|Topic Review (Newest First)|
|01-15-2012 10:45 PM|
|obelisk||project completed without making a hole as originally proposed|
|01-15-2012 09:50 PM|
Stress concentration is one thing, but a hole as large as proposed may actually cause the mast to buckle at the hole, a very different sort of failure.
Gary H. Lucas
|01-15-2012 08:40 PM|
Originally Posted by Bene505 View Post
|01-15-2012 10:39 AM|
Your abilities amaze me. 8 hours aloft shows a lot of endurance and fortitude, as does the local research you did leading up to that day. Congratulations!
|01-15-2012 09:43 AM|
|01-15-2012 09:23 AM|
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.
|01-11-2012 08:26 PM|
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.
|01-11-2012 04:46 PM|
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.
|01-11-2012 03:54 PM|
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?
|01-05-2012 12:40 PM|
Maybe inlarge the hole slightly, round the eges and install a grommet to reduce chafe.
If you need to cut a slot in the grommet to intall around the cable- the grommet should still work.
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