Underwater Rules - FT (long)

G'day guys,

OK I had a bit of a crack at these underwater rules, I've split the post
into 3 here (one for FT, one for DS and one for SG so you can go to
relevant one and they're pretty long). Feel free to poke away, these are
just untested ideas and I'm anything but an engineer. I also put in some
EW
as water allows hide and seek by its very nature, I haven't been
following
the EW thread so its probably all way off so feel free to change bits or
correct me there too.

Cheers

Beth

>>>>>>>>>>>>>>>>>>>>
Notes:
One of the simplest methods would be to just readjust the scale so that
1"
now represents something like 25m instead of 100m for DS for example,
but
then the figs really do look huge with regard to the ground-scale. Thus,
I've opted to go the other way and redefine how the weaponry works in
the
aquatic medium. The following is completely untested and is from someone
with no engineering or electronics knowledge (i.e. I only had my
oceanography lessons to draw upon) so feel free to laugh long and loud
;)

FULL THRUST BASED SUGGESTIONS
Full Thrust is the obvious choice for large-scale (as in vessel size)
marine battles using a GZG product - design ships as usual, but keep in
mind that they're for oceans not space. I'd suggest the following
modifications...

Design system:
Paying for streamlining should be rewarded <in this case its
hydrodynamic
not atmospheric, but the costing is probably just fine as is>, thus
ships
with full streamlining gain 4 thrust free in addition to that provided
by
their engines, whereas partial streamlining provides an additional 2
thrust. All submarines must be fully streamlined.

Weather conditions:
Before the game the prevailing weather conditions and currents should be
decided upon, the following table is a suggested range of conditions and
effects. Roll D6 (or decide by scenario design or by agreement of all
players)
ROLL	CONDITIONS	EFFECTS
1	Glass		Top speed is limited to 8xthrust, sensor ranges
are 1.5x	
2	Normal		Top speed is limited to 6xthrust, no other
effects
3	Normal		Top speed is limited to 6xthrust, no other
effects
4	Rough		Top speed is limited to 3xthrust, after movement
all vessels drift
1" in the direction of the prevailing winds, disposable ordinance has
its
range reduced to three-quarters normal, for every fighter group
launched/landed roll D6 for each fighter in the group and on a 6 is the
fighter is downed, full streamlining only provides 2 extra thrust free,
and
partial only 1.
5	Tempest Top speed is limited to 2xthrust, sensor ranges are
halved, after
movement all vessels drift 2" in the direction of the prevailing winds,
disposable ordinance has its range reduced to 3/4 normal, fighters may
not
be used, full streamlining only provides 1 extra thrust free, ships
without
streamlining have their engine rating reduced by 1 (to a minimum of 1),
the
maximum number of DCPs that can work on a single repair job is 2.
6	Violent 	Top speed is limited to 1xthrust, sensor and
weapons ranges are
halved, after movement all vessels drift 3" in the direction of the
prevailing winds, no disposable ordinance or fighters maybe used, ships
without streamlining have their engine rating reduced by 1 (to a minimum
of
1), the maximum number of DCPs that can work on a single repair job is
1.

Currents:
Currents in an area may also have some effect, one suggestion might be
that
after movement all ships move 1" in the direction of flow of a strong
current, 2" if a very strong current. 

Land and shallows:
Land is another complication (especially if playing along the coast),
shoals or shallows could be identified before the game and associated
penalties and restrictions stated. For instance the following ideas
could
be used:

DEPTH	RESTRICTIONS	
Land/beach	Can not be passed over, landing is allowed by special
craft
Shoal		Can only be passed over by surface vessels of mass of 15
TMF or less
Shallow Can only be passed over by vessels (any type) of mass of 45 TMF
or
less

Vessels that are too heavy to pass over an object hit it instead and are
treated as hitting another vessel that is the equivalent of a
stationary,
undamaged SDN.

Any vessel that runs aground is potentially hulled, if the collision
causes
a threshold check then the vessel is immediately hulled and will take an
extra 2 water/flounder damage a turn until a successful damage check (to
patch the hole is made in a repair phase). If the collision does not
precipitate a threshold check then roll D6 and use the following results
ROLL		RESULT
1-3	External damage only, may move off into deeper water and
continue as
normal
4-5	The vessel is stuck and can not move off the bank for the
remainder of
the battle
6		The vessel is hulled anyway (takes 2 extra damage a turn
until fixed)
and is stuck
 
Collision damage:
For those who are looking for an alternative to the collision damage
allocation method given in standard FT, the following works well. The
collision damage inflicted equals the damage die roll multiplied by the
'speed factor'. The damage die roll is the sum of the rolls on a number
of
D6, where the number depends on the ship's size:
SIZE			#D6
TMF 15 or less	1
TMF 16 to 45		2
TMF 46 to 105		3	
TMF 106 to 135	4
TMF 136 to 165	6
TMF 166 to 195	8
TMF 196 or more 10

and the 'speed factor' is calculated in the following way:
	Hit in the rear arc: Difference in velocity of the two vessels
	Hit head on: Sum of the velocities of the two vessels
Hit on the flank (port or starboard): Velocity of other vessel (i.e.
vessel
takes damage based on the speed of the other vessel hitting it).

Subs:
Due to the fact they work at depth, there are some (potential)
complications you may want to emulate (this is highly optional). To do
this, four terms related to the status of the sub have been added:

Shallow - above the thermocline (i.e. easier to detect), for scenarios
which take place in water that is all shallow then as soon as the sub is
mobile and off the bottom its at 'shallow running'.
Deep - below the thermocline (i.e. at depth so harder to detect), for
scenarios which take place in water that is all shallow then if the sub
is
stationary and 'on the bottom' then its 'deep'. Marked by a chit with a
large D on it.
Silent - passive sensors only, trying very hard not to make a noise,
marked
with a chit with a large S on it.
Active - no care is being taken to reduce noise, so may be venting
exhaust,
firing weapons, using active sensors etc.

If the sub has gone to silent running that turn, then when trying to
detect
it then roll a D6 on a 1 or 2 then you have picked the sub out from its
background. If the sub has been at silent running for more than 1 turn
then
you must roll a 1 to detect it. There is a -1 to the roll if the sub is
currently running shallow. To fire at a sub under silent running you
must
have detected it first, the only exception is that you may drop depth
charges at will (until you run out). You don't have to detect 'active'
subs
before firing at them. 

Subs that use active sensors or fire are considered to be active
regardless
of the status marked down during the orders phase.

Weapons and Firing:
Existing weapons: all as normal, except:
a)	'beams' on surface ships can only target a sub if it is at
shallow
running (and has been detected, if at silent running). 
b)	non missile weapons used by subs (vs anything) may only fire at
close
range <yeah I know they were made for space, but I was thinking more
along
adopting the design system and generic weapons types rather than
strictly
bringing down space weapons to the water>

Depth charge: they are placed in the same fashion as standard mines, but
automatically detonate at the end of movement. Any surface vessel
directly
above it or sub within 6" take a D6 damage, they can not be picked off
by PDS.

Wildlife:
Quite a few whales have been mistaken for vessels over the years, so
large
marine animals could make a nice counterpoint, target or nuisance factor
in
a game. Theoretically they could be of any size, though most likely
destroyer size of less. I'd plot their movement like vessels or just
move
them randomly (1 D6 for arc they head off in and another 2D6 summed for
the
distance). They obviously wouldn't have any ranged weaponry (though the
odd
'dart' or sucker covered arm is possible), but collisions are more
likely.
More importantly they could become 'decoys', if subs and large wildlife
are
both being used in the game then in the deployment phase put extra sub
markers out (with the sub owner recording which are subs and which are
leviathans), once detected, such that SSD info is garnered, it becomes
obvious which are which. Further, if there is a large animal within 3"
of a
sub under silent running which is being fired upon then there is a +1 to
the detection roll and if you roll a 6 you've actually hit the animal
instead. 

Swarms of small 'fish', especially if gelatinous can also effect sensor
info, so you could say that if there is a swarm in the line of fire then
treat as if the target is screened (more a reflection of finding it hard
to
find them then actually preventing physical damage).

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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