Grasers; simplified cost benefit analysis

Grasers are heavy and expensive.
The smallest size costs 3 mass and 12 pts, the same as three class 1 beams in weight and 4 in cost terms. And that's with a three arc, not all round. All round would be 4 mass and 16 pts

Class 2 grasers cost 9 tons and 36 points for a single arc. A three arc class 2 beam costs 2 mass and 6 points. You could get four of them in mass terms and six in cost terms, although a class 3 beam is probably a more accurate comparison because the max range of a class 3 beam is the same as the max range of a class 2 graser and the arc is the same. Class 3 beams cost 4 mass and 12 pts. So two for the price of a graser in weight, three in money.

Class 3 grasers cost 24 mass and and 96 pts. For the same mass you can have 6 class 3 beams, or 3 class 4. Or 12 class 2, if all you want is tubes rather than range. If mass is no object, you can have 8 class 3 beams or 4 class 4 beams. The graser outranges either of them.

Interestingly, the weapons are directly comparable in damage terms, because they hit in the same way. For each die you roll, a graser does 2⅓ points of damage on average and a beam does ⅔ of a point, in both cases disregarding "burnthrough" damage from rerolls following a six. (Just trying to figure out what that might be makes my ears bleed).

So how do they compare? First thing to keep in mind is that weight comparisons are more valid than points comparisons, because taking a greater weight of weapons for the same apparent points cost will have knock on effects in drives and everything else (so you're paying stealth points later).

Within 12"
Class 1 grasers roll one die and the same weight of class 1 beams (or of a mix of class 2 and class 1 beams) will roll three, doing two points of damage on average, or a little less than the graser; the same points cost of beams will do exactly the same damage.
Class 2 grasers roll 2 dice and the same weight of class 2 beams roll 8 dice. On average 4⅔ for grasers damage vs 5⅓ for beams. The same weight of class 3 beams gives only six dice for an average of 4 points, but this is balanced by better range.
Class 3 grasers roll 3 dice, doing 7 points of damage on average; 12 class 2 beams would roll 24 to do 16, 6 class 3 beams would roll 18 to do 12 and 3 class 4 beams would roll 12 to do 8.

Within 24"
Class 2 grasers roll one die. The same weight of class 2 or 3 beams rolls 4 dice. Beams have a slight edge in damage done.
Class 3 grasers roll 2 dice. The same weight of class 2 or 3 beams rolls 12; beams have a decisive advantage here with an average of 8 points of damage vs 4⅔ for the graser

Within 36"
Class 2 grasers still roll one die. The same weight of Class 3 beams rolls 2. The grasers have a slight edge in damage done. (2⅓ to 2)
Class 3 grasers roll two dice = 4⅔; the same weight of Class 3 or 4 beams rolls six = 4

Within 48"
Class 3 grasers roll one die (2⅓); class 4 beams roll 3 (2)

Within 54"
Class 3 grasers can still hurt you....

It's actually worse than it looks for the grasers, because i've made no allowance for the differing arcs of class 2 beams and class 2 grasers. However, the longer range bands of the grasers give some sneaky edges on the margins, and class 1 grasers definitely outclass class 1 beams from that perspective. Whether they're better than a class 2 beam is a tough call to make.

What's interesting is that if you use the graser at the limits of its range, it's a little more cost effective than the competition; but inside that range, the same weight of beams is more effective, sometimes devastatingly so. The graser is a weapon for standing off from the enemy, not closing.

The high mass and cost of the system is reflected in the cost of UNSC ships, the main users. If you saw a Lake class with the mass equivalent in beams of its graser load, you'd think you were facing a light cruiser; it would have 4 (!) class two batteries and a class one.