Simple Boat Maintenance

Pat Manley

• Publisher: Fernhurst Books
• Year: 2014
• Topic: Technology & Engineering
• eBook ISBN:
  9781909911673
• Subtopic: Military Science & Technology
• Index: Technology & Engineering

Simple Boat Maintenance concentrates on the 67 most common boat maintenance jobs. Each is rated for difficulty on a scale of 1-5 and is explained in simple steps with lots of photos and diagrams. No special tools are required and no skill is assumed. Take this book in one hand, a spanner in the other and set to work. Learn how to: solve most engine problems; look after the gas, water, fuel and electrical systems; service pumps, winches, windlasses & sterngear; repair cracks & holes in fibreglass; find & cure leaks.

ELECTRICAL SYSTEM

30 Formulae

BASIC ELECTRICAL KNOWLEDGE

1 Resistance of a wire or component is measured in Ohms (Ω).

2 Volts (V) drives the current through the wire.

3 Current (I) is the flow of electricity through the wire. It’s measured in Amps (A). (Strictly, current is in amperes but most people use the word amps.)

4 Power is the voltage multiplied by the current: Power = VI Watts.

5 Ohm’s Law tells us that the current through a wire is calculated by dividing the volts by the resistance – thus: I = V/R and so V = I x R, R = V/I.

6 Voltage loss in a long wire run should not exceed 3%. On many boats the loss is as much as 10%. This gives dim lights and wastes power.

7 The resistance of several components connected ‘in series’ is the sum of their individual resistances. The same current flows through all of them. The system voltage acts over the complete string of components. (R = R1 + R2 +R3 etc.)

8 The resistance of components connected in ‘parallel’ is a little more complex and is found by:

• For only two resistances this is simplified to:

Energy consumption from a battery

• The energy consumed from a battery by a piece of equipment is measured in amp hours (AH), the length of time it’s switched on multiplied by the current flowing through it.

• A 25 watt navigation light has a current of 2.08 amps at 12 volts (power / volts). Switched on for 8 hours it will consume 16.64 amp hours (amps x time).

Note: Many authors erroneously state this consumption in amps with no reference to the time the current is flowing.

Electronics

Electronic equipment will normally run on a large voltage range: 9 –16 volts or even 9 – 32 volts.

Heavy load items

Fridges, heaters and other heavy load equipment will often be set to cut out if the voltage drops below a critical level.

Note: The voltage drop across a fuse protecting a heavy load may cause the load to cut out. Heavy load items should be protected by a circuit breaker rather than a fuse, to prevent this.

31 Multimeter

Troubleshooting and maintenance of the electrical system is enhanced by the use of a multimeter (diag. A). These meters can ...

Table of contents

• Cover
• Copyright
• CONTENTS
• FOREWORD
• INTRODUCTION
• ENGINES: Cooling system
• ENGINES: Fuel system
• ENGINES: Electricity
• ENGINES: Servicing
• ENGINES: Other topics
• FUEL SYSTEM
• WATER SYSTEM
• GAS SYSTEM
• ELECTRICAL SYSTEM
• HEADS
• BILGE & WATER PUMPS
• SEACOCKS
• STERN GEAR
• STEERING
• ANODES
• ANTIFOULING
• FIBREGLASS
• DECK HARDWARE
• LEAKS
• WINCHES
• WINDLASSES
• INFLATABLES