External mast conduit

[webcraft]

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I want to run an external conduit down the mast on Avy-J for cables. What material is best and how to attach it?

_ W

 

[prv]

Assuming it's an aluminium mast with no space left inside, rather than a solid wooden one.

I think it would have to be some kind of aluminium channel profile - plastic conduit is generally PVC and I'd expect it to go brittle after a few years and then crack when a halyard or sail whacks it. Both stainless and ordinary steel will be heavy and harder to work with; plain steel will rust and stainless will probably be quite expensive.

Attach it with aluminium rivets (no need for great strength).

Pete

 

[rogerthebodger]

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I want to run an external conduit down the mast on Avy-J for cables. What material is best and how to attach it?

_ W

I would look for an aluminium section like this

http://www.capalex.co.uk/standards/tophat_sections.html

 

[fredrussell]

Was thinking of doing the same - would like to run a cable from tv aerial mounted on spreader down to deck.

 

[prv]

Was thinking of doing the same - would like to run a cable from tv aerial mounted on spreader down to deck.

Is there no space left inside? That's the normal place to run cables.

Pete

 

[webcraft]

At the moment the tricolor & Vhf cables are run externally in clips. I need to replace Vhf & fit steaming light. No access to inside of mast - would have to take the base off somehow. Also don't want cable slap in inside the mast.

—W

 

[zoidberg]

Should the only option be for external conduit, then an alumin(i)um protective conduit seems the easiest way, secured by blind fasteners, As mentioned, PVC conduit will degrade under UV, and break off eventually. Such alumin(i)um will need its own coating of protection - possibly spray-on.

Should the mast be hollow, then it is certainly possible to run the cables inside. Guidance on where and how to cut access holes, and 'make good', should be gained online from the likes of AllSpars or Selden, or even here. It's not a new requirement. Internal 'mast slap' may be prevented by fastening cheap cable ties tightly, at intervals, in a 3-star, configuration at short intervals around the cable bundle.

 

[A1Sailor]

Will the mast not have a conduit for cables inside it? The Kemp mast for my 1980 Sadler 25 did. I wanted to fit a steaming light and ended up replacing the two core cable to the masthead with a tri, then ran a two core cable from there down to the new steaming light. The masthead cable up the conduit and the twin down inside the mast but outside the conduit. I obviously had to remove both the base and head bits...

 

[PuffTheMagicDragon]

Also don't want cable slap in inside the mast.

—W

Not necessary to have cable slap inside an aluminum mast. I had this problem when I had a Centaur. I removed the foot by undoing 4 self-tapping screws (from memory) and gentle persuasion through the application of a plastic hammer that dislodged the accumulation of crud between the foot and the profile.
Once the foot was off I made up two lengths of plastic conduit, one to go the full height for the tricolour and the VHF and a shorter one for the steaming light, around one metre above the spreaders.
To hold the conduit in place and prevent it from slapping I drilled some holes inside the luff-groove at intervals of around a metre and a half. Through these holes I poked the 'snout' of an aerosol can and injected expanding foam such as is used for insulation; just 2 or 3 seconds per hole, enough to fix the (invisible) conduit at each location. I had no further problems with slapping. This must have been some twenty years ago and, as far as I know, it is still in place.
Easy, cheap and effective.

p.s. Don't forget to feed a mouse-line before you insert the conduit up the mast.

 

[lpdsn]

If it were me I'd go for a plan A of unstepping the mast and trying to run the cables internally. Obviously it won't be easy without a mouse down the cable conduit but you could get one of those cheap endoscope type cameras so you can see what you're doing internally. Maybe even fancier kit is available from tool hire shops.

Once done it'll be a lot better job than external wiring conduits. It looks bad enough on old houses never mind a boat.

 

[webcraft]

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I don't think my mast has a cable conduit, nor do I think there is any easy way ot check. all indications are that cables have never been run inside this mast.

But I will investigate further,l maybe post some photos.

- W

 

[A1Sailor]

Are there any odd rivets visible on the mast that don't seem to be doing anything? It is just possible that a conduit, if present, might be attached that way.
There's a thread from 2007 here: http://www.ybw.com/forums/showthread.php?116316-Wiring-a-Selden-mast&p=1197437#post1197437 It seems some masts have more than one conduit...
What kind of boat/mast is it Webbie?

 

[webcraft]

Are there any odd rivets visible on the mast that don't seem to be doing anything? It is just possible that a conduit, if present, might be attached that way.
There's a thread from 2007 here: http://www.ybw.com/forums/showthread.php?116316-Wiring-a-Selden-mast&p=1197437#post1197437 It seems some masts have more than one conduit...
What kind of boat/mast is it Webbie?

It's a Morgan Giles 30, completed circa 1978, no idea what tmake the mast is, think this calls for more detailed investigation. Will have a closer look and report back.

- W

 

[prv]

Are there any odd rivets visible on the mast that don't seem to be doing anything? It is just possible that a conduit, if present, might be attached that way.

Yes - though the absence of rivets doesn't imply an absence of conduit, since most are moulded into the mast extrusion.

I'm no expert in spar extrusion history but I would not assume that 1978 is automatically too early.

Pete

 

[lw395]

I would avoid using lots of rivets in the mast.
It's May already, time to crack on with a quick fix.
Dare I suggest running the cables up the back stay?

Lots of dinghies have the luff rope track glued to the mast, as an alternative option.
Plastic conduit will probably die of UV, even in Scotland, but it's not expensive to replace every few years, or when you drop the mast and sort an internal conduit.
UV resistant plastic conduit is around, but it's usually black. A coat of white paint will help UV proof it anyway.

Is it a luff-groove section, not a slider-track?
I've seen cables glued in the corners of the luff groove when there's space.

 

[Billjratt]

I've experienced external conduit - plastic and aluminium and found it worthwhile to cable internally. The plastic was a UV disaster and the sight of a long section of alloy spearing into the sea with the resultant flapping of cables in the breeze convinced me the only way was up the inside. I guess all the halyards are external and you have no existing orifices to probe through - cables may be led through intenal ducts in the extrusion so counting rivets isn't always an option. I guess the mast is coming down anyway, so if the foot (or truck) can't be removed due to white powder syndrome, drilling a hole in the base will allow investigation - there should be one for drainage anyway.

 

[Graham376]

If you must run a conduit externally, there's plenty of ally tube around such as here which can be fixed with saddles - https://www.metals4u.co.uk/aluminiu...-1voRNwEhKqcWC_i6bMLBcuD82mCX_CBoCY0kQAvD_BwE

 

[William_H]

If it were me I'd go for a plan A of unstepping the mast and trying to run the cables internally. Obviously it won't be easy without a mouse down the cable conduit but you could get one of those cheap endoscope type cameras so you can see what you're doing internally. Maybe even fancier kit is available from tool hire shops.

Once done it'll be a lot better job than external wiring conduits. It looks bad enough on old houses never mind a boat.

These endoscope cameras might seem like the answer so I bought one to see if I could find if my halyards were twisted or crossing one another. The camera proved hopeless. The vision is so close that I could not get any perspective on what I was looking at. No use at all for anything ever since. olewill

 

[webcraft]

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Well, I am pretty certain there is no internal conduit. There are some holes top and bottom in the mast which suggest that at some point cables have been run inside.

Contrary to a supposition above, the halliards do run internally, and poking cables up the mast without a conduit seems fraught with the possibility of interference between cables and halliards, with both jamming (of halliards) and chafing (of cables) possible.

Just for more info, at the moment there are two cables up the mast - one seems to go to the steaming and tri lights, one is the VHF cable. They are held in saddles, but the VHF cable is dead skinny and I want to fit a decent one so the existing saddles will be too small.

I guess just having the cables on the outside (no conduit) means pretty rapid UV degradation? Ally tubing with new saddles seems a good way to go. How do you rivet stuff on to a mast?

And - another question - how does a single cable to steaming light and tri work? It goes to a three-pin deck plug at the bottom.

- W

 

[lw395]

You could add a layer of heatshrink tubing to reduce UV degradation.
IME, mast cables don't last forever due to water ingress and corrosion anyway.
You can buy UV rated co-ax and other cable.

I would guess the lights are wired with 3 core, + for white, + for tricolour and -ve.
But there are variations!