-- Last Updated: Nov-12-08 11:05 PM EST --
Most any bait shop will have inexpensive and sometimes free adhesive backed waterproof paper rulers because of today's min, max, and slot size limits. Just cut to length, peel off the back paper, and stick it to the top of the thwart. It will conform to tubular, flat, or whatever thwart profile you have. I have a freebie on the aluminum thwart ahead of the stern seat on my kevlar tripper that has given me 8 years of service now. Very handy.