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 Post subject: Crack in Corner Casting
PostPosted: Tue Apr 19, 2005 12:41 pm 
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Joined: Fri Jun 25, 2004 8:01 am
Posts: 17
I made a very rookie mistake today. I decided to install shims in my pylons to tighten up my 81 Hobie 16, while re-settting the corner castings back onto the shimmed pylons, I stupidly used a hammer, and after the casting was lined up properly with the pylon holes, i noticed that there was a hair line circular crack of about 2 inch diamater around the top of the casting that go's right over the pylon, I am sure it happen form the multiple bangs i gave it when trying to get it back on right.

My question is should I be concerned that it will be OK to sailon, will it get worse, should i fill the small crack with something to prevent seepage? I am just a rec sailor, and I just want to make sure the casting wont give way under sail. The casting still seems structuraly sound.

Maybe someone has an extra stbd forward corner casting lying around!?!?!


thanks for any input


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 Post subject:
PostPosted: Wed Apr 20, 2005 2:49 pm 
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Joined: Sat Jul 26, 2003 12:05 pm
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Location: California
I would not sail with a cracked casing. Theboat really twists while under sail and there is a lot of pressure on the casting. You could always have it heliarc welded but why not change it . We have alot of used ones. Email us at sailboatsbak@onemain.com for price or call 661 3229178. Glad we are getting new sailors in the sport. Dave-Sailboats of Bakersfield.


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 Post subject:
PostPosted: Thu Sep 15, 2005 12:26 am 
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Location: Hong Kong
It is the same case to my H16 too, I found there is a crack on the top of the rear portside corner casting, it is impossible to take it out since the screw of the casting & the pylon has already "have the chemical reaction which glue together", I would like to know whether I can weld the casting or not? and I would like to know what is the material of the corner casting, everyone's insight is appreciate, thanks!


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 Post subject:
PostPosted: Thu Sep 15, 2005 6:20 am 
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Joined: Fri Jul 15, 2005 10:43 am
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Location: St. Louis, MO
Welding on Aluminum castings is usually discouraged. Depending on teh type of casting many undesireable things can happen. The worst of which is introducing more internal stress in the casting due to the high heat of the weld. Depending on the density of the casting, the area around the weld could shrink when it is melted.

As for a replacement, you can find them on eBay, your Hobie dealer, and local boat owners.

Since the corner casting is a major part of the baot structure it would be wise to replace it.

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Nick

Current Boat
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Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO


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 Post subject:
PostPosted: Thu Sep 15, 2005 7:01 am 
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Location: Hong Kong
yes, thanks...

I do want to replace the corner casting, but it is impossible to take off the bolt & nut...................................

Or can i fibreglass the whole corner casting?

Thanks!! :lol:


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 Post subject:
PostPosted: Thu Sep 15, 2005 8:21 am 
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Location: St. Louis, MO
Never say it is impossible. What did to remove my bolts is take some spray penetrant to loosen up the corrosion. Something like WD-40. Spray it aroung the head of the bolt and where the nut is. Let is set for a while and reapply. Don't worry about using too much. After a few applications take hammer and tap the stuck bolt to near flush with the casting.

Now try to use a wrench and remove the bolt. If this doesn't work use some vise grips and try to work it out.

If that doesn't work, then take another bolt the next size down and use it as a punch. What I mean is to set the end of the loose bolt (the punch) on the stuck bolt that is flush with the casting and tap the head of the punch with a hammer.

Once teh stuck bolt is out of one side of the casting you will be able to work it out of the other side.

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Nick

Current Boat
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Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO


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 Post subject:
PostPosted: Thu Sep 15, 2005 11:49 am 
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Joined: Mon Aug 18, 2003 1:15 pm
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I wouldn't weld it and I would definitely not fiberglass it. You can get used castings pretty cheap on eBay--heck, I have 40 of them sitting in a box in my back yard.

Be VERY careful when hammering the casting back on the pylon! If you get to the stopping point and keep hamering, you will push the pylon down into the hull and you will notice a bulge in the side of the hull where the 'nest' has pushed out. ALWAYS use a rubber mallet.

Shims are nice to tighten up the boat, but I prefer just gluing the boat together. The castings slide nicely on the pylon and there is no trauma to the boat. Shims also corrode and then it is about impossible to get the boat apart.

First, take off the castings and use a wire wheel to clean up the inside of the castings and the outside of the pylons. I use the West Marine system with some microfiber filler added to thicken it and make it adhere. You have to make sure the boat is completely level and true because once it cures, that is the shape you are stuck with. I also find it halpful to drill a bigger holes in the castings and to use thicker bolts. Using Mylock nuts is a plus. It just takes one more bit of slop out of the castings. Just don't over tighten the bolts or you are back to having a cracked casting.

Talk about being impossible to get apart--this process is fairly permanent. You will more than likely have to break the castings to get the boat back apart. It is a trade off.


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 Post subject:
PostPosted: Thu Sep 15, 2005 12:33 pm 
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Location: St. Louis, MO
Before you expoy the castings to the frame, would it be possible to cover the extrusions in mold release or some kind of release agent that epoxy won't stick to? Maybe even cover teh inside of the cast too. This would be like a "liquid shim". Any thoughts/comments?

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Nick

Current Boat
In the market
Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO


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 Post subject:
PostPosted: Thu Sep 15, 2005 1:31 pm 
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Be.... Not sure why you have trouble removing the nut from the bolt that holds the corner casting on the pylon - those bolts/ nuts should be stainless steel and should not corrode to bad. If you can not remove the nut from the bolt that holds the corner casting, than cut or grind the head of the bolt or the nut off. A replacement does not cost much and is available. Drive the remainders out with a punch.
One of your other posts sounded like you pylon is loose in side the hull -if this is the case be careful not causing more damage by hammering around the corner casting.

Patrick


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 Post subject:
PostPosted: Thu Sep 15, 2005 8:58 pm 
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Location: Hong Kong
thanks everyone, in fact, I have done lots of work to stiffen her after I bought it from the previous owner.

what is the condition before i bought my 16, the previous owner put it on water and tie her on the mangrove, with drain plugs closed for ~ 5-10 years..... shells are grow on the bottom of the hulls......... and there are more than 50% deliminated......

I guess the "fill in glue" method to fix the delmination is not possible since I think I need to pour tonne of glue inside the void..... therefore i had installed a bar between the 2 bow of the 2 hulls, and i am planning to lay a new layer of fibreglass on the surface of the existing hulls ..... see if it can be strengthened....

Thing always goes worst..... i found there is crack on top of the starboard aft corner casting........... oh my god............ I almost want to throw her away..........

I do not know much about boat repair skill and therefore I have only a very limited know how to do the job....

I am go ing to start the job this weekend and wish I could finish it in 2 months time....


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 Post subject:
PostPosted: Fri Sep 16, 2005 6:14 am 
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Quote:
I almost want to throw her away..........


If your assessment is correct and 50% of the sandwich has delaminated, parting out and finding some other cat might not be a bad idea.
IMHO laminating over the existing shell of the hull is not fixing the problem. The hobie is constructed in a sandwich of inner shell, foam and outer shell. If these three layers separate from each other the integrity of the hulls is no longer maintained. Sure, you could lay up glass to a point where the outer shell would be strong enough by itself... You would end up spending a good amount of money on glass and epoxy. The result would be a quiet heavy boat.
Search the forums... some people have posted on injecting foam in order to heal the separation.
Maybe some else has some more uplifting advice.

Patrick


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 Post subject:
PostPosted: Fri Sep 16, 2005 8:49 am 
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Joined: Fri Jul 15, 2005 10:43 am
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Location: St. Louis, MO
Another thought is to keep this boat as a spare barts supply and find another fixer upper that has better hulls. As yoh said, if that much of the hull is damaged, it may not be worth the effort.

Good luck in whatever you decide to do.

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Nick

Current Boat
In the market
Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO


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 Post subject:
PostPosted: Fri Sep 16, 2005 9:23 pm 
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Joined: Sat Jul 03, 2004 3:28 am
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Location: Hong Kong
YES, THANKS!!

I can try the form injection method to the deliminated part only and see if it work.....

:lol: :lol:


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 Post subject: DIY
PostPosted: Sat Sep 17, 2005 3:42 am 
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Joined: Sun Aug 15, 2004 4:33 am
Posts: 3
Location: israel
Check this...

http://www.thebeachcats.com/modules.php ... =0&thold=0[/url]

erez


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 Post subject:
PostPosted: Sat Sep 17, 2005 6:47 am 
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Joined: Sat Jul 03, 2004 3:28 am
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Location: Hong Kong
Thanks erez,
Read the article and will also try to do that.. :D

On the otehr hand, I have another discovery in a shop...... :shock:
Foam injection...

I just found a kind of injection foam which might be useful....

RAMFOAM
http://www.ramset.co.nz/pdfs/5_4.pdf
http://www.ramset.co.nz/msds/NZ5000.pdf

RAMFOAM (Expanding Polyurethane Foam)
Ramset Ramfoam is a one part self expanding polyurethane foam ready for use direct from the can. Typical uses include fixing and insulating of door and window frames, insulating of pipes and the filling of holes and gaps.

Uses
· Filling gaps
· Blocking out dust, drafts, noise and vermin.
· Insulating window and door frames.
· Insulating pipes and filling pipe penetrations.
· Suitable for external use, provided it is painted over once cured.
· Back filling of wal cladding.
· Filling around electrical cables.
· Insulation, packaging and refrigeration

I am planning to use it to fill the gap between the sandwiches of the hulls, does anyone have the experience of using this kind of material to fix large area hull deimination? please share your opinion and experience, thanks!


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