The ScanFish / ViperFish can enter a series of different flight modes. These are accessible from the Flight Mode button on the online toolbar upon successful completion of the pre flight check. The available flight modes are:
• On Deck
• Go to Surface
• Parking
• Fixed Depth
• Follow Seabed
• Vessel-Aided Terrain Follow
• Undulate Up
• Undulate Down
• Emergency up
• Power Off
• Battery mode - Non-selectable from the Flight user interface. Activated after System (Power) Failure.
When one of the modes is selected, the Flight Mode button label will change accordingly,
On deck
After successful pre flight check, the ScanFish / ViperFish will automatically enter On Deck mode. In On Deck mode the ScanFish / ViperFish is ready to be deployed and will consequently not attempt to navigate by moving the flaps. This mode must always be employed when handling the ScanFish / ViperFish on deck and during the initial stages of deployment and when recovering. As a rule of thumb then the ScanFish / ViperFish should be in On Deck mode when it is out of the water.
Note: When the ScanFish / ViperFish is set to On deck mode, the back-up battery is set to inactive. This is worth noting for the powering done cycle.
Go To Surface
When the ScanFish / ViperFish is set to Surface mode, it will attempt to go and stay at the water surface. This is the mode used when the ScanFish / ViperFish enters the water during launches and before being lifted out of the water during recoveries of the system.
Note: The ScanFish / ViperFish is vulnerable to wave motion when at surface, that may introduce surfing (can be dangerous if more than one system is being towed) and alternately slacking and pulling of the tow cable.
Parking
Parking mode can be entered both from the drop down menu and the quick button in the toolbar. In the Tow panel the user defines a depth the ScanFish / ViperFish will constantly attempt to maintain while in Parking mode.
Fixed depth
Fixed depth mode has the exact same capabilities as Parking mode. When the ScanFish / ViperFish is in Fixed depth it will constantly stay at the same water depth. This is only to give the user an alternative to Parking mode, so for instance one is dedicated to a ‘safe’ parking depth during line turns, while the other is dedicated to survey or as a pitstop between the two.
Follow seabed
In Follow Seabed mode, the ScanFish / ViperFish will maintain a fixed altitude above the seabed that has been defined in the Tow panel. This mode is useful in side-scan sonar and UXO magnetometer surveys.
Vessel-aided terrain follow
In Vessel-Aided Terrain Follow (VATF) mode the EIVA NaviPac software sends corrections to the ScanFish Flight software by a digital terrain model (DTM). The ScanFish / ViperFish will follow a fixed altitude above the seabed, defined as the Follow Seabed altitude in the Tow panel, but if any steep sided obstacles are detected on the DTM, NaviPac will send corrections across to manoeuvre the ScanFish / ViperFish safe over shipwrecks, cliff outcrops etc. Find a dedicated guide to the VATF mode on Freshdesk.
Undulation
In Undulate Down and Undulate Up mode the ScanFish / ViperFish will move in an undulating, continuous V-pattern between maximum depth and minimum depth at a predefined undulate rate defined in metres per second (for both the ascent and the descent) in the Tow panel. Note that the only difference between the two Undulate modes is the initial undulation direction.
Emergency up
Emergency up will bring the ScanFish / ViperFish up till 2 m depth as quickly as possible, ignoring the ascend rate set on the web interface (General Max Rate).
Power Off
The Power Off mode doesn’t actually power the ScanFish / ViperFish down. The user needs to turn the ScanFish Power & Communication off to power the ScanFish / ViperFish down. But to click Power Off at the end of every operation is a good routine, as Power Off sets the battery to being nonactive. This is also done by On Deck mode, but in situations where the ScanFish enters System Failure mode, and Power Off is not activated or the ScanFish is rebooted from the ScanFish web interface, the ScanFish will be running on its internal battery, when the ScanFish Power & communications is powered off.