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Strain relief for wiring at top of mast

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Rewiring the mast over the next few weekends. Was hit by lighting last year.

New VHF coax, new supply for anchor light, bicolor and steaming lights. 

On this mast the bicolor and steaming fixtures are about 20 feet up on the front of the mast. The old wires there just went straight into the back of the fixture. Not sure that anything held the wire before the crimped butt joint with the fixture leads. 

Anchor  light and VHF are at masthead. Anchor light is new. There are holes drilled at the side of the extrusion just below the mast head. Old coax was held with 5200 in the hole before the drip loop. 

What kind of wire clamp is available to hold the VHF coax and the anchor light wire as they exit the mast?  I think something should be taking the strain of 40+ feet of wire. 

No conduit in this mast, so will be attaching tie wraps in 3s to prevent slap. 

Thanks for any advise on the strain relief. 

Bill 

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Is the mast out of the boat?

If you aren't using a conduit, consider running the coax and wires through an epoxy bath as you pull the mouse to feed them into the section.  If your sailtrack (internal ?) is facing down, you can lay the wires alongside the internal web and the epoxy will glue the wires to the alloy section quite successfully, preventing slap and acting as strain relief, as well as positioning the wiring out of the way of internal halyards.  It helps to apply a bit of "fall" to the section so you can pour a bit of epoxy in from time to time and it will run toward the low point, increasing adhesion.

I've done this on dozens of masts (up to about your size - above that it's preferable to use conduit) and never had an issue. 

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Normally  the wire bundle is taped , clamped to a piece of small diameter 1/19 ss rigging wire .  The bundle  is then run inside the mast from mast foot to mast head.

 

The bundle is dead ended at the masthead and mast foot..the mast foot dead end has a small turnbuckle to tension the strain relief wire 

small boat can bury  the electric wires inside the cover of a piece of yacht braid rope that has had it core removed.   Again the bundle is  dead ended at mast head..tensioned at mast foot.

the rope cover gives some chafe protection 

conduit is best .

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14 hours ago, Recidivist said:

Is the mast out of the boat?

If you aren't using a conduit, consider running the coax and wires through an epoxy bath as you pull the mouse to feed them into the section.  If your sailtrack (internal ?) is facing down, you can lay the wires alongside the internal web and the epoxy will glue the wires to the alloy section quite successfully, preventing slap and acting as strain relief, as well as positioning the wiring out of the way of internal halyards.  It helps to apply a bit of "fall" to the section so you can pour a bit of epoxy in from time to time and it will run toward the low point, increasing adhesion.

I've done this on dozens of masts (up to about your size - above that it's preferable to use conduit) and never had an issue. 

Somebody is going to be bitching about you when they get their mast wires fried or cut and you have left a real mess in there that it impossible to remove

Run the wires inside a dyneema chafe sleeve - tie off the sleeve at the masthead and you have a built in strain relief.  For the steaming/bi-color light you just put them through the chafe sleeve at the right height (obviously have to do this before putting the whole assembly in the mast).  The extra weight of the chafe sleeve is negligible and it is as very good protection against rope burns

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Yes on the dyneema sleeve. 

Also for the steaming light, a good idea is to get a normal black rubber grommet sized for the mast hole and cable, snip one side of it, and work it into the hole to protect the cable sheath.  Actually take two up there, as you'll probably drop one down inside the mast.  Don't ask how I know that. 

Don't forget a drip loop in the cable before it enters the light fitting, and ensure that the entrance into the fitting is well rubbered too.  It's amazing what chafe can happen up there if you get a sympathetic vibration in the rig while motoring.

YMMV

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UV burns exposed cable..always spiral wrap the exposed cable to keep the sun off it.

 

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On 4/21/2018 at 2:46 AM, slug zitski said:

small boat can bury  the electric wires inside the cover of a piece of yacht braid rope that has had it core removed.   Again the bundle is  dead ended at mast head..tensioned at mast foot.

the rope cover gives some chafe protection 

I used hollow braid polypro to run my wires.  An eye spliced at the mastend end attached to an eyestrap and a bungie tensioning the bottom.  Feeding the wires though the hollow braid was a PITA.

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R

1 hour ago, xyzzy said:

I used hollow braid polypro to run my wires.  An eye spliced at the mastend end attached to an eyestrap and a bungie tensioning the bottom.  Feeding the wires though the hollow braid was a PITA.

Its easiest  to use double braid.

 Fasten wire bundle to center core,  then pull it plus the wire bundle thru the cover... you are replacing the  rope center core with the wire bundle 

the same way you hang, strain relief , a shorepower electric cable , between boat and dock 

 

this only works with a small bundle of electric wires...if its a big bundle you must use a 1/19 ss wire with the bundle taped to the wire 

P1090947.jpg

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Not knowing any better, I bundled up mine with a small piece of line.  Note that the Ancor five-conductor mast cable appears to have strain relief fibers built into it.

One trick that some previous owner or rigger did was stuff pieces of cushion foam up inside the mast about every 8 or 10 feet.. I think it was two inches thick and bent into a U shape before stuffing it up there.  I thought this was going to give me grief, but I was able to push a fish-tape through the middle without much trouble.  It seems to stop any wire slapping and may provide some support.  But really, I wish I had taken the time to run a conduit with proper junction boxes at top, bottom, and spreaders.  I had basically run out of time and had to rewire the mast at 0200 the night before the travel-lift appointment.  No time to think twice about anything, just go, go, go!  Everything still seems to work after five years.  Out of sight, out of mind...

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  Beware of internal foam!! I started to strip a mast to repaint. Had many tiny 'zits' which I thought were just aluminum corrosion peaks under the paint. But as I sanded the paint off, they turned into holes which expanded on the inside!! Turned out original wiring was stopped from banging about by chunks of foam every 4'..  Well, 25 yrs later, every 4' there were holes right thru the mast wall from the chunks holding moisture. Replaced the spar.

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Thanks for the suggestions. Much appreciated. Will sort out what to do. Soon. Launch date is coming. 

Don't think I would go with the epoxy bath. One of the hanger lines might work. 

Bill

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