The island of Hawai'i is the southernmost island of the Hawai'ian archipelago. It is also the largest island with a land area of
nearly 10,500 sq km. It is the youngest island of the archipelago with ongoing volcanic activity.
Operations Description: From May 21- June 2, 2015, CRED personnel conducted towed optical surveys along the Kohala coast of Hawai'i, between Kawaihae and Mahaiula Bay.
The towed camera sled was deployed from the R/V Kohola, an 11m AMBAR vessel. Operations
were conducted during daylight hours, with seafloor imagery collected using an underwater camera sled, designed and fabricated by Deep Ocean
Engineering, Inc. (DOE) and a drop camera system with video from a Splashcam and still imagery from a GoPro. Optical data were collected with
underwater video and still cameras with lights. These data are used to provide ground-truth validation for benthic habitat
maps based on multibeam echosounder surveys and to gather additional information regarding benthic and fish communities.
Camera deployments were conducted during daylight hours, usually between 0800 and 1500. The duration of each TOAD tow varied, but averaged
about 10 minutes of bottom time per tow. The drop camera system was deployed for an average of 3 minutes per tow. Both camera systems were deployed
from the port side of the vessel. At each station the vessel was positioned with the wind on the port side and drifted downwind; occasional light
turns were applied if necessary to reduce the vessel's motion or to ensure the tethered cable was clear of the outboard engines. The TOAD sled was
lowered slowly to the bottom by a pot-hauler holding 200 m of cable, operated from a control station in the cabin of the vessel. The drop camera was
deployed by hand using 40 of cable. For both systems, the operator monitored a live video feed from the camera system and began recording video onto
media cards using a digital video recorder once the camera reached the bottom. The operator continued to monitor the video feed during the tow and
raised or lowered the sled to maintain a 2m altitude above the seafloor.
Equipment Description: TOAD Camera Sled: The TOAD sled body is constructed from a shortened Phantom ROV body with a tail piece added for stability. The
camera sled is equipped with a Deep Sea Power & Light (DSP&L) Multi SeaCam 2060 low-light color video camera, angled downwards to
provide imagery of the seabed while allowing some view of upcoming obstacles, and a downward-facing Ocean Imaging System 12000 digital
still camera (consisting of a Nikon D90 digital SLR camera within an aluminum housing). Illumination for the video camera is
provided by 50 watt DSP&L LED Multi SeaLites. Illumination for the still camera is provided by a remote flash head (Ocean Imaging Systems).
A pair of parallel DSP&L SeaLaser 100 lasers provided a scale reference in still images. The sled also has a Tritech PA200 Altimeter to detect the height
of the camera above the seafloor, a pressure (depth) sensor and a fluxgate
compass, all installed inside the sled's electronics bottle. The camera sled was attached to the control console (situated in the boat cabin) via a 130 M length (0.5" diameter)
umbilical cable, and was deployed via a pot-hauler with a
300lbs (SWL) capacity, mounted on the port deck of the vessel. A video display monitor mounted on the control console was used to
monitor the position of the sled relative to the seafloor. Video data were recorded to digital files using a digital video recorder
mounted on the control console. A serial cable was connected to a Garmin GPS, to provide position of the vessel. Hypack hydrographic
software (version 2014) was used to record position data (from GPS) and time. The length of umbilical cable in the water was manually
entered into Hypack, this in conjunction with the camera sled depth and vessel position was used to calculate
layback and determine the latitude and longitude of the sled. The calculated position is then recorded in Hypack. Drop Camera: The drop camera
consisted of a Deep Blue Pro Marine video Splashcam angled downwards to provide imagery of the seabed while allowing some view of upcoming
obstacles and a downward-facing GoPro Hero 3+ still camera inside an extreme depth underwater housing. Illumination for the still camera was
provided by two LED underwater lights. A pair of parallel lasers proveded a scale reference in still images. The drop camera was attached to a
small monitor screen on deck via a 40 M length umbilical cable and was deployed by hand from the port deck of the vessel. A video display monitor
was used to monitor the position of the sled reletive to the seafloor. Video data were recorded to digital files using a digital video recorder on
deck. Still imagery was collected at 10 second intervals and recorded on an internal microSD card. A hand held Garmin 76Cx GPS unit was used to
record the position of the vessel. Vessel movement was kept to a minimum to maintain a vertical angle on the umbilical cable.
Data Files: Video data were recorded on media cards using a digital video recorder and later copied to external hard drive digital files. Still
imagery were recorded onto media cards and copied to external hard drive digital files. The position of the TOAD camera sled was recorded using
Hypack 2014 hydrogrpahic software. Position of the drop camera was recorded using the vessel track file from the Handheld Garmin GPS unit.
File naming convention: Each tow is given a name consisting of a 3-letter designator for the island area followed by
a two-digit year and three-digit tow number. During cruise SB1505 the tows were named HAW15103 to HAW15266. Digital videos, still images and paper log forms
are annotated with the associated tow name. Data recorded using Hypack software are of the format 2015KOHHMMSS where HHMMSS is UTC time.
Time Correlation: All times are based on UTC. Clocks were manually synchronized prior to starting data collection each day of operations.
Resource Description: Digital video imagery that is geo-referenced to navigation files.