L27 Changing propellor.jpg | Gwulo: Old Hong Kong

L27 Changing propellor.jpg

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L27 Changing propellor.jpg

I'm not sure how often a submarine's propellor needed changing. Perhaps L27's propellor had been damaged.

Date picture taken (may be approximate): 
Tuesday, January 1, 1929


We are looking at L.9 class sub L.27 having one or both of her props or screws changed whilst alongside depot ship Titania.

Taken from Titania looking from the forward end about midway between her bow and the conning tower in the centre L.27 is very heavily trimmed down at the bow achieved by flooding her forward ballast tanks which releases the air needed to keep her afloat. Her 4" gun is prominent and the device sticking out of the water is her forward torpedo loading derrick. By flooding the forward tanks and retaing all air in the aft tanks her bow sinks and stern rises like a see-saw, in this case well clear of the water enabling any work to be done aft where the pair of props are located. Ensure all hatches are shut. To remove props small explosives are used to help ease them off. This can be quite an evolution as the boat needs to remain in trim and stable. Once completed the forward ballast tanks are simply blown with high pressure air and she will return to her normal surface trim.

The L.9 class comprised 19 completed boats, L.23, 26 and 27 all saw service in and survived World War 2.