Spray 2.0: Development and technology transition of a next-generation underwater glider

Lead PI: Daniel Rudnick, University of California , San Diego
Start Year: 2018 | Duration: 2 years
Partners: Marine Robotic Vehicles, National Science Foundation

Underwater gliders are a technology with a decidedly mixed track record. In the hands of a few expert groups, underwater gliders have proved to be fully operational. A fair assessment is that the Technology Readiness Level (TRL) of underwater gliders depends on the expertise of the people using them. While this outcome for new technology is not surprising, it limits the impact of underwater gliders as an observational tool for ocean sciences. The first objective of this proposal is to develop a next-generation underwater glider, “Spray 2,”which will raise the TRL of the Spray glider to 8 for a wider range of users.

One of the factors holding back the wider use of gliders is the relative difficulty of service. Spray gliders from our lab have been in the water for a sum total of over I 00 years. We have
experience deploying from small boats and research vessels, from urban areas and remote islands. A recurring issue with gliders, as with all oceanographic instruments, is the need for minor refurbishment and repair in the field. A second objective of this effort is to ease servicing by making such components as batteries and sensors simpler to swap.

Efficiency for gliders is surely achieved through missions with greater endurance. A sensible measure of endurance is distance traveled through water during a mission. This distance is the product of vehicle speed and mission duration, so the increase can be achieved with either faster or longer lasting gliders. A third objective is to enhance perfonnance as measured by range through water.

First-generation underwater gliders were designed to achieve long duration missions by limiting drag through a streamlined shape, and by moving slowly. The requirement for a smooth shape puts limitations on the sensor payload. Next-generation gliders will make the ability to carry sensors more central to their design. The fourth objective of this proposal is to create a modular approach to the integration of new sensors, and to allow sensors to occupy locations on the glider with access to clean flow.

A critical step toward raising the TRL for the general community is the transition to commercial production, sales, and customer support. This transition is of equal importance to development, even though agency funds for this activity are traditionally limited. Underwater gliders offer a case study in a successful technical development whose transition to industry has been challenging.The final objective of this proposal is to fashion a seamless transition from development to commercial availability.

The anticipated outcome is a commercially available and supported Spray 2, with lowered barriers to entry for new users, and higher levels of support, documentation, and user-level software tools. This will reduce the set of skills necessary to successfully operate the glider, and improve research outcomes.