Ted, "22-24 wooden panels, abut 2 mlong and 25-30cm wide and 3-5 cm thick,,weighing easy 100 kg" - that's per 1 "hatch cover" & as I see from the pic there are like 8-10 such ones. Where do they store all the wooden panels then?
I'm surprised the method you described is still in use on this ship - could have changed it with something better.

Denis
this is HAND-MACGREGOR, also called MAC-STEMM (Stemm,,from the german word stemmen (lifting) There are usually about this size ship 22-24 wooden panels, abut 2 mlong and 25-30cm wide and 3-5 cm thick,,weighing easy 100 kg if wet and soaked. The Tarpaulin were pulled of, then the wooden panels were taken off and the sherstocks (crosswise to the hold opening in 2m distances where the woods would fit in) were moved by tiny little cars, lamp up and wheels,lifting them a bout 2-3 cm and then manual pushed in the direction where needed to open the hatches. So NOTHING with cranes etc ,,all Hand MacGregor,,means by shear muscle poaer of the crew,, How I know,,been there done that !!!! started on a ship like that sailing in the mid 70,s..was bone breaking work,,special when rain on and off and open and close again and again

Unfortunately I can not answer you to that question Denis, hope there is another member who can answer it for you.
Best Regards
Bendt

Didn't know the system of opening/closing hatch covers with a gantry crane existed since back then. I'm used to see such since 90s freighters, so yeah.