After installing the hasp staple on the top drop board (and getting a little rain in the cabin that night), I discovered after re-reading the instructions that you are supposed to install a block below the staple so that when you lock the hasp to the staple the hatch slide has to come out further over the drop boards, thus keeping the rain out. The only problem is, it does not say how long to make the block. (It also says to make it in the shape of a truncated pyramid, but until I find out how tall it should be I'm not going to all that trouble.)
Looking at the picture, I guessed it to be about 1 1/4" long, so I made it 1 1/2" for good measure. I can always cut it shorter but I can't make it longer. I haven't tested it in the rain yet, but I'm hoping I didn't make the block so big that the hatch lets rain in at the opposite end--a lot more rain! Does anyone know exactly how long the block should be?