lf hand over hand along the line."

"Think, Mr. Danley! _Think!_"

"Uh. Oh. Well, I wouldn't keep pulling. I'd just give myself a tug and
then coast in, taking up the line slowly as I went."

"Excellent! What would happen if you, as you put it, pulled yourself in
hand over hand, as if you were climbing a rope on Earth?"

"I would accelerate too much," Danley said. "I'd gain too much momentum
and probably bash my brains out against the boat. And I'd have no way to
stop myself."

"Bully for you, Mr. Danley! Now see if you can put into action that
which you have so succinctly put into words. Come back to the boat.
Gently the first time. We'll have plenty of practice, so that you can
get the feel of the muscle pull that will give you a maximum of velocity
with a minimum of impact at this end. Gently, now."

* * * * *

Still later:

"Judgment, Mr. Danley!" St. Simon cautioned. "You have to use judgment!
A space boat is not an automobile. There is no friction out here to slow
it to a stop. Your accelerator is just exactly that--an accelerator.
Taking your foot off it won't slow you down a bit; you've got to use
your reverse."

Peter Danley was at the controls of the boat. There were tiny beads of
perspiration on his forehead. Over a kilometer away was a good-sized
hunk of rock; his instructors wouldn't let him get any closer. They
wanted to be sure that they could take over before the boat struck the
rock, just in case Danley should freeze to the accelerator a little too
long.

He wasn't used to this sort of thing. He was used to a taped
acceleration-deceleration program which lifted a big ship, aimed it, and
went through the trip all automatically. All he had ever had to do was
drop it the last few hundred feet to a landing field.

"Keep your eyes moving," St. Simon said. "Your radar can give you data
that you need, just remember that it can't think for you."

_Your right foot controls your forward acceleration._

_Your left foot controls your reverse acceleration._

_They can't be pushed down together; when one goes down, the other goes
up. Balance one against the other._

_Turning your wheel controls the roll of the boat._

_Pulling your wheel toward you, or pushing it away, controls the pitch._

_Shifting the wheel left, or right, controls the yaw._

The instructions had been pounded into his head until each one seemed to
ring like a separate little bell. The problem wa