NavList:

All-

Perhaps you’re missing my point – a sextant needs to be able to be out in the sun  for a good 10-15 minutes, or else you’d never be able to take a few sun shots (esp. in rough conditions). And I’ve never had the misfortune of having the silver scale jump out of the frame –  perhaps my Davis wannabe is built better than I thought it was!

Since some sextants are painted white, I couldn’t understand why they all aren’t done that way – certainly the plastic ones could benefit from this, since they (mine anyway) warp significantly in the time it takes to get a few good shots. I was taught you need to zero them out just before a shot, and then check the index error just after you finish. I’ve always had at least the better part of an arc minute error increase between the two checks in warm conditions. (That’s what I get for buying plastic!)

In any case, I like Ronald’s answer about reflections in a navigator’s dome.  I’ll just have to make sure I have a good 1/8” bubble to start with on a warm day – smaller ones can shrink too much, even in the shade.

-Paul

Agreed Geoffrey.  The navigator is urged to permit the sextant to reach thermal equilibrium prior to observations, but I never recall seeing advice urging the navigator to do that by leaving the device out in the sun!

Best Regards
Brad