Sorry, don't know why the pictures don't show. I'll give it another try with an url:

http://picasaweb.google.com/mariska.hoogenboom/Chesapeake16#5361646986003385426

Mariska,  It is a little difficult to tell from the photo, but it looks like you may have some trapped air pockets.  Adding microballoons does not make a chine stronger, only lighter.  I am not familiar with aerosil, unless it is another brand of silica powder (Cab-o-sil).  It is my understanding that silica does provide a stronger, harder epoxy fillet than microballoons and epoxy alone would.

If those are air pockets, you could fill them with slightly thickened epoxy by drilling a small hole into the bubble and then use a syringe to pump the material into the cavity.  Chances are pretty good that you don't really need to do anything to make them stronger if none of the bubbles are deep into the fillet.  If this is in an area that will show when you are done, like in the cockpit, you could just skim over the fillets with some epoxy mixed with a lightweight filler such as West System's.  Best wishes - Ron

Unfortunatly, I would chalk this one up as a lesson learned and make sure to use wood flour next time.  You can also mix epoxy, wood flour and some silica which makes a nice blend.  I think that your filet is strong enough as it is.  Good luck!

Thanks.

I'm definitely going to use wood flour next time, although it will take some time sanding to create enough!

That's the nice thing of building your first kayak: there are so many things to learn.

BTW: aerosil is a silica powder.

You can buy the wood flour. CLC has wood flour and Woodcraft stores carry it too if you have one near you. Check out their web site.