Ship Launching Airbags

A ship launching airbag is an inflatable cylinder built from raw rubber and multiple layers of nylon-cord reinforcement, closed off by tapered point-ends and fitted with an air inlet valve. Inflated under a hull, a row of airbags acts as a bed of rolling bearings: the vessel rides on air instead of on a fixed cradle.

Because the bags roll, they remove the need for a purpose-built slipway or dry dock — which makes airbag launching one of the most versatile and lowest-capital ways to move a vessel between land and water. It is used by shipyards across Asia, Europe and North America and is frequently the first choice for small- to medium-sized vessels.

The airbags are laid in rows beneath the hull along the slipway centreline and inflated to a working pressure calculated from the vessel's weight and the contact length available. As they inflate, the hull lifts clear of its keel blocks.

Controlled, progressive deflation then lets the hull roll seaward on the airbags until it reaches buoyancy and floats free — a soft, gradual launch. Run in reverse, the same method hauls a vessel out of the water for survey or repair.