Get your boat engine ready for spring – checklist before launch

Plan and Prioritize

Start with the engine. Regardless of whether it's a powerboat or sailboat, the engine deserves first focus. An oil change is ideally done in the autumn, but go through the fuel and cooling systems in the spring.

Around the engine. The propeller, sterndrive/outdrive, controls, and steering should be checked before each season.

Hull and equipment. Prioritize antifouling to prevent growth. Also check safety equipment such as gas leak detectors, bilge pump, and fire extinguishers.

Cosmetic. Do polishing, waxing, and performance fine-tuning once the functional aspects are complete. Set a reasonable level of ambition. What gets done is better than what doesn't get done.

Small checklist – inboard engine

 Check the oil level. (Oil change is best done in the autumn when the engine is thoroughly warm.)

 Change the fuel filter.

 Drain water from the fuel-water separator.

 Inspect the fuel tank for growth or contaminants.

 Bleed the fuel system if necessary (applies to diesel engines).

 Check the level in the freshwater cooling system if your engine has a closed system.

 Check the sacrificial anode in the freshwater cooling system and replace it if it is clearly consumed.

 Drain glycol from the raw water circuit and take the fluid to an approved environmental station.

 Install or replace the impeller.

 Test that the vacuum valve is working correctly.

 Clean the raw water filter and ensure the intake is clear.

 Ensure that the throttle and gear controls move easily; lubricate if necessary.

 Check the alternator belt: no cracks and approximately 10–15 mm deflection when pressed with your thumb.

 Verify grounding for the fuel tank, deck fill, pipes, and vents to the engine block
(inboard) to minimize static electricity.

Lubrication system

If you didn't change the oil and oil filter last autumn, now is the time. Warm up the engine and then turn it off. Warm oil is easier to pump out and therefore easier to remove. Use a special oil extraction pump. Always change the oil filter along with the oil. When refilling with new oil, use the correct oil quality according to the engine manufacturer's recommendations. Fill oil to the "full" mark on the dipstick. Start the engine and check for oil leaks around the filter and plugs. Stop the engine and check the oil level on the dipstick at regular intervals.

Cooling system

Before launching, all rubber hoses, bellows, etc., must be checked very carefully. Rubber parts age and crack. Replace cracked or hardened parts. Check that hose clamps are securely fastened and not corroded. Flush the raw water filter. If freshwater cooling is present, the freezing point and corrosion protection properties of the antifreeze must be checked. If necessary, the glycol/water mixture should be changed. Glycol types (ethylene glycol/propylene glycol) should not be mixed with each other; instead, the same type as before should be used.

Fuel system:

Before the season, it is good to change the fuel filter, both the one on the engine and the insert for the water-separating filter between the tank and the engine. Drain any water from the water separator. Inspect the fuel tank to detect growth. For diesel engines, the fuel system should be bled if necessary. Check the fuel system hoses, pipes, connections, deck fill, and vents. Check that the fuel tank, deck fill, pipes, and vents are grounded to the engine block to avoid static electricity (inboard engine). Leaks must not occur – leaking fuel can not only cause engine failure, but also presents a significant fire hazard.

Electrical system:

Contact spray and 5-56 are good to have on board. Remove the instrument panel and disconnect the connectors, clean and spray the surfaces before reassembly. Check that all fuses are intact and that the main switch is working. Fully charge the batteries, check the battery terminals and clean connections. Replace worn or green/corroded cables and cable lugs. Check the shore power equipment. Rubber hoses for LPG should be fresh and LPG seals should be replaced regularly. If you have a vacuum valve in the raw water circuit – check its function. If you have a black rubber hose in the exhaust installation – check for marking e.g. "Black Jack". This should be replaced regularly every seven years.

Transmissions (sterndrives and reverse gears)

If the oil wasn't changed last autumn, do it now. Anodes on AQ-drives and S-drives are replaced when approximately 50% has eroded. Inside the propeller there is an anode ring, and on the AQ-drive shield there is usually another. Use zinc if you operate the boat in saltwater or brackish water, and magnesium in freshwater. Bare metal areas on the sterndrive should be primed and then touch-up painted. On the shaft, there is a compression cap against the propeller with propeller grease. The packing in the spring housing should be replaced approximately every 4 years. If you have a rubber packing gland on the propeller shaft, e.g., "Black Jack", it should be replaced regularly every seven years.

After launching, various problems can sometimes arise.

Here is a short summary of some common questions we usually receive in the spring.

The engine runs hot

If the cooling system's capacity is reduced, the engine does not receive sufficient cooling. This causes the engine to run too hot and damage can occur. Check the raw water intake, raw water filter, impeller, and thermostat. The thermostat can be tested by removing it and placing it in hot water with a thermometer. Compare the opening temperature against its specification. If the values do not match, the thermostat must be replaced.

The engine doesn't reach high RPMs

This problem particularly arises in boats with gasoline engines, and can be due to either insufficient fuel supply due to a clogged filter or incorrect ignition timing. The solution is to change the fuel filter and set the ignition timing with a strobe light. If that doesn't help, the spark plugs should be changed and the rotor/distributor checked. Compression is important and should be equal in all cylinders. It can also be affected by incorrect propeller pitch. Ensure the correct pitch is in place. Consult your nearest authorized service technician.

The boat checklist

1. LPG system: LPG works perfectly if the system is kept in good condition. Go through it annually. Rubber hoses and seals age and should be replaced regularly.
2. Propeller: Check that the propeller is intact, that the anodes still have sufficient material thickness, and that the propeller is securely attached. A damaged or poorly secured propeller can cause serious problems.
3. Through-hulls and hoses: Through-hulls are common sources of leakage. Feel them from the inside to ensure they are firmly seated. Check that hoses are intact and that there are double, opposing hose clamps where required.
4. Impeller: The impeller drives the raw water flow in the cooling circuit. The water passes through the heat exchanger where the engine's fresh water is cooled and then led to the exhaust manifold to cool the exhaust system. Replace the impeller as recommended and check the flow during a test run.
5. Oil, fuel, and glycol: Oil and filters are normally changed in the autumn with a warm engine. Before the season: confirm levels in the engine and reverse gear. Unscrew the oil plug at the bottom of the sterndrive and let out a few drops – the color should be clear and golden brown. Gray or cloudy indicates water ingress; in that case, the oil needs to be changed and seals repaired.
6. Freeboard – polishing and waxing: This quickly gives visible results and protects the gelcoat from UV. First, wash with a soft sponge and alkaline cleaner – from bottom to top so that dirt runs off the clean surface. Then polish and wax.
7. Antifouling: Growth in the form of slime, grass, and shells slows the boat, impairs maneuverability, and increases fuel consumption. Scrape off loose paint before painting. There are two main types of antifouling paint:
   Chemically active – releases substances disliked by aquatic organisms.
   Physically active – creates a surface where organisms have poorer grip.