# Advice for Keel repairs



## Brett (Jul 16, 2008)

Your procedure sounds much like I would do.
Polyester over polyester will work fine, just has to be sealed over when complete.
Polyester is a lot cheaper than epoxy and CSM is engineered for use with polyester.
The binder in the mat dissolves in polyester resin, but not in epoxy.
If you were to use epoxy, then CSM is not recommended.

http://www.westsystem.com/ss/chopped-strand-mat-epoxy/


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## buddy (Jun 1, 2010)

What should I use as fairing to help smooth it out once done?


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## DuckNut (Apr 3, 2009)

If you use poly then get a marine bondo (NOT automotive). If you use epoxy get some filler such as cabosil.

Cabosil makes sanding a real job - phenolic glass beads make sanding much more enjoyable.


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## buddy (Jun 1, 2010)

> If you use poly then get a marine bondo (NOT automotive).  If you use epoxy get some filler such as cabosil.
> 
> Cabosil makes sanding a real job - phenolic glass beads make sanding much more enjoyable.



I'm guessing you mean something like 3m marine premium filler? That stuff is expensive!! Seems like I may need at least a quart?


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## Brett (Jul 16, 2008)

> What should I use as fairing to help smooth it out once done?


Doesn't sound like big repairs. Over build the laminates at the repair sites
then block sand to level, no fairing compound needed.
60 grit on a small section of 2x4 will cut it down quick.
It's the underside of the hull and is going to get chewed up again.

No need to go for yacht finish...


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## buddy (Jun 1, 2010)

you're right Brett. A yacht it aint. It'll be a pond, creek and river fishin' boat!! And thanks for the help from everyone. Now one more question.

I want to stiffen up the floors and I know I can put down false floors, but I was wondering if I could just lay some biaxial tape down the keel on the inside and then a layer of mat out to the first ridge. 

I would like to add the false floors but I don't want to spend money on the marine plywood and epoxy resin to coat it. If I could get by with top quality plywood and poly resin I would do it. This boat won't see any water from chop or waves. Just from fish and If I get caught in the rain, maybe once a year.

Which way should I go? Plywood and poly resin or just lay biaxial tape and then mat?


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## DuckNut (Apr 3, 2009)

On your second question there is no right answer, you need to decide what will be the best overall solution.

Example: if you are going to haul this in the bed of your truck and drag it into a pond then "I" would not opt to put a heavy sheet of plywood on the floor.  

The hull may seem to be on the flexible side but many small boats are designed that way.  They actually get strength integrity when they are on the water.  If you look up racing canoes you will find that they are so thin that you can see through them and if you stand in them on land your foot will break the hull.  However, when they are on the water they are quite strong.  They are built for a particular purpose and they achieve it well.

Cloth will add some strength, mat will not unless used in conjunction with more cloth (adding more weight). If you have gel coat you would need to grind that down to remove it before you add the additional glass. It is a messy, nasty job.


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## buddy (Jun 1, 2010)

I am having a hard time finding biaxial tape locally. Should I order it or will cloth do the job? Also, I was planning on 6 oz biax tape instead of 12 oz. Which one 6 oz or 12 oz? I am running two strips down the keel offset by 1".


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## DuckNut (Apr 3, 2009)

If you put where you live in your signature then we might be able to assist with suppliers in your area. 

If you are going to continue to drive your boat onto land then go with the 12.


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## buddy (Jun 1, 2010)

> If you put where you live in your signature then we might be able to assist with suppliers in your area.
> 
> If you are going to continue to drive your boat onto land then go with the 12.


Yep that makes since. Signature updated!! 

I never drive it on land just in the water . 

Typically when I off load it I then pull up to the bank and the nose barely sits on the edge of the bank 'til me and my son get in then the same thing when we come back in. If I can find the 12 oz. I'll probably use it but if not i"ll test the 6 oz and see how it performs for me.


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## Brett (Jul 16, 2008)

6 oz will do the job, no problem, just takes twice as many layers.
Build up to the thickness needed, let harden, sand smooth.


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## buddy (Jun 1, 2010)

Okay I ordered the 12 oz biaxial last night. Hoepfully it will be here in a couple of days. Just for funsies I called a fiberglass shop that was rewcommended by a supply house that sells autoboy repiar supply, Finishmaster.

I aksed the fiberglass shop if they had any and they said, we don't use it, why don't you just use some mat. Thats what we do to make repairs on the bottom of boats.

Not saying that it might not work, but that is not in agreement with everything else I have read and learned.


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## buddy (Jun 1, 2010)

This has probably been done before but I thought I would share anyway. 

I was wondering how to get the shape/profile of my keel to make the repairs. At first I bought a pool noodle and it looks like it would work just fine. Then I had an idea about using "flower foam". The green foam that you pute in a vase to hold the flowers!! This is the small pore kind that is easily shaped. There are two types like this, one that is meant to stay wet for live flowers and another that is meant for dry or fake flowers. The dry stuff is tougher than the one that is meant to be wet.

ANyway I used a tablespoon to get close to the shape and then I took the bloakc and rubbed it in the keel on the inside of the boat. A minute later I have the exact profile! I'm gonna put some parchment paper over it then lay the fiberglass!!


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## DuckNut (Apr 3, 2009)

Not sure of what you just said. Did you fill the hole with foam crumbs?

You want the cloth/epoxy to fill the hole and if you filled it with foam pieces then when you apply the epoxy it will stick to the foam and you have not gained much. 

One way to do it is to take a piece of plastic and lay it over the hole on the inside and cover it with something just to prevent the application from the outside from pushing all the way through. Then you make the repair to the outside and after that has kicked off you remove the plastic from the inside and finish the repair. After it is dry then you sand it down using a sanding block or a long board to get the profile.


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## buddy (Jun 1, 2010)

It all sounded just fine in my head. When I was typing the wife was talking!!

What I was trying to say is that I was trying to get a backing for my fiberglass that had the same shape/profile of the keel. I was going to use a pool noodle on the inside but thought of this foam. The foam was "shaped" by rubbing it inside of the boat on the keel. This essentially "sanded" the foam down so it had the exact profile of the keel. 

Make sense now? I am going to cover it with parchment paper, tape it in place inside the boat then start laying the fiberglass up from the outside.

If I didn't explain it clearly that time maybe I should just take pictures tomorrow and post them. I know sometimes the thoughts are clear in the old noodle but the translation between there and the fingers gets garbled sometimes!!


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## DuckNut (Apr 3, 2009)

Yea man you gotta tel the wife to give her jaws a break. Crystal clear now.


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## buddy (Jun 1, 2010)

I have viewed several videos on fiberglass repair and the one thing that is counter intuitive is that when patching a hole, you use a big patch first and then sequentially smaller patches. I would think you would start with a small patch and then get progressively larger.

Why from large to small instead of small to large?


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## Brett (Jul 16, 2008)

The hull around the hole is ground down from the edge of the hole
tapering up to the surface of the undamaged hull.
Fiberglass is laid back in to fill that hole, thinnest at the undamaged perimeter
thickest over the hole itself.

Green is the hull, hole sanded tapering back.
red is the individual layers of 'glass filling in the hole.


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## buddy (Jun 1, 2010)

Thanks for the drawing. That is the way I undertand it should be done, btu my thoguth process is opposite of that. I thought thet smaller to larger would be better. On some sites it shows starting out smaller and working to larger. While the majority shows it like you have.

Also, if I lay up 3-4 layers of poly, mat, biax etc. and then let it dry do I need to sand before applying anymore layers? I think the answer is yes but I am not 100% sure!!

Buddy


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## DuckNut (Apr 3, 2009)

Your thinking is correct.


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## buddy (Jun 1, 2010)

So the fiberglassing has begun. I mixed up a little resin last night to put around the drain hole where the bottom meets the back. The wood had a small crack in it so I poured a little in it. I mixed it so that it would take a little longer to set up so it would soak into the wood. That was last night at 8:00 and it finally "kicked off" around 9 this morning. It was a little cool last night ~60 degrees and humid. 

Today I learned:
-in the heat it dont take long!!
-aluminum foil is not a replacement for peel and ply!!
-I made my first batch of resin jelly (after about 8-10 minutes) then it set up and made a nice resin disk!! I think my son will enjoy it!! 
-I needed more layers than I thought for the first repair. 
-You need to have everything layed out around you prior to starting!!

This will definitely be a DIY adventure. I love DIY because of the learning!!

You know they say the best way to learn something is to screw it up the first time!!! :

I say nothing ventured nothing gained!!! I love the smell of fiberglass resin in the morning!!


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## buddy (Jun 1, 2010)

Repairs are going good. My forms worked well!! I need to build it up a little thicker in a few spots before I put the biax down the entire keel. 

I wont be able to do anything else until Monday. I didn't take before pictures but I will take some intermediate pictures and final finish pictures!!!


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## DuckNut (Apr 3, 2009)

You can trick poly into kicking at 60*. Use a hair dryer on high heat with low blower. Get it warm enough so it will kick but dont get it hot. If you can't hold your hand under the dryer it is too hot. Also heat the surrounding parts of the boat so it will take longer to cool. I have tried it colder but it is a tremendous amount of guess work.

Or you can simply add a few more drops of MEK per the instructions but if you didn't do that in the first place then use the hair dryer.


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## jms (Apr 21, 2011)

try and avoid heating a polyester resin mix-it's gonna cause it to kick off too fast ...

also,that picture showing layers of matting,applied in a "large to small" manner,push on the middle of that,what happens ?
make your repairs opposite of that - "small to large"

on underwater repairs - it's best to use an epoxy based resin - polyester based resins are pourous,which,if not sealed by an epoxy barrier coat,these can suffer from osmosis - water migration...epoxy based resins are a better choice...
also,"parchment paper",you may wanna try waxed lexan,or gloss formica taped in place-this will act as a mold...remember when performing repairs - the hull has to be repaired on both sides,to insure a fully structually sound repair...


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## Brett (Jul 16, 2008)

Small to large? Wouldn't large to small produce a better repair?  :-?

My reasoning being...
The first layers of material are laminated over a larger area of existing hull,
creating a stronger mechanical bond between the original fiberglass surfaces
and the new overlying patch/laminations. With the smaller patches on top,
finish sanding is going to be removing material from the smaller diameter material
leaving the long strand materials still fully in contact with the hull.
I wouldn't use CSM, I'd want woven material in the layup, especially if the repair is made with epoxy.


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## jms (Apr 21, 2011)

small to large - reason being - the entire area is glassed over...
think about a cut for example-you fill the small section first,then continue on with ever widening pieces...also,an area to be repaired is "dished"-by using smaller pieces,cut to fit,all matting is atached,get what i'm saying here ? a large piece first,is gonna be difficult to cover without voids - then,adding smaller pieces to that - what about edges ?-remember,the surrounding area is ground out,to almost a knife point - it "tapers" ...


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## Brett (Jul 16, 2008)

I see your point, it is a double-sided plug.
With it being a tapered fit from both sides of the hole
and bonding to itself through the surface area of the hole,
it's a logical method of lamination and will be as strong as the original hull.


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## buddy (Jun 1, 2010)

Okay guys I have all three holes patched from the outside. I also have all the gel coat sanded off down the keel to the first chine on each side.

Now I am going to lay the biaxial cloth down the keel layering two pieces offset by 1". 

The question is how long should I cut each piece? I dont think I could actually run one piece the entire length (15'), let it set then lightly sand and run the other piece.

I think I'll cut them to some length, maybe 2-3' and lay both pieces at the same time. Let is set then do the next length.

Which way would be best???


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## buddy (Jun 1, 2010)

> Okay guys I have all three holes patched from the outside. I also have all the gel coat sanded off down the keel to the first chine on each side.
> 
> Now I am going to lay the biaxial cloth down the keel layering two pieces offset by 1".
> 
> ...



Any help?? Come one guys...don't let me down. :-?


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## Brett (Jul 16, 2008)

1 long run would be my choice.
Wet out the area with a "cool" mix resin.
Unroll the first strip down the keel, wet it out,
roll the second strip down the keel, wet it out.
Work the air bubbles out of the layup.
Let harden, sand to desired finish.


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## buddy (Jun 1, 2010)

Cold huh..If I typically use 12 drops per ounce of resin, what shiuld I use? Maybe 6-7 drops?


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