Spurred by this image on IWM (which I posted on twitter, out of interest's sake) "The water test: a hull-immersion test for tanks", Terence Cuneo. Art.IWM ART LD 3095 The Water Test : a hull-immersion test for tanks There were some questions on posed on Twitter to which I don't know the answer. First of all, what's going on here? The hatches of the Churchill in the midground are open - does the water look less deep than the hatches to you? Was this a standard test done when tanks were manufactured? Is this related to preparations for, say, D-Day? Unfortunately the image is not given a date on the IWM website. However, there are a couple of other Cuneo sketches related to the Churchill on the IWM site and they give a date of 1943. One of them is titled "On the strip-line: Churchill tanks being dismantled" which I would guess has to do with the Churchill rework programme. On The Strip-line: Churchill tanks being dismantled Thoughts?
Always assumed the sketch was what the title implies & what it looks like. Testing the hull for 'normal' water ingress/making sure all welds/joints/seals secure. Maybe even exposing hidden damage in machines in for repair/rebuild. Vauxhall were quite proud of their more 'full on' efforts in wading/waterproofing, even running s REME fitters school regarding it at the factory, but they tested those machines at a nearby lake, and sometimes the coast. The machine in the sketch has no deep wading gear fitted. If you consider one of Churchill's most distinctive features - its air intakes - their arrangement alone (particularly on early-mid machines like this one.) meant it couldn't wade safely around the level of those front hatches without modifications anyway, so no need to close them.. More Cuneo:: Terence Cuneo paintings
This will be a test for fording depth (usually 3 ft. for tanks) rather than wading depth (usually circa 6 ft.). There were (are) generally three classes of immersion: Fording Wading Flotation The latter is when the vehicle is suspended in the water and the tracks are not touching the bottom.