Quote:
Originally Posted by Spruill242
. . . Tach is new and compatable to the Evinrude tach signal. It is however an analog gauge. So grain of salt... GPS unit, older... Can/Do you calibrate those?
So step one- I'm going to ensure the TB is fully opening. Figured the mechanic would have done that so I didn't check before I took her out... Assumptions and all that.
Step two- Check where the AV plate is height wise. Draw a straight line from the bottom of the hull? AV plate 1" above that line?
If those two check out, take current prop to a prop shop and get it measured.
|
Sounds like a good plan! If you're testing with a relatively light load, you'll want to target the upper end of the optimum rpm range, like 5600-5700, so that you'll still be ok when fully loaded. When prop testing, besides a full fuel tank, I typically fill the live well and fill a couple of 60-70 qt coolers with sea water to simulate a heavy cruising load.
Years ago I had a new OMC tach that read high by about 300 rpm that led me to pick the wrong prop, so just because it's new doesn't mean it's accurate! Dealer checked the tach and replaced it under warranty. Not 100% sure, but I think the Ficht is similar to an E-TEC in that a dealer or you should be able to plug a laptop with the diagnostic software into the EMM and read rpm and a bunch of other stuff, so yes a dealer should be able to tell you if the tach is accurate.
On the AV plate, I think I'd start with AV plate about 1.5" above keel, measured with motor trimmed so plate is parallel to bottom. I like to get it too high to where prop ventilates on a sudden hard turn and then drop it down a hole. How high you can run it depends a lot on the prop. A good highly cupped SS prop can typically run much higher than a cheap aluminum prop w/o much cup. BTW if the prop you have is aluminum, a good shop can repitch it to get you close to optimum before you spend big $ for a SS prop.