If a unit is completely submerged within water (such as a ’Mech
unit standing in water features of 2 or more inches in depth), LOS
to (and from) the submerged unit is considered to be blocked,
even from units operating on the water surface (such as hover,
WiGE, or naval vehicles).
Emphasis added. Line of sight is considered blocked, but only LOS is ever mentioned; physical blockage is not.
Underwater and Torpedo Attacks: Attacks against
submerged units can only be made between units that are also
submerged (see the To-Hit Modifiers Table, p. 37), or by between
submerged units and units operating on the surface of the same
water feature using torpedoes (see TOR# special ability, p. 48).
Emphasis added again (no mention is made of attacks made
from submerged units).
Indirect Fire: If a unit has the Indirect Fire (IF) special ability,
it may still attack targets within its range (and firing arc) even
without a direct LOS. To use indirect fire, the attacking unit
must not have a valid LOS to its target and there must be a
unit friendly to the attacker that does a valid LOS to the target.
(This friendly unit is the spotter.)
Indirect fire attacks use the range modifier of the attacking
unit, the movement modifiers of the target, and terrain
modifiers based on the spotter’s LOS. An additional +1 to-hit
modifier applies to the attack itself, and another +1 applies if
the spotter also makes an attack of its own in the same turn.
Emphasis added as well. Then, on to the question:
If a unit that has the IF# Special is submerged, and a spotter that is not-submerged has LOS to a unit that is also not-submerged, can the submerged unit make an indirect attack using the terrain modifiers based on the spotter's LOS (that is to say, ignoring being submerged entirely)?
My gut says "no", but I can also see the case being made, and thought I should bring it up for review.
