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I managed to get a decent Moon-Venus lunar earlier today in broad daylight. Both objects were above 60° in altitude. The Moon was in the southeast; Venus about 90° away in azimuth in the southwest.

I got altitudes of the Moon and Venus before and after the actual lunar distance observation and averaged them to synchronize them to that time. The full set of observations then was:
  LD: 36°50'
  Venus altitude: 62°41'
  Moon UL alt: 63°02'
My height of eye was about 15 feet. The synchronized time of the three sights was 21:43:25 UT (26 May). The location was Beavertail Point on Conanicut Island in Narragansett Bay.

This was a visually fatiguing observation since Venus was not easy to see in slightly hazy skies. I didn't even bother to read my sextant micrometer for tenths of a minute. I felt the LD as observed was correct to the nearest minute though, and when I ran the numbers that proved to be true. I get an error in the observation of -0.4' which in an average 'longitude by lunar' case would yield a longitude error of 12' which is 9 nautical miles in this latitude. Not bad as it turned out, and it certainly would have been a navigationally "valuable" result two centuries ago.

For this land-based Venus sight I used a combination of tricks. First, I knew the elongation of both Venus and the Moon from the Sun. This is standard astronomical data. We can get it from many sources, including, for example, Stellarium. Venus is 45° from the Sun. The Moon was about 82°. Subtracting 45 from 82, I knew that Venus was 37° from the Moon (we can simply subtract without worrying about geometry because the Solar System is flat, more or less). So I pointed the sextant at the Moon and turned it until the horns of the Moon were horizontal in the field of view (horizontal in the sense that an imaginary line through the points of the Moon's horns appeared to be perpendicular to the frame, like the horizon in a common altitude sight). That should have brought Venus into view. But nothing... I scanned a little, left and right... still no luck...

A trick I've used many times to locate Venus in daylight is to place it near a high foreground object, in this case the tip of a tree limb. I walked to a spot where my sextant lined up a tree limb 37° from the Moon and generally along the band of the ecliptic. Then from that spot, I scanned with binoculars, and I spotted Venus easily. I adjusted my observing position by a few steps until Venus was almost perfectly aligned off that identifiable tree limb. Then back to the sextant. Again at 37°, I turned the sextant until I could find that key branch. I could then hold that spot steady in the field of view, and Venus soon jumped right out. From there the lunar observation could proceed as normal. 

Anyone just starting out with lunars, I'll repeat what I consider good observing practice. Don't work the angle "live" with your hand on the micrometer as you normally would with sextant altitude observations. Instead grab the sextant frame with both hands, one on the handle as usual and the other hand on the front side. This is very stable. Observe the apparent offset between the Moon and the other body (Venus today) and make a visual guess of the error. Then take the sextant away from your eye and adjust the angle by the amount you estimated. Repeat until there's no visible error left. You quickly get better at estimating with each repetition, and I find I'm usually done within four or five tests. It's quick.

Frank Reed
Clockwork Mapping / ReedNavigation.com
Conanicut Island USA