i run a round strainer that is entirely separate from thru hull. I teed off the thru hull one side goes to livewell pump, other to nothing right now capped off, but soon a washdown. used all groco on the Tee and step down sizing pieces, to the livewell pump. make sure its flanged seacock.
I asked the pros at cape and island boat works when they do thru hulls for downeast boats, they did not like the strainer you show-reason it forces a lot of water into the thru hull when running. we run faster than a downeast so that style is really putting more water pressure on the intake. the round type strainer I have still brings plenty of water in trust me. this shows a style I used:
http://www.jamestowndistributors.com...Round+Strainer
my thru hull is on the lowest dead rise panel, but that's more due to the fact I don't have a lot of options. not sure about mounting it on the middle panel I did not have the option so never gave it thought. used a piece of left over Penske from Pat's(Wildman) minty green 23 rebuild, 45 degree bevel on edges better for glassing, triangle shaped to mimic the thru hull flange shape, looks like a home plate shape. then glassed over with CSM, then 1708, maybe 2 layers 1708 I forget. used epoxy. its nerve racking drilling a hole in the hull bottom. I gave a few bucks to a pro in the garage next door to ease my mind off hours, over a couple beers.
yeah it must have some impact on speed I guess. nothing I could notice. and mine being a round strainer with holes all around it lets water pass out much more easily when not running the livewell. makes sense think about the hydrodynamics. I did coat it with my epoxy bottom paint inside and out. prob overkill. and since it is separate, I can remove it and its not attached to the thru hull.
for the intake I used one of these full flanged seacocks BV series I think:
http://www.groco.net/
if you want a pic will be working on boat later and can take a shot inside of hull and outside.