Special Issue Survey of Cetaceans in Captive Care

5. Architectural Design of Pools and Enclosures 341or intentional opening or closing by wave actionor animal play. It is recommended that the operatingmechanism be inspected on a regular schedule.Check that gates are not making a “clanging”noise under water.Watertight Gates—Watertight gates are fullsolid panels made of metal, fibreglass, PVC,painted or plastic coated wood, or compositepanels. They are used to separate two water bodies(e.g., isolation of medical pool) and to allow apool to be emptied while the adjacent one remainsfull. Watertight gates are occasionally needed,especially if a pool is used for quarantine purposesor needs to have repairs.Watertight gates are used mainly in concretepools since semi-natural enclosures rarely allowchanges of water levels. They are much heavierthan non-watertight gates. Hence, they requireseveral people to operate them manually unlessthey are equipped with a winch or ratchet mechanism.They are easier to operate with a poweredmechanism, and their design is very similar toflood or sluice gates.Watertight gates can slide horizontally or verticallyin built-in grooves. For a horizontal slidinggate, a recess is provided within the partition orthe pool deck to accommodate the gate. Becausethe gate is submerged in the water, algae and dirtmay accumulate in the sliding mechanism andaffect its operation. It is therefore recommendedto service and clean the gate regularly to avoid asystem breakdown.A vertical sliding gate is either put in placemanually or is operated by a crane. It also can beinstalled on a frame and lowered into the water bya powered hoist, a ratchet mechanism, or a pulleymechanism equipped with a counterweight. Thisis called a “guillotine” gate. It is a convenientsystem, but it is aesthetically unpleasant. It alsorequires a lot of maintenance because of corrosion.The overhang may also cause problems in gatingthe animals. Hinged or swinging watertight gatesexist, but they were not documented nor reportedin the survey. They are designed using the sameprinciples as flood gates, with ratchet mechanismsand very sturdy hinges.The material used is also important in thedesign of a watertight gate. Some facilities havereported that fibreglass or plastic-coated woodpanels, kept in place by wedges, would pop outafter they started emptying the pool. A system tosecure the gate in place can be installed to preventthis kind of incident.All types of watertight gates are heavy andfairly slow to operate. Pneumatic systems areprobably the most widely used and reliablemechanisms for gate operation. Because of theirslow movement and inertia, watertight gates mayFigure 5.43. Horizontal sliding waterproof gateFigure 5.44. Vertical sliding waterproof gaterepresent a potential danger to the animals.Therefore, trainers operating the gate should beable to see the opening at all times to prevent ananimal from being trapped. The operating systemshould be equipped with a device that reopens thegate if it detects resistance while closing. A manualoverride also should be available as a back-up.Non-Watertight Gates—Non-watertight gatesare used to separate or isolate animals for trainingand show purposes or for medical reasons. Theyare usually bars or mesh made of stainless steel,aluminium, fibreglass, PVC, or chain link that aremounted on a metal or plastic frame.Gates are used frequently in dolphin pools andshould therefore be easy to operate and safe for