Iceberg: high RPMs and more

pg 162

Through the blanket of mist it came as a steady drone: the sound of an engine running at very high RPMs.

Revolutions per minute (abbreviated rpm, RPM, r/min, or r·min⁻¹) is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis. It is used as a measure of rotational speed of a mechanical component.
Standards organizations generally recommend the symbol r/min, which is more consistent with the general use of unit symbols. This is not enforced as an international standard. In French for example, tr/mn (tours par minute) is commonly used, and the German equivalent reads U/min (Umdrehungen pro Minute).

"A hydrofoil. Is that it?"

A hydrofoil is a foil which operates in water. They are similar in appearance and purpose to airfoils.
Hydrofoils can be artificial, such as the rudder or keel on a boat, the diving planes on a submarine, a surfboard fin, or occur naturally, as with fish fins, the flippers of aquatic mammals, the wings of swimming seabirds, or other creatures like the sand dollar.
The term "hydrofoil" is commonly used for the wing-like structure mounted on struts below the hull of a variety of boats (see illustration), which lifts the boat out of the water during forward motion, in order to reduce hull drag; as such, the term "hydrofoil" is often used to refer to boats using hydrofoil technology. Most of this article is about this type of hydrofoil.
As a hydrofoil-equipped watercraft increases in speed, the hydrofoil elements below the hull(s) develop enough lift to raise the hull up and out of the water. This results in a great reduction in hull drag, and a further corresponding increase in speed.
A wider adoption of the technical innovations of hydrofoils is prevented by the increased complexity of building and maintaining them. Hydrofoils are generally prohibitively more expensive than conventional watercraft. However, the design is simple enough that there are many human-powered hydrofoil designs. Amateur experimentation and development of the concept is popular.
A boat equipped with hydrofoils is also called a hydroplane (boat)

 "If I don't, we're going to have bigger trouble than River City."

The phrase comes from a song in Meredith Wilson's The Music Man titled "Trouble" and also referred to as "Ya Got Trouble" or "Trouble in River City."

It is sung by the character Harold Hill (a con-man/traveling salesman pretending to be a music professor). Through the lyrics of the song, Hill persuades the parents of River City that the new billiard table in town is a threat to the moral fiber of the River City youth, verbally illustrating a catastrophic decline of conservative, turn of the century values. All this, of course, is setting the stage for his alternative, wholesome pastime - a boy's band - for which he will sell uniforms and musical instruments.