My best guess is that you have a corroded crimp connection, would create excessive resistance and intermittent contact and blow fuses.
Carefully trace and visually inspect each wire it;s entire lenght....look for knicks, kinks, and chaffing. replace any crinp connectors and use some dielectric grease inside the new ones.

 

Has to be an intermittent short between the two wires or corrosion in between the contacts causing a low resistance path.
Excessive resistance decreases the current. If it worked temporarily when you cleaned the socket check the wiring in that area and replace the socket if possible

 

This is a stretch.....had the same problem (when our boat was new). Our white light is the style which plugs in......light is atop an aluminum tubing/shaft, with the plug at the lower end. Found (heard) a piece of metal bouncing around inside that tubing, which must have been making contact with wiring at the plug end. Eliminated that piece of metal and problem never returned.

 

Could be the switch, bub, socket, fuse or wiring. To check the switch, remove the leads going to the navigation and anchor light. Leave the power and ground (assuming it has an indicator light) connected. Turn switch on and off -- if fuse doesn't blow -- you're good so far. If it blows the switch is mostly likely the culprit. Attach just the anchor lead -- if fuse doesn't blow and lamp lights, your still good. Detach anchor lead and connect navigational lead -- turn switch on and check fuse and lamp. I would expect at least one of these one of these three steps to fail.

If the fuse blows when only the switch is in the circuit and turned-on -- the problem is in the switch, wiring to the switch on fuse panel. If the fuse blows when the anchor light is connected -- the problem is in the wiring, socket... to the anchor light. Finally, if the fuse blows when only the nav. lights are turned on -- the problem is in the wiring, socket... to the navigational lights. If the problem is in the lights to the wiring, remove all of the bulbs, connect the wiring and turn on the lights. If the fuse still blows -- there's short in the wiring. Replace each of the lights one at a time and turn the switch on -- if the fuse blows, you'll know which socket is bad.

You can check shorts in the wiring by using a voltmeter to check continuity. The steps above allow you to isolate the problem with out using a voltmeter. Also, make sure you're using the properly rated fuse and the correct bulbs. Good luck. Send me a pm if you need more help.

 

it it blowing fuses in both positions? or in just one position?

I hate electrical problems that just show up

 

you need to isolate the problem. the switch, nav. light or anchor lt, or a wire running to them. i would try removing all bulbs test continuity at each light , or if you get the test probes under the light socket do that.....should be no continuity. check each one. flip the switch so all light work, reinstall bulbs one at a time....if a fuse blows then its more than likely that circuit.

learn how to use a ohm meter and what the results mean. just make sure you getting good contact with the probes.

then go to the switch and check each position.

hope this helps. i could dispatch goinfishin' but his travel time and hourly rates are high but fair.

 

make sure you remove all power before using an ohm meter otherwise the needle will look like a corkscrew wrapped around the peg. Voltmeter OK with power still applied

 

Thanks for the input everyone. I called the boat manufacturer (Cape Horn) and they put me through to the guy who wires all of their boats. He said his best guess was that the bow receptacle was probably the culprit. He said that the contacts for the fixture were very close together and that they may be touching. Low and behold that was the problem. Both of the connectors had shrink wrap on them but due to the vibration a very small hole had worn through the shrink wrap and was touching. I spread the contacts apart a little bit and will put another layer of shrink wrap on them, that should fix it.

I have to say it was nice to be able to call a small manufacturer and talk directly to the guy who built the boat. I've called down to them about some other things and always get a knowledgeable person. Nothing but good things to say about Cape Horn, they build a solid, affordable fishing boat, and have great customer service to back it up.

Dave