ALARM

Two things trigger the alarm, low oil pressure, and high engine temp. When the engine is not running you have no oil pressure, hence the alarm. Once you start the engine the alarm should stop sounding. If it continues to sound when the engine is running, then you have an issue.

In terms of smoke, black smoke is fuel, blue smoke is oil. A bit of black smoke at start up is fairly normal.

BATTERY

For 12V batteries (6 cells), full charge voltage is 12.7V and full discharge voltage is 11.7V.

Therefore, 12V means that 70% of its capacity (DoD) has been used. 

If this battery is not a deepcycle battery, the battery life will be reduced and the battery will be damaged.

Below you can see the safe discharge levels for different types of batteries

Conventional aqueous lead acid (truck battery): 30% (12.4V)

Gel battery: 50% (12.2V)

AGM battery: 60% (12.1V)

Deep cycle featured battery: can be used up to 80% (12.0V) values.

In case the the level fall below, the battery is physically damaged in each one (lead oxides on the plates are spilled, accumulate on the battery base, its internal resistance increases, does not hold charge, self-discharges, etc.) and the number of charge-discharge cycles (life) decreases.

BATTERY CHARGE

Gel batteries should be charged with currents not exceeding 5% of their capacity and Lead-Acid flooded batteries with currents not exceeding 20% ​​of their capacity.

These percentages are clearly stated in literatures.

If gel type batteries are to be used as service batteries, parallel connected battery groups with high capacities should be created.

For example, considering that an alternator has a capacity of 115 amperes and a battery isolator is used. 

In average rpm this battery will create 115*0.6 = 69Ah 

That means each battery group (service and engine) will be charged with (69Ah / 2 = 34.5Ah).

In order not to exceed the charging current, gel battery group must be fed with a capacity of at least 690Ah (34.5Ah / 0.05 = 690Ah).

Similarly, while charging Lead-Acid type batteries, in order not to exceed maximum charging current, the battery with a capacity of at least 172Ah (34,5Ah / 0.20 = 170Ah) is required.

It is important that the Gel Battery setting is made in battery charger not to exceed maximum indicated number.

Marine type of lead-acid flooded batteries consist of thicker plates than the same capacity batteries of truck type.

That's why marine type batteries has longer life.

In addition, marine type batteries are safer at inclinations up to 55 degrees due to their ability to keep electrolyte liquid inside the case.

It is necessary to have a quality battery booster cable on board.

If the engine battery becomes inoperable, you can start your engine by combining the jump lead with only the + poles of the service and engine battery.

You must remove the jump start cable after the engine has started.

BATTERY ISOLATOR

A battery isolator is a one-way electrical device that allows an electrical current to flow in one direction but not the other. A battery isolator typically is used in situations where multiple batteries are required, and its primary purpose is to ensure that the failure of a single battery will not incapacitate an entire electrical system. Battery isolators are used in large trucks, RV's, boats, utility vehicles and other vehicles that require multiple batteries and backup sources of power.

WINDLASS

1500W windlass consumption is 125Ah. 

Lets assume it works 2 minutes.

It means: 125Ah*2minutes/60=4.16ampere

Lets assume the boat has 115Ah alternator. 

In Idle state which is 1500rpm, alternator produces %40 of its max. output. Which is 115Ah*0.4=46Ah

If battery isolator is used, it will distribute this energy between engine and service batteries. That means 23Ah for the service batteries.

4.16ampere windlass consumption can be regained in  4.16/23=0,181h in this condition.

In conclusion, we can regain the energy, consumed by the windlass, in 0,181h*60=10.85 minutes by engine working (1500rpm).

SAILS (Dacron)

A typical weekend cruising sailor who sails his boat two weekends a month, plus two weeks of cruising during a five-month season will accumulate roughly 240 hours per year. Thus sails will last for 16 years! 

At the other extreme, a person living aboard their boat and cruising the Caribbean extensively will use their sails as many as 12 hours per day, 12 days per month, 12 months a year for an average of 1,728 hours a year. This sailor will need to replace sails every 2.5 years. 

A sail can be used approximately 4000 hours. Do the math for your type of sailing and you’ll get an idea as to how long your sails will last.

Generally for a cruising boat, sails should be replaced every 7-8 years.

Rigging

Lifetime is 10 years (stainless wires not mast, boom and rod kicker)

Engine 

Lifetime is 6000 hours 

Teak

After 15 years, sika should be replaced.

Boat Size

Boats size should be measured as M3 not M2 

40 ft. boat size is 40*40*40=64000m3

45 ft. boat size is 45*45*45=91125m3

91125/64000=1.42 It means a 45 feet boat is 1.42 times bigger than a 40 feet boat.

Maintenance expenses will be 1.42 times more as well.

Sail Drive 

Cone clutch should be replaced every 1500 hours.

Diaphragm should be replaced every 7 years.

Seals should be replaced every year.

NOTES

• If heel angle of the sail boat is more than %12-%15, turn of the engine. 

• The engine's optimum RPM is 75% of the maximum RPM. 

BSCA and PADI No Decompression Stop Time Limits Table

Once you go deeper than 10-15+ metres (30-50+ feet), then it is always recommended you carry out a 5-6 metres (16-20 feet) safety stop for three minutes for every dive you do.