We had a cockpit enclosure fabricated for our Rosborough about a year ago and struggled with the decision of what screen material to use.
We searched the web for the tradeoff in airflow vs. screen pore size, minimum pore size to keep no-see-um's out, what folks use in Florida for patio and pool screens, etc. We finally decided on 90% black Pifertex based on the following thoughts:
1) Any screen will significantly cut down on airflow, regardless of the pore size, and as best we could tell from looking at several technical papers, the hit from going from a "screen door" mesh to a tighter pore size didn't seem to be more than a couple of tens of %. So maybe 20% worse on an already crappy cooling number compared to free air with no screen.
2) The bigger cooling factor of screens according to the Florida patio and pool crowd seemed to come from keeping the incident solar radiation out, i.e., the shading effect of the screen. I know from past experience that direct sunlight vs. shade causes a 10F rise of surface temperature of an object. That would imply a 90% opaque screen would be 300% better than a 30% opaque screen at cutting that heat load, more than offsetting the decrease in airflow due to pore size on still or gentle wind days.
3) We chose black instead of white for visibility when backing and have been very happy with the decision. I was concerned about the visibility with 90% opaque fabric before we finally saw the results. Our screen is fully transparent, objects in the far distance just look slightly fuzzy so reading the fine pring on buoy's is compromised. The only loss of vision is when looking through a screen panel at a glancing angle, say less than about 45 degrees where the fiber thickness of the screen masks the view through all the narrow pore openings at that angle. The effect is similar to looking at some (older?) laptop computer displays from an off angle.
We haven't had any problems with no-see-um's yet but have not really tested with an apples to apples comparison with another boat in a known heavy no-see-um area. We have been on the Okeechobee Water Way for the past week and have not had any problems so there's one datapoint. In any case the 90% opaque material is about as good of a material as you can get for that problem.
--Mike
