Guide to fuel conservation

[Ducimus]

I would increase the 2/3rds throttle percentage in TMaru, except that throttle settings apply to both submerged and surface. Maybe i should change ahead standard?

[WernerSobe]

i think what is calles "standard" should be the cruising speed.

There is no cruising speed submerged. At least theoreticaly electric engines are indeed the slower the further.

[Ducimus]

Well again, my problem is in terms of submerged performance 2/3rds is right where i want it, and 1/3rd is about ok as well. 2/3rds on the surface is 8 kts. Standard is 12, full is 18, flank is 20+.

So i suppose i could make standard around 10 kts, full around 15, and flank at 20. Just feels redundant and silly have the throttle settings so close to each other.
5, 8, 10, then 15 20.

[Von Tonner]

y heart nearly stopped when I was told we were out of diesel. I couldn't understand it as the sub came to a complete stop even though the calculations read that I had a range still of 654nm. But when I asked for 2/3s the engines kicked back in and we were under way again. Reserve maybe?

05.33 CE We're out of diesel fuel sir!
05.33 NA Range to end is 654 nm
05.33 NA Maximum range at current speed is 648 nm

Had to creep into Freemantle at periscope depth for the last 10nm I'm getting there Ducimus, had I not read your fuel post I would again have been stranded.

[dean_acheson]

I'd been running around 8ish, so I'll adjust that.

[Steeltrap]

Originally Posted by Sailor Steve

I don't know what the great one actually did, but engines completely off should be no problem, as the electric motors can accelerate you pretty quickly and you'll want to be diving in that situation anyway.

They remained on the surface without any motors running. As Steve points out, the batteries could deliver power immediately. O'Kane's orders were to manoeuvre on batteries only to alleviate any unpleasant motion caused by the swell. In short, they sat dead in the water and moved slightly on batteries if required. O'Kane demonstrated in a training period pre-patrol that this would enable them to hear an approaching sub before it could get to good attack range. It's also the ONLY circumstance under which the hydrophones should work on the surface.

I actually have taken to remaining dead in the water at 80' depth. It's impossible to remain on the surface without using fuel, even at 'all stop'. You can, however, hover at any depth without using battery power, so you need only surface periodically to replenish the air supply. It's silly, but works as a response to a probelm in the sim vis a vis remaining motionless without using fuel AND being able to 'search' using the hydrophones. I find a good spot where shipping should travel then remain at 80' for long periods of time. It's the same as remaining on the surface and allows using the hydrophones and no fuel, as was actually done in real life, so I accept that hovering was not really possible......

[captiandon]

In short for those who wonder Take how I run. At night I am on the Surface and running at 2/3's Day time I run submerged at 2 kts. I have burned over the same milage half the fuel I would have if I ran on the surface at Standard most of the distance. I have gone from Fremantle to The southern Part of the Celebras Sea on less then 15% of my fuel load. Of course I fueled at The tender at the North east side of Austrailia as well. Figure about a Quarter of your fuel to get to your patrol from Fremantle and I would use about a Quarter on the Patrol its self leaving you with another Quarter to get you home. The Last Quarter should be reserve only in case of Emergancy.

[Powerthighs]

Has anyone quantified the degree to which sea state affects your fuel usage? I assume it increases with wind speed, which to my knowledge is the only thing that affects sea state.

I'm looking for some data points that define the curve of how fuel usage climbs with wind speed. Does the wind direction versus your sub's direction factor in?

[sniperdoc]

Originally Posted by Steeltrap

I actually have taken to remaining dead in the water at 80' depth. It's impossible to remain on the surface without using fuel, even at 'all stop'. You can, however, hover at any depth without using battery power, so you need only surface periodically to replenish the air supply. It's silly, but works as a response to a probelm in the sim vis a vis remaining motionless without using fuel AND being able to 'search' using the hydrophones. I find a good spot where shipping should travel then remain at 80' for long periods of time. It's the same as remaining on the surface and allows using the hydrophones and no fuel, as was actually done in real life, so I accept that hovering was not really possible......

That's pretty much what I end up doing a majority of the time.

If I'm not sure where the shipping lanes are at, I'll submerge to about 80 - 100' and just listen. When I hear faint noises, I'll head there at ~2kts until my air supply runs low, I'll surface replenish the battery and air to 100% and then dive to 80' again and listen until I get a travel pattern of contacts.

Once I have the approximate travel lane figured out, I'll head topside and head out there at Standard speed diving periodically to see how close the contacts appear. Once about 2500' out from the travel lanes, I end up bobbing up and down from 100' to the surface (replenishing my air supply) just listening for contacts and refining my target search.

In the past, if I was trying to conserve fuel, I've always been under impression that going Standard or Full while under diesel, then diving to 50 - 80' and doing electric at 1/3 until my battery is about to run dry and then recharging topside at Standard or Full again, was the way to go... but I guess not?