Have we talked about the phrase/term "use tabby"? It is not unique overshot. I've seen it elsewhere but for now let's assume it occurs with overshot. It means: between every treadled pattern shot/pick/pass, treadle a row of plain weave to tie down the pattern threads. It gets more complicated than that, though. It means you have to set up two treadles that can be treadled as plain weave. On a four shaft loom with a straight draw threading and six treadles, this is means tying a treadle to shafts 1,3 and another to 2,4, leaving treadles the remaining four treadles handle pattern. All overshot patterns I've ever run across are configured so that they can be treadled in plain weave - or pretty close to plain weave.
pass 1: pattern
pass 2: tabby
pass 3: pattern
pass 4: tabby
This concept confounded me when I first started weaving. Less so when I understood it intellectually, and the mystery was completely eliminated when I actually did it. Sort of like double weave.
Almost immediately the next question comes up: which treadles should I use for tabby?
Kerry likes using treadles 1 and 6. When her shuttle is on the left, she uses treadle 1; when her shuttle is on the right, she uses treadle 6. For some this is completely intuitive.
I like putting the tabby treadles on the right hand side. I can slide one foot back and forth between the two tabby treadles (left-most when my shuttle is on the left, right-most when my shuttle is on the right) and my left foot operates the other four. If you have any music training, this might feel alot like playing the piano but with the bass line on the right instead of the left. That analogy falls apart pretty quickly if you go much further so let's not. In any case, I'm more comfortable handling the pattern treadles with my left leg.
Still, though, sometimes I miss the correct treadle. They are so close together! This was a constant problem for me with the Minerva. Slightly less of a problem on the new Tools of the Trade loom. Even less so on MayMac (my Macomber) but...sill an issue...until I remembered that I can shift my treadles! Bwahahaha!
Not everyone has this advantage. I do and I am using it. I increased the gap between treadles 4 and 5 from an inch to 5 inches. It's simply a matter of loosening the screw bolts and scooting the treadles (and their connectors) over.
There's no difference in the shed or the integrity of the lift of the shafts. That gap has made ALL the difference for me and I'm loving it for my latest overshot runner.
Not all looms have a long bar for the treadles but if yours does and there is an extra few inches available, give it a try. You could create a gap between treadles 1 and 2, and between 5 and 6.