Mast Conduit - Best Practice?

[Wotname]

What is the best practice for mast conduit?

Foolishly I didn't fit a conduit during the recent big refit (7 yrs) but I will soon have an opportunity to pull the mast and do the job properly

At the moment I am thinking electrical conduit (PVC) "pop" riveted every foot or 18" or so and done in two sections - first up to steaming / deck light and second from there to mast head. Mast is Al.

Best rivets - sealed Al or SS with stems punched out? Size 1/8" or 3/16" or ??

Would Al tube be better?

Diameter about 1" ID?


Mast wiring is steaming and deck lights above spreaders with Anchor (LED) and strobe at masthead. VHF antenna also at masthead (with RG 213). Wiring exits mast about 9" above the deck step.

Any and all ideas welcome.

[jeremiason]

I made the same mistake with my first boat...

I suggest you select the bigestest conduit you can fit in the mast, without interfering with the internal halyards... The reason I say this is, someday you will have to fish a wire down the conduit and you will be sorry if you don't have enough room...

As fair as PVC pipe, it is commonly used in older masts without a built in wire race. Use a "T-Fitting" at the spreaders for the spreader lights wires...

Fair winds

[Wotname]

Ahh... forgot to add - no internal halyards; so right now I have supersized "conduit", the whole mast section itself . Of course the slapping around of the wiring (especially the coax) is annoying to say the least.

[sdowney717]

Consider using CPVC plastic piping. It is stronger and thinner walled. CPVC was made for hot water use.

[chala]

I used UPVC ( pressure water pipe) it is also lighter than electrical conduit. You have to consider the thermal expansion of plastic, the rivet may rip off. I made SS T brackets shaped to the curvature of the mast with a collar made SS to hold the pipe. You will find some SS pipe that fit nicely around the UPVC. I have steps on the mast and the bracket fit opposite some steps using SS 1/4 bolts.

[Wotname]

Originally Posted by chala

I used UPVC ( pressure water pipe) it is also lighter than electrical conduit. You have to consider the thermal expansion of plastic, the rivet may rip off. I made SS T brackets shaped to the curvature of the mast with a collar made SS to hold the pipe. You will find some SS pipe that fit nicely around the UPVC. I have steps on the mast and the bracket fit opposite some steps using SS 1/4 bolts.

Nice brackets! Is the inner part tapped or have nuts welded in place or ???

I wasn't expecting to have to go to the trouble / expense of making such brackets but appreciate how well they might work. Must be a bit weight though.

[sdowney717]

Then there is HDPE water pipe which you can get in larger sizes. And one solid line with no joints plus it bends

just to see for example this
HDPE Pipes

We used HDPE for water in the ground to an addition, It is nice pipe. Smooth walled and tough, not easy to crack or break. PVC will crack.

[Tristan]

What would you use for an external conduit on a wooden mast?. I've been thinking about copper tubing which I can also use as a ground/lightning connection.
I cannot access internal conduit anymore without ripping the mast apart. This is a metal boat.
T.

[chala]

Originally Posted by Wotname

Nice brackets! Is the inner part tapped or have nuts welded in place or ???

I wasn't expecting to have to go to the trouble / expense of making such brackets but appreciate how well they might work. Must be a bit weight though.

All 3 holes of the bracket are tapped ¼, less chance to brake the tap than 6mm, for easier installation the top is a bolt “duralac ed” bolted from the inside to become a stud the two other holes are used to bring the bracket in position with a string. The stud is tightened first, the string is removed and the other bolts bolted. Duralac used at bolt and contact point. Relatively not heavy 0.13 kg each, one every 4m. Steps 0.215kg each including bolts. As you can see the SS collar was constructed.

[Roy M]

I prefer several conduits. One to the lower spreaders to carry the radar, foredeck/steaming light, hailer horn, spreader lights, etc. One to the masthead to carry the masthead/anchor/strobe lights, instruments, VHF antenna, etc. And maybe a third for future use (I no longer think that I've reached the ultimate installation).

Bigger is better, at any rate. Use the lightest, thin-wall available. It doesn't need strength, only containment.

[Cheechako]

Pop riveted seem to work fine. Good advice on a larger one or two. I would use Aluminum unless you have a bare unpainted mast. Have you considered going internal on the halyards while your'e at it? On boats with double (fore and aft) masthead sheaves it's easy. That gets rid of another slapping noise!

[Wotname]

Thanks everyone for your ideas so far - keep them coming

Originally Posted by Cheechako

Pop riveted seem to work fine. Good advice on a larger one or two. I would use Aluminum unless you have a bare unpainted mast. Have you considered going internal on the halyards while your'e at it? On boats with double (fore and aft) masthead sheaves it's easy. That gets rid of another slapping noise!

Mast is bare (unpainted). No to the internal halyards, I had them before but I am a real KISS kinda guy and prefer externals. Besides I would have to totally rebuild the custom SS mast cap (doesn't have masthead sheaves). I can control any noise from the halyards but not the internal wiring .

As well as the internal noise, I know that the wiring is just working itself to an early failure - what was I thinking a few years back .......

[Cheechako]

"I would use Aluminum unless you have a bare unpainted mast. " Pop rivets that is! I would probably still use aluminum.
As noted above:Two holes at each pop rivet location. One dead center on the conduit location, and one to the side. Use a stiff bent wire like a coathanger on the side hole to pull the conduit up against the inner wall. Fill the extra hole with a pop rivet. Every 18" or even couple of feet should be adequate.

[chala]

Not to keen on riveting an electrical conduit because rivets protruding into the conduit could damage the electrical wiring. When under way there is still a fair amount of movement by the wiring inside the conduit. Also attention must be paid to the way the wiring hang from the top of the mast.

Originally Posted by Cheechako

Have you considered going internal on the halyards while your'e at it? On boats with double (fore and aft) masthead sheaves it's easy. That gets rid of another slapping noise!

And also do not contribute to the bowing of the mast like an external halyards will. Wotname the brackets could also made up, with care, of an aluminium angle or similar material, will save you the welding.

[Dsanduril]

I like to use glass-filled polyurethane u-bolts to secure the conduit to the mast:

McMaster Polyurethane U-Bolts

They take a bigger hole in the mast section, so some may not like that. With the mast laying on trestles, place the conduit on top/outside where you want it. Mark for the u-bolts and drill. Put the u-bolts over the conduit and into the holes. Glue the u-bolts to the conduit (your choice of glue). Roll the mast so the holes are now down. Pick up the whole mess and slide it inside the mast with the u-bolt legs toward the center. Once it is in the correct position roll the conduit so the u-bolts face toward the holes. It may take a little work with a coat hanger to get the bolts to come out the holes, but I've never found it that difficult. Snug up the nuts, then cut off the excess bolt. If you like you can put a little glue on the nuts to make sure they don't some undone.

Our current stick is 46', these have been in place for the last 12 years, and nothing has come adrift. The system is 100% plastic, the bolts are UV resistant, don't have to worry about corrosion except where moisture may get trapped against the mast by the conduit, which will be the same regardless of attachment method. The conduit is clear inside, no rivets, easy to fish. IIRC we put the bolts 5 or 6 feet on center.

Sorry don't have any pictures.