Shooting Underwater

The medium of water tends to severely limit most weapons. This page should help you understand how it effects weapon ranges and damage, and what weapons are most effective when fighting beneath the waves.
== Weapons and Ranges ==
Weapon 	Range (factor) 	Maximum Range (yards)
Bullet, Conventional 	1/1000 	--
Bullet, Dart 	1/25 	--
Bullet, Supercavitating 	1/20 	--
Gyroc, Standard 	1/100 	--
Gyroc, Torpedo 	1These have a base damage of 1d-4	--
Laser, Infrared 	-- 	1also does half damage
Laser, Rainbow 	-- 	2
Laser, X-Ray and Gamma 	0 	0also does zero damage
Laser, Blue-Green 	-- 	60
Particle BeamsCharged particles, antiparticles, flamers, and plasma weapons	1/1000 	XHalf Accuracyusing a particle beam weapon underwater will damage the shooter! This can still be useful as a trap, or against aquatic horrors while wearing a battlesuit!This part of the math is elaborate. This editor suggests that damage is at -2 per die.
Microwave Weapons 	1/1000 	--
Sonic StunnerMust be built to work underwater 	x2! 	--
Explosions (Concussive) 	x3? 	--
Explosions (Fragmentation) 	-- 	1
== Examples ==
All examples are using rifle-sized weapons or close analogues.
Weapon 	Damage 	Range
Rifle, 7.62mm7.62x51mm NATO, such as the Springfield M14reduce Malf by 2 for automatic and semi-auto weapons, or by 1 for other types	7d piercing 	1 / 4
Rifle (Dart) 	7d impaling 	40 / 168
Rifle (Supercav Dart) 	7d impaling 	50 / 210
Rifle, Gauss (Supercav Dart) 	7d(3) pi 	60 / 240
Rifle, Gravity (Supercav Dart) 	4d(10) imp inc 	100 / 300
Gyroc (Standard) 	6d pi++, linked 2d cr ex 	19 / 19
Gyroc (Torpedo) 	1d-4 pi++, linked 2d cr ex 	1,900 / 1,900
Infrared Laser 	6d(2) burn 	0 / 1
Rainbow Laser 	6d(2) burn 	1 / 2
X-Ray and Gamma Lasers 	0 	0 / 0
Blue-Green Laser 	5d(2) burn 	60 / 60
Particle Beam, Blaster 	6d(5) burn, surge (36 at muzzle)	0 / 2
Microwave WeaponsPulse Carbine, in this case 	HT-4 aff 	0 / 1less than a yard
Sonic Stun Rifle 	HT-4(5) aff 	120 / 360
Dinosaur Stunner 	HT-6(5) aff 	260 / 800
Explosions (Concussive) 	4d cr exfrom a 25mm grenade 	4 / 8much less penalized than in air
Explosions (Fragmentation) 	1d+1 cut 	0 / 1?max range is 1
== Conclusions ==
The gyroc torpedo is ideal for long-range engagements, when using sonar to identify and track targets. Amphibious attack units should be armed with blue-green lasers (for accurate close-range fighting) and utilize gyrocs for area attacks. For fighting submarines and underwater robots, it may be best to use HEMPhigh-explosive multi-purpose torpedoes. Note that laser weapons, while having more limited range, have much higher accuracy and ammunition. A support gyroc (12 lbs) carries 30 shots, but a laser rifle (8 lbs) carries 83! 
As a side note, sonic stunners actually have improved range underwater, which may be useful for knocking out seagoing leviathans without risking a fight. 
== References ==
* GURPS Fathom Five, Pyramid #3:26: Under Water Adventures
Category:Concepts