Question

Describe, with the aid of a sketch a wire single pull folding hatch cover.

Describe 4 methods that are used to check the weather tightness of hatch covers

Answer.

The hatch cover illustrated consists of a series of panels: each reinforced by stiffening webs.

The panels roll along tire coaming track way on rollers.

A central balancing wheel is used for stowage and engages on the rising track as it is pulled along to the stowage area.

Each of the central wheels project outside of the line of the rollers and as the rollers travel down the falling track, the stowage wheels engage on the rising track and the panel tips into the stowage position.

Each of the panels are joined together by a chain linking the stowage wheels so that all the panels of the hatch cover travel simultaneously with a single pull.

The operation is reversed-when the panels are replaced on the hatch coaming.

The panels are raised/lowered off/onto the coaming by hydraulic jacks.

The hatch covers, when in the closed position, are made watertight by cleats at the sides and wedges at the cross joints.

(b) Four methods of checking weather tightness would be:

(i) Hose test - impact jet on seats from one metre distance - inspect

(ii) Chalk test - on top of bar that the hatch sealing rubber rests

(iii) Ultrasonic testers are available to check the seals

(iv) Inspect from inside of the closed hatch for any light penetrating