So I'm starting up a OW group and one of the ideas for a custom regiment was making one that specialized in both in and out of the water. While I don't have a problem with this the only real hiccup I'm having how or even if energy (besides Melta) weapons would function underwater. Any suggestions because I currently have A.) cut the range in half or B.) give them a crossbow as a "counts as" harpoon gun for underwater and lascarbine on the surface. And if it helps here are Regiment components they're thinking about

Death World (Strength, Toughness)

Phlegmatic

Guerrillas

Close Quarters Battle

Survivalists (Aquatic)

The Few

So any suggestions would be awesome

Yeah, maybe say the range is reduced by half and they gain a -10 to hit due to diffraction, or something like that. Although harpoon guns are undeniably cool.

I agree, harpoons are a great idea. Maybe energy weapons don't work at all underwater, only solid projectile or low tech weapons. Maybe a reduction in sight and sound perseption and navigation (land) while underwater ?

It all sounds good to me though

Ok thanks for the input guys , I think I'm going with the half range and -10 fro Las and plasma weapons. And I'm also going with harpoon guns that mounted on the underside of the lascarbine like the auxillary granade launcher so that they're not lugging around two weapons, so crossbow that I'm tweaking to be Pen 2 if they end up going with the aquatic regiment (it's between that and a Guerrilla Foregeworl regiment)

I like the underslung Harpoon gun quite a bit, for practicality sake maybe it should be fired with compressed air so reloading is as simple as pulling another harpoon from a quiver and slotting it into the barrel, reducing reload time from 2full from the regular crossbow to a full or half action reload.. the tank would likely need to be reloaded after 50 shots or so.

I'm thinkin I might roll up a heavy reconassaince aquatic regiment with Sentinels equipped with ballasts and flipper feet… maybe even a thruster system so they can leap from the water to land on the decks of ships and reek havoc only to dive back into the sea. It would be easy enough to just say missile launchers are torpedo launchers; Plasma weapons might also be viable under water weapons.

I think I'll use the hand crossbow for stats, it's reduced range but we're using a grid that is 1 square = 1 meter and it's only 18 by 24 or something like that so it's not to big a problem. I might do the compressed air to. For bad guys I'm modifyinf Stormboyz for underwater use with spears and 'big speer gunz' and love aquatic heavy recon regiment been thinking of tweaking sentinels for back up

One thing to consider with plasma is that that stuff is really goddamn hot, and underwater you might be heating up the water near you to boiling levels very fast. Not sure how you'd represent this mechanically. Maybe 1d5 I damage to the firer?

Tom Cruise said:

If you go that route, consider the smoke-like effect it would have on the water surrounding the weapon (and target too). However, I'd rule that plasma weapons do not function underwater. IMO, the best option for use underwater would be specially adapted bolter weapons.

Well, I think it could be argued that one way to explain how plasma guns work is by containing the plasma within a "Magnetic Bottle" then launching it from the weapons, so I think overheating occurs when too much plasma is allowed to charge into a single magnetic bottle and that extra plasma is vented which could potentially harm the operator. so basically the heat is contained even while underwater and the plasma does not actually burn anything until the magnetic bottle is "popped" against a sufficiently hard surface… So if anything Plasma weapons would be perfect underwater, albeit travel much slower due to the density of the water compared to air, also the water could help mitigate overheating by either absorbing the heat in the water making it somewhat uncomfortable but safe or tossing the weapon away from yourself in the water and hanging onto a lanyard like a surfboard until it cools. I would definitely impose a penalty of some kind to ballistic tests to account for having to lead the target more and better predict a targets path. Same goes for Bolters in terms of penalties, and it really wouldn't have to be a special bolter just a special bolter round with the first stage rocket remaining but the second stage rocket being replaced by a little bitty propeller.

I think Plasma guns would look like deadly bubble blowers under water likely making a hefty "Blub" like a belching sound when fired, maybe that's even what an aquatic regiment would call them "Bubble Blowers" the same way a Meltagun is referred to as a "Cooker" because it would definitely super heat and form a bubble-steam cloud when it hit as well. Also still advocate the Missile/Torpedo Launchers, grenade launchers could counts as mini torpedo launchers.