Sand until they are smooth . . . or you are sick of sanding (whichever comes first). A light sanding is enough to prepare for varnish.

Of course, the best way to get smooth fillets is to rub them smooth with denatured alcohol while the epoxy is still tacky.  

   Roger that.  The hull was assembled in a class at the GLBBS I did'nt learn that little trick until returning home.  While I look forward to the finished project, I am enjoying the "process".  Thanks for the reply...........

FYI, another way to get glass-smooth fillets is to paint them with unthickened epoxy using a chip brush. Using epoxy avoids introducing a solvent/contaminant, as well as providing a very thin top layer of pure epoxy which is much easier to sand than even an alcohol-smoothed fillet. It also provides a bit of extra eposy to help wet out any tape that gets put over the fillet.

If you don't mind a bit of extra weight on the boat, you can also apply a cosmetic layer of epoxy woodflour to the existing fillets and paint those smooth. You'd be trading weight + larger fillets for less sanding.

Have fun,

Laszlo

Laszlo, not sure i understand, when  you say "paint them with unthickened epoxy"?  Would you not get the same effect after applying a coat of unthickend epoxy to the entire interior of the boat per the instructions?  I also did not smooth my fillets out with  alcohol before they cured and was thinking that subsquent coats of expoxy would fill the craters.  

Oceanluver,

The trick is in the timing. If you paint the fillets with epoxy while they're still soft, they get glass smooth. If you paint them after they've hardened then you have to count on the epoxy filling the craters. That works fine on small craters, but not on larger ones, or on bumps and valleys. Painting the soft fillets takes care of those.

Laszlo

 Good stuff, thanks for the advice..........................Dave  

   If you still need them to be smoother after all the above, you can use the rounded end of an old hacksaw blade like a cabinet scraper to greatly reduce sanding time.  The back side of the blade (opposite the teeth) makes a pretty good scraper for flat surfaces.

Hooper Williams - Brevard, NC

   Working in the Florida heat, the window for smoothing the fillets with alcohol is easy to miss. I found that shavehook blades worked extremely well to smooth them after the mixture has cured. If you can't find the exact profile (I've collected almost a dozen over the years), they are easy to shape on a grinder. 

   Wrap a piece of sandpaper around a piece of foam pipe insulation. You can squeeze the foam to conform to different fillet radii.

  Roger that.  thanks for the advice