M/V Wyman's tankage

The 1947 Owens Flagship 42 bridge-deck cruiser Wyman was launched into Chesapeake Bay in the spring of 1947 and has worked her way west by stages over the following seventy-nine years — to Lake Erie in 1962, to Lake Michigan in 1971, by rail to Tacoma in 1988, and to Port Townsend in 2014, where her present owner bought her from the estate of the trustee who had owned her in Tacoma. Her name is the original. She was named, in 1947, for the wartime US Navy destroyer escort USS Wyman (DE-38), an Evarts-class hull commissioned at the Puget Sound Navy Yard in Bremerton on 1 September 1943 and decommissioned on 17 December 1945, after two years of Pacific-theater convoy escort.¹

The boat is named for the ship; the ship was named for a junior officer named Wyman. The lineage is, as is often the case with names, lost. What is not lost is that the boat herself was commissioned, indirectly, by the same Puget Sound Navy Yard whose destroyer escort she carries as a name — when her then-owner had a friend at the yard fabricate her original water tankage, in 1947, from the same black-iron stock that the wartime yard had on hand from the still-fresh end of destroyer-escort construction. That tank is the one we removed on the second week of March 2026.

The original tankage

The boat's original tankage was a single 56-gallon water tank of welded black-iron plate, hot-rolled, 3/16" wall, with a hot-dip galvanizing applied at the time of fabrication. The tank sat aft of the engine in the engine room, on a cradle of black-iron strap welded to the engine-room sole stringers. It supplied a single 1/2" copper run forward to the galley and the head. Total useful capacity at launch was 56 gallons; by the time we pulled the tank in 2026, the bottom 6 inches of the tank were unusable owing to a corroded weep seam in the after-end weld that the prior owner had patched, more than once, with cold-galvanizing paint and J-B Weld.

The patches were the kind of work that gets done at sea by a competent owner who is not a marine plumber, and they had held for, in this case, eleven years — long enough that the present owner had assumed the tank was sound and had not budgeted for its replacement. When we hauled her in March we found the tank weeping in three places, the galvanizing on the outside corroded through to bare iron in most of the lower third, and the rust scale on the inside of the tank (we cut a 4" inspection port to look) accounting for perhaps 30 lb of mass.

Why aluminum and not stainless

The question — which we get a letter about in every issue, and which is the subject of the present issue's Tankage Notes department — is: aluminum or stainless? The short answer is: aluminum, for any custom freshwater tank under approximately 100 gallons; stainless, for anything larger or for fuel tankage. The longer answer involves welding cost, weight, galvanic isolation, and material price; we lay it out in the Tankage Notes.

For Wyman, aluminum was the right answer for three reasons. First, the engine room is a galvanically complex space with a bronze rudder shaft, a copper-grounded engine block, and a stainless rudder log — adding more stainless to the mix would not have helped. Second, the weight matters: the original 56-gallon black-iron tank, including its cradle, weighed approximately 320 lb dry. A welded-stainless tank of the same capacity would have come in at about 230 lb; the welded-aluminum tank we built came in at 90 lb dry. The 230-lb reduction is meaningful on a 27,000-lb wooden cruiser whose center of gravity sits low and aft. Third, the fabrication cost: a welded-aluminum tank of this size from Bay Welding in Bellingham runs about $1,400 in mid-2026; an equivalent stainless tank from the same shop runs about $2,800.

The fabrication

The tank we specified is 5052-H32 marine-grade aluminum, 3/16" wall on the bottom and sides, 1/8" wall on the top, with internal baffles on 12" centers. Total capacity at launch is 94 gallons — up from the original 56 by virtue of the fact that we re-shaped the cradle to recover six inches of engine-room sole height that the original cradle had wasted. The useful capacity (above the bottom 1") is 92 gallons. The owner has, in one refit, more than recovered the 30 gallons he had been losing to the corroded weep, and added 36 more on top.

The fittings are all top-mounted, following our standing rule (see the Tankage Notes for the argument): one 1/2" NPT supply outlet feeding the existing copper run forward, one 1" NPT vent run up to a stainless mushroom vent on the engine-room overhead, one 4" inspection port with a bolted aluminum cover and a Buna-N gasket, one 1/2" NPT deck-fill from the existing deck plate on the cabintop, and one 12-volt SeaLevel ultrasonic tank-level sender that replaced the previous owner's float-style sender (which had failed in 2018 and had not been replaced).

Galvanic isolation

The single largest risk in installing an aluminum tank in an engine room with bronze rudder shafts and copper-grounded engine blocks is galvanic corrosion. Aluminum is anodic to bronze, copper, and stainless steel; an aluminum tank that is electrically continuous with any of those metals will, over the boat's life, give up its electrons to the more cathodic metal. We isolate the tank from the boat's electrical system with: a continuous PVC sleeve on every through-bolt; a neoprene gasket between the tank's mounting feet and the welded-aluminum cradle; a separately-fused zinc bonded directly to the tank via a 4-AWG lead, replaceable annually; and an isolating union (a brass-bodied union with a plastic insert) on the 1/2" supply line where it transitions from aluminum to copper.

The zinc is the critical detail. It is sacrificed deliberately; we use a Camp Company Z-1 pencil zinc, and we have specified that the owner inspect it annually and replace it when it reaches 50% wastage. The annual inspection is documented in the boat's logbook.²

The cradle

The original black-iron cradle came out with the original tank. We replaced it with a welded-aluminum cradle of the same 5052-H32 stock, sized to the new tank's footprint, with neoprene-padded mounting feet bolted (through the PVC-sleeved through-bolts) to the engine-room sole stringers. The cradle is dimensionally identical to the original aside from being 1.5" lower at the after end, which recovered the inches we needed for the larger tank. The original mounting bolts in the stringers had survived seventy-nine years intact; we reused them, after re-tapping the threads in the holes for the new fasteners.

Pressure test

The new tank passed a pressure test at 5 PSI for 30 minutes with no observed draw-down on the digital gauge. The test was conducted with the tank installed, the vent line capped, and the supply line capped, with the inspection port bolted down to its rated torque. The test is recorded with photographs in the install report, which the owner keeps in the boat's logbook.

The aside

(One first-person aside per feature, from the tradesperson who led the work. — Editor.)

I want to say a word about the present condition of black-iron tankage on the West Coast. There are perhaps four hundred working-condition pre-1955 American-built motorboats still in commission on this coast — Owens, Stephens, Matthews, Trumpy, Chris-Craft, the rest of the lineage — and probably three-quarters of them still carry their original black-iron tankage. The tanks were built well; they have lasted seventy and eighty years, in many cases with no real attention. The next decade is the decade in which most of them will fail. The work I have on the books for spring and summer 2026 is half tank replacements on pre-1955 hulls. I would rather see them planned and budgeted, on the owner's schedule, than emergency-replaced after the boat starts taking water at the dock. If you own one of these boats and you have not had the tankage inspected since 2015, please call the shop. The Classifieds desk will get you on the calendar. — M.G., 28 March 2026.

What it cost

The full refit invoiced at $5,840 plus tax: $1,420 for the fabricated 94-gallon aluminum tank from Bay Welding (Bellingham), $480 for the welded-aluminum cradle and the new mounting hardware, $380 for the SeaLevel ultrasonic sender, $260 for the new vent line, deck fill, and inspection port hardware, $190 for the isolating union and the bonding lead, $80 for the Camp Z-1 zinc, and $3,030 in labor across 17 working days. The Port's haul-and-launch tariff was $760 (22-day yard slot at the published spring rate, Block 7).

Returned to the water

We launched Wyman at 1110 on Monday 30 March 2026, on a 9.8-foot incoming tide, into a slack window. The Yanmar 6BG1T fired on the first crank after sitting for 24 days. The owner ran her up to Mystery Bay on the afternoon tide and tied her back on her swing mooring. The tank, two months later, is full and quiet.