Roof hatches

[Geoff Winnington-Ball (RIP)]

The rectangular hatch was in place from inception of the CMP to 1944, when it was gradually superceded by the round hatch. I don't know why, except to guess that perhaps it was cheaper to engineer and build, and certainly provided more support to the human standing inside it.

[Hanno Spoelstra]

Originally Posted by Geoff Winnington-Ball

The rectangular hatch was in place from inception of the CMP to 1944, when it was gradually superceded by the round hatch.

Actually, the square roof hatch was optional on all models. I recon in practice it was fitted as standard to all mid-war production CMPs, and it was superceded by the round one in 1944/1945 production. It was not so much of a hatch, more a round hole with canvas cover.

HTH,
Hanno


Source: Interesting pic of CMP