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 Post subject: Hobe 16 Mast repair
PostPosted: Tue Sep 01, 2015 12:19 pm 
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Posts: 6
Hi, I was wondering if anyone can give me some advice on whether it is safe to weld a cracked Hobie 16 mast. I was told by a dealer that it was caused by water freezing in the mast as it lay on the boat. It is a vertical crack about 5" long. Thanks


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 Post subject: Re: Hobe 16 Mast repair
PostPosted: Tue Sep 01, 2015 1:21 pm 
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Joined: Mon May 09, 2005 10:25 am
Posts: 3086
Location: Jersey Shore
Where is the crack?

Down low is probably OK. The higher you go, the riskier it gets.

sm


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 Post subject: Re: Hobe 16 Mast repair
PostPosted: Tue Sep 01, 2015 1:58 pm 
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srm wrote:
Where is the crack?

Down low is probably OK. The higher you go, the riskier it gets.

sm


It is higher up about a foot below the connection point of the forestay & other cables (Excuse the lack of correct terms!)


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 Post subject: Re: Hobe 16 Mast repair
PostPosted: Tue Sep 01, 2015 2:00 pm 
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Joined: Sat May 02, 2009 5:22 am
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Location: Columbus, Indiana
I have two extra Hobie 16 mast hanging on my fence if you need one, come and get it. :D

_________________
Bill 404 21SE
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 Post subject: Re: Hobe 16 Mast repair
PostPosted: Tue Sep 01, 2015 2:15 pm 
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Bill 404 wrote:
I have two extra Hobie 16 mast hanging on my fence if you need one, come and get it. :D


Thanks for the offer Bill but, unfortunately I am in Pennsylvania so you are a bit too far away. Thanks anyway


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 Post subject: Re: Hobe 16 Mast repair
PostPosted: Tue Sep 01, 2015 6:42 pm 
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What kind of a crack and how did it crack? Aluminum weld creates a more brittle area than the substrate and tends to concentrate the stress at the weld instead of dispersing it as the mast is designed. If you have a stress fracture, a crack will develop along the weld. As stated earlier, down low, likely not an issue, but up higher with the mast bend, you're likely to have a failure along the same line. I've seen it many times in aluminum trailers, I can't see why the mast would behave differently.


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 Post subject: Re: Hobe 16 Mast repair
PostPosted: Wed Sep 02, 2015 4:51 am 
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Joined: Mon Jul 14, 2003 7:11 pm
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Location: Detroit, MI
The problem with welding the extrusions has to do with the heat treatment (tempering) process that the extrusions go through after they're extruded.

The process increases the tensile and yield strength of the material significantly - by a factor of at least two.

When you weld a crack, there's an area around the weld (the Heat Affected Zone - HAZ) where the tempering has been removed. It's not so much a brittle spot as a soft spot.

Read this more more info on the 6061-T6 aluminum that's used for the extrusions: https://en.wikipedia.org/wiki/6061_aluminium_alloy

That being said, a 5" vertical crack, a foot below the hounds (that the proper term for the standing rigging attachment point) could probably be successfully welded by an experienced welder who can control the heat to minimize the HAZ. You really have nothing to lose.

I'd certainly keep an eye on it afterward to make sure the crack doesn't reappear or some strange deformation doesn't develop.


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 Post subject: Re: Hobe 16 Mast repair
PostPosted: Wed Sep 02, 2015 8:13 am 
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Joined: Mon Sep 19, 2005 10:18 am
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Location: Virginia Beach VA
Years ago I bought a H16 that had pitch poled in shallow water and broke the comp tip out of the aluminum extrusion. In the process it cracked the mast about four or five inches at this point. It was welded and I sailed the boat for years with no problem. You really have nothing to lose (unless you are three or four miles off shore and it breaks again :)).


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 Post subject: Re: Hobe 16 Mast repair
PostPosted: Thu Sep 03, 2015 3:37 pm 
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Joined: Tue Sep 01, 2015 11:50 am
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MBounds wrote:
The problem with welding the extrusions has to do with the heat treatment (tempering) process that the extrusions go through after they're extruded.

The process increases the tensile and yield strength of the material significantly - by a factor of at least two.

When you weld a crack, there's an area around the weld (the Heat Affected Zone - HAZ) where the tempering has been removed. It's not so much a brittle spot as a soft spot.

Read this more more info on the 6061-T6 aluminum that's used for the extrusions: https://en.wikipedia.org/wiki/6061_aluminium_alloy

That being said, a 5" vertical crack, a foot below the hounds (that the proper term for the standing rigging attachment point) could probably be successfully welded by an experienced welder who can control the heat to minimize the HAZ. You really have nothing to lose.

I'd certainly keep an eye on it afterward to make sure the crack doesn't reappear or some strange deformation doesn't develop.



Thanks for the info I will give it a try!


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 Post subject: Re: Hobe 16 Mast repair
PostPosted: Thu Sep 03, 2015 3:39 pm 
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Joined: Tue Sep 01, 2015 11:50 am
Posts: 6
sunvista wrote:
Years ago I bought a H16 that had pitch poled in shallow water and broke the comp tip out of the aluminum extrusion. In the process it cracked the mast about four or five inches at this point. It was welded and I sailed the boat for years with no problem. You really have nothing to lose (unless you are three or four miles off shore and it breaks again :)).



Thanks, I currently only use it for recreational sailing in light winds, so will give it a try.


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 Post subject: Re: Hobe 16 Mast repair
PostPosted: Thu Sep 03, 2015 3:41 pm 
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smattie wrote:
What kind of a crack and how did it crack? Aluminum weld creates a more brittle area than the substrate and tends to concentrate the stress at the weld instead of dispersing it as the mast is designed. If you have a stress fracture, a crack will develop along the weld. As stated earlier, down low, likely not an issue, but up higher with the mast bend, you're likely to have a failure along the same line. I've seen it many times in aluminum trailers, I can't see why the mast would behave differently.


The crack occurred I believe when water in the mast froze & split the mast. I will take what you have said into consideration & thanks for the advice.


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