Not to throw a wrench into the works or dampen anyone's enthusiasm...
But, trying to apply real world logic/facts/figures into the simulations we're playing here is not always particularly useful, really. The SH4 game engine, derived from the SH3 engine, simulates a U-boat mechanical/electrical propulsion drive system. It's not even close to the US "Fleet" boats' diesel-electric drive system...not even in the ballpark, totally incorrect. To start with, those boats not only had four diesel-generator sets for main propulsion, but also from one to three auxiliary/emergency diesel-generator sets that could provide all ship's service electrical power, charge the batteries, or drive the propulsion motors just as well as the main DG sets could, but achieving a much slower speed. Yes, the design performance characteristics are useful in attempting to get the simulated submarines to behave as "realistically" as possible. But even there I would suggest the word "accuracy" is more correct than "realism" (which is something that IMHO applies to everything in the world of computer games/simulations...the "realism" involved in sitting at a computer playing games/simulations is 0%).
One of the comments made about the meaning of the term "Standard Speed" is quite correct. Ships, warships especially, are designed to meet a broad spectrum of specified performance requirements. Standard Speed is exactly that...a speed (with a specific propeller turn-count) to meet tactical maneuvering requirements, including turn-rate, Advance and Transfer, and Tactical Diameter of turns, in order to be able to safely maneuver in a Formation of other ships, including different Types and Classes. In the USN, prior to WWII as well as now, that speed was 15 kts, at "Full Load" displacement, with excess shaft HP to allow for bottom fouling. Making turns for Standard Speed with a clean bottom and/or at "Light Load" displacement, would typically provide for 16-17 knots or possibly even more, depending on weather and sea-state. For the "Fleet" boats, which were designed to operate with the Fleet, the variable of being able to change the ship's surfaced draft was an added dimension that just serves to make the problem in our game engine(s) even more difficult. Preparing for conducting Full Power Trials and Economy Trials always includes correction of the required turn-count based on draft and bottom condition. USN Economy Trials are always run at 15kts "through the water" (as differentiated from "over the ground").
The propulsion plant is designed to provide for "economical" cruising at that same speed. Here, the key is something that also has been mentioned before in this and other threads on SubSim forums. Standard Speed is the "economical" speed for a warship, but does not necessarily mean the most fuel-efficient speed; it's a combination of time and distance. If you are lolly-gagging around taking your merry time to get someplace where you're supposed to be, you'll find yourself being relieved of Command in short order.
Tweaking the game files to achieve 100% "realism" in propulsion plant performance is impossible. It would require a super-computer to do that and that is beyond the financial means of any/all of us...we had one (or two) of those at NAVSEA and used them to make 100%
accurate models of ships and ship propulsion plants. Even then, Trials with real ships seldom produced the same results as our simulations. The most powerful computers still can't match Mother Nature's weather and other variables, environmental and man-made.
Anyway...not to throw a wrench into the works or dampen anyone's enthusiasm...we do need to use whatever tricks and tweaks that can be done to ensure that our boats can get to their assigned Patrol/Special Mission areas with enough fuel to complete the mission and get back home again. Whether a needed Mod/tweak increases the fuel capacity to ridiculous amounts or ridiculously improves propulsion plant efficiency probably doesn't matter. I would simply finish by suggesting that nobody get too wrapped up in trying to achieve 100% "realism" or accuracy, because it's never going to happen here.
Oh, there is one other thing. My wish list includes a fix for the incorrect engine orders and the completely incorrect rudder angles. We hear "Ahead Slow" for the Ahead 2/3 engine order telegraph setting. There is no "Ahead Slow" engine order in the USN...Ahead 1/3 is ahead slow (or slow ahead if you prefer). The use of 40 degree "standard" rudder is ridiculous, in any Navy. You're putting the rudder into the stops at 40 degrees, which is a good way to jam the rudder hard over. Depending on the design of the ship and the desired performance characteristics, "Standard" rudder is typically 15-20 degrees; "Full" rudder is usually 25-30 degrees and "Hard" rudder is normally 5 degrees less than putting the ram(s) into the stops. Instead of fixing the hydrodynamic drag for a 40 degree "standard" rudder, couldn't we change the normal rudder angle used to 20-25 degrees (and then tweak the turn rate & etc.)?
