Date: 2009-12-14 21:49:00
marginal costs of leisure activities
I just sent a resignation email to the Canterbury Gliding Club. I haven't been flying in something over a year, and I couldn't justify the continued membership expense if I'm not even going to fly.

Flying with Fault Line Flyers in Texas was pretty much a no-brainer for me at the time. It was about US$23 for a tow, and time in the air (glider rental) was a flat $3 or so per flight. I was living by myself and had plenty of time and enough money to spend on a weekend activity.

Here, a similar tow is about NZ$50, and glider rental is just under $1 per minute of flying time. As you can imagine, that adds up extremely quickly and the reality is it exceeds what I can justify for a weekend activity today. Especially since I like to spend weekend time with my wife (as one or both of us often seem to be busy during weeknights).

Coming to this conclusion was tough because I truly enjoy flying, but was always conscious of how much it cost. Naturally, that dampened the enjoyment somewhat. I realised that there are two types of leisure activities: those that have a marginal cost, and those that don't. Activities with a marginal cost are those where you have to shell out some amount of cash every time you do whatever it is. Gliding is definitely one of these activities; skiing, skydiving, and golfing are other examples. On the other hand, activities without a marginal cost usually require you to purchase equipment of some kind, but doing the activity just once doesn't cost anything. There are many examples of this: cycling, surfing, hiking, fishing, diving, even things like sailing or motorcycling (where the initial cost might be substantial). I have discovered that I'm a no-marginal-cost kind of guy. (Having said that, I'll still go skiing!)

Speaking of gliding, congratulations to Terry Delore who just yesterday broke the world distance gliding record with a 2501 km flight!
That is indeed quite a difference between the flying costs in TX and NZ!

The binary idea that an activity either has a cost each time or does not seems less clear-cut to me in some cases. E.g. motorcycling has the cost of gasoline each time - granted, it's less than flying or skiing, etc, but sufficiently nontrivial that I had to reread that sentence, out of confusion!
There's the cost of fuel and the cost of wear and tear. The advantage of renting the equipment is the marginal cost is apparent. With driving or motorcycling on back roads, the "wear and tear" marginal cost is much less apparent and much more difficult to accurately measure than the cost of renting the equipment.
You're right, there are some edge cases that aren't quite as clear-cut. On one hand, I was originally thinking that with your own self-powered glider you might have zero marginal cost (and a six-figure startup cost!), however, regulations require a formal inspection every 100 hours of flight, plus airfields usually have a "landing fee" to cover use of the facilities, plus whatever fuel you might use getting airborne.

Or, hiking might have a nonzero cost in fuel to get where you're going (unless you live on a mountain, or cycle in boots to get there). Perhaps motorcycling was a poor example because the actual activity consumes fuel at a pretty constant rate.

There is nearly always some marginal cost associated with outdoor activities, in the form of transportation to get wherever it is. You'd have to live in a pretty magical place to be able to, say, surf, hike, cycle, dive, and fish all within walking distance!
Greg Hewgill <>