NavList:

Well I'm aboard the ship again. I pulled out my rangefinder binoculars and took a measurement from me standing on the bridge down to the water.  There were waves down there at about a foot to a foot and a half.  My rangefinder measures in whole meters, so was bouncing between 33 and 34 meters as I took my measurements.  I ran my dip formula and the measured distance was within a meter of my calculations.  I would say it's a good way of getting dip, but a bit too innacurate for draft surveys.  I'd need a rangefinder with more resolution.

I have never tried to quantify the effects of waves and swell at the horizon on the sights I take.  I group them into a general idea I call "horizon quality."  The height of the waves and swell mix with the haze in the atmosphere and poor contrast between the sky and sea to make an indistinct horizon.  When the horizon isn't clearly defined, proper placement of the body becomes difficult and affects accuracy.  A nice crisp horizon with minimal wave action on the horizon and vessel make for far more accurate positions in my experience.  I recognize the various conditions when they occur and temper my expectations accordingly.  In my logs you can see plenty of "poor horizon" notes.

As an aside, the 3rd mate is a retired USN Quartermaster Chief and took pride in showing me he CelestComp V.  Less impressive was my review of the compass correction log showing only three observations since I departed in August.

Jeremy