Start With Two Clocks: Calendar and Hours

Every powerboat runs on two clocks. The first is your engine hour meter, which dictates oil changes, impeller swaps and gearbox servicing. The second is the calendar, which governs everything the sea does to a boat while it sits still: corrosion, perished rubber, stale fuel and seized seacocks. A seasonal maintenance schedule works because it respects both.

Whether you keep a RIB in a marina berth, a sports cruiser on a swinging mooring, or a race boat that lives on a trailer, the principle is the same. Write the tasks down, record your engine hours after every outing, and note what you did and when. A simple notebook or spreadsheet beats memory every time, and it pays dividends when you come to sell the boat.

Monthly: Ten Minutes That Save a Season

During the season, monthly checks are about spotting small problems before they strand you offshore. Set aside an hour, ideally with the boat alongside or on the trailer.

• Engine fluids. Check oil level and colour on a cold engine, plus power trim and steering reservoir levels. Milky oil means water ingress — investigate immediately.
• Fuel system. Drain a little from the water separator into a glass jar and look for water or debris. Check primer bulb and fuel lines for cracks or hardening.
• Batteries. A rested, healthy lead-acid battery should read around 12.6 volts; 12.2 volts is roughly half-charged. Clean terminals, check strap tightness and test the charging output with the engine running.
• Seacocks and strainers. Exercise every seacock through its full travel. Clear raw-water strainers of weed and grit.
• Anodes. Dive or haul to inspect. Replace when roughly half-consumed — a fast-wasting anode is telling you about stray current or a bonding fault.
• Bilge and pumps. Lift the float switch by hand to confirm the pump runs. Check hose clips and the discharge outlet.
• Safety kit. Check flare expiry dates, fire extinguisher gauges, kill cord condition and lifejacket inflation cylinders.

Quarterly: Fluids, Anodes and Deeper Checks

Roughly every three months, or around 50 to 100 engine hours, go deeper. Change engine oil and filter if you are running high hours, and inspect the impeller housing — a missing vane will overheat an engine within minutes. Grease steering rams, trim rams and throttle linkages, and check hydraulic steering fluid for colour and level.

Inspect the hull below the waterline for blistering, osmosis and damaged antifouling, and check the sterndrive or outboard leg for fishing line wrapped around the propeller shaft — a classic cause of leaking seals. Look at bellows, water hoses and exhausts for cracks. Test navigation lights, the VHF radio and the DSC registration, and check that your automatic bilge pump and high-water alarm both function. If you tow, repack or replace trailer wheel bearings and check tyre pressures and age — tyres over five years old are a risk regardless of tread.

Annually: Pre-Season Commissioning

This is the big one, ideally completed a fortnight before your first serious passage so faults can be fixed without panic.

• Full engine service: oil, filters, spark plugs, fuel filters, belts and impeller, plus a compression or diagnostic check if the engine has been troublesome.
• Cooling system: flush and refill, and replace the thermostat if it is due.
• Drive and propeller: change leg oil, inspect seals, check propeller for dings and balance, and confirm the correct pitch for your typical load.
• Hull: fresh antifoul, new anodes, rudder and trim tab inspection, and a check of skin fittings and their backing pads.
• Rigging and deck: stanchions, cleats, bow roller, windscreen and hatch sealant, canopy zips and press studs.
• Documentation: insurance, licence, charts, and an up-to-date passage plan for the season ahead.

Winter Lay-Up and the Work Cold Weather Reveals

A proper lay-up is not simply mooring up and walking away. Flush the engine with fresh water, fog the cylinders, drain and refill the leg with fresh oil, and remove the propeller so it cannot corrode onto the shaft. Fill the fuel tank to reduce condensation, add a stabiliser if you run petrol, and run the engine briefly to circulate treated fuel.

Drain raw-water systems and any freshwater tanks, remove batteries and store them charged and above freezing, and leave cabin lockers and hatches cracked open for airflow. Cover the boat so water cannot pool, but allow ventilation. Winter is the ideal moment for jobs that need dry, stable conditions: gelcoat polishing, upholstery repairs, and electrical upgrades you would never attempt at anchor.

Records, Spares and a Boat That Starts First Time

Keep a spares box aboard: impeller, fuel filters, fuses, hose clips, cable ties, engine oil, a spare kill cord and a set of basic tools. In UK waters, where weather can turn a short hop into a long day, reliability is a safety feature as much as a convenience.

Finally, review your schedule at the end of each season. Note what failed, what nearly failed, and what you wish you had checked sooner. Adjust the calendar, then do it all again — because the boats that give the least trouble are almost never the ones that were looked after hardest, just the ones that were looked after on time.