Hydroplane

A hydroplane (or hydro, or thunderbolt) is a very specific type of motorboat used completely for racing.
One of the unique things about these boats is that they only use the water they're on for propulsion and steering (not for flotation)—when going at full speed they are primarily detained aloft by a principle of fluid dynamics known as "planning", with only a tiny portion of their hull actually touching the water.
The basic hull design of most hydroplanes has remained comparatively unchanged since the 1950s: two sponsors in front, one on either side of the bow; behind the wide bow, is a narrower, mostly rectangular section housing the driver, engine, and steering equipment. The aft part of the vessel is supported, in the water, by the lower half of the propeller, which is intended to operate semi-submerged at all times. The goal is to stay as little of the boat in contact with the water as possible, as water is much denser than air, and so exerts more drag on the vehicle than air does. Basically the boat 'flies' over the surface of the water rather than actually traveling through it.

Inflatable boat

An inflatable boat is a lightweight boat constructed with its sides and bow made of elastic tubes and a flexible flat floor. Often the transom is rigid allowing a location and structure to fasten an outboard motor onto, and this type of boasting balloon is sometimes called a "Zodiac boat". Often, inflatable boats are intended to be packed into in a small volume, so they can easily stored and transported to water when needed. This feature allows such boats to be used as life rafts for larger boats or aircraft, and for travel or recreational purposes.
Other conditions are "inflatable" and (an old term) "rubber dinghy".
The modern RIB (rigid-hulled inflatable boat) is a growth of the inflatable boat using a solid or section ally rigid floor and capable of taking a high powered transom mounted outboard engine appropriate for high speed operations well up into the ski boat speed ranges.

Dredging

Dredging is excavation movement or operations regularly carried out in part underwater, in shallow seas or fresh areas with the normal and usual purpose of scraping sediments off the floor and in general raising the depth of water in a routing channel used by shipping, yachtsmen and barges.
Other common dredging reasons include:
* Spot excavations lowering the sediment beds as far as automatically possible preparatory to major waterfront construction of a bridge, pier, or dock foundations.
* Harvesting storm detached sands and restoring a swimming beach.
* Waterways management and maintenance for flood and corrosion control.
It is fair to say that without the many and almost non-stop dredging operations world wide, much of the world's commerce would screech to a halt in a few months and many of us would freeze, starve, or lack desired goods, for the world's ships are of essential importance to the lifestyle of the developed world's populations. Moreover, recreational boating would be severely forced to the smallest vessels. The majority of marine dredging operations (and the disposal of the dredged material) will require that appropriate licenses are obtained from the relevant narrow authorities.