Fascinating stuff. Not sure if you have a repository for all the test hulls you do, but if you don't, it would be great to have them all in the Files section.
Looks like rudders have to go on my to do list as well.
rob
Curiosity got the better of me.
I have looked at the lowest drag hulls for 4t combined; with 3t on the lw and 1t on the ww. The hulls just happen to end up 21m and 13m long and total drag at 15.9kts is 2360N. The individual hulls have a drag of 1577N for the lw and 779N for the ww. So the interference is detrimental even at the optimised speed although I did have a max beam constraint of 8m and settled at 7m WOA.
There is detrimental interference maximising at 37N at 11.8kts when total drag is 1196N. Above 17kts the interference is mostly beneficial but too small to worry about. - always well under 1% of total.
This initial look suggests wave interference is a second order factor. It would pay to do a check with the ww hull more heavily loaded.
Putting time into the rudders is going to be much more rewarding in terms of performance than playing with wave interference. Likewise the selection and placement of the rig has big potential.
Rick