Here is a beginning list of things to check before starting on an ocean voyage. I did not include electronics as I posted that in another place. I know there is a lot more than this so feel free to add items:
Departure Checklist
Check bilge for unexpected fluids, and also check under engine.
Check stuffing box for excessive dripping, it should be about a drop of water per minute while the engine is running and transmission engaged.
If equipped with heat exchanger, engine coolant level and condition (rust)
Check oil level and also look for water or antifreeze in oil. Change oil and filter if past 100 hours since last change, could go 200 hours if continuous operation. Check owner’s manual for recommended hours between changes, it might vary. I would change at 50 hours if the engine gets little use.
Have sample of old engine oil sent in for analysis to check for metals indicating unexpected wear.
Check hoses, squeezed and no give, any cracks, or leaking, replace. Check that risers are clear of obstructions.
Belts for cracks underneath, if serpentine belt cracks are OK if no chunks missing.
Fuel filters, check gauges for pressure drop from dirty filters and glass bowls for water. Use a biocide
Check raw water impeller for cracks by pulling cover; replace every two years.
Check fuel for contamination by taking a sample off bottom of tank and by inspection of fuel filters. Do this each time you fuel, especially at a marina new to you. For clean diesel, you may have to use a product such as this:
Fuel Right Canada
Check all through hulls for easy operation and ascertain if proper fitting for the application (no gate valves). Check hoses of cracks, are the hoses pliable, make sure hoses have double clamps for security.
Check raw water strainer.
Tag the ignition switch if someone is going into the water: “do not start!” Don wet or dry suit if needed and use
an air line from a 12-volt compressor. This is called a hookah setup and is much less cumbersome than scuba tanks, or scuba tanks can be left on deck with nose to diver. Check raw water intakes for marine fouling especially for the engine, clean hull and propeller. Check propeller for damages as any roughness or distortion will have decrease efficiency considerably. Remove barnacles as even a few can adversely affect fuel consumption. Check cutless bearing for play by grabbing propeller and trying to move shaft from side to side. If the propeller needs to be pulled, do not use a slide hammer as this might damage the transmission. Use a propeller puller. You may want to take a spare propeller and puller with you on your voyages. Check rudder pivot points for slack. Check speed indicator paddle.
On steering cables, check sprocket or drum, cable sheaves, quadrant or tiller and turnbuckles for tensioning. You must have dedicated ports or panels for a proper inspection, else Murphy’s Law will apply and probably at the worst possible time. The cables take considerable loads over long periods of and run over the sheaves at the same place. Check emergency tiller. Note that considerable force may be necessary to use an emergency tiller. Two strong pad eyes and cleats through bolted to the hull and clearance to swing the emergency tiller are usually necessary.
White or blue smoke after warm up indicates a major engine problem; see compression check below.
Compression test, preferably leak down type where measured amount of air is introduced to the individual cylinders to see percent that leaks past rings and valves.
Is there sufficient cooling water out exhaust?
Listen for exhaust leaks in engine compartment. You can move your hand near the exhaust system and feel for the draft of exhaust escaping.
Check engine mounts for alignment and condition. Does engine rise up on one side as full power is applied. Do this while underway. Sometimes bad motor mounts will cause vibration approaching a given RPM; do not exceed this RPM until cause is determined. An engine mount has some give; engine should lift up on one side about half an inch or one centimeter as power is increased from idle to maximum RPM.
On engine with heat exchanger or keel cooler, coolant should be about 185 degrees Fahrenheit, 86 Celsius. If you cannot hold your hand on engine for more than a second, consider using an infrared temperature sensor on the engine. For direct seawater cooling, temperature should be about 140 degrees Fahrenheit, 60 Celsius.
Check oil level in transmission. Does it smell burned, if so replace and make sure transmission shifts crisply without slipping while engine is at idle.
If hydraulics are used for windlass or steering, check fluid levels, look for leaks around hydraulic cylinders, hoses and pumps.
Measure voltage at battery with engine running at fast idle. Should be about 14.2 volts at room temperature. Very cold will be higher and very hot, lower voltage.
The best battery check is to apply a discharge to each battery to see how long it will take to get the battery to its amp-hour rating. For instance if you have a 100 amp-hour battery and you discharge it for twenty hours at 5 amps, it has full capacity. Complete discharge is rather hard on a battery, as completely discharging every time the battery is discharged, will cut the life of a deep discharge battery in half vs. discharge to 50 percent.
Check batteries with hydrometer if equipped with caps. This is as good a check as complete discharge as above; otherwise, charge batteries, let stand overnight and test with sensitive voltmeter, which should read 12.65 volts with battery swithch in off position. Test each battery individually as good battery could pull defective battery up to its voltage. If water level is below plates on any cell, replace the battery, the cell will not take a charge. Bring water level up to plastic ring about half an inch below the top of the battery opening.
If the batteries are five years old or more, replace even if appear good by testing as above. Three years would be prudent if long trips are planned.
Check battery terminals at battery for corrosion, remove, sand clean battery post and inside battery cable terminal, or use special wire cleaning brush, and apply grease to prevent corrosion. The grease will squeeze out when terminals are tightened and you will have a good electrical connection that lasts for years. Wash hands carefully after servicing battery cables as lead is a major ingredient and is toxic if even a little is injuested. Also, battery acid is 32% surfuric acid, which is unconfortable if left on the hands and can easily eat holes in fabric, especially cotton.
Inspect wiring on boat for corrosion. Apply electrical loads and as a crude check, feel for hot spots at terminals; otherwise, use voltmeter on one volt range to check for voltage drop across terminals with loads applied to the circuit in question. Voltage drop should be less than 0.2 volts on terminals. Note that bad electrical wiring is a major cause of boat fires. I would check everything with a sensitive voltmeter.
Lifejackets, check condition and correct size for crew and guests.
Check battery dates on EPIRB (Emergency Position Indicating Radio Beacon)
Check battery dates on all electrical gear, GPS, hand held VHF, carbon monoxide, smoke detector,
Check dates on flares.
Check dates on fire extinguishers and the pressure gauges if so equipped.