This procedure applies to Ocean Alexander yachts equipped with Headhunter Mach 5 freshwater pressure pumps. Performing this preventive maintenance every 6 months, or whenever a pump experiences nuisance alarms or excessive cycling, helps maintain consistent water pressure, improves pump performance, and extends system life.
Recommended Maintenance Interval #
- Every 6 months
- After extended vessel lay-up
- Following freshwater system repairs
- Anytime the pump alarms, loses prime, or cycles excessively
Required Tools #
- Tire pressure gauge
- Air compressor or hand pump
- Screwdrivers and basic hand tools
- Flashlight
- Replacement filter elements (if required)
Procedure #
1. Fill Fresh Water Tanks #
Verify the vessel’s freshwater tanks contain sufficient water before beginning maintenance.
2. Disconnect External Water Supply #
Disconnect any dockside water connection and ensure the vessel is operating solely from the onboard freshwater tanks.
3. Inspect the Accumulator Tank(s) #
Ocean Alexander yachts are typically equipped with one or more freshwater accumulator tanks.
- Remove the cap from the Schrader valve.
- Briefly depress the valve stem.
Normal: Air is released.
Fault: If water is discharged from the valve, the internal bladder has failed and the accumulator should be replaced.
4. Depressurize the System #
- Turn OFF all Mach 5 pumps.
- Open multiple faucets throughout the vessel (galley, heads, crew areas, flybridge, wet bar, etc.).
- Allow the system pressure to completely bleed off.
5. Check Accumulator Air Pressure #
With the plumbing fully depressurized:
- Measure accumulator pre-charge pressure.
- Adjust to 30–35 PSI.
- Replace any accumulator that will not maintain pressure.
6. Inspect the Pump Suction Side #
Before restarting the pumps, inspect:
- Suction strainers
- Filter housings
- O-rings
- Hose clamps
- Flexible hoses
- Isolation valves
Even a small air leak on the suction side can cause nuisance alarms, loss of prime, or dry-run faults. This is one of the most common causes of Mach 5 issues on larger yachts.
7. Purge Air from the Plumbing #
If the vessel has dual freshwater pumps:
- Start Pump #1 only.
- Leave several faucets open until a steady stream of water is produced.
- Repeat with Pump #2.
- Continue until all air has been removed from the plumbing.
8. Verify Pump Operation #
Close all faucets and allow the pumps to build pressure.
Confirm:
- Pump reaches shut-off pressure.
- No alarm indicators are present.
- Pumps stop normally.
- No rapid cycling occurs.
9. Inspect the System #
Walk the vessel and inspect:
- Machinery space
- Utility room
- Crew areas
- Galley
- Heads
- Exterior wet bars
- Flybridge
Check for leaks, drips, or unusual pump noise.
10. Return the Vessel to Service #
- Reinstall any removed filter elements.
- Restore normal pump configuration.
- Reconnect dock water if required.
- Verify stable operation before departure.
Common Ocean Alexander Findings #
During routine service, technicians frequently encounter:
- Low accumulator air pressure
- Air leaks at suction strainers or filter housings
- Loose hose clamps
- Dirty inlet strainers
- Waterlogged accumulator tanks
- Pumps that have lost prime after freshwater tank service
These conditions often cause intermittent alarms, excessive cycling, or reduced water pressure without indicating a failed pump.
Service Recommendation #
Ocean Alexander Service recommends incorporating this inspection into the vessel’s scheduled preventive maintenance program. Recording accumulator pressure, pump operating condition, and any corrective actions during each service visit provides a useful maintenance history and helps identify developing issues before they result in pump failures or loss of freshwater service.
