Sailing Dinghy Hull Repair

[hatcheb]

Hey Guys,

looking for a bit of help with a project i am going to have on the go. My sailboat(Code 40) now has a nasty split after last winter(pics below).

i am trying to figure out the best way to approach this as i do not have access to this spot from the inside, so the repair will have to be completely done from the outside.

i am thinking about making some sort of backing plate out of fiberglass and resin to shove in the crack and epoxy/glue it to the under side to create some sort of backing plate to start laying fiberglass etc. Then only problem is it is not a flat surface, and i think it would be difficult to get it to stick properly and be strong enough.

Any advise or help at all would be greatly appreciated.

i am hoping the photo link i posted below works

Thanks,



http://s1254.photobucket.com/user/bhatche/story

 

[fhhuber]

Pic isn't working here....
Maybe put it on imgur.com They are pretty clear about what link to copy and paste.

Without seeing it, an option for bridging a hole is to cut a few strips of stiff foam and glue them inside.
You can "pin" them in place with toothpicks inserted at angles while the glue dries.
Now you have a backing to support new fiberglass.
Pull the toothpicks before applying the actual patch.

Shape the foam as needed... maybe apply some filler to bring it to the right final shape. (this filler is not doing anything but shaping the fiberglass you'll put on top of it)
remember... you'll add the thickness of the fiberglass on top of this!

You don't really care if the foam strips stay, but the "fiberglassing" is pretty sure to make them permanent.

Just have to not use a foam that gets dissolved by your resin (if using poly) but probably you'll use epoxy and cloth (not mat) so this shouldn't be an issue.

The patch will all be outside... so you sand/grind out tapering the edge of the damage out appx 8 X the thickness of the fiberglass.
First cloth layer doesn't quite touch the old fiberglass, second overlaps maybe 1/4 inch , third about 1/2 inch etc till you have the right total thickness and are just out to the gel coat.
Let that cure, and then sand smooth and apply gel coat.

 

[hatcheb]

Thanks for the tip i like that idea with the foam,I am trying to upload photos so you can have a better look, but it does not seem to be working.

 

[hatcheb]

Hopefully one of the below links work




http://imgur.com/C8ZhaH0

http://i.imgur.com/C8ZhaH0.jpg

[Imgur](http://i.imgur.com/C8ZhaH0.jpg)

<a href="http://imgur.com/C8ZhaH0"><img src="http://i.imgur.com/C8ZhaH0.jpg" title="source: imgur.com" /></a>

 

[DeepBlue2010]

Post a picture of that "split", depends on what it is, the repair techniques will vary. Whatever it is, you need to determine why it happened before thinking about fixing. If the cause of the damage is not remedied, your fix will be temporarily. Niw, this mighr apply to your situation or it might not, I dont know. That is why pictures are always helpful

 

[Woodonglass]

Based on your pics here's how I'd recommend doing it. Using a jigsaw or a thin blade on an air grinder or a multitool or dremel I'd cut the crack/split portion open to about 1 1/2" wide. This will allow you to reach inside with your fingers/hand and sand the inside surface with 60 grit paper and then wipe it clean with acetone. Once this is done. You will lay up a series of 12" strips of patching backers. These will be made from one layer of 2 layers of 3oz fabric and cut into 6" x 12" strip. Lay them on a piece of plastic on your bench and wet them out with epoxy resin. I'm recommending Epoxy due to it's added strength and better ahderance properties. Let the first one cure for about 2 hours then peel it off the plastic and take it to the boat. Mix up some thickened resin (Resin and Cabosil till it's the thickness of Creamy Peanut Butter) use a putty knife to butter the inside edges of the crack with the PB. Poke 3 holes in the middle of the Patch about 2" in from each end and on in the middle. Put String thru the holes with a Knot in the end so it won't pull thru. Butter the Patch with some additional PB. Hold on to the strings and slide the patch into the slot then pull it up into place so that it squeezes the PB and mooches it out onto the inside of the hull and out onto the backer plate. Use a stick or whatever to tie the string off and hold the patch in place while the PB cures. 2 hrs and you're ready to repeat the process until the crack has been patched on the back side. You can now effect the glass repair on the outside in the normal way. Again, I'd do all the repairs using epoxy and epoxy based fillers. IMHO you need the added strength. You could use poly/Vinylester but they're not as strong and a bit more problematic to use if you are not experienced using them.

That's how this Old Dumb Okie has Done This type of repair many times with GREAT success!!!

 

[DeepBlue2010]

Never mind, you did it as I was typing. Any idea how did this happen?

 

[hatcheb]

Thanks Woodonglass!. That is a great help, that is how i am going to do it. Which is better to go with Polyester or Epoxy. I see you mentioned Polyester which i like because it is a lot easier on my wallet, according to the research i have been doing. i would like to go with Polyester for the complete fix on this which i believe should be okay/

Thanks again much appreciate, i will post pictures latter on when i get some of the work done.


Deepblue, i am not exactly sure how it happend.the crack was not as big originally as shown in the picture, i cut it a bit to see if i could see inside. The only thing i could think of the happened is that water was left it the boat and was not drained before winter came(by fault) or maybe a lot of condensation was inside which cause it to crack.

 

[DeepBlue2010]

While the technique you intend to use is very well know and documented on the internet and youtube like in these links

most of which I posted in my replies in the past to give reader a visual of the method (not to be confused with trying to claim credit I don&#146;t deserve), this technique &#150; in my opinion &#150; is better suited for the kind of damage demonstrated in the videos where you have unrestricted space behind the damage that you can&#146;t practically or creatively use to your advantage.

Before you settle with a cookie cutter approach, with some awkward/unnecessary steps like widening the damage by further cutting it to be able to sand inside or trying to glue the backing plate by pulling strings but probably most importantly is the risk of deforming the keel shape with the cutting to the point that the backing plate will not be able t o restore the original shape. Here is what I mean&#133;



consider this technique instead which I think more suited for your specific situation, and type and location of damage. You mentioned that you have no access to the damaged area from the back so I am making a reasonable assumption that you have a deck in the bottom of the hull from inside. Something like this



This deck by itself is a backing plate; the trick is to use it as a backing plate for the actual backing plate you need. Let me explain. If you pour in pourable foam in the empty space you have there (the blue colored area in the picture above) and let it over flow (of course you will clean, wax around the damage and mask off the rest of the bottom) then let it cure. Then with a narrow width box cutter blade start shaping the foam to your keel shape, you got yourself the backing plate you need with much less hassle. Grind down, fill and fair as needed to create the shape you are comfortable glassing over.

Now you need to just glass over it as described in the videos above. This is how I would fix this specific damage assuming my assumption of the deck (the backing plate) holds true; but you follow whatever technique you feel comfortable with.


Finally, to address your question about resin, polyester will do the job

 

[DeepBlue2010]

Double post. Please delete

 

[Woodonglass]

Back in the Late 60's and Early 70's when I worked in a small marina, the old codger that taught me about fiberglassing taught me how to do this. We had a lot of Sunfish type sailboats with this exact type hull damage and what I described is exactly how he taught me to do the repair. It always worked great. I've also used in on other types of repairs where it's not possible or necessary to tear out the deck to get to the inside of the hull. If you can get to the inside to sand and clean the hull to get a good bond it works really well. Poly will work just fine. If you use it then the patch layup should be 1 layer of 1.5oz csm, 1 layer of 1708 biax and one final layer of csm. Let cure for 30 mins. Install and let cure for 30 mins and then do the next one. Never had any issues with the hull warping or deforming due to enlarging the crack. I won't happen. If your hull was already a foam filled hull then DB's method would be the way to go. Since it doesn't have foam in it, I'd do it this way unless you want to fill it with foam which, in itself, is not all that bad of an idea since it would add to the safety of the hull!!! Either method will work!!