Although Michelin could play for hours with Mr Bee I on the other hand would prefer that those insects would stay outside the boat. Since they are bound and determined to get inside it is necessary for the cruising boat owner to be a little creative in keeping the pesky insects out. I have here for your inspection a few of those ideas that have worked for me. Lets start with the obvious, those big openings called ports and hatches. Most manufactures make screens for their openings but what about the ports that are no longer on the market or the manufacture has gone out of business? You could try to glue a screen in place or velcro sells a kit, but I've found they don't last or the sun's UV rays will break down most glues. I have made my own using 1/16th inch ABS plastic sheets and the heave screen fabric used for Lawn & Garden furniture. Cut a cardboard template that fits in the port from the inside and will stay in place when the port is closed. While it is closed go outside and trace the opening on the other side. When you remove the template from the port you will see how much material is going to form the screen frame. It should be at least ½ inch add too it from the inside of the template if it is less. Cut out the pattern place it on the sheet of ABS plastic trace and cut 2 of the patterns for each opening you wish a screen for. Lay out the screen fabric over the plastic and cut it out so it is 1/4 to ½ larger than the plastic all around. Now for the messy part too glue it .. Using the same glue a plumber uses to cement ABS pipe together apply a generous amount to one side of two of the plastic frames. Lay the screen on the frame and apply the second plastic frame on top of the screen . Be quick to align them . Once they are aligned put a board on top of them and a heavy weight on top of the hole thing. Leave them for about an hour to make sure the glue has set. When you remove the board a little trimming is necessary to make a neat screen . I have drilled a couple of holes in the screen frame for screws so they don't fall out of the ports. To insure that the sun won't damage the plastic, or the glue, paint the plastic screen frame with a automotive paint. Keep a plastic copy of the pattern for future screens. I know that my cat scratches at the screens to get at her favorite playmates.
For those vent, cowl or clam shell openings. From the galley a wad of stainless steel scrubber pad stuffed into the opening will allow a breeze in and keep out the pests . I use to use pantie hose over the cowl to keep out the no-seeums but as a single guy I had a hard time getting them. I found that a light spray of cooking no-stick spray on the screen would act like a glue for those insects small enough to get through the screen.
Now for the hard one and I'm not yet completely satisfied with the solution. But? Since I have a pet on board I need to provide a way for her to get in and out of the boat or I'm forever getting up for her. To date the best solution for this is several layers of plastic sheets over a hole in the drop boards that she can fit through. The plastic keeps out the insects and the rain , for some reason this cat wants to be out in the rain usually under a piece of plastic or crouched under some line somewhere. On those hot days when every port and hatch must be open I have a piece of screen fabric with a heavy line sewn around it that will just drop over and cover which ever hatch or port I put it on.