What is Chalk Test of hatch covers ? |

What is Chalk Test of hatch covers ?

When performing a chalk test, the top edge of every compression bar is covered with chalk. Hatches are then fully closed and reopened. The rubber packing is examined for a chalk mark, which should run continuously along the packings centre.

Gaps in the chalk mark indicate lack of compression. Chalk testing merely indicates if hatch panels are aligned and compression achieved.

It will not show whether compression is adequate and therefore it is not a test for weather tightness

You may also know water hose test –

Water hose tests are used to determine weather tightness of hatch covers. If correctly performed, hose testing willshow hatch joints that leak.

The general procedure for hose testing is to apply a powerful jet of water from a 20-50mm diameter hose fitted with a 12mm diameter nozzle held at a distance of 1-1.5 metres from a hatch joint, moving along the joint at a speed of 1 metre every 2 seconds.

The drawbacks of hose testing are:
  • The hold needs to be empty;
  • It cannot be performed in sub-zero conditions;
  • It requires the deck scupper drains to be open (potentially causing pollution);
  • The test cannot pinpoint leaks on the cross-joint or side joint accurately;
  • Two people are needed to supervise the test.

 

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