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FINDINGS LIBRARY · GAS AND SAFETY

LPG locker drain: how surveyors check a boat's gas locker and what they write up

UPDATED 5 NOVEMBER 2026 · 3 EXAMPLE FINDINGS · 3 SOURCES

Why propane sinks and a gas locker has to drain overboard, what ABYC A-1 asks of LPG lockers, what a surveyor checks, the common faults and three example findings graded A, B and C.

AT A GLANCE
LPG locker drain
USUAL GRADE
A for a cylinder stored inside the boat or a locker that drains into the hull. B for a drain outlet too low, blocked or kinked, or a locker full of gear. C for an aged drain hose or lid seal
FOUND WITH
Opening the locker, following the drain from the locker bottom to its outlet, checking the outlet's height above the waterline, and looking for anything stored with the cylinders
JUDGED AGAINST
ABYC A-1, which asks for cylinders outside the accommodation in a locker that's vapour tight to the hull interior, above the waterline and drained overboard from its lowest point
REPAIR COST
From fitting time for a cleared or rerouted drain to a new moulded locker, priced per boat

Propane and butane are heavier than air. A small leak from a cylinder valve or regulator doesn't drift away; it sinks, and inside a hull it settles in the bilge waiting for a spark. The gas locker exists to keep that leak outside the boat, and the drain is what makes it work.

What the standard asks

ABYC A-1 covers LPG systems. In our words, as quoted by Soundings and on owner forums: cylinders must be secured for sea, readily accessible and kept on the outside of the boat or in a dedicated locker. The locker must be vapour tight to the hull interior, sit above the waterline, open from the top, and drain overboard through a dedicated vent from its bottom to an outlet lower than the locker floor and above the waterline, with no low spots on the way. Soundings adds that ABYC recommends LPG vents at least 20 inches from any hull opening into the boat. ABYC A-30 keeps cylinders over 8 ounces out of the boat entirely.

In the UK, the Boat Safety Scheme rule quoted on the YBW forum covers the low locker problem: any space below the drain that could hold leaked gas has to be filled with gas-resistant material.

How a surveyor checks it

Open the locker and look at what's in it: cylinders only, secured, with the regulator and hose in good order. Find the drain at the bottom and follow it to the hull. It should fall all the way, with no kinks or loops, to an outlet clear of the waterline. Check the locker's sides and lid against the hull interior: a gap into a cockpit locker or the engine space defeats it.

The most common faults are mundane. Fenders, fuel cans and lines stored with the cylinders, a drain blocked with leaves, or an outlet that dips under water when the boat heels.

LPG locker drain: example findings

The same defect written up at each grade, the way Axsail writes it from what the surveyor says on board. The grade follows what was found, so use these as wording, then grade what you see.

GASA
LPG cylinder, cockpit locker

4.5 kg propane cylinder stored in the general cockpit locker, which opens into the engine space. No dedicated gas locker or overboard drain.

Recommendation: Do not use the gas system until the cylinder is moved to a dedicated, vapour-tight locker draining overboard, or stowed outside the hull.

GASB
Gas locker, stern

Dedicated gas locker fitted. Drain hose kinked where it passes the steering quadrant and its outlet is about 50 mm above the waterline at rest. Fenders and a fuel can stowed in the locker.

Recommendation: Reroute the drain so it falls continuously to an outlet well above the waterline, and remove all gear from the locker, within 12 months.

GASC
Gas locker

Locker and drain in good order. Lid gasket perished in places.

Recommendation: Renew the lid gasket at the next maintenance period.

ASafety. Safety or compliance deficiency. Fix before the vessel is next underway.
B12 months. Deficiency that needs timely attention. Fix within about 12 months.
CRoutine. Note or observation, cosmetic or maintenance. Routine maintenance at the owner's convenience.

What the fix costs

Job Reported cost
Clear gear out and clean the drain Owner's time
Reroute or replace a kinked or low drain hose Fitting time
Renew a lid gasket Small parts
New dedicated moulded gas locker Priced per boat; owners describe them as expensive

Photos to take

The open locker with the cylinders, the drain at the locker bottom, the outlet on the hull with the waterline in frame, and anything stored in there that shouldn't be. With Axsail, say what you see as you photograph the locker and the photos go on the gas finding.

Writing it up

Say where the cylinders are stored, whether the locker is sealed from the hull interior, where the drain runs and how high its outlet is above the waterline, and what else is in the locker. If there's no proper locker, the recommendation is not to use the gas until there is one.

Frequently asked

Why does a gas locker need an overboard drain?

Propane and butane are heavier than air. Gas that leaks from a cylinder or regulator sinks, and in a sealed hull it collects in the bilge until a spark sets it off. A locker that's vapour tight to the hull and drains overboard from its lowest point lets leaked gas run out of the boat.

Where does the gas locker drain have to come out?

Overboard, above the waterline, lower than the locker bottom, with no dips for gas to sit in. Soundings reports ABYC recommends LPG vents at least 20 inches from any hull opening into the boat. Low lockers can make that hard, and the UK Boat Safety Scheme asks for any space below the drain to be filled with gas-resistant material.

Can I keep a gas cylinder inside the boat?

Not a full-size one. Soundings quotes ABYC A-30 as saying cylinders over 8 ounces must be stored outside the boat, and A-1 as requiring cylinders in a ventilated location on the boat's exterior or a proper gas locker.

Can I store other gear in the gas locker?

No. ABYC asks for lockers designed to discourage use as gear storage. Fenders and lines can block the drain, and anything metal can damage a regulator or hose.

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Standards it's judged against

ABYC

American Boat and Yacht Council standards

What the American Boat and Yacht Council is, how its standards are written and kept up to date, why they're voluntary but still decide survey findings, how to get the full text, and the standards surveyors cite most.

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ABYC A-1

Liquefied Petroleum Gas (LPG) Systems

What ABYC A-1 asks of propane (LPG) systems on boats, the gas locker and drain rules, cylinders, solenoids and detectors, what a surveyor checks and how to cite A-1 in a finding.

What surveyors check
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ISO standards for small craft (ISO/TC 188)

The ISO small craft standards behind CE-marked boats, what each covers, how they line up with the ABYC standards US surveyors use, and how to cite them in a finding.

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