Hi,
If you want to play around with your speed you can
use the excellent tools created by Timetraveller
(Sh3 Inspector).
Or if you prefer learning how it work, you have to know that
the speed is a floating point value converted to Hexadecimal.
There you can find a nice program that help you doing the
conversion from Hexa to Floating point, or vice-versa.
http://www.61131.com/bits/FPconvert.zip
After that you have to find the text "max_speed" in your
".sim" file for the sub you want to mod.
Then look at the hex value after the word.
For exemple the VII-C sub is supposed to reach 17.2 knots
surfaced and 7.6 knots under water.
If you put the 17.2 knots in the Floating point translator
you have something looking like
"999A" "4189" in the bottom "Hex Words 32 bit float".
There we look at the 4189 value, it's the big part of it.
(4189 translated into floating point value = 17.125 )
Now you take a look in your file just after the max_speed and
you can spot the value "8841" .
That's the value you are seeking for (4188 translate into 17.0)
You have to look and try a little but every time the speed
value is stored in the file right after the "max_speed" text.
If you get lower you find another "max_speed" usualy after a
"E_propulsion" text. That's the speed under water.
If we take the VII-C case, you find the value
"3333" "40F3"
There the 40F3 is the part we are interested in. As it
translate into "7.59375" in floating point unit.
Now you only have to do some trying, but don't overdo it.
Higher speed don't come without a cost. When you
get higher speed, you have more troubles stabilizing your sub
or you can have "surprises" when diving (like overshooting
the diving depth you have asked for, or crashing to the
bottom because of too high speed).
In hope it helps.
Stavinsky