I bought a 'vimpel' yesterday, and on the package is a table:

Height Length Length
of pole of flag of pennant
3-4 m 100 cm 150 cm
4-5 m 150 cm 200 cm
5-6 m 150 cm 250 cm
6-7 m 200 cm 300 cm
7-8 m 200 cm 350 cm
8-9 m 225 cm 400 cm
9-10 m 250 cm 450 cm
10-11 m 275 cm 500 cm
11-12 m 300 cm 500 cm
12-14 m 350 cm 600 cm
14-16 m 400 cm 700 cm
16-18 m 450 cm 800 cm
18-20 m 500 cm 900 cm
20-22 m 600 cm 1000 cm

Ole Andersen, 7 September 2002

This works for Dansik flag and pennants only, I guess. Then again maybe not. In any case, it gives following rules:
pole height = 4x length of flag
length of pennant = 1.5x length of flag

Of course, much approximated. I'd say this seems reasonable (for the kind of flying the Danish flag is typically used, this does not work for, say vertical flag hoisting favored in Central Europe, the knattefane (sp?) of German
surroundings and other "untypical" flags). Željko Heimer, 7 September 2002

I guess it is Danish-only - I seem to remember one of our members comparing this, and noting that Danish flags are quite small on a pole.

The flag-to-pole ratio is, regulated, while the pennant-to-pole ratio is a recommendation from the flagmaker only. Ole Andersen, 7 September 2002

What is the proper height of the ensign relative to the water when displayed from the stern of a single masted sailboat?

We have been told it should just be touching the water when at rest.

Touching the water? I wouldn't think so, but maybe. The rule I've seen in U.S. sources is that the ensign should measure at least one inch on the fly for every foot of height of the mainmast for a sailboat, or for every foot of overall length in the case of a powerboat. "At least" in this case provides for one to round up to the next commercially available flag size. I believe this is in the NY Yacht Club "Yacht Routine," Chapman's Modern Piloting, and similar sources. Joe McMillan, 12 September 2002

Proper height does not depend on distance to the water. Ensign's height must be relative to
boat's length, and it should not touch the water at all, so, if proper height
the ensign gets too close or touches the water, the mast should be changed. Jose C. Alegria, 12 September 2002