"Abstracting torpedo attacks - ideas?" Topic

Here's what we've come up with in our FAST PLAY homebrew rules thus far:

1. Torpedo attacks are resolved at once (no multiple turn runs).
2. Long lance go farthest, then other vessel launched, aerial torpedos have the least range.
3. 1d6 per torpedo launched – hit on 4,5,6 short range; 5,6 med range, 6 long range.
4. For movable launchers dice penalties: On a template that is a half circle, divide it into 5 equal arcs. Flat side of the half circle set against the firing ship with the center of the flat side placed at the centerline of the movable launcher. If the target sits within the center arc – no penalty. If the target sits within either of the arcs immediately adjacent to the center arc -1d6 penalty. If the target sits within either of the far outside arcs -2d6 penalty.
5. For speed of play we force shooters to use up a launcher with each shot.
6. Instant sink test on a hit – smaller ships CL and below: roll doubles and ship sinks. For bigger ships roll 2 or 12 and ship sinks.

What's missing and what do you think?

What sort of damage equivalency should we install on a ship that is not sunk instantly – i.e. what is the shell strike HE equivalent of each torpedo type?

Thanks,
Mike

If you're abstracting the whole "torpedo in the water -- evasive maneuvers!" thing, you should work in a modifier for range (representing time spent travelling). Sure, the range NOW may not exactly reflect the range when it was launched, but it's not a bad representation.

So, big penalties for the further away you launch. Maybe bonuses for rough weather and other conditions that would make spotting a torpedo difficult.

Your going to need at least a D20, if not percentile dice, since the chance to hit should be pretty low, I suspect.

I see you slipping into charts and charts and charts.

Define the critical factors you want to model.

Then ask how long you want the whole process to take (gaming time is precious -- don't blow it on stuff that doesn't justify the time spent).

Then decide how you want to represent these factors.

My rules just add or subtract dice on one end and allow dice in opposition on the other end. This allows both players to be involved.

Short range three dice. Medium two dice; long 1 die. Long lance +1 die.

Dice in opposition are awarded for evasive maneuvers, unreliable torpedo, vessel speed, and angles.

Compare the rolls and you hit or don't hit -- fast as two simultaneous die rolls.

mjc

Quick Play Rule.
1. Go to far side of room.
2. Roll dice toward ship model.
3. If it hits, ship is sunk.
4. If it misses, no damage.

I would certainly suggest that the time period is important . . . the range and effectiveness of torpedoes has changed greatly.

There is a world of difference between pre-Dreadnought torpedoes and those of late WWII for example . . . they are hardly the same thing.

-- Jeff

TooMuchLead is correct in the sense that what really matters for the continuation of the game is did it hit or did it miss?

Therefore point 1 is correct.

Point 2 is correct too, but remember the Japanese calculated on large salvoes because they knew the percentage of hits would be small. Aerial torpedoes are sometimes the same as others. They are just launched from close range because otherwise they would not have much chance of hitting at all.

Point 3 is a typical board game way of resolving things.

Point 4 is something similar to what I do as the angle of bearing is very important.

Point 5 probably speeds things up, but is not very correct if anyone wants to stick to historical style battles.

Point 6 is way over the fence. Not all ships sink immediately. If they dont, their presence and the attempts to assist them can be very important. However in general it is a typical board game resolution. Therefore in principle I would not agree with this idea, but could live with it in some gaming circumstances.

Combining the KISS principle with the actual inaccuracy of torpedoes (the Type 93 could be almost a mile off-target at it's theoretical max range and it was arguably the best surface-launched torpedo of WWII), how about this:

1. roll one die for each torpedo launched
2. at maximum range, one hit for every three 6s rolled
3. at medium range, one hit per two 6s
4. at short range, one hit for each 6

You'd probably need to make some provision for target speed and angle, preferably by subtracting dice from the total.

Same number of dice regardless of range, no opposed die-rolls, and requires lip-service at least to historical tactics (e.g.,a Tribal-class destroyer with four tubes isn't going to launch at max range but a Japanese Mogami-class cruiser with 12 tubes might and the Oi with 40(!) was designed to[and yes, I know the huge torpedo battery was a retrofit]).

LT

I think it is entirely reasonable to swim the torps out to the target instantaneously -- in reality it's almost certainly too late to comb once you see tracks in the water, if you ever see them, and you should comb the threat of a fish attack, not wait until launch.

The main factors controlling hit probability are range and angle on the bow, and target movement if it is highly unpredictable or if the target is very slow or dead in the water. Your best hit chance should be for shots from the bows; then the beams; then the quarters; then dead ahead, and dead astern worst of the lot.

The final point is that the P(hit) of each fish in a spread is not statistically independent. Better to resolve hits by spread, with a chance of a single hit higher than statistical independence would indicate, but lower chances of multiple hits. Resolving an entire spread at once seems to me right for surface actions, but submarines might want to shoot smaller spreads or single shots.

All the best,

John.

The threat of torpedoes is usually more significant than the actual chance of them hitting – so encouraging targets to take evasive action is important.

And what's the problem with having a delay? Just mark the position of the firing ships.

Oh, boy. Where's my copy of Thunder Below?

I'll look at this from the point of view of submarines, since that's what I'm familiar with.

You're not shooting a number of single shots, you're throwing something more like a shotgun pattern. A single 21" torpedo can do nasty things to any ship cruiser-sized or smaller, and the Long Lances could really hurt a Battleship.

A typical torpedo attack from a submarine would be a salvo of 4-6 fish. Good/insanely brave submarine captains would do an attack in the middle of the convoy, so that they could fire all 10 tubes (6 bow + 4 stern) quickly, and then leave to reload and come back in from another side.

TML: Your probability of hit is too high.

The elements of a torpedo attack are:
1) Target's course (more technically, angle on the bow)
2) Target's speed
3) Range

Those three elements combine to produce a probable location where the target will meet up with the salvo. A salvo is then fired to bracket this area, similar to shell-fire, but with more expensive shells.

Dazzle camo is designed to counteract the visual estimation of angle on the bow and speed, and is still useful against submarines today.

A typical spread of 4 with a minor range error would have one fish go past the bow, another past the stern, and catch two fish amidships. (Ideally, you'd want all 4 to hit, but catching the target in the center of the spread indicates that the target was farther away than you'd thought, but course and speed were correctly estimated)

2 fish into a transport would sink her, but not immediately. Even 4 fish would not immediately sink a transport, unless it was a gasoline tanker or an ammunition ship. Typical sinking times are in the neighborhood of 10 minutes, so unless your game has a 5-10 minute turn length, there should be no chance of instant destruction.

These comments only apply to WW2 or earlier vintage torpedoes. Modern torps are pretty much a 'one-shot, one-kill' weapon on any ship smaller than an aircraft carrier, due to their keel-breaker warhead design.

The most successful torpedo attack was the sinking of the IJN Shinano (Yamato-class carrier). The sub got close enough to hit with all 6 torps, and since the Mk14s were thought to run deep (they ran exactly on ordered depth, but had faulty exploders), the fish were set to 10 feet. 10 feet below the waterline was where the torpedo belt merged with the side armor on the Yamato-class, and the torpedos ripped the carrier's side open. She sank within 30 minutes of being torpedoed. It helped that the Shinano didn't have full watertight integrity *installed*, let alone set.

Lion in the Stars wrote:

A typical torpedo attack from a submarine would be a salvo of 4-6 fish.

True for US or British subs, but U-boats would typically fire single shots, especially against independents. I gather that there was some complaining about the number of merchant ships that took two fish to sink.

Another thing to think about -- especially if considering subs -- is that there were a lot of problems with torpedo fuzing at various times during the war. The US submarine force problems are probably the best known, but I believe every nation had problems at one time or another, especially when trying the more exotic influence pistols, and in these cases there should be a significant probability of a torpedo that hits failing to detonate.

Finally, as we're now talking about submarines, for U-boats late in the war you need to think about how to deal with pattern-running torpedoes such as the FAT and LUT, and, for German and US subs in the final years, acoustic torpedoes such as GNAT and Cutie.

All the best,

John.

Now, from what I know about WW2 surface torpedo use (not much), the general process is similar, but with better range estimation due to bifocal rangefinders and/or radar, plus continuous observation to get a better target track estimate.

your TDC (torpedo data computer) has inputs from own-ships speed and heading, and takes estimates from the fire-controlman at the rangefinders. Again, similar to gunfire, but with much slower shells (50 mph instead of 1000mph), so the lead you need to pull is much greater.

I like the "roll 1d6 per torpedo, count up 6s" approach that brass1 suggests.

That procedure would be fun to do in a game and keeps the odds of hitting low without large spreads and close range.

The rest of your system looks great. Combine it with brass1's system for determining hits and I think you'll have a winner.

Another point about a spread of fish: Against a warship, it was expected to have two fish miss in the spread (like in my range-error example), because you wanted to limit the warship's maneuvering options. If the warship turns towards the fish, she's getting closer to the track of one fish, while turning away or slowing down will put her into the track of another.

Funny enough, that's similar to how the kinetics are used in Attack Vector: Tactical (to deny certain maneuvers to your target for fear of destruction).

Seriously, read Thunder Below, by Gene Fluckey (Admiral, USN, retired). You'll never look at subs or torpedo use the same way again.