Rather than getting agitated when my fishing buddies tie my boat bumpers out at the incorrect levels -- allowing the boat to rub against the dock -- I created this simple device I call the "bumper mate."
If you already have bumpers or fenders, then you should have most of the
supplies. But you will need to purchase some 1-inch OD PVC pipe from a home-supply store.
Cut 1-foot sections of the pipe for each of your gunwale rod holders. About 2 inches from the end of one section, drill a 1/2-inch hole through both walls of the pipe. Place this piece of pipe in a gunwale rod holder with the drilled side up. Slide your 3/8-inch bumper line through the holes to the other side. (If your lines measure differently, just make the pipe hole slightly larger than the diameter of the line.) Position the bumper exactly where you want it to rest alongside the boat, then tie a figure-eight knot in the tag end of the line.
Using a waterproof marker, label the pipe so you can tell which rod holder it should occupy. Now when you dock, you can easily tell your friends to place the bumper mates in their respective places.
Ardsley, New York