Mast wiring conduit

Mast wiring conduit

Postby midnightsailor » Thu May 11, 2017 8:02 pm

I am installing a combination masthead/decklight combination on the foremast of my F33. I have several questions. First has anyone succesfully installed a wiring conduit inside the mast? Particularly , by removing some of thesailtrack rivets and using those holes to then rivet both track and a pvc conduit to the mast interior ? If so, how did you hold conduit to mast side? I am thinking of inserting a loop of monofilimant or fishing leader wire into the hole and trying to run the conduit tube through the loop and then pulling it tight up against the mast interior wall. I am wondering if the small rivet whole will be big enough to do this. Any thoughts? If i cant come up with a satisfatory way of doing this I suppose Ill resort to the tie wrap star method to silence the wiring and just hang it.
The other question concerns the rivets...any idea size that would be satisfactory? I believe I read somewhere here that the length needs to be about 3/4" so that would likely mean a 3/16 rivet. For the mast/conduit rivet im sure id want at least 3/16 but for thr light itself Im sure a lighter rivet would be fine but i dont believe they would be available in 3/4" length. Id like to go with Monel but have not been able to locate any, Stainless appear to be easier to find, but if anyone can suggest a supplier I would like to know of it.
The last question has to do with the rivet tool. I am expecting to use a standard heavy duty manual rivet tool. Hopefully it wont be too difficult since i shouldnt need to place too many rivets, any comments here?
Thanks folks. Anxious for any feedback, Rick
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Re: Mast wiring conduit

Postby midnightsailor » Wed May 17, 2017 11:35 pm

So I guess im going to be the first to try and attempt to install a mast wiring conduit inside of the mast instead of the popular wiretie method. I have pulled out the original wiring bundle and was surprised to find that the original method of wrapping the wire bundle in a thick layer of foam neoprene rubber was still instact. The whole thing came out like a big long rubber snake! I did also find a 6 foot length of foam rubber tube much like the foam used to insulate domestic water pipe loose inside the mast,it fell out when unstepping mast but it did not appear to be from the rubber that the wire bundle was wrapped in. My only guess is that a previous owner had intruduced it to cover the last few feet of the wire bundle as it exited the mast. It was in rather distintergrated shape and is likely what produced all the foam dust and particles I found covering the mast step.
My next steo will be to remove the mast step so I can clean up the white corrosion aluminum oxide that is trying to take it over so I can clean , prime,seal and paint it...Im considering having it powder coated but perhaps that is a bit overkill and unneccesary..?
I also plan on stripping all hardware and sail track so I can perform Sponbergs suggested repair . I am trying to decide on the type of sock , the "chinese handcuff" kind of tube that will be slipped over the mast. I have read of using both dynel socks and fiberglass ones. and also I believe Sponberg recommends two layers , but I also have read of others who have done just one layer or one sock. Curious on the results of using just one layer. I also would like to find out how the dynel compares to the fiberglass, my guess would be it is more flexible. Also, regarding flexibility, I am considering using a G-Flex epoxy resin so if anyone has any thoughts on this , I would welcome them chiming in.
Well this does seem like a rather daunting project , what with atleast 110 rivets in trhe sail track alone to drill out so I best get moving! Rick
1982 Freedom 33 Cat Ketch, Hull # 53, Standard Booms, deep keel ,tall rig
An armed man is a citizen, An unarmed man is a subject. George Washington
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Re: Mast wiring conduit

Postby ewsponberg » Thu May 18, 2017 4:17 pm

Hi Midnight Sailor,
I just happen to be browsing the forum and found your recent postings. First, on the rivets. Monel is a good material in many carbon situations, but it is not really the best choice when attaching an aluminum track to a carbon fiber mast. The reason is because Monel is electrolytically very close to carbon fiber, which is quite noble, and therefore, both monel and carbon fiber are very cathodic to aluminum. This means that in a marine environment where carbon, Monel, and aluminum are in contact with each other, the carbon and Monel are immune to corrosion, but the aluminum will corrode very quickly. You don't want that to happen. As a result, stainless steel rivets are a better choice because they are strong, they are only slightly cathodic to aluminum, and if well insulated with caulking when installing them, they will help insulate the aluminum from the carbon fiber laminate. For length, you'll have to do a bit of trial and error--if you measure the thickness of the mast laminate at the base and add the thickness of the sail track flange, that's the grip length that you want. Three-quarters of an inch sounds about right. However, the wall thickness gradually gets thinner as you go up the mast, so as you go along, you may need shorter rivets. The only way to gauge is to do some thickness measurements as you go and purchase rivets of various lengths accordingly.

As for the wire harness, your idea of using a conduit does not seem too secure to me. On my boat, Corroboree, it's original mast (we're on the second one) was fitted with a 1/8" dia. 1x19 stainless steel wire harness that was dead-ended near the top and bottom of the mast. That is, there was an eye with a thimble at each end and clamped with a Nicro-press clamp. The electric wires, including the VHF coax, were cable-tied to this wire harness, each set of wires allowed to terminate where they will, for example 3 wires exit at the steaming light/deck light. Also, the lower ends of the wires had enough slack and extra length in them to get them through the boat to the bus bar inside the boat. The stainless wire was through-bolted to the mast at each end--near the top below the masthead fitting, and near the bottom above the mast heel fitting. The length of the wire harness was perfect dimension so that when bolted into place, it was just tight enough so as to not sag inside the mast, yet is was flexible enough to bend as the mast bent. This harness was also oriented in the mast to be clear of the halyard exits, so I believe it was located in the forward third of the mast circumference.

I say that this was in Corroboree's first mast. That one, as well as the boat itself, were in a fire in 1995 and the mast and deck of the boat were badly damaged. Insurance paid for rebuilding the deck, including new deck hardware, repainting the boat, and making a new mast. However, the first mast was outfitted by Hall Spars who knew what they were doing, and the second mast was fitted out by someone else in Michigan, where the boat was who did not know entirely what they were doing. Whoever transferred the old mast hardware from the old mast to the new mast forgot about the wiring harness. As a result, all the wires are loose inside the mast, and have been that way for 20 years. When I bought the boat two and a half years ago, I did not appreciate the fact that the wires, being loose, makes for a rather disturbing wire slap-slap-slap noise when sailing and when in a rolling anchorage. It's quite nerve-wracking the first time you sleep through it, but you learn to ignore it after a while. It has been doing that for 20 years now without too much ill effect, so I am not too worried. However, the next time I have the mast down--and I don't know when that will be--I will rig up a new stainless steel wire harness as described above so that I can quiet the mast wires.

I hope that helps.


Eric Sponberg
Eric W. Sponberg
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SY Corroboree
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Re: Mast wiring conduit

Postby Camino » Thu May 18, 2017 8:56 pm

Hi - I have the F35 so not quite sure with your 33 -question is respectfully why do you want to install a conduit? Pretty intensive that - if the answer is to avoid cable rattle inside the mast- easy fix is to add cable ties with ends proud (not cut) every 12"-18" of cable being dropped down the mast. Cables will be quiet in the mast. I realize you described that already occurring. The cable ties should be long and thick - acting like shock absorbers inside the mast.
Tom and Stephanie
Good Way II F 35 (P)
1999. Wing Keel 5’
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Emery Cove, CA
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Re: Mast wiring conduit

Postby andygc » Fri May 19, 2017 6:13 am

My F30 CK had its masts down for a road move late last year. It has the standard wishbone rig, so no track and no rivets. One mast is original, one a replacement made by Carbospars in the UK. The replacement has a plastic conduit, but it is not riveted. The masts were last down in 1999. The cables in the original mast were run through foam insulation used for lagging copper pipe. Most of it was perfectly fit to be reused and there was no significant amount of dust at the foot of the mast. I re-used the old stuff, added a few metres of new, and I'm sure that'll last for at least another 17 years.
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Re: Mast wiring conduit

Postby mike cunningham » Fri May 19, 2017 12:11 pm

Sort of piling on this topic but, for what it's worth, I have had the mast down twice in the past year to rewire the whole thing and to fix a mistake I made during said rewiring. I found the use of cable ties to have worked out extremely well over 5000 miles of sailing. I was worried there would be some interference with halyards but that has not been the case at all and there is no mast slap.

The mistake was a poor effort to use a single cable to supply the masthead and the steaming/deck light which I installed about two feet above the jib/spinnaker sheave box.
The steaming/deck light wiring failed soon after I got the mast back up due to poor measurements and workmanship on my part.

The second time I had the mast down I ran a completely separate cable for the steaming/deck light and used a second set of ties to secure it in the mast. All has been well with the new install. I did use a stress relief line for this new cable.

I would also like to point out a part which I found extremely worthwhile in relieving strain on the main cable to the mast top. The original Freedom installation had the cable secured with a big wad of silicone and the wiring of the cable itself which was attached to the original steaming and anchor light. I replaced that light with a tricolor/strobe/anchor combo so I needed a new way to secure the wire at the masthead, not to mention the fact the original method was pretty flaky.

I used one of these. When you have cable inserted and pull on the bundle the webbing compresses and grips the cable.. very effectively! It is able to cinch up on multiple wires if you have more than one to run. I attached the threaded end to the mast cap plate. It was bit of a PIA to get everything run properly in the tight confines of the mast cap but, in the end it worked out great. It is probably not as effective as the stainless wire suggested by another poster but it is fairly simple and carries the weight of the wiring without damaging it. I took a look at the bundle (which includes wind transducer, power and LMR 400 coax cables) when I had the mast down the second time and all looked in excellent condition after many sea miles. ... ain+relief
Mike Cunningham
Freedom 30 (Mull) Hull #3
Build date...June, 1986 . Freedom Yachts USA, sloop, shoal keel
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Re: Mast wiring conduit

Postby midnightsailor » Fri May 19, 2017 10:27 pm

Thanks to all for your input and suggestions. I was consiidering a conduit because i wasnt happy with the way the wires are secured on my mast, though I have to admit I havent had any trouble and I believe its been secured in its method for probably as long as the masts have been in the boat ,1982. I was hoping to improve things . The wire bundle is secured at the crane head by a metal strap clamped over the wires and the exterior top of the mast head crane. It just seemed like a lot of weight and starin on the wires and a poptenial for abrasion and possible shorting, The strap is directly on the wire insulation ,, perhaps all i really need to do is add some extra insulation or chafe protection between the strap and the wire bundle.
Thjat sai , I do like the idea of the stainless cable secured at the top and bottom of the mast withthe wire bundle attached to that as Eric S. describes. Since I plan to perform the mast repair procedure that Eric S. shared and that sevral others have performed on their masts , and because I am adding a steaming /deck loight combo to my foremast, I wanted to go ahead and address and improve if possible the dangling rubeer hose covered wireing bundle. The simple and elegant wire tie wrap method to silence any banging may be how i go if I decide to stay with the current securing strap arrangement.
Im, sorry, no phots. I intended to post a number of photos i took to help illustrate what i have going on but after a number of attempts I have had no success. I seem to be running in to trouble with file size being to large. I recall having trouble trying to post photos in the past. It has always been one of my weaknessses, that is ,trying to figure out how to shrink and post photos. I will try to figure this out but for now ,no photos :(
1982 Freedom 33 Cat Ketch, Hull # 53, Standard Booms, deep keel ,tall rig
An armed man is a citizen, An unarmed man is a subject. George Washington
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Re: Mast wiring conduit

Postby SFBaysailor » Thu Apr 18, 2019 9:49 pm

Question for anyone with an older cat ketch: Where do the wires exit the mast? I’m not to that point yet, and I believe I only have a single anchor light up high, on top of the main mast. I’d like to put a vhf whip on each mast, one for radio and one for AIS, as well as a tricolor.

Is the baseplate drilled out? Does wiring require dropping the mast?

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Re: Mast wiring conduit

Postby Castaway » Tue Jun 04, 2019 6:17 pm

Jeff asks:-
Question for anyone with an older cat ketch: Where do the wires exit the mast? I’m not to that point yet, and I believe I only have a single anchor light up high, on top of the main mast. I’d like to put a vhf whip on each mast, one for radio and one for AIS, as well as a tricolor.

Is the baseplate drilled out? Does wiring require dropping the mast?

On Castaway, the wires from the main mast exit through a hole in the base within the mast collar, which also drains any rain/condensation, and run through the under-berth locker. On the mizzen, although there is a similar hole, they exit through a small hole in the mast about 1m above the base, then run outside the mast (but within the covering headliner fabric) and under the floorboards.

Technically, one might be able to drop a moused line from the masthead and through the hole, but you would be lucky to retrieve it through the 3cm drain hole, which is not easily accessible from below. The only practical solution is to drop the mast, but it pays to leave a spare line as a pull through for future use.

If you do lower the mast, it also makes it easy to apply cable ties or sponges to the cable bundle, which prevents insanity due to mast-slap at night.

Gerald Freshwater,
s/y 'Castaway', (UK F35 cat ketch, centreboard, 1987)
Lerwick Boating Club
Shetland Isles, Scotland
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