RTB speeds.

sharkbit · 04-14-10, 07:44 AM

Quote:

Originally Posted by jimbuna

Agreed....flank speed was only used for convoy interceptions and for as short a period as possible because of the wear and tear/maintenance issues it created.

It sounds like those diesels could be maintenance nightmares.
I'm reading Clay Blair's "Hitler's U-Boat War:The Hunters" and it is filled with instances of boats aborting patrols due to engine problems.

rudewarrior · 04-14-10, 09:52 AM

Thanx for the responses. I've read some of the books mentioned here, specifically Iron Coffins (excellent book). Yeah, trucking across the Bay of Biscay later in the war was a real bitch, and I seem to remember reading somewhere that they would try to make it through the bay as quickly as possible. I remember reading that they would try to dive and surface at top speeds due to the "speed is life" idea. This minimizes the chances of them not being able to react to a situation that arises after the act of surfacing/diving. Since they are trying to react to aircraft buzzing around all over, I could see them trucking across the bay at top speeds as SOP. That would certainly minimize their dive time.

I know not to "cruise" at flank speed. Any mechanical engineer will tell you that is not what it is designed for. Flank speeds mean operating outside a normal range, and it would obviously only be done for a recommended period of time, which I can assure means no longer than a day, let alone the two weeks I need to get back.

I do recognize the engine breakdown argument. It's an obvious one, and it bears consideration, but I'd like to see some specifics about their return cited somewhere. The engines may break down, etc., but at the same time, from my own understanding of how militaries function, I also think there would be some impetus to return quickly. It is incredibly militarily inefficient to have a boat "taking its time" to get back. After all, that time is the period when the boat is most ineffective. It has no ordinance, with the exception of the deck and flak guns (for whatever that is worth). So essentially it is not a fighting capable unit, and it won't be UNTIL IT GETS HOME. Then it can be reoutfitted, and returned to sea to sink more shipping.

Having been in the military, I can't see taking a boat like that out, expending all of my ordinance, and then cruising back. It would seem that my superior would be screaming at me, "Get your ass back here, NOW!"

Again, the breakdown argument isn't necessarily wrong, it's just that the nature of these two arguments conflict enough such that I would really like to see some evidence supporting one or the other.

Maybe neither. Was fuel conservation an issue for the Kriegsmarine any time during the war? Just another issue to consider.

Capt. Morgan · 04-14-10, 10:11 AM

Quote:

Originally Posted by sharkbit

It sounds like those diesels could be maintenance nightmares.
I'm reading Clay Blair's "Hitler's U-Boat War:The Hunters" and it is filled with instances of boats aborting patrols due to engine problems.

Reminds me of that part in Robert McNamara's Fog of War where he talks about instituting the 50 mission limit for U.S.A.A.F. bomber crews in WWII.

The number of mission aborts due to engine failure dropped dramatically once the crews believed they had a chance of surviving the war (though statistically, their odds were no better than before).

Similarly, I'm sure that by late '42, many U-Boat commanders would use any opportunity, or excuse, to RTB early (and possibly at not so high speed).

sergei · 04-14-10, 10:52 AM

Quote:

Originally Posted by Capt. Morgan

Robert McNamara's Fog of War

I got that on DVD a few months back.
It's a very interesting film.

rudewarrior · 04-14-10, 04:16 PM

Quote:

Originally Posted by Capt. Morgan

Similarly, I'm sure that by late '42, many U-Boat commanders would use any opportunity, or excuse, to RTB early (and possibly at not so high speed).

Be more agressive.
-BdU

HW3 · 04-14-10, 07:25 PM

Many U-boats missions were ones where no targets were found or maybe just one. Their mission length was decided by the amount of food and fuel left. That is why u-tankers were used mainly for the resupply of food and fuel, and not so much for torpedoes.

04-14-10, 07:25 PM	#6
HW3 Navy Seal Join Date: Apr 2005 Location: Gresham Oregon Posts: 6,576 Downloads: 458 Uploads: 0	Many U-boats missions were ones where no targets were found or maybe just one. Their mission length was decided by the amount of food and fuel left. That is why u-tankers were used mainly for the resupply of food and fuel, and not so much for torpedoes. __________________ "Some ships are designed to sink...others require our assistance." Nathan Zelk

04-14-10, 09:52 AM	#2
rudewarrior Sonar Guy Join Date: Apr 2005 Location: Middlebury, VT, USA Posts: 378 Downloads: 165 Uploads: 2	Thanx for the responses. I've read some of the books mentioned here, specifically Iron Coffins (excellent book). Yeah, trucking across the Bay of Biscay later in the war was a real bitch, and I seem to remember reading somewhere that they would try to make it through the bay as quickly as possible. I remember reading that they would try to dive and surface at top speeds due to the "speed is life" idea. This minimizes the chances of them not being able to react to a situation that arises after the act of surfacing/diving. Since they are trying to react to aircraft buzzing around all over, I could see them trucking across the bay at top speeds as SOP. That would certainly minimize their dive time. I know not to "cruise" at flank speed. Any mechanical engineer will tell you that is not what it is designed for. Flank speeds mean operating outside a normal range, and it would obviously only be done for a recommended period of time, which I can assure means no longer than a day, let alone the two weeks I need to get back. I do recognize the engine breakdown argument. It's an obvious one, and it bears consideration, but I'd like to see some specifics about their return cited somewhere. The engines may break down, etc., but at the same time, from my own understanding of how militaries function, I also think there would be some impetus to return quickly. It is incredibly militarily inefficient to have a boat "taking its time" to get back. After all, that time is the period when the boat is most ineffective. It has no ordinance, with the exception of the deck and flak guns (for whatever that is worth). So essentially it is not a fighting capable unit, and it won't be UNTIL IT GETS HOME. Then it can be reoutfitted, and returned to sea to sink more shipping. Having been in the military, I can't see taking a boat like that out, expending all of my ordinance, and then cruising back. It would seem that my superior would be screaming at me, "Get your ass back here, NOW!" Again, the breakdown argument isn't necessarily wrong, it's just that the nature of these two arguments conflict enough such that I would really like to see some evidence supporting one or the other. Maybe neither. Was fuel conservation an issue for the Kriegsmarine any time during the war? Just another issue to consider.