Installing a Conduit in an Aluminum Mast

[SabreKai]

My mast is old style, and has no conduit as part of the extrusion. I want to put an electrical conduit in but have no idea how to secure it in place. Anyone done this? If so, how did you secure the conduit to the inside of the mast, some 40 feet of pipe with no way to work on it except from the outside?


Sabre

[David M]

Why do you want an electrical conduit inside your mast? Sailors have been getting by just fine without it. No sense in reinventing what has worked for a long time.

[Beausoleil]

Use 1" or 1-1/4" PVC pipe riveted every couple feet or so along the forward face of the mast. Since it's not really load-bearing, you can use aluminum rivets. Make sure you cut the pipe in two near the location of your steaming and fore-deck lights so the wiring can exit easily. My Selden mast came that way from the factory.

It's best to do it with the mast off the boat and on some stands/saw-horses. Start at one end of the mast and drill and rivet that end. Run a messenger line (or better yet, a wire) through the conduit and draw it tight to center the conduit, then slowly work your way from the anchored end, drilling and riveting one hole at a time so the conduit doesn't move much off center. You'll have to take care, slowly drilling through the aluminum, then even more slowly through the PVC. You'll have better luck if the holes are somewhat closely spaced - the conduit won't be able to move very much as you drill... Make sure you knock out all the rivet mandrel heads as you go...

[DeepFrz]

http://www.cruisersforum.com/forums/...ast-32227.html
This thread has some ideas and links that you may find helpful.

[SabreKai]

Originally Posted by David M

Why do you want an electrical conduit inside your mast? Sailors have been getting by just fine without it. No sense in reinventing what has worked for a long time.

Neatness, and to prevent all the wires banging around. I have 4 internal halliards, two sets of spreaders and a staysail stay fitting all bolted onto the mast with various long and nasty bolts. Putting the wires through bundled with wire ties would work if I could get them past the spreader mounts and the staysail fitting but I'm worried about them possibly binding the halliards.

One problem I have is that the mast cap is welded in place, so there is no way to work on the conduit from the top end. Any conduit at the 12 oclock position would terminate in the middle of the two fore halliard sheeves and be a real pain to wiggle the wires past. So the conduit would have to be at the 0130 or 1030 position in order to get the wires past the sheeves but not so far over to the side as to run into interferance from the spreader mounts.

Sabre

[cwyckham]

One idea from a local rigger: drill two holes. One for the rivet and one for the wire hook to hold the conduit in place for drilling and riveting. Than plug the extra hole with a rivet.

[SabreKai]

He he, I can see where this isn't going to be a very fun experience. I think the first thing I'm going to do is give the mast a proctological and see whats up there. I should be able to stuff a small video camera up there on a long pvc conduit and see where all the nuts n bolts are and what sort of mess I have to deal with.

Sabre

[boden36]

We have our conduit (made from folded alloy sheet) screwed to the outside of our mast. Unobtrusive and very easy to get to the wires if you need to add or repair something.
Regards,
Richard.

[svadagio]

Added a conduit to my mizzen. Really not hard. Start by laying the mast down on saw horses etc. Make up your conduit and add pipe holders. These are little brackets that are intended to hold pipe to walls etc. Get the alloy ones. They must be rigid. Not able to move on the conduit. Bend them if needed to fit. Now lay the conduit along the mast with the holes in the pipe holders against the mast. You will need to turn the conduit over to do this. This lines the holes up the way they will be when inside the mast. Drill the holes for the pop rivets. Slide the conduit inside the mast and line up the first hole near the bottom where you can see. Pop rivet. Turn the mast so the conduit lays in the bottom and the holes line up. Use a drift to help line up. Pop rivet. Done. Easier done than said.

Advantage, no pop rivets inside the mast to hang up the wire going in.

Bob

[skipmac]

Originally Posted by svadagio

Added a conduit to my mizzen. Really not hard. Start by laying the mast down on saw horses etc. Make up your conduit and add pipe holders. These are little brackets that are intended to hold pipe to walls etc. Get the alloy ones. They must be rigid. Not able to move on the conduit. Bend them if needed to fit. Now lay the conduit along the mast with the holes in the pipe holders against the mast. You will need to turn the conduit over to do this. This lines the holes up the way they will be when inside the mast. Drill the holes for the pop rivets. Slide the conduit inside the mast and line up the first hole near the bottom where you can see. Pop rivet. Turn the mast so the conduit lays in the bottom and the holes line up. Use a drift to help line up. Pop rivet. Done. Easier done than said.

Advantage, no pop rivets inside the mast to hang up the wire going in.

Bob

Hi Bob,

Am familiar with several types of pipe holders but none that sound like what you describe. Can you post a photo or a link to an online source?

Thanks
Skip

[allanpeda]

Originally Posted by skipmac

Hi Bob,

Am familiar with several types of pipe holders but none that sound like what you describe. Can you post a photo or a link to an online source?

Thanks
Skip

I resist jumping into the fray, but unless metal is a necessity for strength, I'd fasten plastic conduit with plastic clamps and avoid the possibility of galvanic action. Maybe the OP speaks of this? Edit: they come in other sizes, I just picked one.

[svadagio]

Hi
The ones I used are the ones that look kind of like a bent J. A loop to go over the pipe with a tab to pop rivet to the mast. Pop rivet on one side only. I thinnk the plastic ones are too weak. The steal ones will rust. The alloy ones worked for me. Try Home depot. I am in Honduras right now and do not have the ability to post pictures. Sorry.
Bob

[Chasing Summer]

I also have an "old school" mast ... 48 feet. It had a 1" rivited conduit in it. Really??? rivets and wires???? So, I drilled out all the rivets and trashed the conduit. I got new gray pvc electrical conduit: 1/2 for wiring to the masthead, 3/4 for coax, & 1/2 to the spreaders. As I glued them together I ran a bead of Sikaflex 291 along the conduit printing. I also ran 3/8" rebar inside for weight. When I got the conduit where I wanted it I rotated the printing down, worked it back and forth a bit, and let it cure. No rivets and that stuff ain't goin' anywhere. :-)
Just my opinion: several smaller is better than one large one.

[Orion Jim]

Originally Posted by Chasing Summer

I also have an "old school" mast ... 48 feet. It had a 1" rivited conduit in it. Really??? rivets and wires???? So, I drilled out all the rivets and trashed the conduit. I got new gray pvc electrical conduit: 1/2 for wiring to the masthead, 3/4 for coax, & 1/2 to the spreaders. As I glued them together I ran a bead of Sikaflex 291 along the conduit printing. I also ran 3/8" rebar inside for weight. When I got the conduit where I wanted it I rotated the printing down, worked it back and forth a bit, and let it cure. No rivets and that stuff ain't goin' anywhere. :-)
Just my opinion: several smaller is better than one large one.

Very resourceful

[roverhi]

Originally Posted by cwyckham

One idea from a local rigger: drill two holes. One for the rivet and one for the wire hook to hold the conduit in place for drilling and riveting. Than plug the extra hole with a rivet.

Did that with mine. Used schedule 20 1" PVC irrigation pipe in two sections. Ran messenger lines inside the pipes. Made a hook out of some stiff welding rod, predrilled holes in line up the mast, inserted the hooked rod into the holes and pulled the conduit up against the mast, drilled holes into the conduit and pop riveted the conduit in place with structural aluminum rivets. The two sections of the conduit, one above the spreaders and the other below allowed me to fish out the wires at the spreader through the largish bolt holes from the lower shroud tangs. Had the advantage of a removable mast head cap so had the extrusion open at both ends. Without that would have had to remove the masthead sheaves to get access to the messenger wires. Took much of a day to install the conduits, pull the wires and install the lights, Windspeed wand, etc. Mast was on saw horses. Wouldn't think of doing it any other way. Used a pneumatic pop rivet gun which made doing the rivets just a matter of pulling the trigger. Installing structural aluminum pop rivets with a hand riveter just isn't in my Pop Eye forearms.