how do you measure dive times correctly?

[Webster]

like the title says, how do you measure dive times?


first what qualifies as a dive and how should it be measured? should you measure the dive at flank or full stop? some other speed?

is it only counted after you level off at periscope depth?

is it counted as soon as the tower is covered but scope is still showing?

is it measured by crash dive or regular dive?


i dont even know what the dive time is supposed to be but i first need to understand HOW its measured so i know if im doing it correctly.


the reason i need to know all this is i want to test the s-class to see if they have realistic dive times and if not i will try to set them correctly.

[Ducimus]

I don't know if there is a "correct" way to time dives, but i'll tell you the methodology i used.

Only dive time worth measuring (in my opinion), is crash dive. To do that, i set up a test mission where the starting position has you doing 10 kts (or whatever your average cruising speed is), with a preset waypoint, and a windspeed of say, 3 to 5 kts. (heavy winds slow you down, and a perfectly calm day is unrealistic, though i don't think it makes you go any faster)

Anyway, when i start the mission, all i have to do, is hit the return to course command/button/hotkey. Then, i advance time compression for a minute, just to make sure the boat is fully under way, and at the the cruising speed. Then i bring the TC back to normal.

For the purposes of testing, i'll have the unit cam enabled and the camera positioned in such a way where i have a good broadside view of the boat. Now with my stop watch in hand, and the camera set, i'll hit the C key. I start the stop watch as soon as the engine telegraph is all the way into flank. I stop the watch when the CE/DO calls out 40 feet. During this time im watching the boat just to see where the periscope shears are, the angle of the dive, and just how much of the boat is exposed. But 40 feet is usually where i stop the stopwatch.

However you measure it, be consistent.

[Webster]

I don't know if there is a "correct" way to time dives, but i'll tell you the methodology i used.

....


However you measure it, be consistent.


ok so it sounds like your looking for the tower tub to just be covered correct?

and crash dive is used to initiate the dive from an ahead std speed ging time for the sub to reach ahead std before diving.

is that 40 ft depth in reference to an s-boat or was that what you used for fleetboats?

and it sounds like a big grey area with no real answer but do they have specs somewhere on what the correct dive times should be or is it all guestimation based on logs.

what would help me to decide if stock dive times are too fast or too slow because my opinion might be different then the next guys.

[Ducimus]

>>ok so it sounds like your looking for the tower tub to just be covered correct?

I used 40 feet primarily because the diving officer reliably calls it out, and doesn't skip it. I was looking for solid benchmarks, and 40 feet was always being called out.


>>and crash dive is used to initiate the dive from an ahead std speed ging time for the sub to reach ahead std before diving.

I crash dived on standard speed because it is tuned to be the default cruising speed, and started my timer when the engine telegraph went to flank (not the sub, just the telegraph), because at that point, it's visual confirmation that the process has been initiated. Again.. reliable benchmarks. Another reason was, it was a virtual simulation of when a player would acutally use crash dive the most. On the surface while cruising, and hitting the C key in a panic on a SD contact or visual sighting of an aircraft.

>>and it sounds like a big grey area with no real answer but do they have specs somewhere on what the correct dive times should be or is it all guestimation based on logs.

From what i understand, and have read, a fleet had to be able to dive to periscope depth in 60 seconds at a minimum or it wasn't deemed fit for patrol. To carry that along further, crews worked to reduce that time, and ive seen reference to 35 seconds in two different books. Which is where reworking crew skills became a really nifty idea.

As an aside, another reason i used 40 feet as my mark to stop the crash dive timer is because the bow is deeper (probably 60 feet), and by that time the boat is well on it's way down.

[Rockin Robbins]

In the real subs, the dive time was from giving the order to periscope depth. And for them, there was no such thing as a crash dive. Every dive was a crash dive, which was a normal dive.

In the game, periscope depth is a bad thing because the boat actually starts to level out before it is fully submerged, making dives using the P key really slow. I've noticed that although the diving officer reliably calls out the 40' mark, he doesn't always do it at the same time, as his call can be interrupted by other events going on at the same time. I suppose in controlled test conditions that might not be a problem.

But I'd be inclined to use the depth gauge and use 60' as my timing, to correspond with the real submariner's use of periscope depth. They would yo-yo through the depth on their timing runs, overrunning and coming back up to actually use the periscope. We can do the same thing by using C and hitting P as we break 40'. For timing purposes, though, I wouldn't hit P at all, just stop the clock when the sub passes 60'.

[Sailor Steve]

I don't know enough to comment, but here's the 'Official' word from the period:
http://www.maritime.org/fleetsub/chap18.htm#18A

[Webster]

ok, thanks guys

i'll use 60ft for fleets and 50ft for the s-boats since their scope depth is 10 ft shallower

i'll go for a 45 second benchmark and call that the realistic "average" time for fleets

any ideas on the s-boats "realistic" dive time because i wouldnt think it would be the same as fleets?

@ ducimus - since you played with dive times before, whats the best value to change to do it and what are the "side effects" of other things changing with it?

[Rockin Robbins]

Looks good Webster.:up:

@Steve: Wow! no timing standards for dive drills there! And blowing negative at 45' is very interesting! Sure wish we had a negative tank...

[Webster]

update:

i was able to get the following s-boats dive times

crash dive by hitting "C" @ ahead std speed= 32 seconds to get to 50 ft (stock was 17 seconds)

dive to periscope depth by hitting "P" @ flank speed= (1 minute 15 seconds) 45 seconds to leveling off point (45ft) and another 30 seconds to settle at actual periscope depth (47ft) stock was (2 minute 30 seconds)

but i had to use some really screwy numbers for balast tanks so im worried about side effects but i dont see any :06:

[Ducimus]

Aside from MBT_Floodrate, Try increasing surface and submerged displacment. It doesn't have to be the historically correct number. Remember, the end user NEVER see's this in game. So it doesn't have to be a realistic number so long as realistic results are achieved.

[Webster]

ok, thanks


what about the numbers i have there? do they look close?