Acoustic kayak drone

We have constructed an electric kayak drone equipped with advanced echo sounders mounted on a retractable keel. The drone can be deployed from research vessels or from the shore, using a modified boat trailer. The steering of the drone is facilitated through either wireless remote control or by autonomous operation where the vessel follows a predefined sailing route. All the software systems have been tested during sea trials, this includes motor and remote control, as well as data logging. The first full-scale experiment was carried out west of the Runde bird cliff, Western Norway. The experiment showed that the seabirds did not react to the approaching silent kayak, which made it possible to observe the natural seabird - fish interactions. With the current battery, the sailing range of the kayak drone is approx. 35 km with a sailing speed of about 10 km/h. However, by installing an extra battery in the second available battery chamber, the sailing distance will double. It is possible to extend the range even more by purchasing more powerful batteries, but the kayak hull has to be adopted to these batteries. The kayak drone will be used in the two remaining demonstration tests in November and December 2018. Firstly, the kayak drone will be tested in the fjords near Tromsø on a cruise carried out by Research Vessel G.O. Sars. The purpose of the demonstration is to test and improve the launching and retrieving procedure of the kayak drone from a large vessel. We also plan to use the kayak drone to monitor the avoidance reaction of herring to a sailing research vessel in standard cruise speed. Secondly, the kayak drone will be tested in a sprat cruise in the Sognefjord, western Norway in December 2018. The objective of the test is to make a comparison of acoustic density of sprat measured with a large research ship and the kayak drone. It is expected that the kayak drone will observe more sprat near land and closer to the surface as the kayak drone can operate in shallower waters and more sprat avoid the sailing path of the ship than the silent and smaller kayak drone. Next year, the kayak drone will be tested in the Nordic Council of Ministers project on Hydro-acoustics and Autonomous platforms. IMR is a partner in the project, where the main objective is to use autonomous platforms to monitor coastal ecosystems with a focus on seabird-fish interactions.

A prototype of the acoustic kayak drone has been made in the project, and in spite of some technical problems and delays in the project, the prototype is ready to be used as an autonomous platform for coastal acoustic surveys and experimental offshore studies. The first coastal study is done, and two more studies using the kayak will be carried out in the autumn of 2018. The kayak drone will also be used in a new Nordic Council of Ministers project, which started in the summer of 2018

The 2014 call from the HAVKYST sub-program 'methods, models and technology' asks for the development of cost-efficient observation methodologies to monitor the water column and habitats in the sea and coastal waters. The overall goal in the project is to construct a surface drone equipped with multi-frequency echo sounders and optics as standard, which will allow scientific surveys in shallow areas unavailable for larger vessels, and replace time-consuming data collection and provide additional information on fish behaviour and coverage in expensive oceanic and coastal surveys. The acoustic data collected with the drone will be of the same format as used in standard acoustic surveys, which is a tremendous advantage as both post-processing systems and data bases already are available. Thereby, the data can easily be scrutinized, processed, stored and used as input to contemporary assessments of the marine environment and fish stocks. This allows implementation of new cost-efficient technology without jeopardizing current time series information. The project will focus to keep the complexity and the cost low so that future projects and monitoring programs can easily access and use the drone in surveys. The drone should be robust as it will be used in many different survey situations. Projects working with coastal monitoring and MPAs, monitoring of the North Sea sandeel stock, and scientific questions regarding vessel avoidance have already shown large interest in the project.