Hi Belton,
I have been paddling/racing a RBA for several years without a rudder. I paddle inland waters including large lakes, small lakes, fast moving rivers and flat water (no current) rivers. The only times I wish for a rudder is bouy turns during races or high wind conditions in open water. Understern rudders work quite well but they are easily damaged or fouled with weeds.I used to own a Plastex Marathon Master Carbon/Kevlar Race boat with an understern rudder.This boat had a small fixed skeg forward of the rudder to protect it.The fixed skeg was always getting dings but it did protect the rudder. I have seen more than one paddler quit a race because the understern rudder failed. Most racers in my area prefer overstern/kick-up rudders. If you will paddle mostly open water, the understern rudder should be ok.
I added a temporary fixed skeg to my RBA. It is just a long tapered piece of wood, suggested by Jay Babina. It's about 2' long and is only about 3/4" at the deepest end. It really works quite well and does not add drag. I attached it with double sided carpet tape 5 years ago with the intention of glueing it on if it worked out. I have never touched it since I installed it. It has been hanging on for all these years of racing/training with just carpet tape holding it.
I suggest you try the fixed skeg for the RBA or an over stern rudder if you really need it.

$.02
Larry C.

: I'm working on a Guillemot RBA and am considering trying to make the above
: for it. Any one have experience, plans or advice for this?

: B