Page:Self-righting boat design.pdf/8

 hypalon coated fabric, similar to that used in manufacture of inflatable boats and are inflated using compressed gas infected under pressure. The gas canister is usually fired manually from the inverted vessel and has attached them to a tether line running from the stern. This keeps crew in contact with the boat before, during, and after righting. To fire the bag automatically with personnel still underneath could result in injury and, in strong winds, the upright vessel being blown away from the crew before they can re-board. Automatically activated inflatable bags are occasionally fitted on vessels where the wheelhouse volume provides insufficient buoyancy to effect satisfactory and reliable self-righting.

Benefits of the inflatable bag method include: Disadvantages of the inflatable bag include:
 * Simple and light weight.
 * Volume can be adjusted by changing the size of airbag.
 * Easy maintenance as bag can be removed and replaced with a substitute.
 * Bag must be fitted and folded correctly to achieve reliability.
 * Roll bar structure and bag attachment must be substantial to resist the forces present during the righting process, particularly at 90 degrees heel.
 * Provides a once only righting ability. Some boats are fitted with duplicate gas cylinders for 100% system redundancies and to provide a second inflation, should this be necessary, but the bag is not repacked between firings.
 * Bag liable to damage if inflated in shallow water or close to a casualty.
 * Gas pipework and bag injection point must be correctly designed to avoid freezing.