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 Post subject: hull repair guidance
PostPosted: Mon Jun 26, 2017 9:39 am 
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Joined: Wed May 18, 2016 11:44 am
Posts: 42
Location: Traverse City, MI.
had some what I though was gel coat cracking in starboard inner hull last year, never took on water and did not feel too soft pr flexy.

was checking it the other day, and now I don't feel comfortable putting it in the water, I'm sure it will float and all, but Id rather fix it first and not make it worse. there is some flex when I push on the area, and makes a little crunchy noise. when I knock on different parts of the hull it sounds the same. anyway, heres a couple pictures of the inner side of the bow. How should I repair it? will I need to fiberglass it or can I just epoxy? never done this before, read a few things online but always worth asking for specific situations
thanks guys, I wanna sail! its almost july

Image
Image
both side have the lights spider web cracking

the darker crack is not as soft as the lighter cracking areas, but the bows have some flex to them correct? also, looks like there was some work done before on both hulls but the port hull is holding up really well

thanks


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 Post subject: Re: hull repair guidance
PostPosted: Mon Jun 26, 2017 11:46 am 
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Joined: Wed May 25, 2011 3:15 pm
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Location: Buffalo, NY
Hard to tell how bad it is without seeing the fiberglass underneath the gel coat, but it is something that will definitely require fiberglass work. The appropriate way to make the repair is to first sand down the gel coat in the area to see how far the damage goes. Fiberglass should appear somewhat translucent. If the glass in the surrounding area is white and opaque, it is damaged glass that needs to be sanded out. Everywhere you see the spider cracks in the gel coat, the fiberglass underneath is probably also damaged. Once you sand out all the damage, you'll need to cut some pieces of fiberglass cloth about the size of the repair area. The appropriate approach is to use alternating layers of fiberglass cloth and chopped strand matte (CSM) fiberglass. Once you have the pieces cut to size, you'll have to mix some polyester resin with MEK catalyst at the proper ratio. Using a brush, you coat the repair area in resin and soak each piece of cloth/matte with resin, so that it looks completely clear. then you build the area back up with the resin soaked pieces of cloth and matte, and let it cure. Sand the repair down to a little smaller than the final dimensions, and then mix and apply some gel coat. Sand down the gel coat fair, and then buff back to a shine.

It's not hard, but it takes some time. I'm a bit of a perfectionist, so this would probably be a two or three weekend project for me. One to sand down and apply the fiberglass, another to sand it down, color match and apply the gel coat, and then probably a few days of finish sanding and buffing. You can use epoxy instead of polyester, but gelcoat doesn't adhere to epoxy, so you'd have to paint over it if you wanted it to be white.

Fiberglass cloth, CSM, resin and gelcoat will probably run you about $120. You could probably find a boat repair shop to do the repair for ~$300-$500, in about the same timeframe.

The "crunch" sound is typically a sign of a soft spot, aka delamination between the foam sandwich and the fiberglass. That makes me wonder if water is getting into that foam layer or if it was just that bad of an impact that it damaged the foam sandwich. The typical repair for a soft spot is to drill holes and inject epoxy to glue the fiberglass and foam core back together. The foam sandwich doesn't start until you get ~4-6" aft of the bow. How big of an area do you hear a crunch on and get flex when you press on it? There is some flex to the bows, but not like a soft spot. The bows will have a little give to them, but a soft spot will deflect over a small area, with as little as maybe 10-15 lbs of force, and often will make that "crunch" sound.

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 Post subject: Re: hull repair guidance
PostPosted: Mon Jun 26, 2017 10:46 pm 
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Joined: Wed May 18, 2016 11:44 am
Posts: 42
Location: Traverse City, MI.
the crunch i hear is only at the tip of the bow, the darker serious looking crack. the spider cracking/ lighter cracks are just soft feeling, the surrounding area when pressing on them indents as I press into it, not a lot of pressure. The soft area is extends about 6-7" aft of the tip of the bow on both sides.

Stopped in at West marine to look at products. Wasn't really sure what I need, so I did not buy anything. Sales help was not very helpful with advice or what to buy. Only thing I figured out was they have some white "ink" I can mix with the hardener(?) to help match the hull color.

What thickness cloth would I want?

what is CSM?

thoughts on the soft area extending 6"?

thank you


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 Post subject: Re: hull repair guidance
PostPosted: Tue Jun 27, 2017 8:02 am 
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Joined: Wed May 25, 2011 3:15 pm
Posts: 532
Location: Buffalo, NY
If the crunch is only in way of the crack, then it's probably just damaged fiberglass that you're hearing. I just picked up a pack of fiberglass woven cloth and fiberglass matte from my Hobie dealer/west marine, and used that. Not really sure what thickness. CSM is chopped strand matte fiberglass, it's just a fiberglass matte with a bunch of random glass strands in every direction. It's thicker than the cloth, so it's better for building up glass, where the woven cloth is more for strength. The matte is typically applied between layers of cloth, and as the top layer before gelcoat.

For the fiberglass repair, this video is a good introduction/overview to the basic approach:
https://www.youtube.com/watch?v=rz5WCfipaNw


This video series provides a very thorough walk through, from fiberglass to gel coat. I watched all of these before attempting my first repair, and it helped a LOT! The guy is kinda goofy, but he knows what he's doing. It's about an hour in total.

Fiberglass Repair (4 parts):
https://www.youtube.com/watch?v=i9hfpOCnzEs

https://www.youtube.com/watch?v=gGr-OsUdf0A

https://www.youtube.com/watch?v=0-kVRKhyb3g

https://www.youtube.com/watch?v=Flj8vapM5mU


Gelcoat Repair (4 parts):
https://www.youtube.com/watch?v=yoURRmkD8MY

https://www.youtube.com/watch?v=MxzCZ-5lMxY

https://www.youtube.com/watch?v=5MWN7kbzutM

https://www.youtube.com/watch?v=v962wu8Euoo


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 Post subject: Re: hull repair guidance
PostPosted: Tue Jun 27, 2017 9:17 am 
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Joined: Mon May 09, 2005 10:25 am
Posts: 3529
Location: Jersey Shore
Assuming the glass is cracked (which it looks like it probably is), this is a list of what you would likely need to correctly complete your repair. None of these are individually very expensive, but there is a fair amount of stuff and you'd need to decide if it's really worth purchasing this or just have a pro do the repair. If you aren't overly concerned with cosmetics, you could save some cost.


Materials:

Various sand paper grades & sanding block.
Grindng wheel (Roloc) to be used in a right angle drill - Not required but highly recommended.
Acetone
Paper towels
1" disposable brushes
Latex gloves
Mixing cups & sticks
Dust mask / respirator
Safety glasses/goggles
Gelcoat, tint, surfacing wax, thinner
Masking tape
Polyester resin & hardener
3/4 ounce glass mat and/or 6oz woven fabric
Sprayer, Preval, or roller for gelcoat.
Formula 27 filler
Plastic spreaders




The general procedure is:

Grind out all damaged material and feather/taper back a few inches beyond the damage.
Clean surfaces with acetone.
Cut glass patches to build up damaged area.
Mix resin/hardener.
Wet out the glass, apply over the repair and allow to cure.
Sand out edges of repair to blend and rough fair the surface.
Clean with acetone.
Apply F27 filler to fill imperfections
Sand smooth and repeat fill process if needed.
Clean with acetone.
Spray or roll gelcoat and allow to cure.
Sand smooth & polish.

sm


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 Post subject: Re: hull repair guidance
PostPosted: Fri Jun 30, 2017 1:45 am 
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Joined: Sun Aug 14, 2016 10:13 am
Posts: 43
Location: France
the "general procedure" posted here above by srm gets it down to the point.

I recently repaired a friend's surfboard (tree cracks that let water in). I cut pretty large holes in the board and built it up again. The process ist exactly the same like on your hulls, except that you don't have to hassle with epoxyd on your Hobie 18. Polyester is cheaper, less harmful to the environment (incl. your health) and will do perfectly.

Here's the album: https://goo.gl/photos/djufMfHBcak588iA6

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 Post subject: Re: hull repair guidance
PostPosted: Fri Jun 30, 2017 7:59 am 
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Joined: Wed May 25, 2011 3:15 pm
Posts: 532
Location: Buffalo, NY
Stefan S wrote:
Polyester is cheaper, less harmful to the environment (incl. your health) and will do perfectly.

I don't know about how environmentally friendly either type of resin is, but I know for sure that polyester has some awful VOC's and fumes as it cures. I did it in an enclosed garage once, and I'm still finding dead bugs from the fumes! You want to do fiberglass/gelcoat work in a well ventilated area. Epoxy doesn't have the same issue.

Polyester resin is definitely cheaper than epoxy though, but also not as strong, nor as rigid. Polyester resin is typically chosen for fiberglass construction primarily because of cost. If the entire boat was made using epoxy resin, it probably would've cost twice as much, though it would've been a little more rigid and possibly a little lighter if they had tried to build it a little thinner to match the strength of the polyester. The boats also would've been painted rather than gelcoat. Gelcoat is essentially tinted polyester resin, and polyester resin doesn't adhere well to epoxy (though epoxy resin will adhere just fine to polyester).


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 Post subject: Re: hull repair guidance
PostPosted: Mon Jul 10, 2017 6:04 pm 
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Joined: Wed May 18, 2016 11:44 am
Posts: 42
Location: Traverse City, MI.
thanks for the videos and advice. I'm gonna sail it for the summer and do the repairs in the fall once it gets too cold to sail. Hopefully then I will have more patience to do it right and not be so eager to put it in the water


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 Post subject: Re: hull repair guidance
PostPosted: Mon Jul 10, 2017 6:29 pm 
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Joined: Wed May 25, 2011 3:15 pm
Posts: 532
Location: Buffalo, NY
black4est wrote:
thanks for the videos and advice. I'm gonna sail it for the summer and do the repairs in the fall once it gets too cold to sail. Hopefully then I will have more patience to do it right and not be so eager to put it in the water

Not a bad idea, projects like that tend to take a little more time and get a little more involved than they seam at first. As long as it's just bow damage and it hasn't compromised the strength between the bow tangs and the forward crossbar, you should be fine. I'd cover the crack with tape to keep water out of the hull and/or foam core.


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 Post subject: Re: hull repair guidance
PostPosted: Wed Jul 12, 2017 10:17 am 
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Joined: Wed May 18, 2016 11:44 am
Posts: 42
Location: Traverse City, MI.
its way up at the front of the boat. I sanded down the bigger crack to cover the area with epoxy for the time being. Glass was looking pretty good underneath. Maybe it will be an easier first time glassing experience. find out later


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