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PostPosted: Sat Nov 27, 2010 3:38 pm 
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So I've been doing crazy research and looking everywhere for information but I cant find anything for this type of blind hole fix for so much missing material.


Right now I am thinking of just trying the "this old boat" description from hobie Hotline. -Using fiberglass layer backing with polyester resin, using fishing line to keep it stable, then filling the outside with crazy layering and much more resin.

Does this seem to be the right process for something like this? I just got her and after the first launch the putty (bondo?) holding her together just came apart. Im also worried about keeping the right profile, does anyone have any ideas?

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Image

Thanks guys!


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PostPosted: Mon Nov 29, 2010 7:46 pm 
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Location: Bowie, MD
I am working on repairing a similar hole in my boat.

Image

I used the blind hole repair from This Old Hobie just as you described. Getting the backing piece to conform to the sharp angle of the bow was a little tricky. I ended up creasing / folding the piece in half (after it had cured) to get it to follow the sharp angle of the bow. So far, following the directions as outlined in the This Old Hobie article. I will post more photos when I get home.

Jim


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PostPosted: Tue Nov 30, 2010 2:34 pm 
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I did a repair like this using a piece from a trash hull. If you can find a soft one, cut out what you need and install it. Makes a perfect fit.


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PostPosted: Sat Dec 04, 2010 12:46 am 
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I paid a professional to repair the gash in my bow. It was much worse than yours and the pro's work is excellent, including matching the color of 19 year old gelcoat. Fortunately, I got more money than time, and though the repair isn't rocket surgery, I don't feel like experimenting on my only boat.


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PostPosted: Sat Dec 04, 2010 4:23 am 
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Key is don't make it more than it is. You have an easy shot at the back, so any way you can, get a piece of glass mat back there suck to the backside of the hull. (after you clean it off a bit with sandpaper/acetone). Let it cure and then start a regular external glass patch. Very simple.

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PostPosted: Sat Dec 04, 2010 12:19 pm 
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divimon2000 wrote:
Key is don't make it more than it is.


This is how I would do it as an exterior repair.
1.) Prep the work area. Grind back the gell coat and feather the fibergall about 1/2 to 3/4 of and inch from the hole. (like the white hull posted above)

2.) Prepare your patch. Cut 3 or 4 layer of fiberglass to cover hole and exposed fiberglass. Cut 2 addtional layers that are the size of the hole only. (I preffer mat over cloth)

3.) Mix your resin. On a peice of cardboard lay out one of the larger layers. Pour the resin on it or use a brush to saturate the fiberglass. Add the second large layer and repeat with brush, then the third. Repeat with the small layers. Next use a paint stir stick and press the sandwich together. Your wanting to work out air bubbles and excess resin. FIBERGLASS HAS STRENGHT RESIN ONLY HOLD IT TOGETHER!!!

4.) Apply patch to boat. Brush a little resin onto the preped area of the hull to wet. Apply patch. use your stir stick to press the patch against the hull. Work out any excess resin and air bubbles. Next take strips of duct tape and streach across repair. This will keep the fiberglass in place while it cures and it will help it conform to the shape you want.

5,) Rough in the new patch. Remove the tape and sand down any high spots. Then add filler (fiberglass, Bondo or Adheasive) as need to restore shape.

6.) Sealer. I would spray a paint sealer on next. Sand lightly

7.) Finish with gell coat or get some really cool sticker to cover it up.

Grand Auto has diamond plate decals???

Hope this gives you some ideas.

If you want to do a internal / external repair send me an email. Corkguy1390 (at) SBCglobal.net

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PostPosted: Sat Dec 04, 2010 3:32 pm 
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Cork Guy wrote:
Grind back the gell coat and feather the fibergall about 1/2 to 3/4 of and inch from the hole. (like the white hull posted above)


I would go even farther than 3/4". Probably closer to 2" or 3". You want to bond the repair over a large area in order to maximize strength. A 30:1 taper is the standard I've seen for aircraft composite repairs and while this repair may not be as critical as an aircraft component, you still don't want to cut yourself short on strength by tapering over too short a distance. You also want to cut your repair patches so they increase in size to match the taper of your hole. Each patch should be slightly larger than the one before it. If all the patches are the same size, you will minimize your bond area and you'll also create a stress concentration at the edge of the patch.

sm


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PostPosted: Sun Dec 05, 2010 3:31 pm 
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Here are a couple of pictures after the blind hole repair cured.

Image
Image

Here is a picture after six layers of glass mat applied. Built up a patch of three layers as described by others above, applied and let that cure. Wasn't quite enough, so I built up another three layer thick patch and resined that on. The glass mat did not want to conform to the sharp curve of the bow, so I put a piece of wax paper over the patch and taped it to the hull while it was curing.

Image

Now all that is left is to sand back the excess resin that you can see along the edges, fair it all in with some Formula 27, sand that down and then spray the gelcoat.

Jim


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PostPosted: Thu Dec 09, 2010 9:40 pm 
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kagortime101
Any news on the repairs??

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PostPosted: Fri Dec 10, 2010 9:20 am 
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Outstanding repair! I'm sure that Rick Buchanan shed a tear of pride. :D

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PostPosted: Sun Jan 02, 2011 3:52 pm 
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Thanks for all the Help. I cant explain how awesome you all are.
Sorry about the late reply. After a few days I didnt see the post up so I thought some angry mod didn't let it go through.

Well I have some pics of the Finished product. Got a little messy at times but the repair came out great. Shes an old bird so I didnt add any color to the resin to try and get her to match but she filled in nicely.

I followed the links in those hobie magazines about "This old hobie" and used the fishing line technique and it works great! I threw in a bunch of wet layers next to the folded piece set inside so that when I pulled the inside backing piece to the hull it filled in nice and fully.


Getting the profile right was really simple but was tricky when I thought about how to do it. I wasnt sure if I should apply resin layers and fiberglass in small strips and work bigger or go big and work smaller. In the end I was just overthinking it. I laid layers all about the same size but using 45 degree angling in there for extra strength. The profile was mainly shaped after it all cured.

It was a rough cure so I used the metal sheets that come with surf repair kits that are like cheese graters and that worked great to shape out the majority of it. Then like any fiberglass repair, its all about the sanding. Got my sander out and went to work. first with 80, then 120, and finished with some sexy wet 300. Feels like the bottom of a baby's glass*.

Image

Image

Image

Image


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PostPosted: Sun Jan 02, 2011 4:27 pm 
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Jim- Doty - You were right on the money about folding the piece to get it to conform. I had it almost fully cured when I folded it so that it could still mold itself right when I set it. I found that because the gashes went so far up on the sides that the fishing line only was able to hold down the bottom of the backing piece and not so much the sides. I let it flatten out a little more while curing and then it slipped snugly into place with some added resin.

ncmbm - Doing a repair from a trash hole? lol. Sounds like more work than just filling it but I bet for larger holes that would be a great idea.

Divimon - "Key is don't make it more than it is." You were right. Spent more time thinking about it than just doing it. It all came together once I just got my hands dirty.

Cork Guy - Thanks for the tons of help. That's pretty much the technique I used but I ended up using the cloth because that is what I had. The duct tape idea was great but I didn't end up needing it on this repair since I used layers of fiberglass that were very easy to shape and fill with resin. Ive used the tape idea on smaller repairs on the deck side of the hull with plastic bags (because the resin doesnt stick to it) and that formed the hull well where there were chips. Really useful to cut down on sanding. Thanks!


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PostPosted: Sat Jan 29, 2011 10:06 am 
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Hi everyone!
A buddy and I recently bought an 18 and we have been having a blast on it. We have broken nearly everything, so she is quickly becoming a new boat. Just yesterday, the left pontoon started filling with water so we took her back to the beach to investigate. We found the crack in the front of the left hull. I would insert a picture here, but can't quite figure out how just yet. Anyhow, there is no way to get behind the crack to support it from the rear, is that critical? or can I just grind down the exterior and glass over it?
Thanks so much.


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PostPosted: Mon Jan 31, 2011 9:47 pm 
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Murph,
If you would like help please discribe in more detail where the crack is.

Second let the form know where you are.

Cork guy H18 x 3

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PostPosted: Tue Feb 01, 2011 10:56 am 
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Thanks Cork guy,
First time poster. Guess I'll get better over time, sorry....We are in Orlando, Fl. The crack was kind of like the yellow boat above, a little aft of that position only it was not missing and fiberglass. If you pushed on it, it would move to the side and allow water into the hull. I think it happened because we propped up the rear end of the boat on the beach to upgrade our rudder system to the new style which put the front end into the sand. When we were done we slid the boat around and I think that flexed it apart....The front on the 18 is SUPER thin!
Anyway, I took the advice from this forum and watched a couple youtube videos....presto, back sailing with no water intrusion. I just cut fiberglass 1/2 inch bigger than the crack then 2 inches then finally 3 inches for the final layer....let stand, light sanding and a little paint. It's not real pretty if you look up close, but its functional. Thanks for the help!


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