Microbubbles for end pour?

Does anyone know the approximate weight advantage in using the appropriate mix of microbubbles vs straight resin/hardener for the end pours on a Chesapeake 17LT?

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RE: Microbubbles for end pour?

Hi Gibbs, 

my back of the envelope is anywhere between 3 to 6 oz.

i have a lot of experience building these boats and getting them done at their target weight or better....and to do that you need to pay attention to each step and accumulate a lot of little savings over many steps and then it really adds up to something.

to get a light end-pour, the first trick is to do the end-pour before you do the deck so you can control precisely where the end pour is and minimize its volume.   then, once you do that, you fill that volume with the lowest density material that will do the job.

on the first part, control where the end-pour goes, you only need it big enough to cover the hole you drill into the bow for a toggle or rope.  the end pour's main purpose is when you drill a hole it goes through the end pour and does not open up into the cockpit (which would let water into the boat).  so for me, when i create a little dam to hold the end pour material where i want it, i only leave between 1/4 to 1/2 inch of material aft of the back edge of the hole i am drilling for the toggle straps.  this will typically make an end pour substantially smaller than if you are pouring it blind with the boat standing on its end.

on the second part, what material...i usually use microballoons as well.  the important part is lots of microballoons until you get a peanut butter/whip cream consistency.  otherwise, its no less dense than straight resin.  since the end-pour is being done with the deck off, you can trowel it into place...becuase it definitely is not pourable.

if you already have the deck on, the ability to do above does not exist..there is no weight saving with microballoons unless the consistency is peanut butter or better...and in that case, its not pourable.

i hope this helps


RE: Microbubbles for end pour?

If you're painting your boat, there's also a weight advantage in filling the weave and fairing with microballoon mix, not to mention less work sanding. Same proviso as Howard mentions - make the mix as balloon heavy as possible.


RE: Microbubbles for end pour?

���Tilt the boat. Don't rely on failing end dams. Your weight will be less.

RE: Microbubbles for end pour?

Hi Laszlo,

now I'm curious as I'll have to apply another end layer of epoxy on my WDD underside & cockpit: how to apply the heavy balloon-epoxy-mix in the best way?

BR, Johannes 

RE: Microbubbles for end pour?

Hi Johannes,

I used a plastic epoxy spreader, also known as a squeegee:

The only difficulty is that the more balloons you mix in, the more difficult it is to spread the mix, but for best results you really need a thick mix. A thick mix will tend to curl up in front of the squeegee and need to keep getting smoothed down. It's not a huge problem, but it can be frustrating if you don't expect it. Use slow hardener, mix small batches and plan on taking more time than you expect, at least until you get used to working with the stuff.

You can make it easier to apply by adding more epoxy (but that adds weight and the chance for sagging and dripping, as well as making it harder to sand) or adding cab-o-sil (but that makes it harder to sand, especially if you accidently add too much). Once you get used to working with it it's not really a problem and you don't really need the additives.

Another thing you can do is not worry too much about applying a really smooth and even layer. Smooth and even is great, but the stuff is so easy to sand after it cures that it's easy to fix any problems with sanding.

Before you apply it, prep the surface the same as you would for applying another coat of epoxy.

If you're filling the weave, you can typically do the job with a single coat. For fairing, sand the surface, then put new mix only on the low spots. Repeat until the low spots are all filled in.

Clean off any dust with denatured alcohol and wait double the normal time for the alcohol to evaporate from epoxy. That's because the balloons are hollow and when you sand through the shell it makes a sort of sponge that absorbs the alcohol, so it takes a little more time to completely evaporate.

That's all I can think of for the moment, have fun,




RE: Microbubbles for end pour?

   Thanks a lot!

RE: Microbubbles for end pour?

   I had a lot more luck carving a wood block(cedar), fitting it in and pouring around it. Took a lot of the weight out of it.

RE: Microbubbles for end pour?

  Stripper, " I had a lot more luck carving a wood block(cedar), ........."



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