Underwater Rules - DS (long)

G'day,

Here's the DS version...

Beth

>>>>>>>>>>>

DIRTSIDE SUGGESTIONS
With regard to smaller scale encounters, (thinking here of vessel scale
more than numbers involved), DS/SG are the more sensible option. The
following is some suggested ideas (modifications) for underwater duels.

Detection Range:
Electronic sensors will continue to have long ranges only if they are
acoustic, every other form of radiant energy is absorbed very quickly by
water. However to expedite measures, assume sensor suites in marine
vessels
(including amphibious vehicles) have at least some sonar capabilities.
For
ease of play the following sensor ranges (based on Fire control rating)
are
proposed 
Superior = 60"
Enhanced = 40"
Basic = 20"
None = 4" if in clear water, 1" if in turbid water.

Anything outside of the detection range is considered hidden (often just
being in the water is enough to make you hidden, so the usual rules of
needing to be in cover need not apply if just at distance from each
other,
but it'd help), however as soon as its detected by one unit then all
units
on that side know its position. As in land warfare it isn't possible to
go
back to completely hidden once found (pesky AIs...), but it is possible
to
make it harder to be hit by going to silent running (i.e. being
semi-hidden). To go quiet you must move less than half of you BMF, do
not
use any kind of weaponry or sensors and then pass a reaction test based
on
the following:
CIRCUMSTANCES				THREAT LEVEL
Boat, amphibious walker in shallow	+2
Boat, amphibious walker in deep 	+1
All else except non-amphibious		+2
walkers or wheeled vehicles*
*Non amphibious walkers and wheeled vehicles stay found once they've
been
picked up once.

Until successfully detected again, or until you expose yourself through
the
use of active sensors or fire you get an additional D6 target dice, this
is
in addition to any you may have already got for soft cover etc.

Weapons:
These changes may make the action seem cramped and are only suggestions,
it
may also just be easier to say Infantry, APSW, RFAC and HVC ranges =
normal/4, HKP - normal/3, MDC and DFFG = normal/2 and missiles are
unaffected.

SYSTEM	CLOSE	MED		LONG
HEL		30" (if clear open ocean waters)
		10" (if coastal waters)
		5" (if turbid estuarine waters)
RFAC/1	2"		3"		4"
RFAC/2	3"		4"		5"
HVC/3		4"		6"		8"
HVC/4		5"		8"		11"
HVC/5		6"		10"		14"
HKP/3		5"		10"		15"
HKP/4		8"		13"		18"
HKP/5		11"		16"		21"
MDC/1	4"		8"		12"
MDC/2	6"		10"		14"
MDC/3	12"		18"		24"
MDC/4	15"		21"		27"
MDC/5	18"		24"		30"
DFFG/1	2"		4"		6"
DFFG/2	3"		6"		9"
DFFG/3	4"		8"		12"
DFFG/4	5"		10"		15"
DFFG/5	6"		12"		18"
SLAM*	12"		24"		36"
GMS/L*	36"
GMS/H*	48"
IAVR*		4"
APSW		4"
Militia 	1"
Line		2"
PA		3"
*Assumed to be modified designs suitable for use underwater.

Mobility and terrain effects:
It is assumed here that all battles are undertaken in good to mild
weather
if in shallow, surface weather means little if at depth. However, large
internal waves (waves or currents along depths where there are sudden
changes in water density, temperature, chemical make-up) can be quite a
hazard.
CFEs can only act as normal for 8 turns (in DS), before it must surface
to
'breath'.
Movement is slightly modified compared to land:

Unsuited Inf - BMF: 2
EASY = With strong current
NORMAL = Flats, below wave breaking zone
POOR = Kelp forests, reefs, rough, mountainous,

DIFFICULT = In wave zone or turbulence, against strong current
IMPASSABLE = Deep water (vertically), very strong currents, high
turbulence, frigid waters

Power Armour/ Cav/Scooters - BMF: 6/8/6
EASY = With strong current
NORMAL = Flats, below wave breaking zone
POOR = Kelp forests, reefs, rough, mountainous, wave zone or turbulence,
against strong current
DIFFICULT = Deep water (vertically) if PA, very strong currents if Cav,
frigid waters if PA
IMPASSABLE = High turbulence, frigid waters if not PA, deep water
(vertically) if not PA or if remain with mount (marine fauna may usually
descend at 'normal') 

Amphibious Low/High-Mobility Wheeled - BMF: 4/6
EASY = Pebble flats
NORMAL = Sandflats
POOR = Mudflats, wave zone, against strong current
DIFFICULT = Low story kelp bed (like scrub on land), high turbulence or
rough if high mobility
IMPASSABLE = High turbulence or rough if low mobility, deep water, kelp
forest, reefs, mountainous, 

Slow/Fast tracked - BMF: 6/9
EASY = Pebble flats
NORMAL = Sandflats
POOR = Mudflats, wave zone, against strong current, low story kelp bed
(like scrub on land), high turbulence, rough 
DIFFICULT = Kelp forest, reefs, mountainous
IMPASSABLE = Deep water 

Slow/Fast GEV - BMF: 12/15
EASY = Above water's surface
IMPASSABLE = All else 

GRAV - BMF: 15
EASY = Flats, 
NORMAL = Wave zone, against strong current, low story kelp bed (like
scrub
on land), rough
POOR = High turbulence, reefs,
DIFFICULT = Mountainous, deep water
IMPASSABLE = Kelp forest

Slow/Fast/Attack Boats - BMF: 8/12/15
EASY = Flats
NORMAL = Low story kelp bed (like scrub on land), rough
POOR = Wave zone (if amphibious), against strong current, high
turbulence,
reefs,
DIFFICULT = Kelp forest, mountainous, deep water
IMPASSABLE = Wave zone or shallows if not amphibious

Walkers (non-amphibious) - BMF: 10 
EASY = With strong current
NORMAL = Flats, below wave breaking zone
POOR = Kelp forests, reefs, rough, mountainous, wave zone or turbulence,
against strong current
DIFFICULT = Very strong currents, high turbulence
IMPASSABLE = Deep water (vertically) 

Walkers (amphibious - have thrusters to allow 'swimming') - BMF: 10 
EASY = Flats, with strong current
NORMAL = Wave zone, deep water (vertically), against strong current,
turbulence
POOR = Kelp forests, reefs, rough, mountainous, very strong currents
DIFFICULT = High turbulence
IMPASSABLE = None (assuming pressurised for abyssal depths, if not then
some depths would be a barrier)

Many more vessel types will gain the VTOL 'pop-up' ability, these would
include GRAV, boats (subsurface ones), Infantry, Cavalry, Scooters and
PA
and amphibious walkers.

Scooters:
Scooters are size 1 vehicles, but they are an exception to the
'riverine'
armour rule and may carry armour of class 1.

Explosive effects:
If a hit is scored by any type of missile or explosive artillery system
or
if any vehicle is destroyed by a boom counter (regardless of the weapon
type that caused it) then every element (whether of the same or
different
unit, friend or enemy) within 3" must roll a D6 on a 6 they too have
been
hit (the shock wave from the explosion has had a knock on effect). For
every hit pull 2 chits, all specials (except firer's systems down) DO
count
against vehicles.

Close Assaults:
All unsuited (i.e. non-PA) infantry have an addition +1 to their threat
levels. 

DFO:
Depth charges are assumed to be a type of the deadfall ordinance, in
this
case DFO's may be delivered by surface vessels not just aerospace
vehicles.
For a surface vessel to drop DFO they move as normal and must place the
fire marker at some point along that path. However do not forget that
anything (including surface ships) caught within 3" will roll to see if
they take damage, so be careful where you drop it...

Smoke (well ink really):
Well smoke itself would be useless you could use 'ink' instead with no
change to the rules as they stand.

Wildlife:
There are MANY possibilities here, but just to kick the ball off, here
are
a few ideas.

Casualties in the water can breed their own threat via large aquatic
predators. A number of explosions would chase them off (so they're less
likely to hang around if there's lots of 'missiles' flying), though
tonnes
of dead or stunned fauna floating around may well be an obscuration
issue
in itself. However, if vehicles and squads are being removed be direct
fire
than there may well be large predators and scavengers attracted to the
site. Things that would threaten vehicles would have to be very large,
so
they could be any size (but I wouldn't give them armour beyond 1 or 2
regardless of size) and I'd let them pull 5 chits (it needn't even be
due
to teeth etc, just getting hit by a whale's fluke could cause big damage
to
many vehicles). Smaller (more earth-sized) predators could threaten
unsuited infantry, cavalry or scooters. I'd give them a BMF of 8-10,
they
must be in contact to attack and they pull 3 chits if an individual, 4
if
in a pack. For all of these only numbered chits would count, all colours
vs
unsuited infantry, red only against vehicles and PA.

Swarms of stinging wildlife (like jellyfish on earth) could also be a
threat if encountered in swarms. These would move with the currents and
if
they end on the same spot as a unit then they will smother it. Vehicles
and
PA don't take damage, but they are hampered and must spend an activation
doing nothing but moving slowly to clear their hulls. Unsuited infantry
suffer an attack, the jellyfish pull 2 chits and all colours count.

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Elizabeth Fulton
c/o CSIRO Division of Marine Research
GPO Box 1538
HOBART 
TASMANIA 7001
AUSTRALIA
Phone (03) 6232 5018 International +61 3 6232 5018
Fax 03 6232 5053 International +61 3 6232 5053

email: beth.fulton@marine.csiro.au