YSI SonTek RiverSurveyor, System Manual

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SonTek/YSI Inc
RiverSurveyor System Manual (May 1, 2007)
73
6.1.2. What type of vessel (moving platform) should be used for measurements?
There are many types of moving platforms that are used to make RiverSurveyor measurements.
Basically, they can be separated into three categories:
•
Motorized vessel with operator
•
Tethered platforms (non-motorized)
•
Remote-controlled, motorized platforms
Motorized vessel with operator
These vessels can vary from a few meters to over 100 meters in length. This class of moving
platform is the most common. Safety is a primary reason. In general, relative to the RiverSur-
veyor measurement: the vessel should have adequate space for a computer operator and a vessel
operator; the draft of the vessel should be low enough to operate in shallow water; the sides
(gunnels) of the boat should be high enough to prevent water from coming aboard and damaging
any electronics; a roof or sun-shade is beneficial to minimize the glare on the computer as well
as avoiding excessive exposure to the sun; and the fuel and battery capacity of the vessel should
be adequate enough to power all components during the measurement cycle. This type of moving
platform is most preferable when accessing remote sites, visiting multiple measurement locations
on the same river during a measurement set, and collecting data in large rivers/bays/estuaries.
Tethered Platforms (non-motorized)
These types of moving platforms have quickly gained in popularity over the past few years. They
have the advantage of letting users access hard-to-reach sites, quite frequently, from a bridge or
walkway over the stream. SonTek offers tethered platforms, including our RiverCat (§
3.1.3
).
However, some users prefer to build and integrate their own tethered platform. In any case, the
platforms are typically in a catamaran (two-hulls) or trimaran (three-hulls) configuration and
come equipped with internal radio modems (for communication to computer located on the
shore), 12–24 volt power, ADP and electronics, hulls (aluminum or fiberglass), and of course a
line (floatable) used to tow the platform across the river. In general these types of platforms
should be light-weight (less than 20-kg), durable enough to allow the operator to routinely drag
the hulls up along the riverbank, stable enough such that the ADP does not experience an exces-
sive amount of pitch/roll/heave, and designed such that it can easily be pulled across the river
with a minimum amount of drag force while maintaining a steady course and speed. Maximum
hulls speeds typically range from about 3–4 m/s.
Remote-controlled, motorized platforms
This type of platform has a similar design as the tethered platform with the addition of a re-
motely controlled motor. In addition, depending on the complexity of the vehicle, they come in a
variety of shapes and sizes. This configuration allows the operator to control the speed and direc-
tion of the platform and the ADP via a radio-link. In addition to the operating criteria described
above, the remote-vessel should: have a minimum of 1-hour operating life (without having to re-
place / recharge batteries), weigh less than 30-kg, and have the ability to maneuver quickly to
avoid other objects on the river. These types of systems are most useful: in remote areas where
there is no access across the medium-to-small rivers and a manned motorized vessel cannot be
used; during floods when operating a manned vessel is dangerous; or to simply save the time and
expense of operating a regular-size, manned vessel.