It's sort of a sighting, and sort of a slide rule.

I was looking through a boat design forum, and found a link to this
little paper:
http://www.boatdesign.net/forums/attachment.php?s=dd19e8fce8774b27ece9df153ec69ae2&attachmentid=379

It mentions the ``... CATERPILLAR Hull Speed Estimator slide-rule.
This was issued in 1961, under copyright, by the CATERPILLAR TRACTOR
CO., Engine Division in Peoria, Illinois as Form No. 40-20442.''

Actually, it sounds like a slide chart. Has anyone every seen or
heard of this one? I'd surely appreciate a picture, if some lucky
soul has one.

Nels