Ya ever look at your dash or if not on your dash, see an hour meter? Well, we asked Dave VanNess of VanNess Engineering what the deal is. And were kinda surprised by the answer. They are not all that accurate. WHAT? Well, turns out they are set for a RPM of 1,725. Now that may be the average speed you travel. But does it count the hours of No Wake Zones, or that time you raced that Jet Ski…and lost? Well, turns out NO. Now of course once you think about it, it kinda makes sense. And of course someone shot on youtube a video of one working. You can watch the hours go by.
I will add that watching grass grow is more interesting.. No Really.. Look!
Really? That sucker is over an hour long! When did you figure that out.. 30 minutes into it? Well, if you had a good rebuilt hour meter from Mark Clawson from Clawson Classic Instrumentation, you may have been able to keep track. But when we spoke to Mark, he ilaberated on the subject even more.
“Matt, it’s actually WAY worse than 1725 RPM. I’ve seen some pretty random numbers occasionally. The Stewart Warner tachs used in Chris Crafts from 1957-70 were hardly ever printed with it but some did have 2,250 as the designated “hour”. AC had at least 1,725, 1,750, and here’s a few for you, how about 1,790 or 3,080!
Engine hours on mechanical tachs are directly driven off the cable with a 2 worm gear system. The faster the engine is running – the faster the hours rack up. So when your CC cruiser putts around the harbor barely above an idle it’ll take about three hours to get the same hour the ski buff is getting at full throttle. The latter of which is probably getting an hour in 45 minutes.
A few were produced with “revolutions per thousand” printed on the face. All of this is probably more meaningful to an aircraft guy as these indicate wear not time running. An engine hour is NOT a clock hour.”
Thanks Mark, SO? Confused? Care? I suppose its like anything. Its something to reference. But in the Woody Boater universe where we are exploring the most minute details. Hey 4500 stories and counting, and we still found something new here to talk about aint so bad. Or not! Thanks Mark Clawson and Dave VanNess for the inspiration.