What makes a research ship special?
The modern research ship has it origins in the early voyages of exploration. HMS Endeavour, used on Cook’s first expedition (1769-81) and HMS Challenger, used for the first true oceanographic cruise to circumnavigate the globe (1872-6), were typical of research vessels up until the latter part of the 20th century. Both ships were conversions; Endeavour had been a Whitby collier, whilst Challenger used to be a steam corvette. Both vessels were chosen for conversion to a research ship due to their ability to operate in extreme environments. They were also fitted with a range of research facilities, covering a variety of disciplines.
This trend of converting other vessels continued up until the latter part of the 20th Century, when oceanographic research disciplines (physical, biological, and chemical oceanography; marine geology and geophysics; ocean engineering; and atmospheric science) became much more demanding and specific in their requirements of a vessel.
Some of these needs are unique to certain disciplines, while others such as the need to collect seawater samples throughout the water column are more universal. On modern research ships, these varied disciplines are now often pursued on the same research cruise. Consequently the design of these vessels is a complex exercise in balancing conflicting discipline-specific functions within economic constraints. It is now potentially a much more costly and complex solution to convert an existing vessel designed for another purpose than to build a new ship from scratch.
Features of a research vessel
Science is likely to be conducted in increasingly remote and environmentally challenging areas, including the polar seas, so the ability to operate with minimal interruptions from the natural elements remains unchanged from the days of the Challenger Expedition. However, the following areas of functionality are becoming increasingly important in modern research ship design:
Handling Equipment
The safe handling of increasingly large and more complex platforms and instruments over the side in high sea states (up to sea state 6) means that handling arrangements are critical. In the case of the RRS James Cook, the handling gantries have been designed with a safe working load of 30T. Both this ship and the new RRS Discovery have a complex suite of electrically driven winches permanently installed, handling 5 cables ranging from 8,000m of steel wire to 10,000m of synthetic coring rope, as well as 10,000m fibre-optic tow cable. The installation of heave compensation, to isolate deployed packages from ship motion, is also becoming increasingly common; the CTD winches on the NOCs ships have this functionality. In addition, gliders, autonomous underwater and unmanned aerial vehicles (AUVs and UAVs) and remotely operated vehicles (ROVs) require specific deployment and recovery procedures and equipment.
Acoustic Quieting
Many of the sensors on a modern research ship employ acoustic energy, including multibeam echosounders, Acoustic Doppler Current Profilers (ADCP) and underwater positioning and telemetry systems. Such systems operate at an optimum level when acoustic interference is minimised. A specific requirement in some ships, aimed at avoiding disturbance of fish (to ensure accurate biomass measurements can be made) is detailed by the International Council for the Exploration of the Sea (ICES) report Underwater Noise of Research Vessels, and is commonly referred to as ICES 209. The RRS James Cook is built to the ICES 209 (with a slight modification at very low frequencies), while the new RRS Discovery is being built to a NERC defined standard, which is optimised for control of frequencies that interfere with acoustic sensors, including seismic measurements. Much of a ship’s noise comes from its machinery, so double raft mounting and/or resilient mounting of this machinery is employed, while the design of the ship’s propellers also has a major effect. These ships operate 24-hrs a day, so more and more, ambient internal noise around cabins has to be controlled using design approaches which have their origins on cruise liners. These measures commonly increase the cost of the vessel, so careful definition of operational acoustic requirements is required.
Dynamic Positioning
Dynamic positioning describes the ability of a ship to automatically maintain a stable position through a combination of propellers and thrusters. This is conducive to the safe handling of over-the-side packages, but also critical for accurate navigation of remotely operated vehicles which may be maintaining position on fixed points on the seabed, or else following specific tracklines. The RRS James Cook and new RRS Discovery have both been designed to maintain position beam-on in at least sea state 6/7, 30 knot winds gusting to 40 knots, and a 0.5 knot surface current. In considering the propulsion configuration to be used, there is also the need to balance this requirement against that of acoustic quieting as quieter configurations tend to be less efficient in terms of Dynamic Positioning. The configurations used on the two NOC ships are quite different, mainly due to the difference in acoustic requirements.
Hydrodynamic Performance
Although related to acoustic quieting, hydrodynamic performance is somewhat different. Acoustic quieting relates to internally generated sound, whereas the hydrodynamic performance is concerned with design features aimed at reducing hull-induced flow noise. Both the RRS James Cook and new RRS Discovery have 2 drop keels which are designed to be lowered ca. 2.5m below the keel and lower than any bubbles being swept along the bottom of the ship. Due to their size, these are only suitable for mounting smaller instruments such as ADCPs and small echosounders. Much more problematic are the large, low frequency (usually 12kHz), multibeam arrays which may be several metres in both width and length and which need to be fitted to the bottom of the ship. Some research vessels have these fitted in a gondola, which is again designed to lower them below hull bubbles, but which suffer from increased draft and drag, leading to increased fuel costs (an increase of 15-20% is not uncommon). In attempt to compromise on these issues, the new RRS Discovery is designed with a ‘blister’ on the ship’s bottom which houses an array that is ca. 8m x 8m.
Laboratories
The wide variety of science activities conducted concurrently means that modern research vessels are built with plentiful laboratory spaces, often sub-divided into ultraclean, clean, normal, and temperature-controlled areas, with sufficient flexibility to be used for multiple needs. Specialist laboratory needs are often provided through the use of containerised laboratories, while there is also a requirement for a substantial scientific stores area, including areas for frozen and refrigerated sample storage. The RRS James Cook and new RRS Discovery have 278m2 and 389m2 of laboratories respectively, as well as positions for up to 7 x 20’ container laboratories on deck - although it would be unusual to use more than 3 of these on board at any one time.
Working Decks
Research vessel working decks are designed with flexibility in mind, with deck areas uncluttered by fittings and as open as possible for fitting of a wide variety of equipment. Ships such as those operated by NOC facilitate the fitting of equipment and storage and laboratory containers on deck by means of a matrix of deck sockets. Ideally, research vessels would be designed with low freeboard to facilitate deployment and recovery of over-the-side equipment, but in rough sea this leads to these decks becoming submerged regularly, limiting working conditions, while modern damage stability requirements are leading to higher freeboards. Once again, the design has to be a compromise. RRS James Cook has a total of 446 m2 of open working decks, while the new RRS Discovery will have 432 m2. Both ships have slots for 18 x 20’ containers (including 4 in the aft hold in the case of RRS James Cook).
Future of research vessels
The limitations of remote sensing mean that, for the foreseeable future, ships will remain the primary method of conducting oceanographic research, both through direct observation as well as deployment of autonomous vehicles and installations. At the same time, research vessels are likely to be required to support increasingly complex, multidisciplinary, multi-investigator research, which will drive many aspects of design, including power plant and propulsion, laboratory and working deck layout, over-the-side handling, launch and recovery, and equipment changeover. Because technology changes rapidly and ship lifespans are long, future research ship design will need to be highly adaptable as needs change.
For more detailed consideration please see ‘Science at Sea’, chapter 4, published in 2009 by the USA National Research Council
