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 Post subject: Cored hulls
PostPosted: Mon Feb 03, 2014 8:15 am 
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Joined: Tue Nov 12, 2013 10:29 am
Posts: 7
I recently purchased a 1981 hobie 18. I need to make two repairs to the starboard side deck. One spot is from the stern forward about 16-24", the other about 16" forward of the front cross bar about the same size. They are soft probably from walking on them. I might be able to do the front repair from the access opening with some luck. How about the rear repair? Any info would be greatly appreciated. I'm thinking epoxy resin for repair and then a new awl grip paint job. Thanks


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 Post subject: Re: Cored hulls
PostPosted: Mon Feb 03, 2014 9:40 am 
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Joined: Mon May 09, 2005 10:25 am
Posts: 2553
Location: Jersey Shore
The typical soft spot repair is to inject epoxy into the core of the deck. Drill a series of holes through the outer skin and into the core, but not through the inner skin. Then inject epoxy into the holes until it squirts out from the adjacent holes. This will re-bond the skins to the core. If the delam is minor, this is a reasonable repair method and has been discussed countless times on the forums and there are also detailed instructions in the FAQ section.

If one of the skins is cracked, the hull would require more extensive repairs. For your delam located in front of the front crossbar, I would use a light and mirror through the access port to inspect the inner skin of the deck. If the skin is intact, then proceed with the injection repair. If it's damaged, you can inject and then reinforce the skin through the access port.

For the soft area in the aft deck, I would probably just do the injection first and see how the deck looks after the epoxy is cured. If there is still movement after the injetion repair, then add a 5" diameter access port and reinforce the hull from inside. A lot of H18 sailors add access ports behind the rear crossbar anyway to reinforce the aft crossbar attachment area as well as improve hull ventillation.

There was also an article in the July/August 2009 Hobie Hotline that discussed adding reinforcing bulkheads to the decks. You may want to download and review this article.

sm


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 Post subject: Re: Cored hulls
PostPosted: Tue Feb 04, 2014 7:17 am 
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Joined: Tue Nov 12, 2013 10:29 am
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I failed to mention that I believe the hull is not cored. Is this possible


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 Post subject: Re: Cored hulls
PostPosted: Tue Feb 04, 2014 9:15 am 
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Joined: Mon May 09, 2005 10:25 am
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Location: Jersey Shore
About 90% of the hull is cored/ sandwich construction. The bottom of the hull is solid laminate, the sandwich extends down to about two to five inches from the very bottom of the hull. Then there are various non-sandwich areas of the hull like the crossbar saddles and anchor points for the crossbars and shrouds. The very bow is also solid laminate. Otherwise the rest of the hull is sandwich. To my knowledge there have never been any 100% solid laminate Hobie 18 hulls built. The sandwich constuction is what gives the hulls their light weight and stiffness.

sm


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 Post subject: Re: Cored hulls
PostPosted: Thu Feb 06, 2014 8:30 am 
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Joined: Sun Aug 26, 2007 5:40 am
Posts: 410
Location: Metuchen NJ
I currently have the same deck soft spot on the rear of my port hull, just in front of the crossbar. Here are a couple things to look out for in this repair:
I located the extent of the delamination and marked it's perimeter with a pencil line, drilled two spaced holes in the center and then smaller holes around near the perimeter. I injected a Git Rot mixture into the deck sandwich and was waiting for it to begin squirting out the holes. When it didn't that's when I discovered the bottom glass layer was ALSO split open, allowing the Git Rot to run through. This became evident as it set up along the bottom of the hull, which I pulled it right out.
I'm describing this to you because it is an easier way to tell if your bottom layer of glass is split, BEFORE you cut an access port behind the rear crossbar.
If you have to go the route of cutting that access port, be sure to keep it at least 8" aft of the rear crossbar to retain structural integrity around the crossbar.

Once all this snow melts I'll be doing this same job.

_________________
Chris
'88 H18SE Arís


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 Post subject: Re: Cored hulls
PostPosted: Mon Feb 10, 2014 10:49 am 
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Joined: Tue Nov 12, 2013 10:29 am
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Finically drilled some holes and yes it is cored. Going to inject some west system into the needed areas with a little suction to help move the epoxy around. Will finish with an Awlgrip paint job. Thanks for the help. Looking to paint the crossbars, mast and boom. Any suggestions? Thanks


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 Post subject: Re: Cored hulls
PostPosted: Mon Feb 10, 2014 4:10 pm 
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Joined: Mon May 09, 2005 10:25 am
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Location: Jersey Shore
Be sure to mask off the deck everywhere you drill a hole, otherwise when the epoxy oozes out of the holes, it will get into the nonskid and make a huge mess. Have paper towels and acetone handy to clean up any mess.

james1 wrote:
Looking to paint the crossbars, mast and boom. Any suggestions? Thanks


Unless you don't mind maintaining the paint job, it's generally considered a bad idea because the paint has a tendency to chip and scratch which ends up looking worse in the long run than faded anodize.

sm


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 Post subject: Re: Cored hulls
PostPosted: Mon Feb 10, 2014 11:52 pm 
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Joined: Sat Nov 23, 2013 12:52 am
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I recently repaired a soft spot on an 18 deck deck by injecting epoxy in holes. You need more holes than I had hoped to get the epoxy to flow from one hole to another so it is not a very easy to over look when complete. It was a very messy job and I agree you have to have plenty of acetone and paper towels handy. I found the epoxy would also shrink back into the holes after it gelled when it fully cured. I checked for leaks through the lower glass layer and had none. I still had to refill the holes a couple times to get it flush to the skin. I suggest you not paint but cover the effected area with some foam deck pad or carpet for traction, comfort and a cosmetic cover up. There is a limit to cover ups of course. Painting hulls is the last resort for an old boat. Paint has a life that when it's over is more than likely the end of the boat. Good paint can withstand UV better than gelcoat but not so much that it is worth loosing the easy patch repairs with gelcoat. The thing is that general resufacing of hulls with gelcoat is more work than most of us are willing to do versus buying a new boat. So paint while not ideal is often the only viable option to extend the life of a boat with major areas to resurface. If you do use paint get the best you can. It pains me to see Hobies in the sun with no covers when for $25 you can make a great cover from a tarp and a gromet kit. You can buy a lot of $20 tarps for the cost of one tramp let alone new hulls.
Steve


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 Post subject: Re: Cored hulls
PostPosted: Wed Feb 12, 2014 5:52 pm 
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Joined: Fri Dec 27, 2013 6:44 pm
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There is no core also within about 3" of the outer edges of decks along the entire length of hulls. Ask me how I know... you will drill all the way through even with a proper drill stop. Never see this important little bit of info mentioned on this subject... :-( But thankful for all the great info here! )

Be sure to get a drill stop, also. It is a very inexpensive bushing that tightens down on your drill bit to prevent it drilling any deeper than exactly what you want. Very hard to stop even a slow turning bit by "feel"..., as soon as it touches the bottom layer of FG, it wants to grab the cloth and punch all the way through.

Had to patch a lot of through-holes myself.... Ah but then I found I also had the dreaded split interior crack spilling all the epoxy into the boat. Agree that is the FIRST thing to check for! (never saw it mentioned till now either.)

Some time I will post photos on my unique " Epoxy Adventure " (nightmare).... Ended up with Second hatches near the rear crossbeams to get it all repaired with glass and epoxy from inside, then had to fair in around the 2nd hatches with light microballoon filler and epoxy, then a layer of glass on Top, thats right.... and finally some lovely cushy Seadeck... Bulletproof, Beautiful and nice on my Butt too, lol!

I know the uber racers may whine about the extra 8-9 pounds but with my custom insulated fat bags, thats about a nine-pack of beer and ice!
RB


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