I don't know how many of you have used these but they are great. They are a chart that wound on two shade rollers that are housed in a half peice of PVC. It is totally waterproof and can be adjusted so that only the part that you need is showing. It is worth it's wiehgt in gold of open boats where standard charts blow around, and are hard to stow. Check them out. I will be putting a picture of it up soon. The man who makes them can be reached at (860) 489-2974 or at [email protected] They are called Roller-Maps. They cost $54.95 and come in a huge variety of charts. They can even be made with a chart you have.