extra strong frame composed of plates and bars fitted between every fifth and sixth frame. the spacing of web frames depends on the position of th ship. They never fall between existing frmaes, but replace a normal frame. They maybe spaced closer together than the normal frame spacing Source: Country Life Book of Nautical Terms Under Sail and Pract [..]

A specially deep transverse frame in the form of a built girder.

Transverse side frame with deeper web, spaced at multiples of main frame stations for the provision of extra strength.