I taped the ones on my WD12.

The only reason I can think of for not taping them is that while the taped seams are stronger, the untaped ones are strong enough. That being the case, untaped would be lighter, cheaper and need less labor.

Have fun,

Laszlo

Additional thought -  your manual says "Every interior joint of the hull assembly will get a thick epoxy fillet..."

I made my fillets as thin as possible. I used the approach that the fillet is there only to support the glass and to make sure that it meets the minimum bend radius for the glass. The actual mechanical strength comes from the glass tape.

It sounds as if your construction manual is depending on the fillets providing the strength and the glass providing extra strength where the fillets aren't strong enough.

Personally, I like the minimal fillet + glass approach better. If the glass by itself is strong enough (and it is), why add the weight and expense of thick fillets?

Additionally, fillet material is brittle when it cures while glass retains some flexibility. Long term this should mean better performance from the thin fillets in an application where everything flexes, such as a boat.

FWIW, even with the glassed fillets and completely glassing the inside of the hull and deck (which was not in the manual), my WD12 still came in below the catalogue target weight. And it's lasted over 7 years.

Have fun,

Laszlo

   "minimal fillet" ............ok but on the bulkheads with a likely 90 degree joint you don't want the tape to have a "sharp" non radius turn. Sharp turns in cloth can make voids and or be brittle.  Don't make your fillets to minimal. Be sure during tape application that the space behind the tape gets full penetration and filling.  

As long as it meets the minimum bend radius requirement it can be arbitrarily thin. Any thicker is wasted weight.

The required thickness is 0 for perfectly flat butt joints and is maximum for 90 degree joints, going back down to 0 as the joint closes up like a book. Probably proportional somehow to the sine of the angle of the 2 pieces of wood.

A good way to make fillets be minimal yet thick enough to meet requirements is to use a rounded putty knife to apply the epoxy/woodflour mix. For 6 ounce or lighter cloth the minimum bend radius is about the same as the US nickel, so just round the putty knife to that radius. Then, put the putty in the joint and slide the rounded putty knife over the fillet. The result will be the minimum size fillet needed to support the cloth at its minimum bend radius. It automatically adjusts for the joint angle.

Have fun all,

Laszlo