The location of laboratories on shipboard, the amount of space devoted to them, and the facilities installed depend upon the size and nature of the vessel and the types of investigations to be made. The laboratories may be classified as deck laboratories and analytical laboratories. The deck laboratory opens on the deck and is used for storing certain oceanographic equipment. There the reversing thermometers are read, water samples are drawn from the sampling device, and certain preliminary steps are taken in the preservation or preparation of water and plankton samples. The deck laboratory should contain racks in which the water-sampling bottles may be placed as soon as they are removed from the wire rope. These racks should be so arranged that the temperatures can be read and the water samples can be taken out without removing the bottles. Space should be provided for the glass bottles in which the water samples are transported, for certain chemical reagents, and for the solutions required for the preservation of biological material. A bench where records and labels can be prepared is also a great convenience. A large sink with running fresh and salt water is very useful, and the deck should be watertight and provided with drains because water is spilled in filling the glass bottles. Deck laboratories are a great asset on oceanographic vessels, particularly in bad weather and at night, as much more satisfactory work can be done under shelter where there is good illumination.
The analytical laboratories are usually located below decks where there is the most space and where the motion of the vessel is at a minimum.
Vibration transmitted through the vessel from the engines and motors is often more troublesome in the laboratory than the roll or pitch of the vessel, and consequently the engines should be mounted, when practicable, on flexible springs or on cork or rubber. The equipment used in the laboratories will generally be identical with that used on shore, but the benches, storage space, and methods of securing apparatus to the benches must be adapted to work at sea under any conditions. Work benches are usually of such a height that the worker can be seated on a stool or seat that is fixed in place and so arranged that he can brace himself with his legs, thus leaving his hands free. In some cases provisions are made for a bench mounted on gimbals, but the advantages of a relatively level surface are often outweighed by its unsteadiness. All apparatus must have suitable storage compartments in which there is no danger of the apparatus falling out or smashing together in a high sea. Burettes and other instruments, while in use, must be secured to the bench or to permanent burette stands.
The analytical laboratory should be provided with running fresh water and a source of distilled water. The latter may be carried in large bottles or, preferably, in specially installed tin-lined tanks. On a long cruise it may be necessary to provide distilling apparatus. When living organisms are to be investigated, a source of cooled sea water or a cold box is necessary. A cold box is also desirable for preserving water or sediment samples for bacteriological examination.
Laboratory work on shipboard is usually kept to a minimum because of the undesirable working conditions that arise from the cramped space, the motion of the vessel, vibration, and the time required for merely collecting the samples. However, there are certain chemical tests that must be made immediately after the samples are collected, and generally these must be made on board. The methods of analysis are referred to in chapter VI. On longer cruises it may be necessary to do more of the work on board, but in such cases the analyses may be done when the weather conditions are favorable or when the vessel is in port or at anchor. Biological work on board the vessel is limited in character, since most specimens can be preserved for later examination ashore and because vibration and motion of the vessel make the use of microscopes virtually impossible.
Samples of water, organisms, or sediments that are to be examined ashore are usually not stored in the laboratory but must be kept in a place not subject to wide ranges in temperature or to extreme temperatures. High temperatures lead to the disintegration of the rubber washers used on most bottles and thus permit evaporation, which will ruin the specimens. Fluctuating temperatures may loosen the stoppers and lead to evaporation, or may even break the bottles. Freezing temperatures must also be avoided, owing to the danger of breakage.