SUBSIM Radio Room Forums - View Single Post - SH3 -- should I be able to run on batteries on surface?

aj906 · 03-08-12, 01:47 AM

I'm currently reading Feindfahrten by Wolfgang Hershfeld and in it he describes a trip down to ET89 in U-109 and the concern there was over the fuel requirements getting them home. From memory (The book is not by my side at the moment) there was something like 38 cubic metres of oil left in the bunkers when off Freetown and that was apparently sufficient only for a trip to the Azores. U-109 is eventually resupplied by U-460 but again there is anxiety over whether they will reach Lorient. He states that the only option then available to them would have been to jury rig a sail (quite how, and from what, he doesn't say). I can't imagine this would have been the most useful method and the question would then become one of rations about the boat and how long they would last as opposed to how quickly landfall could be made.

Similarly he notes that during the northerly trip home as much running on batteries as possible was employed and that the engineers transferred the oil around the various tanks to change the boyancy of the boat, thereby lowering the draft and thus improving fuel economy. This raises a peculiar question - at ahead 2/3rds I get 4knots underwater in calm seas in a IXC. I wonder what you could get with a 1/3 of the boat (and thus resistance) out of the water

Nevermind that extra few feet of draft saved by the loss of the weight incurred by all those eels!

03-08-12, 01:47 AM	#8
aj906 Helmsman Join Date: Mar 2008 Posts: 107 Downloads: 5 Uploads: 0	I'm currently reading Feindfahrten by Wolfgang Hershfeld and in it he describes a trip down to ET89 in U-109 and the concern there was over the fuel requirements getting them home. From memory (The book is not by my side at the moment) there was something like 38 cubic metres of oil left in the bunkers when off Freetown and that was apparently sufficient only for a trip to the Azores. U-109 is eventually resupplied by U-460 but again there is anxiety over whether they will reach Lorient. He states that the only option then available to them would have been to jury rig a sail (quite how, and from what, he doesn't say). I can't imagine this would have been the most useful method and the question would then become one of rations about the boat and how long they would last as opposed to how quickly landfall could be made. Similarly he notes that during the northerly trip home as much running on batteries as possible was employed and that the engineers transferred the oil around the various tanks to change the boyancy of the boat, thereby lowering the draft and thus improving fuel economy. This raises a peculiar question - at ahead 2/3rds I get 4knots underwater in calm seas in a IXC. I wonder what you could get with a 1/3 of the boat (and thus resistance) out of the water Nevermind that extra few feet of draft saved by the loss of the weight incurred by all those eels! __________________ Gott weiß ich will kein Engel sein...!