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

> [quoted text omitted]
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).