Speed measurement - historical

[CaptainNoob]

Hi everybody!
I have a question about the historical speed measurement. Could the Uboats in WW2 actually measure their current speed? Or did they just know that a ceartain rpm setting correlates to a certain speed in optimal conditions? In other words: Is it realistic, that we can see our current speed in knots in the hud?
Cheers

[KaleunMarco]

Originally Posted by CaptainNoob

Hi everybody!
I have a question about the historical speed measurement. Could the Uboats in WW2 actually measure their current speed? Or did they just know that a ceartain rpm setting correlates to a certain speed in optimal conditions? In other words: Is it realistic, that we can see our current speed in knots in the hud?
Cheers

welcome, captainnoob.

at sea, during WWII, kaleuns set their RPM rate and then measured their speed over a certain distance during a certain time span. the navigator takes a position setting at pre-established times and then compares it to the last setting and that yields speed over a distance.

SH5 is a game. repeat that to yourself.

the word realistic should not be used when playing a game at home.

if you want realistic, join the navy and then volunteer for sub duty.

or, buy a 55 gallon metal drum. run electricity to it and connect it to a single light bulb through the lid. get into the drum and have someone put the lid on it, then throw it into a pool, pond, lake whatever and then have that person bang on the sides with a bat.

the point is that this is a game. have fun with it. park the realism with Fortnight.

[derstosstrupp]

Originally Posted by CaptainNoob

Hi everybody!
I have a question about the historical speed measurement. Could the Uboats in WW2 actually measure their current speed? Or did they just know that a ceartain rpm setting correlates to a certain speed in optimal conditions? In other words: Is it realistic, that we can see our current speed in knots in the hud?
Cheers

Hi CaptainNoob,

Yes, U-boats had a speed measurement system. There was a transmitter speed log in the control room, and a repeater in the tower. The system operated on the same principles as pitot tubes on aircraft. I put the following deck together, hopefully it’s helpful. The system was identical on all boats. Should also be noted that that gives you speed through the water, and not speed over ground.

As far as the engine and motor room crews were concerned, they were setting based on RPM, with charts available to them to show the number of RPMs that corresponded with the particular telegraph order. They were not as concerned about speed, that was only visible in the control room and the tower.


https://docs.google.com/presentation...qHPdZyEfg/edit

[Aktungbby]

Captain Noob!

Originally Posted by derstrosstrupp

Yes, U-boats had a speed measurement system. There was a transmitter speed log in the control room, and a repeater in the tower.

and is called a Enternungsmelder as opposed to knotmeter-with pitot tubes ie: the Fahrtmetessanlage.The gizmo in the tower (of U-505 in Chicago-photo by derstroostrupp) is the Enternungsmelder. Germany lost WWII because of the time wasted on all these long words!

[Bilge_Rat]

There has always been some sort of speed measuring system. Sailing ships used a rope with knots and measured how many knots were counted in a set time, which is why speed is still referred to as “knots”.

Speed measurement was more accurate in WW2, but still subject to the vagaries of weather, ocean currents, etc. which is why ships using “dead reckoning” (speed+heading) would quickly build up navigation errors and would require periodic navigational fixes. It was only once the navigator determined the exact position that the exact speed could be calculated.

Exact speeds could only be calculated on the fly once ships were equipped with INS and/or GPS systems post-WW2.

So yes, the speed measurements in SH5 and most other WW2 sub sims are too accurate, but fine for a game.