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Old 21-10-2009, 21:40   #1
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Need a Larger Conduit in My Mast

I don't have enough room in the conduit that runs up my mast and want to install a larger one. I can't tell exactly how the existing one is fastened to the interior of the Mast but I do see rivets on the outside of the Mast from top to bottom. If removed I can't see how I could possibly hold/place/position the new larger conduit to reinstall rivets at the same location and so .....
I'd like your opinion on my idea for replacement/enlargement. Also any other ideas would be great.

I figure I would tie a line to a knife (see attached blade style) and pull it up the existing conduit to put a slice in the inboard face of the existing conduit.
Then I would spread the existing conduit open and take my new larger conduit (suggestions for light weight conduit welcome) and pull it up inside the old one. This should hold the new one in place. I think it sounds simple but will likely take some work at every step. I do think it's doable through. I will have to try and control the blade position so it stays on the inward face of the existing conduit and doesn't swing/move around to the adjacent mast wall.
If the knife can't cut it perhaps I can get an old wood burning set and make a custom end for it which I would pull through the conduit using it to melt a slot into the existing plastic conduit.
I have one more silly idea which would be to try to route a solid core insulated wire up the inside of the existing conduit, out the top and then back down the outside of the existing conduit (all this is within the mast which is on saw horses). I would then have to find a way to strip the insulation off 4" + - where it doubles back over the top (perhaps have it pre-striped). Once both ends of the wire were out the bottom of the mast, I would hook a battery to the wire so that it gets hot and I would pull the hot wire through the conduit.
Once slotted I would preheat the existing conduit (hair dryer) so that it spreads easily. I'm also thinking I would use liberal amounts of lubricant (the type used to help pull electrical wire through conduit).

What do you think?
Will it work?
Any other ideas?

If you think I'm retarded, that's okay too.

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Old 22-10-2009, 01:09   #2
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Your mast is on horses now?
You can see your conduit?

I think you have some novel solutions....
If the conduit is PVC pipe, it may be difficult to cut.....the hot wire trick sounds do-able but I wonder how long it would take and if it will stick back about a flexible abrasive in the Rambo knife has in the tie a string on both ends then back and forth...if you can get that in and out of the conduit like the hot wire idea...not sure if you'll be able to keep your line straight.
I'm not sure that once the conduit is split you would be able to spring it enough to get another one inside.
May want to find out how they put the conduit in to start with…that may tell you how to reinstall it and get the holes to line up… many places is it fastened?

S/V Arctic Lady
I love my boat, I can't afford not to!
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Old 22-10-2009, 01:37   #3
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If the mast is off the boat, it shouldn't be too hard to replace the conduit. Each rivet should hold the conduit in place well enough so you can drill and fit the next rivet.

If you're trying to do this with the mast standing... good luck.
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Old 22-10-2009, 03:38   #4
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Originally Posted by 44'cruisingcat View Post
If the mast is off the boat, it shouldn't be too hard to replace the conduit. Each rivet should hold the conduit in place well enough so you can drill and fit the next rivet.
If you're trying to do this with the mast standing... good luck.
Don Casey has a description of this painfully finicky procedure, on pages 100 through 102, in his book “This Old Boat”

Beginning here:
This Old Boat - Google Books

roveri & others also have some advice, here
Banging noise inside of mast?

Originally Posted by roverhi View Post
Many mast manufacturers ran conduit attached to the mast via pop rivets. Typically they drilled pairs of holes up the mast. One was used for to pop rivet the conduit, the other was for a piece of wire/rod to hold the conduit temporarily in place while it was riveted. After the conduit was riveted, they usually put a pop rivet in the unused puka for appearance sake. Look for these rivets. If there, it's probably the conduit flopping about because it's broken loose from the rivets.
Peter O.
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Old 23-10-2009, 13:46   #5
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There must be many ways but this is the one I know:

remove cables and wires. Drill out the rivets and remove conduit. Take very thin steel or monel wire and fold it double and insert it through the rivet-holes, pushing it in so that a loop forms on the inside. Turn the mast so that the conduit can go in at the lowest point. One handles the conduit while another check if it passes through every loop, pulling the conduit in place at every loop (leaving the wire in). When the conduit is in, pull the all the wires tight and drill the first hole using a smaller drill bit so that the wire stays intact and you can pull it while drilling. Follow up with the right size drill bit which might break the wire but hopefull you get the hole in the PVC anyway (it works). Put the aluminium rivet in.

You can test with the first one because you can stabalize the conduit by hand. Some try to get all the wire out but I see the ends cut at the rivets on my Forespar masts.

check all the wiring before pulling it in again.

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