Keel Repair

[orienter]

While on a business trip, my boat slipped its moorings. It's basically ok but there's a small (5x5 inches?) dent in the keel. What's the best way to repair this?

[c_amos]

Welcome aboard!

What boat do you sail?

There is quitea bit of info here, the 'search' button is your best bet to find it.... But Tim's repair of the Keel on Ariel #24 is probably a good start...

Here is the link. (http://pearsonariel.org/discussion/showthread.php?t=1558)

[commanderpete]

Basically, you have to grind back/bevel the damaged area. Then lay in layers of fiberglass to build it back up. Then fair it smooth

Some people use progressively larger patches of glass, some the other way. You can use just cloth, but layers of matt between the cloth adds bulk quicker

A good DIY project, since its hard to screw up, if you measure the epoxy right

Pics always help

[commanderpete]

While I'n thinking about fiberglass.....

I like the 2:1 epoxy since its more foolproof to measure

When you think its mixed enough, mix it some more

Its too expensive to use a graduated mix cup for each batch. I'll dedicate one for resin and one for hardner and pour each into another container for mixing

The picture below shows some of the implements I was using for a fiberglass job

The rectangular plastic containers were probably for holding acetone soaked rags, with the lid on so they don't dry out. I usually mix the epoxy in small round plastic food storage tubs.

Also not pictured is those tinfoil roasting pans or lids I sometimes use to wet out the fiberglass on.

There should be some white vinegar around

Even with a brush. roller and squeegee, most times I end up using my hands to mush things around

[carl291]

Enclosed are a couple of pictures of a keel repair I'm starting on. My question is , should I just cut back a couple of inches from the damage,"V" the hole out and start laying in the cloth for the repair, or should I make this a uniform shape and then lay the filler back in? I would think the smaller the "patch" the better!
I might add this is in the encapsulated ballast area. The ballast on this boat is totally sealed off from the bilge, which in this case was a very good thing since only enough water entered to fill the ballast area, had this area been open to the rest of the bilge it would have surely sunk the boat.
I've drilled a couple of holes to drain the water out and dry before starting repairs. I also plan to put a couple of gallons of 4 to 1 epoxy in to fill what I believe is a hollow area under the lead ballast.
Thanks Carl

[c_amos]

Carl,

It it were me, I would get an angle grinder and grind out the bad until I got to the good.

Basically, I would keep the cutting wheel broad to the cracks and grind out the cracks until there were no more cracks. The nice thing is that your repair (done correctly) is going to be as strong or stronger then the area you repair. I would get as much of the damage out, and not be too concerned with getting a geometric shape (circle, oval, whatever).

The grinder will tell you when you are done. Go slow, and take frequent breaks.

It will all be ok.

[ebb]

Hey Carl, one opine here...
You know you're going to have to dish that broken area out,
So I would draw a generous border around the damage with a sharpie.
A border that represents the last and largest of concentric fiberglass pancakes you will fill the dish with.
In the beginning I would try to stay within the border.

I would start grinding on the completely broken piece in the center
- and just DISH out the damage until you see what you have. Widen the dish shape from the center. You may have enough integrity in the attached pieces that they might stay. If there is any white in the attached hinge parts (broken glass or crystallized plastic) you will have to remove it. Either you will end up with a very small hole OR a large one.

After you have ground out the dish:
You can use the lead ballast to build on if you see it in there. Use it to rebuild the hull composite by making a landing to start the first skin repair layers. It might be argued by some that you don't want to glue this one piece of the hull to the ballast. Make the separation with anything: cardboard, fairing putty, even a wad of folded cloth. It'll get semi saturated. But you want to rebuild skin integrity with a repair that is more or less the same scantlings as the original.

I'd want to immobilize the broken pieces you believe are OK to stay. I would V down into the broken seams to see what's there. Hopefully it's solid not frizzy. Fill the grooves with a chopped strand putty mix.
But I would stay with an overall dish motif, so that you have a regular shape to fill. You fix the oddball broken bits as you sculpt the dish.
In other words: fix V-grooves, fill holes, let them set then regrind to your dish. However you could, if you are a magician, do all holes and glass layers in one a final coup.

GUD LUCK

But make sure you end up filling the depression with a multitude of concentric fiberglass pancake layers - smallest in the deepest part building out with larger pieces.

- that's where the strength of the repair will come from.


If you have a plan you can precut the whole stack of glass cloth/Xmatt, wet the stack out on a piece of plastic, and slap the whole thing in the hole. I'd probably do it in thirds.
Then you want to put mild pressure on the patch to prevent sagging and to compact and squeeze out extra epoxy juice - until it begins to set
Thin bendy ply with a SeranWrap (polyethylene film) or Mylar separator.

Use the best 100% solids (no solvent), no blush, laminating epoxy. 1 to 1 or 2 to 1 - part A to part B. West Systems has a bad rap with blushing and formaldehyde in the hardener , so see if you can find another brand.*
Commercial alcohol does a good job with cleanup - avoid acetone.


If you are using a 4" Makita-style grinder, some of the best angle grinding is done with the diagonally stacked compact sandpaper disks. There are a number of different styles and brands.
__________________________________________________ ____________________________________
*However, West Systems 407 fairing powder that you mix with laminating epoxy to make a fairing compound 'putty' is great stuff and can be used below the waterline.

(this is all imco)

[carl291]

Ebb and Craig , Thanks
I attacked this with an angle grinder, then switched to a 4" cut off wheel on my drill, the grinder was just too dusty!
The few pieces left are just thin cloth pieces I left to have some type of backing for the first layer of cloth. I'm installing two layers of cloth at a time, I must be working slow cuz the epoxy is beginning to kick before I can do the third layer.
This damage is actually above the ballast area in the bilge as noticed when I saw the bottom of the water tank through the hole I cut. Rule must make a good pump to have kept up with this leak!:p

[ebb]

Carl, I think you should go wider with the dish.
Meaning shallower not deeper. Go further out from the hole. Like four/five inches. Can't tell the scale.
I think more repair cloth should be attached to more good hull.
The last wider pancakes are fewer in number so you want more area to attach them to.
I would use cloth rather than Xmatt.
And turn the weave of the cloth 45 degrees when you stack them. Random.
If you are going to stack more than the hull thickness and grind down to fair the patch with the hull, top fabrick layer should be Xmatt.

The pieces you have left as backing are probably thin enough not to detract from the final thickness of the repair. It looks like you have a hull like #338 which is not very heavy in thickness. 5/16" is what Little Gull has.

I think the repair will benefit with wider patches - even if there will be fewer layers of them. Try not to use any fairing compound to fill any depressions in the patch itself. Fill with cloth, grind flush, then fair with compound for a smooth surface.

This dish thing is to make a bowl, however flat a bowl it is. I don't believe a flat center with short rising sides to be a strong shape. It's OK to have a flat, but the sides need to be widened and stretched way out to get benefit from a graduated layer patch.


Put it on your future list to add cloth to the inside of the patch if the area ever gets exposed. This will lock the repair in place.
__________________________________________________ ___________________________
I hope you go with a much wider dinner plate (maybe 'dish' is not appropriate). Might take a piece of 6oz cloth and lay it in wet over the whole prepared area inside the blue surround
making an inner skin for the rest of the filler layers.
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The UNCONVENTIONAL way. (this is all thrown out here for discussion - not instruction.)
I believe this is the BEST WAY for a thin laminate:
I came across a guy once who did the whole conventional sequence backwards, starting with the largest patches first, then smaller and smaller ones in til the hole was level and the hole closed.
The argument for this is that when you end up grinding on the patch to make it flush and smooth you are more likely to be grinding only edges on the filler layers. Each layered piece in the bowl is still whole except for its perimeter getting smaller. That means the integrity of the patch is unchanged as it gets thinner with grinding. IF grinding proceeds only smaller end pieces get wasted, not the important ones tying the hull together.
This is not the case if you grind into the last layers of the conventional scenario.

Each to his own, imco.
__________________________________________________ ________
If you end up with a large hole I have an idea for an even stronger repair....

[carl291]

Ebb,
I agree with you on a wider "dish". I've stacked 6 layers of biaxial cloth randomly and then came to the conclusion I needed a wider base to grip the new material to the hull. Next weekend I'll sand of about 2 layers off, go bigger on the repair. 5/16" is correct I would think on hull thickness in this area, so I need plenty of grip area for the patch.
Also, the water tank is easily(??) removed and I will clean up the inside of the keel and put a large patch there.
The entire afternoon I was patching this I wasn't happy with the way I had cut back the hull for the patch, it just didn't seem like enough grip area. It is very helpful to see your post confirming my thoughts.
Thanks again for your help

[mbd]

I wonder if you could approach your keel repair similar to Tim M's repair on A-24? He detailed the job very nicely.

Start on post 88...

http://www.pearsonariel.org/discussion/showthread.php?t=1558&page=3

[Commander 147]

if the hull is 1/4" thick you take 12 times 1/4" or 3" wide bevel around the hole. Just measure out a point 3" around the cutout several places and connect the dots. Then grind out to the line.

My experience with 1708 biaxal mat while I closed off a couple of through hulls was that it took 1 layer of mat for every millimeter in hull thickness to bring the patch flush with the surounding surface. 1/4" is 6.35 millimeters so use 7 layers. You can always grind it down a little if you need to. Here is a link to a metric convertion web site. Just plug in the dimension you know and click the calculate button to find the metric conversion.

http://www.worldwidemetric.com/metcal.htm

The way to size the patch layers is to decide how many layers are needed. Then make the smallest patch the same size as the actual hole. The largest patch is the same size as the widest point of the bevel. So for example if the bevel is 3" wide as in the above example and you are using 7 layers of biaxal mat each patch would be approx 7/16" smaller all the way around (7/8" less in diameter) than the preceeding patch.

Carl in your case due to the size of the hole you will need to install a backer on the inside of the hole. Follow the method mbd gave you the link to for Tim M's repair.

You can wet out the entire stack of patches on the bench on top of a piece of visqueen. Wet out the smallest patch first and then the next larger and so on until the largest patch is on top. Before you start wetting out the patches wet out the bevel area around the hole on the hull.

Then you can pick up the entire stack with the visqueen and put it over the repair area. The largest patch goes against the hull first. Then because you have the visqueen still covering the wet patches you can just squeege out the entire stack of patches all in one fell swoop. Leave the visqueen on the patch until it cures and then peel it off.

After that when the epoxy has cured you can grind any high spots and then mix a small batch of epoxy with microballons to make a fairing compound to fill any low areas. After that has cured sand flush and wet out the entire patch area with one more layer of epoxy to seal everything. Then you are ready for barrier coat and bottom paint.

That's my opinion and I'm sticking to it. ;)

[ebb]

Mike's Post #11:
.
Lots of photos, well documented, innovative.
Tim also starts with the largest fabric in his baklava and proceeds with progressively smaller. That's the way to go.

Jury's out on whether to start with a clean hole or leave the attached 'flaps' for backing in the hole. Can argue that the flaps are well attached(?) to the inside of the repair. That's a good thing in my book, because that will help bond the repair.

If I had a hole I would take the largest piece of fabric, put it over the hole, draw the shape of the hole with a sharpie, lay it out on the visqueen, wet it out, then cut with a new utility blade a series of triangular darts from the center to the perimeter. You might find that a new pair of Fiskars type scissors does the job easier and cleaner. Then place the wet cut piece back over the hole and tuck the darts inside around the hole. That's your lock on the hole.
Then proceed with the next layer and merely span the hole. If your cloth is too thin then put a piece of wet 24oz Xmat across the hole.

Or you can, of course, let the bendy span set up and get hard, then proceed.


I also disagree strenuously with the use of amine blush epoxy. I am a stop and go again epoxy guy. I depend on cold laminating steps. Often I want to stop, let the work set, then proceed. When it's hot this is the only way. Imco you have maybe 3 days to layer new fabric on a series repair with no prep (sanding to create tooth.) You cannot do this with epoxy that blushes - all laminations have to be hot/wet. You cannot remove amine blush until the epoxy is cured hard. You have to scrub it off with a scothbrite pad and water. You cannot sand it off. (West Systems says you have to assume that all their epoxies will blush every time they are used. If you let their epoxy go hard then you must wash and sand to go on to another step.

RANT
Why scrub and sand your work, as Tim has to, to remove the blush so you can go on to the next step?
How can you know you are removing all the oily wax from the weave of the cloth?
Epoxy that blushes is CHEAP EPOXY no matter how much you paid for it.
It is adulterated epoxy no matter whose name is on the label.
I have to depend on cold bonding if I stop and go.
How can I trust my build-up and laminating if I have to scrub contamination off my work each time I want to proceed?
There already are myriad steps and pieces, time constraints, tools and bits, mixtures and mixing to epoxy work.

Get a pure no blush epoxy from a reputable manufacturer or dealer.
There are ethical people who make it.
That will mean you can stop, let the work set, and then proceed without BS.
Get your stuff from them and insure that you are not creating a STICK & PEEL repair on that underwater hole on your baby..
END OF THIS RANT

[carl291]

I manage to get on the repair today,
I ground off about two layers, excluding a couple of small high spots which I smoothed out the patch is now as true as the rest of the hull.
I then beveled the hull out about 2.5 inches all around the hole and then layed on a 12"x16" patch. After this was done I came in and turned the computer on:eek:!!!!
I'll need one more layer to bring the height up to match the hull. At this point I'll grind out about 2 more inches around the last layer and lay the final patch on. Smooth and quit, on the outside. Then I'll lay a 12x16 patch on the inside
The small hole at the bottom of the keel I'll use to pour epoxy into to fill the void beneath the ballast. On this hole I'll try the large patch first and work smaller from there. As Tim did on A 24
I'm using 1:1 epoxy from Fiberglass Coatings Inc. out of FL. This stuff is nonblushing , in this temperature has about a 25 minute working time.