In calm water, neither of the seals is actually supposed to be in contact with the water surface and typically they are "mostly" not. In waves...that's another matter altogether.
Are you focusing your efforts primarily on the calm water case?
As for wash, as you are already aware, I'm sure, that is the one parameter we almost never try to measure when conducting SES tank testing or even full-scale tests. About the only truly solid wash data I've ever seen for an SES remains classified as far as I know.
Yes, calm water only at this stage. If I tried real conditions with waves, that
would certainly drive me to drink!
I know seals are not in direct contact with water, but there are difficulties
(for me) in modelling the small gap behaviour and effects on resistance and
splash. Modelling the seals as planing surfaces does seem to move resistance
predictions in the right direction at low Froude numbers, but as I said, I'm
not all that convinced it is the best way to go. In any case, low speed
performance of SES is not a huge issue for me - it just makes the plots look a
little better when low speed experimental points are included in graphs of
resistance vs speed.
I didn't know that SES wash wasn't routinely measured, but I'm not surprised
- SES testing seems to be a monumental enough task without that
complication.
I'm Ok for that aspect, though, because I have good tank data with
longitudinal wave cuts at different distances from the vessel and at different
speeds. My modelling is quite good for wash because the hulls are so thin and
the theory gives very good results (better than for displacement hulls) for
travelling pressure distributions.
Are there any upcoming conferences that you know of that are more
specifically focused on SES and ACV than FAST? Or are they not a
sufficiently popular type of vessel to warrant separate treatment? (I
appreciate that there are a lot of commercial/military confidences that are in
play too.)