A Schenker on a Lyra 48

The ketch Greta came down to us from a swing mooring at Mystery Bay on Marrowstone Island on the morning of 13 February, motoring the 14 nautical miles to the Boat Haven on her original 1973 Yanmar 3GM30F at 3.2 knots in a falling barometer. Her owner, who had bought the boat in 2019 and lived on her for the four winters since, had wanted to get the hull underneath her since the second one. She had not been hauled out since July 2019 in Friday Harbor. The bottom paint, when we put her on the slings, came off in chestnut-colored sheets.

The refit we were hired for, however, was not the bottom paint — that was a wash-and-roll done by SEA Marine after we were finished. What the owner had hired us for was a freshwater refit. The Lyra 48, as designed by Knud Reimers in 1969, carries 28 gallons of fresh water in a single galvanized-steel tank under the cabin sole, fed by a manual pump at the galley. Greta had lost the original tank to a corrosion failure in 2017 and the previous owner had replaced it with a 24-gallon polyethylene bladder strapped into the same space — adequate, but the owner had reached the point in his cruising where 24 gallons (about a four-day supply for two people at conservative usage) was the gating constraint on every passage. He had spent four years filling his daily-use jugs at the public freshwater spigot at Mystery Bay's day-use dock, and was no longer willing to.

What he wanted was the option not to. He wanted, in the language of the trade, to become self-sufficient at anchor — to be able to drop the hook in Echo Bay or Spencer Spit or Sucia and not have to think about water for two weeks. That meant, in 2026, a watermaker. It also meant, by extension, a re-fabricated PEX manifold, two new through-hulls, a re-thought hot-water arrangement (since the existing engine-loop calorifier only made hot water while the engine was running — adequate for a daily-use cruiser, marginal for the kind of cruising the owner now had in mind), and a re-survey of the freshwater system end-to-end. We scoped the refit at four weeks. We went into the fifth.

The unit and the math

The watermaker the owner had specified — after a winter spent reading Practical Sailor's 12-volt watermaker comparison, and after a long conversation with Bram in the shop in late January — was a Schenker Modular 30, the small end of the Schenker line at 30 liters per hour (about 7.9 GPH), drawing approximately 4 amps at 12 V. Schenker's distinguishing feature, the one that pushed the owner past the Spectra Ventura-150 he had also been considering, is the patented Energy Recovery System: roughly 4 watts per liter of fresh water produced, which is, per Schenker's own published figures, about eighty percent below a high-pressure system of equivalent output.¹

The other factor was the runtime budget. Greta's house bank is two Trojan T-105 6-volt golf-cart batteries wired in series for 12 V at 225 Ah — about 110 Ah of usable capacity at 50 percent depth-of-discharge. The owner's solar (a single 100-watt Renogy panel on the dodger) makes, on a clear day in the San Juans in July, about 30 Ah back into the bank. A Schenker Modular 30 producing 30 liters per hour at 4 amps draws 4 Ah per hour. To make the boat's daily consumption (15 liters for two people, conservative) takes 30 minutes of runtime per day at 2 Ah cost. That math closes. A Sea Recovery Aquamatic-150 at the same output would not have.

What we installed

The unit went into the starboard cockpit locker, on a fabricated 1/8" aluminum mounting plate that we bonded to a 1/2" Coosa-board base epoxied to the locker bottom. The locker had previously held the holding-tank discharge hose and a quart-can of bottom paint; we routed the discharge hose down through the existing chase to keep the locker accessible for the watermaker's service position. The membrane housing (a single 21" Filmtec SW30-2521 element, swapped from Schenker's original housing into a longer one to allow membrane access from above) went athwartship along the locker's outboard wall. The high-pressure pump, the Energy Recovery System, and the boost pump went into the same locker on a vertical chase. The pre-filter (a 20 micron sediment cartridge in a clear bowl) went above the engine in the engine room.

The raw-water intake is a new through-hull on the port quarter, immediately aft of the cockpit drain, fitted with a Marelon ball valve and a strum-box strainer. We considered using the existing engine-cooling intake (a tee off the raw-water seacock); we did not, because Schenker's installation manual specifically advises against sharing intakes with the engine, on the grounds of priming behavior during membrane flushing. The brine discharge runs to its own through-hull on the starboard quarter, well above the waterline at heel, on the theory that an underwater brine discharge is one more invisible failure point we would rather not have.²

The product-water line — 5/8" reinforced food-grade PVC, sourced from Trident Marine's 1612-series — runs from the membrane up over the engine-room bulkhead, through a new charcoal post-filter (which the Schenker installation does not require but the owner wanted, on taste grounds), and into the new freshwater tank.

The tank

The original galvanized-steel tank had been replaced in 2017 with a Plastimo 24-gallon bladder; the bladder was, on inspection, intact and serviceable. We were inclined to keep it and add a second 24-gallon bladder in the port settee chase. The owner wanted, on principle, to go to a rigid tank.

What we built him is a 38-gallon cross-linked polyethylene tank fabricated by BGS Industries of Bellingham, with internal baffles on 9" centers, two top-mounted 1/2" NPT inlets (one for the watermaker product, one for the deck fill), a 1" NPT vent run up to the cabin-top mushroom vent we re-bedded on the same job, a 3/4" NPT supply outlet feeding the manifold, and a 4" deck-plate inspection port on top. The tank sits in the chase under the cabin sole, beneath the saloon table. We measured the chase, sent dimensions to Bellingham on a Tuesday morning, received the tank on a Friday afternoon, and dropped it in on the following Tuesday. The lead time, for the curious, was nine working days.

The manifold

Both inlets, the supply outlet, the vent, and the deck fill all needed connections. The previous owner's manifold, a brass and copper affair tee'd off the bladder fitting with hose-clamped reinforced PVC, was the system's weakest point and had been the source of two of the four leaks the owner had documented over four seasons. We tore it out and built a new manifold in Uponor AquaPEX-A (the marine-rated version, certified to ABYC H-23 and to NSF/ANSI 61 for potable water³) with cold-expansion connections and Uponor ProPEX fittings, mounted to a Coosa-board panel screwed to the inside of the chase. The manifold has six outlets: galley cold, galley hot, head cold, head hot, deck wash (cold), and the watermaker product-water return.

The hot side is fed by a new Isotherm Slim-Square 6L calorifier — small (1.6 gallons) but adequate for two-up cruising, with both a 750-watt 110V shore-power element and a single engine-loop coil. We considered a 12-volt heating element in addition (Isotherm makes the option), but the owner declined: he is comfortable with making hot water only on the engine and on shore power, on the grounds that the electrical budget for a 12V immersion element is incompatible with the watermaker runtime budget on the same bank.

Through-hulls

Two new through-hulls were added: the watermaker raw-water intake on the port quarter and the brine discharge on the starboard quarter. Both are bronze, both are fitted with Groco BV-series flanged ball valves, both are backed with a 1/2" Coosa-board reinforcement disc bonded to the inside of the hull. We tested both at 30 psi for 30 minutes, with the boat on the slings; both held. The torque on both bolt-circles was set per Groco's published spec.

What can go wrong

An aside from the watermaker tech

(The following is Bram Halvorsen's first-person aside on this refit. The journal carries one tradesman's first-person aside per feature. — Editor.)

I want to say a word about why I have stopped recommending the Spectra Ventura for boats this size. The Ventura is a fine unit and I have installed seven of them; the math on its energy-recovery does close on a 225 Ah house bank, which is what most cruising sailboats this size carry. The reason I have stopped recommending it is service. Spectra moved Pearson-pump rebuild kits to a quarterly stocking cycle in 2024, and on this coast that means I cannot reliably get one in under three weeks when an owner is mid-cruise in the Broughtons. Schenker, for the small units, ships from California with a working five-day lead time on a service-kit replacement to anywhere on the I-5 corridor. That service horizon is what is driving my present recommendation. If Spectra fixes its kit stocking, I will rewrite this paragraph. — B.H., 11 March 2026.

What it cost

The full refit invoiced at $13,840 plus tax, broken down approximately as: $4,950 for the Schenker Modular 30 unit and accessories; $1,180 for the fabricated cross-linked polyethylene tank from BGS Industries; $620 for the calorifier and shore-power element; $480 for the through-hulls, valves, and backing plates; $310 for the PEX-A manifold and fittings; $2,200 in labor for the fabrication and install of the manifold and tank; $1,800 in labor for the watermaker install and commissioning; and the remainder in fittings, miscellaneous, and the post-install commissioning report. The owner additionally paid the Port's haul-and-launch tariff ($890 for a 30-day yard slot at the published 2026 rate, plus the launch and re-launch fees, separately invoiced by the Port — see the Port boatyard tariff).

The bottom paint, done by SEA Marine after we were finished, invoiced at $2,140 — a complete strip and a fresh roll of two coats of Pettit Trinidad SR. We mention it only because the owner has asked us, more than once, why marine refits "always end up costing more than the quoted number." The answer, as is usually the case, is that they don't — the quoted number is for what was quoted. The additional cost is for the work that was added during the refit because something else was found. In Greta's case, very little was added.

Returned to the water

We launched Greta at 0930 on Thursday 12 March 2026, on a 9.4-foot incoming tide and a 4-knot ebb against the Travelift pit. The Schenker came online at 1110 and made its first 60 liters of fresh water under shop supervision while the owner stood on the dock and watched. The product-water specific conductivity at 70°F came in at 218 µS/cm against a Schenker specification ceiling of 500 µS/cm — well in spec. The owner motored her up to Mystery Bay on the afternoon tide, and at 1632 (per his text) tied her back on her swing mooring.

She will be back here in October for the season-end pickling clinic.