Nav lights duff?

jcpa

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I can’t understand what’s going on.

I’d done a stack of mods behind the switchboard (Plastimo trip switches, circa 1984 vintage), including moving a switch to separate the stern and bow lights (so I can show the bow lights with the masthead anchor light when motoring).

On testing everything, the bow lights were fine (but I had to go to the pulpit to check properly). However, back on deck after going below to flick on the stern light, the nav lights had all tripped out. I switched the stern light off again and reset the breaker switch, but still no bow lights. So had the bulb just failed and was it now shorting?

The filament looked ok, but the multi-meter suggested an open circuit across the contacts - is this a valid test, or do I need to apply 12v? I replaced the bulb anyway, but still no bow lights. I checked the voltage across the light fitting terminals (0v), and then at the trip switch outlet (sometimes 12v, sometimes 7v [???], sometimes 0v – but I have found the circuit trips can take several seconds to activate). So is there a short in the bow-wiring – perhaps caused by flexing the cable to get behind the switchboard?

The meter did not find a short across the light fitting (so no obvious short in the feed wires), but these wires run in a channel within the balsa deck sandwich (near the hull to deck joint), and then seem to feed up through the pulpit tubes. It would need some ferreting to check the wires physically. Moreover, the headlining is also stapled into the balsa in places, so maybe someone stapled the cable too?

Or is the trip switch duff? If so, could I get a replacement after all these years? I believe I could separate the switch from the panel, and maybe swap it for the auxiliary switch on the end (one that could possibly be replaced with a newer style switch – and be usefully uprated too!) – but what a palaver!

I tried the tests several times, including turning everything off, and restarting the battery charger - it goes off when I switch off the house battery, which I’d done when I started my “stack of mods” several hours earlier, and with the fridge still on, and later the cabin lights, the battery level had dropped to around 12.3v (I think). Still the bow lights wouldn’t work, and I began to believe the wiring or trip switch really were duff.

Feeling utterly depressed, I went off for a cup of coffee. It was dark when I returned 30 minutes later, and would you believe it, the stern light was on (and presumably had been for those 30 minutes). I had left the bulb out of the bow fitting, with the nav lights turned on, and the stern light switched in. Maybe there isn’t a trip switch or wiring short after all?

It was too late and dark to mess around putting a bulb back in the bow light, and SWMBO had already called me home, but presumably that is what I should try next. I could also try a temporary wire from the switch panel to the bow light. This will mean digging out lots of sealant from the back of the light fitting – but I’ll probably have to do that anyway.

Dammit, will I ever get sailing?
 

AngusMcDoon

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It was too late and dark to mess around putting a bulb back in the bow light, and SWMBO had already called me home, but presumably that is what I should try next. I could also try a temporary wire from the switch panel to the bow light. This will mean digging out lots of sealant from the back of the light fitting – but I’ll probably have to do that anyway.

Dammit, will I ever get sailing?

I don't know what the problem is, but they're only lights. Rig up some temporary wiring, buy some emergency nav lights just in case, and go sailing - equinox 4 weeks today. Fix it another time.
 

prv

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why the Bi & stern on different switches

In the OP - so I can show the bow lights with the masthead anchor light when motoring.

Presumably he doesn't have a separate "steaming" light, in which case an all-round white at the masthead plus bow "sidelights" is a legal alternative for medium-sized boats.

Pete
 

AngusMcDoon

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In the OP - so I can show the bow lights with the masthead anchor light when motoring.

Presumably he doesn't have a separate "steaming" light, in which case an all-round white at the masthead plus bow "sidelights" is a legal alternative for medium-sized boats.

Pete

All combinations (sailing/motoring/anchored) can be done with 3 lights (bow bicolour/stern/masthead all round white) and 2 switches, up to the size limit. The wiring takes a bit of thinking about but can be done to save on switch panel space. It's standard on all Dragonflies.
 

prv

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All combinations (sailing/motoring/anchored) can be done with 3 lights (bow bicolour/stern/masthead all round white) and 2 switches, up to the size limit. The wiring takes a bit of thinking about but can be done to save on switch panel space. It's standard on all Dragonflies.

I do five different combinations with a single switch :D

(Ok, it's a rotary switch with six positions including off)

The combinations are:
  • Sail Low (bow bicolour, stern light)
  • Sail High (masthead tricolour)
  • Motor Low (bow bicolour, stern light, "steaming" light)
  • Motor High (all-round white at the masthead, bow bicolour)
  • All Round White (not labeled as "Anchor" because I prefer a hanging light above the ball in the fore-triangle)

The first four also turn on the compass light, and an LED that illuminates the masthead windvane.

I have a little scrap of veroboard with a few diodes on, behind the electrics panel, to set up the combinations. The wiring to each light is individually fused so that a short inside the mast or pulpit doesn't take out everything, and the blade terminals on the mini fusebox also mean that I could re-patch things if for some reason I wanted to show an odd combination of lights.

Pete
 

jcpa

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Thanks all for your comments

AngusMcDoon is probably right about a temporary fix, and I do have emergency battery lights - but I doubt they are legally bright enough (single D cells).

Also, I would need to screw back the switchboard knowing I'll need to take it down again; it is very heavy and awkward to fix, and getting the headlining and wires/looms placed properly takes some time. I really only want to do it once, with everything working!

I was just hoping someone had some ideas on testing bulbs or trip switches, or could somehow shed some light on my problem. What sort of resistance should a 25w filament bulb show, about 6 ohms when glowing? What when not? I should probably have a test socket on a flying lead. How do (current?) trip switches behave when they fail? Has anyone had a similar tripping problem with an old plastimo switch panel I don't have a model number, and can't find details on web, but it 15amp overall, with six breakers (panel on, cabin lights, deck level nav lights, masthead tri-colour, masthead all-round white, and "auxiliary")? Could my lighting cable insulation be cracked (or pierced by staples), and could damp cause intermittent shorting? To where else might current leak from the circuit wires? Two cables feed through that deck channel, and I think the other one may be for the front cabin lights.

PRV is quite right on why I have a switch for the stern light. A whole new system with rotary switch might be a good aim, but I have to start with what I've got!

Thanks again

John
 
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