un-sticking a 2 piece Moth mast
#1
Posted 05 March 2012 - 02:39 PM
My Moth mast is carbon, 2 piece, sealed at both ends and stuck together by sand in the seams. To separate the halves, I've tried:
- three men at each end turning in opposite directions while pulling.
- putting the mast between two coolers and using a feeler gauge and mid- mast compression to seperate the halves.
- standing the mast up and shaking.
- deploying harsh language and threats.
Nothing...
I don't want to assert one of the "Darwin Award" solutions like using a car and a tree as that looks like a 2K non-solution.
Someone out there, more clever than me, has the solution. Help...
Paul
#2
Posted 05 March 2012 - 03:21 PM
#3
Posted 05 March 2012 - 04:19 PM
Try using two windsurfer booms if you have them. They have a nice grippy clamp that's padded, and they give you enough leverage to twist the two halves apart. Just attach one boom to each side of the rig as if you were setting up a windsurfer and twist. Can also be done with one if you have a few people to help out
I tried two plumber's srip clamps with extensions on the handles (essentially the same idea) ut with no movement...
#4
Posted 05 March 2012 - 04:32 PM
I've only ever lashed a line around the base adn then to an innanimate object. Hold the top half tight and tug. It was the tugging that made it work, not a constant pull. Also, good advice I was once given was to take care how to lash onto the mast - I was originally using the main halyard from the masthead crane but it was pointed out that was a great way of tearing the thing out of the top of the stick. Thats why I now lash around the bottom of the tube.
Another good tip I got was to wash thoroughly after separating and grease up with vaseline - that should minimise the amount of grit getting into the join next time.
#5
Posted 05 March 2012 - 04:35 PM
shit the bed! Thats going to take some tugging!
Try using two windsurfer booms if you have them. They have a nice grippy clamp that's padded, and they give you enough leverage to twist the two halves apart. Just attach one boom to each side of the rig as if you were setting up a windsurfer and twist. Can also be done with one if you have a few people to help out
I tried two plumber's srip clamps with extensions on the handles (essentially the same idea) ut with no movement...
As the blisters build up just think - are you prepared to admit to the world you were beaten by mud...?
#6
Posted 05 March 2012 - 05:51 PM
Use a hair drier to warm the section of the mast that slides over the fixed sleve.
With some skill, patience and luck you can thermally expand the outer section enough without expanding the sleve at the same time.
All it takes is a fwe thousandths .
I seem to recall moth mast sleves are carbon so expansion rates should be OK, if it's alloy, all bets are off.
Good luck,
#7
Posted 05 March 2012 - 06:10 PM
Have you tried heat?
Use a hair drier to warm the section of the mast that slides over the fixed sleve.
With some skill, patience and luck you can thermally expand the outer section enough without expanding the sleve at the same time.
All it takes is a fwe thousandths .
I seem to recall moth mast sleves are carbon so expansion rates should be OK, if it's alloy, all bets are off.
Good luck,
Hmm, I thought carbon fiber's coefficient for thermal expansion was something like .0000001 J/mol? Nonetheless, given that it's you Del (the great paragon of truth and wisdom in all things dinghy related) i'll give it a try.
Thank you,
PK
#8
Posted 05 March 2012 - 07:54 PM
#9
Posted 05 March 2012 - 08:07 PM
Put the mast between 2 elevated objects - base and tip, wd40 or mclube the connection, then push/bend the mast down at the connection, twist 90 degrees, repeat bending. You're effectively trying to crush the sand into smaller particles. Then the twisting and tugging. It's worked for me at the windsurf park...
Thank you, i'll give this a try as well.
PK
#10
Posted 05 March 2012 - 08:15 PM
#11
Posted 05 March 2012 - 09:03 PM
Avoid using the car because: 1, you will over load the clutch or auto transmission at high load and no forward motion. And 2, if it does work the half of the spar attached to the car by rope will spear through the back of the car as the tension is released suddenly.
My successful method is the same used when trying to get home made carbon tubes off mandrels: Use two trees and lots of rope and tackles. Like a vang system multiplied by 4 or 8. You need sturdy rope, good blocks and good knots. I tied the biggest ropes with rolling hitches below the hounds fitting and above a temporary bolt through the goosneck hole. Set the rope tackle up tight and stretch it as hard as possible before starting to use the 200/1 takle tail. You will break any ropes not up to the job, but when it starts to move be carefull not to spear the mast halves through any cars, houses or people. They go a long way when they let go. Whatch where you are aiming, choose appropriate trees.
Heat or cold does not work with carbon/epoxy, the thermal co-ef is almost zero.
#12
Posted 05 March 2012 - 10:42 PM
#13
Posted 06 March 2012 - 12:32 AM
If it is, try to "push" the outer section rather than pull the inner section, if you can get something on the edge to tap it.
#14
Posted 06 March 2012 - 01:44 AM
I filled the mast with mineral water/ tap water via the boom holes at the base; left the mast standing so the ferrel junctions were submerged; emptied the mast and tied the base to a tree with several clovis hitches; clovis hitched the mast top section to my car trailer hitch with every extra block I own and pulled, really,REALLY hard.
I compare the euphoria at hearing the "thuuunnnk" as the sections separated to registering for the first time, the cries of my child at her birth (at times I think dinghy sailing is stealing my sanity).
Truly appreciate all the help.
PK
#15
Posted 06 March 2012 - 03:58 AM
Next time if you want to try something not quite so mechanical that has worked for me several times was to use the formula F=MA (pre-accounting studies). This translated into a a really non stretchy piece of rope with a rolling hitch around the fat end of the mast and then tied to an immovable object like a house. Hold with the rope slack and then yank it so the rope goes taught. The deceleration is so great that the force is pretty good and has worked so far - oh and wear leather gloves.
Bob
#16
Posted 06 March 2012 - 04:38 AM
#17
Posted 07 March 2012 - 01:32 AM
#18
Posted 07 March 2012 - 02:54 AM
#19
Posted 29 March 2012 - 02:34 AM
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