Rewiring the Mast

[Stemar]

Today, I wanted to run new cable for my masthead and steaming light/deck flood, but both cables are jammed solid inside the mast. I could get away with the steaming light, but the masthead needs three conductors for the two lights. so must be changed. There was plenty of loose wire tucked in at the foot for both cables and at the masthead, while the steaming light end isn't going anywhere and a disused wire for, I believe a Decca navigator is also well stuck.

Any ideas?

It's a Kemp mast around 10m long, and out of the boat. The foot looks to be held in by three pop rivets, and seems to be in good condition. and the head plate and block assembly appears to be held on by a pair of bolts with ~17mm nuts. I'm thinking that the foot will have to come off and, quite possibly the masthead plate. Are there any gotchas I need to know about? Any tricks if they get stubborn?

BTW, I've seen discussions on masthead anchor lights, so I'm aware that I and all those in the anchorage around me will die if I use it.

 

[Boathook]

You are doomed to failure relying upon an anchor light at the top of the mast.

My mast was and still is a kemp and the wires run up a tube inside on the front. There are visible flush rivet heads about every 3 feet visible on the front.
One of my cables was stuck and it was gunge on the cable.
Taking the masthead of I seem to remember it was the bolt through the side of the mast rather than the 2 on the head itself. Or was it the other way round but after 5 years ...

 

[William_H]

Re removing the foot of the mast. It is usually a neat fit of a casting inside the ali mast extrusion by about 50mm. Corrosion can make this difficult to remove. Try hot water etc. If it is too difficult then leave it in if you can manage. If you can't then try cutting around the extrusion about 25mm up and peel away the ali. This may enable you to free the base. If not cut a bit further up, or eventually cut off the base. Brutal and leaves the mast shorter. I hope it does not come to that.
Mean while there are various tricks with diodes at switch and light which enable you to use just 2 wires for 2 different lights. Just a thought which you may wish to pursue. ol'will

 

[Stemar]

It won't be coming to cutting the mast, that's for sure! I think I'll drill out the rivets and see what happens. If a kettle of boiling water on the mast doesn't ease it, I'll replace the rivets!

I'd thought about the diode trick; Does anyone have a circuit diagram for please? I could probably work something out, but I'm no electronics engineer, and I'm sure there's a neat and clever way that'd be way better than any bodge I could come up with.

 

[Boathook]

I'm sure that the bolt just visible on the side of the mast just below the casting was removed, allow the casting to be removed. Took a bit of persuasion with a mallet to get the casting off. I did this as the pulleys were starting to 'jam'.

 

[doug748]

I have had my Kemp mast down 4 or 5 times over the years and never been able to solve this problem.

The head casting on mine is fixed with two L bolts with the nuts on the top of the casting. As mentioned you may give up on the foot but I caught mine in time and it is now held with screws and I take care to grease the thing before replacing it. Use all the tricks, soak it in diesel for a week and try to get a hammer behind it if you can improvise this without damage (you may be able to bolt a block to it) - sometimes with corroded ally it is impossible without cutting tactics, don't be afraid to give up.

I have just ordered something like this for another job, it may help:

endoscope for sale | eBay

The jeopardy is that you might damage or break the existing cables half way up the mast and be stuck with them. If the original cable still has continuity it may be best to cut your losses and continue to use it for a single nav light.

.

 

[Stemar]

If the original cable still has continuity it may be best to cut your losses and continue to use it for a single nav light.

I'm tempted, but I just spent far too much money on an tri/anchor LED light. I can't get to the boat today, so I'll spend some time researching ol'will's diode idea.

 

[BabaYaga]

To the OP: If your mast head is similar to the photo in post #5, then it is also the same arrangement as on Seldén masts from that era.
As mentioned in post #6, the hex bolt heads on the mast side just below the top casting/extrusion are on cranked bolts, so do not try to undo these. To remove the sheave assembly, just remove the two nuts on the mast head.

 

[Stemar]

To the OP: If your mast head is similar to the photo in post #5, then it is also the same arrangement as on Seldén masts from that era.
As mentioned in post #6, the hex bolt heads on the mast side just below the top casting/extrusion are on cranked bolts, so do not try to undo these. To remove the sheave assembly, just remove the two nuts on the mast head.

Thanks. I'd guessed it was something like that, but it's nice to have it confirmed