Newer owner of a 1974 Cat27. Knot Meter was inop so I located the speed paddle wheel and housing inside the bilge as it exited the side of the keel. The paddlewheel has some broken fins. Think I'd prefer to replace the housing as well though I saw in another thread that the holding pin can be pushed out and the wheel replaced. Not sure brand but am sure it was the original equipment and the boat was manufactured here in California. Seems others identified Raymarine, Standard Instrument, and Autohelm? Thought I'd check all three of their websites. I see others that have decided to throw in the towel and to use the handheld GPS units but there is so little original equipment that isn't still operable so I'm inclined to exhause this effort of replacing with original equipment replacement.