I so far like Monolith's chron unit, as well as FREETACO's system. My idea is for the chron to be used mainly by people living in space, especially people who will be working in space transport one day.
There are two things that this unit needs to work for. It needs to be both useful as a unit of measuring stand-alone time (19 seconds till liftoff) and time as compared to the passage of it (it is 1800 hours). But before we go into doing this arbitrarily, we need to consider some other factors. In other words, we need to compromise between Monolith's and FREETACO's systems and then innovate. Compromise and innovate.
Where will it be used?
Since it will be used mainly in space, we need it to work well for the people who work in space. This presents another argument altogether.
Who will be using it?
Well, people who work and/or live in space, of course, although I'm sure it can be adapted to other uses. One important thing to factor in here is that we are making this system for the future, not for now.
Why is it necessary?
Living on a Terran timetable when you're living on Luna is stupid. Living on a Terran timetable when you're living in orbit around Venus is stupid. Especially when you're travelling between planets, and spend a lifetime doing this, it is necessary to base your time system on something that doesn't change. Monolith's writeup proposed the use of the speed of light for this. I couldn't agree more.
So tell me about this new system.
Note from Monolith's writeup that one of his chrons would equal the amount of time it would take for light to travel one billion (1 x 109) meters. I had three options when choosing the base unit for this, but there were some things I needed to consider before just picking one arbitrarily. The three options were to make the base unit equivalent to 1.08 hours, 10.8 hours, or .108 hours. To have this be compatible with space operations, I tried for the 1.08 hours in hopes of making one of the space "days" equivalent to 10 chrons.
The Space Day
A day needs to have time for all of the basic functions of life. 10.8 hours is way too little to accomodate work, sleep, and play. 21.6 hours isn't. One needs plenty of time to sleep in space (sleep prevents accidents, and keeps you fit), and 9-10 hours is an optimal amount of sleeping time. A 10.8 hour day would work nicely assuming that the first day would be used mainly for work and play (7-8 hours work, the remaining amount play), and the majority (9-10 hours) of the next day would be used for sleep, with the rest for play. This gives about 4 hours of free time every cycle.
Why didn't you just make it a 21.6 hour day?
Because then it wouldn't be Base 10, now would it? Besides, if a cycle would be equivalent to a "day" then it's no problem, right?
Recap
Note that all figures are approximate.
One decachron (daq) (space day) == 10 q == 10.792 hours (556 minutes)
One chron (q) == 1.0792 hours (55.59 minutes)
One decichron (dq) == 0.107 hours (5.559 minutes)
One centichron (cq) == 0.0107 hours (0.5559 minutes) (33.3564 seconds)
One millichron (µq) == 0.0093 hours (3.33564 seconds)
So how will this work with one's daily schedule?
Well, for one thing, let's stop thinking in hours and seconds, and start thinking in chrons. Otherwise, this is going to get pretty confusing.
One cycle would equal 20 chrons. This is equivalent to one of our days. Let's break it down into the human necessities.
1 q - Wake up / Clean
0.5 q - Breakfast
4 q - Work
0.5 q - Lunch
4 q - Work ----- That's 10 chrons so far.
3 q - Dinner / Free Time
7 q - Sleep
There would be 5 cycles in a week. In other words, it's a five day week. This works out nicely to being 100 chrons in a week. A 50-cycle year is also a good idea, since it works out to a nice 10,000 chron year. Interested yet?
Practical Details
Unless you never intend on walking on your homeworld again (assuming its Earth), zero-g exercises are important to do every day when you're in space. To allow time for this, things like TV, music, or internet-surfing can be combined into the same time period as your exercise, when needed. For example, in addition to .2 or so chrons of exercise in the morning, one would spend about 1 chron of their dinner/free time to exercise and at the same time watch the news, since riding a stationary bike isn't a really mind-consuming exercise.
Since being in space is expensive, days in which you are free would be limited. One day every decacycle free could work well.
Conclusion
This system obviously won't be in use for a while, as it is only practical when one spends a lot of time in space, or travels between celestial bodies very frequently.
Let it be noted that practicality and adherence to Base 10 were my main concerns when working the system out.
Excalibre informed me of something fun-- the circadian cycle. I guess a 24 hour schedule wouldn't be SO bad-- it would work nicely, in fact, since you can have three 8 hour shifts.