Just a small correction. When soaring and trying to climb in thermals, you should fly at your min sink airspeed, not best glide (L/D max). Min sink speed is slightly slower than best glide. There's a good article in this month's EAA Sport Aviation on how to calculate these speeds.

Minimum sink is, just like it sounds, the speed at which the aircraft is losing the least altitude in a given amount of time. In other words, this is the speed that will keep you in the air for the maximum amount of time. It is a good speed to fly in lift for maximum altitude gain.

Best glide speed is the speed at which the aircraft will cover the most distance from a given altitude. This is generally a slightly higher speed than minimum sink. Flying at best glide speed, your flight time would be shorter, but you would go farther across the ground. If you have an engine failure, you want to descend at your best glide speed.

One clarification: While circling in a thermal, the Minimum Sink Speed will be the Minimum Sink Speed for the angle of bank that you are using to stay in the thermal. The Minimum Sink Speed for a particular bank angle will be higher than the level flight Minimum Sink Speed. For shallow bank angles there is not much difference, but you normally cannot 'core' a thermal at shallow bank angles.

Min sink speed plus
 

Besides min sink speed, I find it useful to put down 10 degrees of flaps to fly even slower. The slower speed allows for a tighter turn at a slower airspeed even thou if the min sink may be a little higher. Its all about maximizing the climb speed in the thermal.

Looks like fun, but remember one thing. If you are shutting off your engine to soar and have a problem that gives you ?press coverage? the NTSB report will not be kind!

It strikes me that during this entire conversation no one mentioned the word variometer.

Reminds me of that line from the Ironman movie:

"How did you solve the icing problem?"

"What icing problem?"

"You might want to look into it."

:)

I know there are portable variometers, might want to look into one if you are serious about soaring.

Variometer
 

I havent been in a power plane that doesnt have one. Power pilots call them rate of climb indicators?

Variometers are typically IVSI. Standard VSIs have a delay that makes them somewhat unsuitable for soaring.

Total Energy Compensated Variometers
 

Not to mention that variometers in most sailplanes include total energy compensation to eliminate 'stick thermals'. A stick thermal is a false indication of rising air (lift) caused by slowing down and climbing due to trading airspeed for altitude. Total energy compensated varios show what the air mass is actually doing by factoring out any climb or descent rates caused by slowing down or speeding up.

Knowing how fast the air mass is rising or sinking, by excluding the rate of climb or rate of descent caused by changes in airspeed, makes it much easier to locate and center thermals.