Keel gaps revisited

[tomstock]

Well, today was the day. I finally decided I had done enough work on the topside and flipped the boat to prepare the bottom for glassing. Now, keep in mind I haven't seen the bottom of the keel since Week 1. Boy was I disappointed. I guess I have come a long long way, because my early mistakes are painful to look at. I have gaps between the planks along the bottom of the keel wide enough to stick a credit card in. There are also a few spots where I can see light between the hull bottom and the keel.

Obviously I'm stuck with this, but I have an idea:

I could go ahead and fillet the keel to hull with bondo. Mix up a batch of epoxy thinned with denatured alcohol, and use a syringe (or a few) to squirt thinned epoxy down between the keel layers until I fill up all of the visible air space (the fillets will keep it from running out of the bottom). Obviously I can't get fill all of it, but it's better than nothing.

Second idea is this:

Use fiberglass resin to fill the space since it'll be easier to sand and surform. Use thickened epoxy for small fillets (for strength), and then bondo over them with larger fillets for looks. Fiberglass is pretty brittle, so I'm thinking epoxy is the way to go.

opinions?

[ken connors]

if your looking for opinions, heres mine...... forget about the bondo. it never really seemed like suitable filler for a boat to me. not that i can say i really know what im talking about. my boats only been at her mooring about 3 weeks. she could have an epoxy failure and sink tomorrow. but i used thickened epoxy for all those types of things. if it was structural, i used wood flour. if it was just fairing, i used microballoons for easier sanding.

[tomstock]

I hear you on the epoxy. I've used thickened epoxy for all of the gluing on my boat and the stuff is incredibly strong. I was able to break the joints of the resin glue, but no way I can do that with the epoxy.

However, I did use bondo for a lot of filling, fillets, etc. Epoxy for that was just overkill and a lot of work to sand.

[Frank Hagan]

Here's the thing about mixing Bondo and epoxy:

Epoxy will stick to Bondo, which is polyester resin based.

Bondo will not stick well to Epoxy.

It sometimes works, especially if the Bondo is encapsulated in epoxy. It then serves the same purpose as a piece of wood in there.

Otherwise, I think your plan is sound, but may even be overkill. Put the fillet along the keel and try filling the cracks. They could take a lot of epoxy though, and that could get expensive.

Are you going to trailer sailer the boat? If it is going to spend most of its time on the trailer, and has time to dry out between sailings, you can probably get away with using enough epoxy in the cracks to seal the wood down there, but if it gets to looking like it will take up your epoxy budget to completely fill the cracks ... don't worry about it. If the water can drain out, and it won't be sitting in water at the dock, you won't have a problem. There were lots of wood boats before there was epoxy.

The one thing you want to avoid is having a pocket of air in there, so you're right in not wanting to just lay glass over the top and try to seal it up. Water will get into that pocket of air and then it will rot, because it can't drain out and dry out the wood.

[Craig]

Good advise Frank. Tom, the smaller the keel fillets are the better. Use thickened epoxy and keep the about 3/4 to 1" maximum. If you recall the older aircraft all had big wide sweeping fairings between the wing and the fuselage. I made a fine living ripping these off and making smaller speed fairings. Speed fairing and squaring the wingtips of a DC3 would add 8 kts to the maximum airspeed. The drag coefficient works the same way in water. I'd say use epoxy fairings and fill till you are tired of it, paint the keel and go sailing. Believe me I know about bad keels. I am reworking mine now. Your narrow gaps will not readily take much epoxy so, unless you are prepared to open them up and pour in the epoxy follow, Franks advise.

[Florin {VACATIONER}]

Like Craig said, use the epoxy... we've ended up having the same problem but we've noticed it before we installed the bottom to the keel. Either way, we warmed up our epoxy components in hot water before mixing to help thin them out as much as possible and injected them into the cracks with a disposable syringe. Yes, it took some time but it was worth it I think. I don't believe thickened epoxy would flow in as well... you may end up with some undesirable air pockets which may get filled with water later on and create delam... yuck!!!

Good luck

Florin

[Barry Pyeatt]

If you heat the epoxy to about 110 -120 degrees before you mix in the hardner. It thins out to allow it to penetrate and flow deep into the voids. This can best be accomplished by heating a container in hot water.

Then you can use a syringe if it helps or just pour it into the cracks if they are oriented so that pouring is practical. I've often used a section of vinyl tubing on the end of a small funnel or syringe to get it into some areas.

Surprisingly, it doesn't take a lot of epoxy to fill most separations as long as the separation is closed so it doesn't just run out. For larger areas do it in stages that will allow it to settle and cure before adding more epoxy.

[Zeroice]

I used polyeruthane glue to fill these kind of gaps. It flowed int th egaps well and expanded as it dried so that it spread into the entire gap well. At the time of pouring the glue the boat was upside down. It also filled the gaps I had between the boat bottom and the keel.

I've had my boat in the water a few times last year after completion and it survived a wet cold winter on the trailer outside as well with no keel delamination.

[Florin {VACATIONER}]

I did my best to stay away from "foaming" polyurethane glues under the waterline. Since when they cure they are poros, I'm not sure if they wouldn't end up wicking up water in the joint if the finish layer was breached.

Glad to hear I was wrong about that.

Cheers

Florin

[tomstock]

Hi everyone. Ok, today I spent the entire day working on the bottom of the boat. I trimmed the hull sides, filled in all screw holes with bondo, and rounded the keel with my router. It's looking pretty good.

I mixed up a huge batch of bondo to make the fillet along the keel, and quickly discovered it was going to be a mess and the bondo was curing faster than I could work. I removed all of it when it got rubbery, and mixed up a big batch of thickened epoxy. I did the fillets with that and they look good. I had plenty of working time since this stuff takes about 12 hours just to get tacky. Haven't filled the gaps yet. Will do that this week.

Once it cures it's incredibly strong. So strong that today I tried to remove a screw which was placed when the epoxy was wet. The screw head spun right off the screw.

Anyway.... fillet looks good, but the bad part is that I managed to get epoxy and bondo all over my hands and my stomach (no shirt on). I scavenged my father's house for vinegar and the best he could do was hand me a pint can of pickled jalepeno peppers. Well, the bondo was starting to burn so I had no choice. I washed my hands in the vinegar from the peppers (and ate the entire can of peppers in the process).

Problem is, it's now 2 hours later and my hands are burning again. I can't decide if it's the epoxy, the bondo, or the pepper juice. I've washed my hands in everything I can find (vinegar, alcohol, soap, etc) and it hasn't changed much. My side isn't burning, and I didnt get epoxy there only bondo, so I'm guessing it's the epoxy.

Lets just say I learned my lesson. I'll be wearing gloves from now on.

Does this mean I just became sensitized to epoxy?

BTW: I thought the hand burning was painful until the peppers made it through my digestive tract.... things really got interesting for an hour.

[Frank Hagan]

We'll have to make you "safety monitor"!

Usually the sensitivity to epoxy causes a rash, not burning. The pepper juice might be causing the burning, so try some baking soda mixed with water to make a paste. Or calamine lotion.

Check your local Home Depot or Lowes for latex gloves and maybe a tyvek painter's overalls or jumpsuit. It will save you money in the long run.

The one thing I worry about with applying vinegar or acetone to epoxy on the skin is that it will cause the thinned epoxy to penetrate into the skin, increasing the chance of developing a sensitivity. This happens through latex gloves as well, although it takes about 30 minutes for vinegar to penetrate latex, IIRC. Better to not get the stuff on your skin in the first place, and change gloves rather than trying to clean them.