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Go Back   SailNet Community > On Board > Gear & Maintenance
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  #11  
Old 01-04-2012
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Damn it, there is no way on this earth I would drill anything in there that I did not have to. It hasn't cracked so far. Just leave it. Make best use of what you have.
If you drill a slot, your buckling resistance will drop as the mast finds itself with a new freedom to fold. It may not crack, but cracking is not the only way it can fail.

Squirt WD40 around those hole edges regularly to help fight corrosion.

Please leave it the way it is.

Please.

Last edited by Rockter; 01-04-2012 at 09:54 PM.
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  #12  
Old 01-04-2012
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No way I'd combine them. Maybe after talking with a spar experts, but I'd want several separate opinions at least. And I'd want to know that they did some math on the loading at that location of the mast in the conditions I might even remotely find myself in. I figure they build masts to be a light as reasonable possibly given the stresses they can have. If you could drill big holes, then they greatly overbuilt the mast, which is unlikely.

Imagine the difference in small versus large holes if you needed 400 square inches of "hole". You could make one big 22" diameter hole that stretched all the way around the mast. Or you could drill 100 2" holes in random locations. The 2" holes would weaken the mast, but the 22" hole would bring down the mast in a slight breeze.

Put another way, look at a steel truss and notice the "holes" between the members. Bigger holes mean thicker members - a thicker mast would be needed. The aluminum between the existing holes are acting like the holes in a truss. IMHO, bigger holes are very bad.



Regards,
Brad
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Last edited by Bene505; 01-04-2012 at 10:10 PM.
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  #13  
Old 01-04-2012
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the problem is that the bends in the wire create horrible wear on the wire sheaths. what brought me to this point was a VHF problem--I came to find out that the mast had worn all the way through the coax RG-213 cover, wire mesh and dielectric and the main wire was exposed.

while i'm at it, everything is getting rewired and i don't want to have to revisit this problem again any time soon. The existing holes are between 3/8" and 9/16". with a wall thickness of 1/4" or 5/16" on the mast extrusion, it necessarily creates VERY sharp bends in the cable.

the wires do run up through a dedicated race but they are loose in there. to this point i have had no problems father up the mast but i guess we'll see once i pull some new wires through and check for chafe points.

any way to lessen the angle here would help. maybe just enlarge the holes?
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Old 01-04-2012
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The coax is the stiffest. Maybe file just that hole a little, slotting and angling the hole the way it needs to go.
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Old 01-05-2012
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Maybe inlarge the hole slightly, round the eges and install a grommet to reduce chafe.
Grommets:
http://www.mcmaster.com/#push-in-grommets/=fob04s

If you need to cut a slot in the grommet to intall around the cable- the grommet should still work.

Last edited by casey1999; 01-05-2012 at 11:43 AM.
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Old 01-11-2012
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Thanks for the replies.

After a bit more examination and many, many hours of fishing wire spaghetti out of those holes in the mast I have uncovered another problem. It seems that the aluminum tube inside the mast has come unfastened from the pop rivets that secured it to the mast extrusion and slid down the mast. the only thing supporting it, or at least the bottom section, is the drip loops in the wiring. That weight and abrasion from the bottom lip of the pipe has chewed through the wire jackets and almost entirely through my VHF coax cable, which bore the brunt of the weight.

I have put a call in to Eric Pearson who has taken over Hood mast legacy systems but would like to get some opinions while I wait for an answer.

How would I go about refastening the extrusion without unstepping the mast? I am in Chile and the facilities are limited. Another problem is that the old rivets wallowed out larger holes while pulling their way out and the largest pop rivets I can find here are 3/16". I'm stumped. It seems the tube has separated in at least one place and is floating separately. Even if i can resecure the sections to the mast, aligning and reconnecting the tube sections into one could prove impossible.

Any suggestions? Anyone attempted or experienced anything similar?

Thanks.
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Old 01-11-2012
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WOW looks scary. I was never a big fan of rivets. But getting a screw in there may prove difficult.

If I was to design a mast I would have all electrical wiring in a rigid poly tube fastened to the inside with enough diameter for all wiring, and attacted to the mast at the through hole with a bulkhead permanently welded and made of the same material as the mast.

For a repair I would stick with what you got. After all it lasted how many years already? Rounding the holes should remove little material, and greatly reduce chaffing. A small sleeve with the ID equal to the rivets OD should hold a non structural rivet.
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Old 01-11-2012
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do it once, do it right

Checked out all the time and expense you have gone to so far. A vessel of this size and caliber deserves to have the work done right. You're covering a lot miles and territory and don't need a greater, unexpected failure due to half ass repairs to your spar. My opinion is find a suitable place to pull the mast and do it right. If not a club or marina, maybe a mobile or barge based crane, friendly cargo ship with crane, etc.
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  #19  
Old 01-15-2012
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update

after spending 8 hours in the bosun's chair yesterday, i have managed to completely rewire my mast. I began thinking about rugosa's post and I do want to do it right but after talking to some folks about unstepping the mast here, i was less and less keen on the idea. the BEST solution i could find was a guy whose friend works at the commercial port here. he said that if i went and anchored off the costanera, i could wait for a ship to leave and that would give about a 2-hour window to unstep with the crane. aside from being rushed, there was nowhere to put the mast afterward--it would have to be lashed to a boat trailer and hauled down the road to my contact's back yard for service. the idea of hauling a 70' mast horizontally down Chilean roads was too scary. the reverse applied to restepping. other solutions got REALLY frightening. also, none of the ,marinas here were capable/willing.

I have been planning to unstep the mast and replace the furler in New Zealand anyway, so i decided to fix the problem until then (maybe one year off) and go from there. Buty once I got into the project it went smoother than anticipated. I was able to raise the tube and secure it at the top with some pop rivets and I proceeded down from there. It took a long time but was not as difficult as anticipated. I used my hook and probe set to hold the aluminum tube from the spare hole while I riveted the other hole.

once in pl;ace, fishing the wires through was no problem and took a very short while. only problem there was that yesterday was when all the fishing boats returned from their trips and they do not slow down for someone up the mast.

in all, a much better short-term fix than running wires up with the halyards but i will still remove and replace the tube when we reach NZ. thanks for all the comments.
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Old 01-15-2012
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Mission accomplished!
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