also called bushings. Lay down a bead of sealant on the innermost edge of the flange, and lay our old friend butyl tape on the outside. Both sealant and butyl will stand proud of the plastic stand-off strip. Restore the aluminum roof and replace properly sized bolts, nylon washers and nuts through the mated holes and tighten. For those holes tapped directly into the aluminum framing, use Tef-gel or Duralac to isolate the dissimilar metal. Dog down bolts (there's 40 of them) and trim any overflow. None of the stainless steel fasteners should, if I do my work well, be in contact with either the steel or the aluminum, and yet they will all be compressed firmly and will keep everything snugged down. Yesterday was the day I measured all the holes and the (slightly variable) thicknesses of the un-mating surfaces in order to order the proper bushings. It's a glamourous life I lead.
The front of the "lid" has a sturdy flange of plate aluminum underneath into which I expect to rivet or bolt some "eyeline" armatures for screens that can be lowered as needed.
Once the bolting together and sealing part is finished, we can restore the electrical runs, the closed-cell insulation and the rather handsome cherrywood battens and stretches of white masonite that make the restored pilothouse a pleasant place from which to run the boat. So I will remast as soon as I can to get this done before it gets stonking hot in the spring.

Lastly, Valiente's is now on Yachtworld.com. Maybe she's got a future in the States. She's priced to appeal to that particular currency's wielders and it is now, as foretold, in the hands of the broker. I've been asked to elaborate on my painful and boring journey of discovery as it relates to the failure to privately vend a discounted boat; I will consider it after she's sold.

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