Axsail
How it worksFor SurveyorsFor OperatorsPricingGuidesAboutVisual Evidence ↗Coming soonStart free
FINDINGS LIBRARY · GAS AND SAFETY

Bilge pump float switch failure: how surveyors test automatic bilge pumps

UPDATED 5 NOVEMBER 2026 · 3 EXAMPLE FINDINGS · 1 SOURCES

Why float switches fail, the switch types Practical Sailor tested, how a surveyor tests an automatic bilge pump, what new switches cost and three example findings graded A, B and C.

AT A GLANCE
Bilge pump float switch failure
USUAL GRADE
A when the automatic bilge pump doesn't start, or the boat has no working bilge pump. B for a sticking switch, a switch in debris or no high-water backup. C for cleaning and securing
FOUND WITH
Lifting the float by hand or flooding the switch, checking the pump runs and discharges overboard, and looking at the switch, wiring and bilge around it
JUDGED AGAINST
Whether the pump starts on its own when water rises. Practical Sailor recommends a second pump and switch mounted higher than the primary
REPAIR COST
From about $24 (€21) for a basic pivoting float switch to about $100 (€87) for an electronic one, Practical Sailor test prices

An automatic bilge pump is only as good as the switch that starts it. When a boat sinks at its mooring with a pump in perfect order, the float switch is a common suspect: stuck down in sludge, its pivot seized, or its light wiring corroded through.

The switch types

Practical Sailor tested bilge switches in a simulated bilge of seawater, motor oil, sawdust and fibreglass shavings, with water surged across it. It groups them as pivoting arm floats, vertical floats with a magnetic reed switch, and sealed electronic switches. Pivoting floats are the cheapest and most common, and the most prone to cycling the pump as water surges. Electronic switches have no moving parts; the Water Witch 230 performed flawlessly in the worst conditions of the test.

For installation, Practical Sailor's tips: mount a pivoting switch facing aft and within 3 inches of a bulkhead, and fit a second pump and switch higher than the primary.

How a surveyor tests it

Find the pump and switch, then make the switch do its job. Lift the float by hand and check the pump starts and stops. Where possible, pour water into the bilge, because a switch that works by hand can stick under water with debris on its pivot. Check the pump discharges overboard, the wiring and connections in the bilge are sound, and the switch base is secure.

Then the system. Is there a second pump, a high-water alarm, a manual pump the crew can reach. A boat whose only automatic pump won't start is an A, more so if it's left on a mooring.

Bilge pump float switch failure: 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.

BILGE PUMPINGA
Main bilge, automatic bilge pump

Float switch does not start the pump when lifted by hand. Pump runs on the manual switch at the panel. Float pivot clogged with debris and corroded.

Recommendation: Replace the float switch and clean the bilge before the vessel is left unattended or next underway.

BILGE PUMPINGB
Main bilge

Automatic pump and float switch work on test. No second pump or high-water alarm. Bilge holds hair, sawdust and oily water around the switch.

Recommendation: Clean the bilge and fit a high-water alarm and a second pump with its switch mounted above the primary, within 12 months.

BILGE PUMPINGC
Main bilge, float switch

Pump and switch work. Switch base held by one screw and moves slightly.

Recommendation: Secure the switch base 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 a new switch costs

Job Reported cost
Pivoting float switch, basic About $24 (€21), Practical Sailor test price
Pivoting switch, mid-range About $47 (€41), Practical Sailor test price
Electronic switch About $100 (€87), Practical Sailor test price
Second pump, switch and high-water alarm Parts and fitting, priced per boat

Prices are from Practical Sailor's test and may have changed. Cleaning the bilge costs nothing and fixes many switches.

Photos to take

The pump and switch in the bilge, the debris round them, the panel switch, and the overboard discharge. With Axsail, say what happened when you lifted the float as you take the photo and it goes on the bilge finding.

Writing it up

Say which pumps are fitted, manual and automatic, whether the automatic one started when the switch was raised and how you raised it, the state of the bilge and wiring, and whether there's a backup or alarm. Then the fix, and with an A, say the boat shouldn't be left unattended until it's done.

Frequently asked

How do I test a bilge pump float switch?

Lift the float by hand and check the pump starts, then let it drop and check it stops. Better still, pour water into the bilge to raise the switch the way a leak would, because a switch can work by hand and still stick under water with debris round the pivot.

Why do float switches fail?

Debris and oil round the pivot, corrosion, and wiring that's too light for the load. Practical Sailor notes pivoting float switches usually use 16 to 18 gauge wiring, which limits their current and adds a failure point, and that water surging in the bilge makes them cycle the pump too often.

Are electronic bilge switches better?

Practical Sailor found sealed electronic switches with no moving parts performed best in its debris and surge test, the Water Witch 230 flawlessly. It also notes oil can stop some electronic sensors working, so they still need a clean bilge and a test.

Should a boat have two bilge pumps?

Practical Sailor recommends a redundant pump and switch mounted higher than the primary, so a failed switch or a big leak still gets pumped. A high-water alarm tells the crew the primary isn't coping.

Your full survey report, minutes after the walk-round

Dictate as you inspect. Axsail builds the findings and the report for your signature

Start free

Standards it's judged against

ABYC H-22

Electric Bilge Pump Systems

What ABYC H-22 asks of electric bilge pump systems, how pumps are rated, where the inlet and discharge go, the high-water alarm on boats with enclosed accommodation, and how to cite H-22 in a finding.

What surveyors check
46 CFR SUBCHAPTER T

Small Passenger Vessels (Under 100 Gross Tons)

Which charter boats fall under 46 CFR Subchapter T, the Certificate of Inspection and annual inspections, drydock intervals, bilge pump and fire extinguisher tables, and how to cite Subchapter T in a finding.

What surveyors check

Related findings

Findings library
UNDERWATER GEAR

Seized seacocks

Why a seacock that won't close is a safety finding, how surveyors check seacocks and through-hulls, the ABYC strength test a ball valve on a through-hull can fail, replacement costs and three example findings graded A, B and C.

How to find and write it up
ELECTRICAL

Unsecured batteries

What ABYC E-10 asks of battery installations, why a loose battery is a safety finding, boxes versus straps, insulated terminals and three example findings graded A, B and C.

How to find and write it up
GAS AND SAFETY

LPG locker drain

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.

How to find and write it up
GAS AND SAFETY

No CO alarm

Where a boat needs carbon monoxide detectors under the revised ABYC A-24, which detectors qualify, where not to fit them, what a surveyor checks and three example findings graded A, B and C.

How to find and write it up
GAS AND SAFETY

Expired life raft

How often a yacht life raft needs servicing, what ISO 9650 and the makers ask, what a service costs, when replacing beats servicing, and three example findings graded A, B and C.

How to find and write it up
GAS AND SAFETY

Expired fire extinguishers

When a disposable marine fire extinguisher expires under the US Coast Guard rule, how to read the date stamp, what makes an extinguisher good and serviceable, and three example findings graded A, B and C.

How to find and write it up

Report templates with this finding

FREE TEMPLATE · WORD

Pre-purchase survey

A free Word template for a yacht pre-purchase survey report: every section explained, example wording, the sea trial and valuation, and example findings graded A, B and C.

Open template
FREE TEMPLATE · WORD

Insurance survey

A free Word template for a condition and valuation survey report for boat insurance: each section explained, the insurer's requirements, market and replacement value, and example findings graded A, B and C.

Open template
FREE TEMPLATE · WORD

Charter and fleet condition

A free Word template for a charter or fleet yacht condition report: safety equipment, systems, inventory, damage since the last check, readings and sign-off, with example findings graded A, B and C.

Open template

Related guides

INSPECTION CHECKLISTS · 7 MIN

Yacht survey checklist: what a surveyor inspects, system by system

The full boat and yacht survey checklist, from hull and keel to rig, engine, gas and safety kit, and what changes between a pre-purchase and an insurance survey.