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Sleeving broken ali mast #218749
09/02/10 03:55 AM
09/02/10 03:55 AM
Joined: May 2006
Posts: 1,382
Kingston SE South Australia
JeffS Offline OP
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JeffS  Offline OP
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Kingston SE South Australia
G'day I've picked up a Aluminium Taipan 5.7 mast thats broken about 3ft from the base and I want to repair it as a spare to keep at the club. I have mast section to sleeve it with and I have cut the twisted pieces of. My plan is to put a new section on the base then internal sleeve followed by an external sleeve to be welded.
My question is what length would be right for the internal sleeve?
What length for the external sleeve?


Jeff Southall
Current boats
Nacra 5.8 1703 Animal Scanning Services
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
-- Have You Seen This? --
Re: Sleeving broken ali mast [Re: JeffS] #218895
09/06/10 11:53 AM
09/06/10 11:53 AM
Joined: Aug 2007
Posts: 190
lesburn1 Offline
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lesburn1  Offline
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Hi Jeff, I know it's against the rules, but I make a sleeve out of glass and carbon fiber, then cut the parts to be connected straight, then epoxy the sleeve in place.
( first dry fit everything and make some jigs to hold the mast in alignment) Once the sleeve is done I prep the outside of the joint and tape up the mast track with "flash tape" ( http://avtcomposites.com/order.php3?i=91 ) not (http://www.herroom.com/braza-1009-flash-tape.shtml ) and vacuum bag on a few (5+) layers of carbon.
I have done this more then a few time and never had a problem. (yet!!)


Best of luck.
les


lesburn1.blogspot.com

A-Cat USA 49
18Sq 49

member- Royal Society for Making Cool Stuff
Re: Sleeving broken ali mast [Re: lesburn1] #218902
09/06/10 03:30 PM
09/06/10 03:30 PM
Joined: May 2006
Posts: 1,382
Kingston SE South Australia
JeffS Offline OP
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JeffS  Offline OP
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Thanks for your reply, I've already got the ali parts to sleeve it but using resin to put it together is a new idea to me and appeals to me more than welding. Could I use vinyl ester to glue the sleeves in place? How long are the sleeves you use?


Jeff Southall
Current boats
Nacra 5.8 1703 Animal Scanning Services
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
Re: Sleeving broken ali mast [Re: JeffS] #218904
09/06/10 08:57 PM
09/06/10 08:57 PM
Joined: Aug 2007
Posts: 190
lesburn1 Offline
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I would use epoxy (not five min.) and you should sand off any anodizing and use a surface prep. ie. acid wash.
If you weld you will lose a lot of the strength in the mast.
The sleeve I have used are about ten inches long.


lesburn1.blogspot.com

A-Cat USA 49
18Sq 49

member- Royal Society for Making Cool Stuff
Re: Sleeving broken ali mast [Re: lesburn1] #218913
09/07/10 08:33 AM
09/07/10 08:33 AM
Joined: Jun 2001
Posts: 778
Houston
carlbohannon Offline
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Houston
Originally Posted by lesburn1
I would use epoxy (not five min.) and you should sand off any anodizing and use a surface prep. ie. acid wash.
If you weld you will lose a lot of the strength in the mast.
The sleeve I have used are about ten inches long.


I agree. I would not weld a mast unless the builder agreed.

Keep in mind there is a lot of compression load on the mast at this point. Make sure the external splice to mast joints are square. The parts will be pressing against each other with 100's to 1000's of lbs of force.

I once saw a 18 square mast with a splice like you are talking about. The splice kept breaking so the owner kept beefing up the splice. Finally he had a 3 ft internal splice and it held. I looked at it a couple of years later and the metal at the splice had deformed where it was pressing.

Re: Sleeving broken ali mast [Re: carlbohannon] #218951
09/07/10 05:34 PM
09/07/10 05:34 PM
Joined: Jul 2001
Posts: 1,197
Vancouver, BC
Tornado Offline
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Vancouver, BC
Never weld alloy...it will take the stength down about 2/3rd's that of the original tempered material.

My first T boat I sailed on when I was a kid had a spliced mast. Dad put it together from two damaged sections laying around the SailCraft of Canada factory.

Had an internal sleeve section and an array of large (1/4"?) Monel rivets. That beast held together for decades. I believe the splice was beteween the hounds & spreaders.
Had to keep a low profile/avert eyes/ whistle/etc. at a class meeting during the CORK regatta as a teenager one summer when they starting talking about a vote to ban "compound" masts that top guys were experimenting with to design in differenential flex charactistics between top & bottom sections...


Mike Dobbs
Tornado CAN 99 "Full Tilt"
Re: Sleeving broken ali mast [Re: Tornado] #218966
09/08/10 02:03 AM
09/08/10 02:03 AM
Joined: May 2006
Posts: 1,382
Kingston SE South Australia
JeffS Offline OP
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JeffS  Offline OP
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Thanks for the info guys it sounds like epoxy is the go as it will spread the compression load if it adheres to the ali all the way up inside and out.
regards


Jeff Southall
Current boats
Nacra 5.8 1703 Animal Scanning Services
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
Re: Sleeving broken ali mast [Re: JeffS] #218970
09/08/10 04:38 AM
09/08/10 04:38 AM
Joined: Aug 2007
Posts: 142
3 weeks Newman WA 1 week Robe ...
Brian P Offline
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Brian P  Offline
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3 weeks Newman WA 1 week Robe ...
jeff, i have sleeved plenty of masts before, always an internal sleeve 600mm to 1000mm. using about a dozen 3/16 inch stainless rivets was enough. using some epoxy glue to take up any voids. never had to use external sleeve or to use cloth on it. i have heard of carbon going straight on to alloy and the alloy is completely eaten out in about 6 months. but make sure you cut the existing bits with a drop saw or similar so that the both ends are perfect.
cheers.


Brian Partridge
STINGRAY 580 "Fantasia"
A Class 585 "FHARKEN A"


YOU CAN'T POLISH A TURD
BUT YOU CAN ROLL IT IN GLITTER!!!!!
Re: Sleeving broken ali mast [Re: Brian P] #218973
09/08/10 06:06 AM
09/08/10 06:06 AM
Joined: May 2006
Posts: 1,382
Kingston SE South Australia
JeffS Offline OP
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JeffS  Offline OP
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Kingston SE South Australia
Thanks Brian, I've trimmed the ends perfect with my drop saw. The Taipan section has irregular reinforcing inside and its really a bitch to sleeve. I have to make a fore and aft sleeve to slide in seperately. Then there are 3 thicker wall areas on the section so I cant really slide a neat outer wall on.


Jeff Southall
Current boats
Nacra 5.8 1703 Animal Scanning Services
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
Re: Sleeving broken ali mast [Re: carlbohannon] #219091
09/09/10 09:10 AM
09/09/10 09:10 AM
Joined: Jun 2001
Posts: 778
Houston
carlbohannon Offline
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Houston
I am going to change my mind about epoxy bonding aluminum.

I just went through a similar issue, 3000 psi bond of 2 aluminum sheets. To get a reliable bond you need to sand, 2 part etch and then use a pressure and temperature cure epoxy. The curing requires the 2 plates to be pressed together at 5 psi or more and cured at 250F. A no pressure room temp cure will have a lot lower bond strength, 100 psi(?). The larger gap of a no pressure cure also makes the bond easier to break (don't ask me how I know).

The reason we have gotten away with this in the past, is the loads are mostly compression and if the fit at the joints is good, most of the load is taken up mechanically. Just as a guess, to handle the load with bond only, you will need about 200 sq inches in each mast segment. Consider the 3rd segment as just a spacer.

If I ever have to do this again, I am going to use epoxy and add a couple of monel rivets

Re: Sleeving broken ali mast [Re: carlbohannon] #219109
09/09/10 11:21 AM
09/09/10 11:21 AM
Joined: Aug 2005
Posts: 2,921
Michigan
PTP Offline
Carpal Tunnel
PTP  Offline
Carpal Tunnel

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Posts: 2,921
Michigan
how does one make the internal sleeve?

Re: Sleeving broken ali mast [Re: PTP] #219131
09/09/10 02:54 PM
09/09/10 02:54 PM
Joined: May 2006
Posts: 1,382
Kingston SE South Australia
JeffS Offline OP
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JeffS  Offline OP
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Kingston SE South Australia
I'm cutting up mast section to a snug fit then plan to knock it in tight.


Jeff Southall
Current boats
Nacra 5.8 1703 Animal Scanning Services
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
Re: Sleeving broken ali mast [Re: PTP] #219141
09/09/10 09:07 PM
09/09/10 09:07 PM
Joined: Aug 2007
Posts: 190
lesburn1 Offline
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lesburn1  Offline
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Joined: Aug 2007
Posts: 190
I take a mast section and clean up the inside.
Then wax it ( 5 times) than put on pva.
With the section on its side layup ten layers of glass (with epoxy) on the bottom, when it is mostly cured (still sticky) rotate the section and do the other side. Do this most the way round, I leave a gap at the mast track area. When it is fully cured use wood shims to pry it loose.


lesburn1.blogspot.com

A-Cat USA 49
18Sq 49

member- Royal Society for Making Cool Stuff

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