SNORKELBOT
Unlimited Autonomous Shallow Reef Monitoring
Snorkelbot is a solar powered, unmanned, self-righting surface vehicle, for making high definition gimbal stabilized underwater videos on shallow reefs and coastal seabed.
Data collection can be stereoscopic, which makes this platform a data gathering tool for Structure from Motions and Orthomosaic modelling.
Missions can be multiple days, even weeks long. Vast areas of interest can be documented without needed interference by an operator. GPS locations of the vehicle are transmitted regularly by satellite, and pointed out on Google Earth. To prevent algae growth on the camera dome, it’s mechanically self-cleaning, insuring high quality photography, independent of mission length.
A low profile ensures minimal wind influence, and the substantial weight of 150 kg at low center of gravity and a length of over 3 meter or 10 feet makes the boat glued to the waves. Despite having a draft of only 37 cm or 14.5 inch for sailing in shallow waters, Snorkelbot has a self-righting system.
Snorkelbot is rudderless, and steers vector controlled by a bow thruster. This results in low drag, the absence of wear and tear, and as such a neglectable chance of mechanical failure during a mission. Pinpoint maneuvering is another benefit of this design, insuring revisiting of locations for comparative data collection.
Setting up a mission is done by plotting waypoints on Google Earth, and by use of included software which translates this to navigational data for Snorkelbot’s onboard computer.
Navigation between waypoints is done by self-learning software, which compensates for current and wind, so that within limitations, sailing will be done in straight lines.
In seas with up to 0.45 m/s or 1 mph current, this is still to be expected.
0.45 m/s is also the maximum current on a reef, for Snorkelbot to remain close to the target location.
During multiple-day missions in cloudless tropical periods, continuous (during day and night) sailing of 86 km or 53 miles, ex current, is feasible.
The batteries of Snorkelbot are always being charged when possible; the sailing itself is not depending on sunshine.
Before reaching a target location on a reef where photos and videos are to be captured within a radius of approximately 30m or 100 feet, Snorkelbot can be instructed to pause and wait at location until its batteries are sufficiently charged to proceed. This ensures ample energy is available for the reef tasks and for safe navigation away from it afterward.
So, there's no dependency on cloudless days to deploy Snorkelbot on a mission.
Snokelbot’s location and status is daily sent to the operator by satellite. In the same way, the operator can remotely change the mission, for instance to sail to and remain at a save location, in case an unexpected storm is approaching.
Basic vehicle design includes 2 down/forward looking sonar sensors under the bow. The final approach of a shallow target location can be aborted using this, to prevent collisions. Yet, in general, missions over shallow water should be planned with local reef-depth knowledge and detailed online-available tides timing. Sailing and recording over a less than 1m or 3.3-foot depth can as such safely being done.
Snorkelbot Stereoscopic video, as taken in the Maldives.
Single camera video
Data is stored on a USB Stick, which is retrievable from deck after a mission.
Daily capacity is at minimum 100 videos of 60 seconds, or over 2800 photos.
The route and headings, taken during shooting a video, is presented after post-processing on Google Earth. So, the exact location of a frame of interest can be found easily.
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