Q. Is it safe to replace an autopilot fuse that occasionally blows with a higher-rated fuse?
A. Take blown fuses seriously. When fuses continue to blow immediately or intermittently, that’s the sign of a problem. Increasing a fuse size can damage the equipment and create a possible fire hazard.
An autopilot will tend to draw excessive current when its computer/processor or its drive unit is underrated for the boat’s steering. Your dealer or manufacturer’s website can help you confirm the right-size autopilot for your boat.
A blown fuse or tripped circuit breaker also might be caused by a fault from another device or the wiring connected to it. Turn off other electronics and disconnect units like a radar antenna, depth-sounder/fish-finder module, heading compass, GPS sensor, network cables, stereo amplifier, etc., and see if the fuse continues to blow. This can help point to where the real issue might lie.
With newer electronics that meet NMEA 2000 interface standards, you have a significant advantage in troubleshooting equipment problems. Each instrument can be easily disconnected from the NMEA 2000 network until the problem-causing device is found.
Troubleshooting the Electronics
If your boat is equipped with newer electronics that meet NMEA 2000 interface standards, you have a significant advantage in troubleshooting equipment problems. Each instrument can be easily disconnected from the NMEA 2000 network until the problem-causing device is found by process of elimination.
While troubleshooting, be wary of amateurish, haphazard wiring. Unlike strict building and house-wiring codes, professional marine wiring standards are not always applied on boats. If you are unsure of the correct practices and procedures, it is best to have factory-authorized or NMEA (National Marine Electronics Association) or ABYC (American Boat and Yacht Council) certified technicians perform your electronics and electrical work.
Unsecured, dangling wiring and cables lying loose at the bottom of the bilge are sources of pending problems that can cause electrical shorts. Here are 14 tips for avoiding electrical problems:
1. Avoid spiderweblike connections where many wires are connected together. This frequently occurs as additional equipment is added over the years. Such an electrical bottleneck can add to excessive current loads.
2. Follow recommended and safe electrical wiring standards and limit connection points to no more than three wires. Spread out electrical loads by using separate terminal blocks and electrical subpanels or circuit breakers (see bluesea.com).
3. Keep all connections tight, neat, clean, and away from water.
4. Turn your battery switch or circuit breaker panel off when working on your electrical system.
5. Remove all metal objects, including rings, bracelets and hanging neck chains, when checking your wiring to prevent an accidental short.
6. Take care when removing fuses from a fuse block. The use of metal tools to remove a fuse can easily cause a short.
7. Be wary of forced, sharp cable bends in power-cable wiring, particularly when the wiring is pressed against metal objects.
8. Avoid running power cables in a position where they might be crushed or stepped upon.
9. Prevent voltage-carrying wires from lying loose on the deck or the bottom of the bilge.
10. Keep electrical wiring a safe distance from engines and other heat-producing sources.
11. Secure your wiring to prevent it from coming in contact with water.
12. Be sure to provide a plastic cover for your boat battery(ies) and/or positive battery terminals. This will guard against accidental shorting of the battery terminals due to a dropped tool or coming in contact with other metal objects.
13. Make use of terminal wiring blocks and cable junction boxes with protective covers to insulate wiring contacts.
14. Refer to your owner’s manual or manufacturer’s website to determine the current rating of each instrument. Add together the current draw of each instrument. Use the Circuit Wizard on the Blue Sea Systems website (bluesea.com) to calculate the safe required fuse and wire size to handle the current demands of all your electronics and electrical equipment.