YSI SonTek RiverSurveyor, System Manual

Page: 88 / 194

SonTek/YSI Inc
RiverSurveyor System Manual (May 1, 2007)
76
6.2.2. What are the requirements for the ADP mount?
The ideal requirements for a boat mount would be as follows:
•
Constructed of non-ferrous material (1” to 2” aluminum pipe works best with stainless steel
bolts).
•
Must be rigid and level when the transducer is in the water to minimize the amount of vibra-
tion in the mount.
•
Retractable – the mount is easily moved into a secondary fixed-position when the boat is in
transit.
•
Transducer depth should be adjustable if possible (usually a minimum of 5-cm increments).
•
Typically, on small to mid -sized boats (i.e.; 10’ – 25’), the mount can extend over the bow.
This helps with stability on the smaller boats and is also easier to maneuver into position.
•
On larger boats, it is preferable to mount the ADP on either the port or starboard side near
mid-ship (generally the most stable area on the boat). The only concern is to make sure the
ADP is at least a few meters away from the engine or any other ferrous objects mounted to
the boat. Mounting the ADP over the bow becomes difficult on larger boats mainly because
the bow will have significant pitch compared to the mid -ship.
•
The transducer depth should be as shallow as possible. Depths of 5 to 50 cm are common.
The pitch, roll, and boat speed (relative to water speed during a measurement) need to be
considered when setting the transducer depth. For example, large pitch and roll requires
deeper transducer depths to keep the ADP submerged in the water. Similarly, the higher the
difference in speed between the boat and the water, the deeper the transducer will have to be
mounted in the water to prevent cavitations.
•
The transducer beam orientation (axis alignment) relative to the boat or stream is irrelevant
for river discharge measurements. The ADP is typically programmed to measure discharge
in ENU coordinates (East/North/Up), and so will always measure the true azimuth of the ve-
locity vectors. The advantage of aligning the ADP axis with the boat axis will be that the
pitch/roll of the boat and the ADP will be similar.
•
The standard-housing ADP is usually attached to the mount from its base plate. The base
plate is 19.1 cm (7.5”) in diameter. There are three holes on the edges of the base plate that
can be used to bolt the ADP to a mounting plate.
6.3. Setting up the RiverCat
For information on setting up the RiverCat system, refer to
Appendix D
.