Jump to content


un-sticking a 2 piece Moth mast


  • Please log in to reply
18 replies to this topic

#1 pkilkenny

pkilkenny

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 141 posts

Posted 05 March 2012 - 02:39 PM

Hey Team,

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 tbd678

tbd678

    Newbie

  • Members
  • Pip
  • 6 posts
  • Location:United States

Posted 05 March 2012 - 03:21 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

#3 pkilkenny

pkilkenny

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 141 posts

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 skiffboy

skiffboy

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 956 posts
  • Location:here to wherever

Posted 05 March 2012 - 04:32 PM

Car and tree technique was used on my mast by previous owner with no ill effects. Each to their own I guess.

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 skiffboy

skiffboy

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 956 posts
  • Location:here to wherever

Posted 05 March 2012 - 04:35 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...

shit the bed! Thats going to take some tugging!

As the blisters build up just think - are you prepared to admit to the world you were beaten by mud...?

#6 Del Olsen

Del Olsen

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 89 posts
  • Location:SF Bay

Posted 05 March 2012 - 05:51 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,

#7 pkilkenny

pkilkenny

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 141 posts

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 Liquid

Liquid

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 2,271 posts
  • Location:Portland, OR area

Posted 05 March 2012 - 07:54 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...

#9 pkilkenny

pkilkenny

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 141 posts

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 mad

mad

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 13,116 posts

Posted 05 March 2012 - 08:15 PM

Small hole in the base with a fitting for an airline, watch where you aim it :D

#11 Phil S

Phil S

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 1,756 posts
  • Location:Sydney

Posted 05 March 2012 - 09:03 PM

I have had the same problem with a CST mast which seems to have a tighter fit sleave than the mach2. The shims method worked for me once but the second time it was too tight.

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 gui

gui

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 817 posts

Posted 05 March 2012 - 10:42 PM

I use a car and a tree on a regular basis. A couple of hose clamp and a bit of line. The load required to pull them apart is so tiny that your won't even notice when you pull with your car.

#13 Strayned

Strayned

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 432 posts
  • Location:Australia, Earth

Posted 06 March 2012 - 12:32 AM

Are you positive it is a 2 piece mast :P


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 pkilkenny

pkilkenny

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 141 posts

Posted 06 March 2012 - 01:44 AM

OK, its unstuck...

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 Bobby Lewis

Bobby Lewis

    Newbie

  • Members
  • Pip
  • 8 posts

Posted 06 March 2012 - 03:58 AM

Glad to hear you've succeeded.

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 punter

punter

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 1,473 posts

Posted 06 March 2012 - 04:38 AM

I had a mast base post stuck in the hull of my previous Mach 2. The only way to get it out was an inch thick metal bar through the mast base and 2 guys rotating it. It had basically glued itself to the boat. Wasn't too messy, but was the only option as the boat was off to the Oz worlds the next day and couldn't fit in the box otherwise. Since then use the Protect Tapes on the mast base post to prevent it re-occuring.

#17 fairdinkum

fairdinkum

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 429 posts
  • Location:Bermuda

Posted 07 March 2012 - 01:32 AM

Use a spanish windless next time.

#18 RobG

RobG

    Anarchist

  • Members
  • PipPipPipPipPipPipPip
  • 727 posts
  • Location:Brisbane, Australia

Posted 07 March 2012 - 02:54 AM

One method not mentioned is to repeatedly hit the spigot with a rubber mallet while pulling the ends apart. Worked well for me.

#19 i42

i42

    Newbie

  • Members
  • Pip
  • 4 posts

Posted 29 March 2012 - 02:34 AM

There is a goofy trick we use with windsurfing masts sometimes. It is slightly hard to describe. Essentially, you get a guy at either end of the mast and then they pull and wag the mast violently back and forth while pulling. Sometimes a third guy will actually grab the middle and bend the mast back and forth. This normally works pretty well at loosening them up too.




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users