AC-b Trident: Colonial submarine with two fixed forward Moray torpedo tubes, 80-degree firing arc (40 degrees left/right of bow). Crew of 8: driver, diving officer, 3 ballast operators, 2 torpedo gunners, secondary gunner, periscope operator, sensor operator.

Periscope depth limit: The periscope cannot detect surface ships when the submarine is below 10 meters. The sub is invisible to surface observers and map intel below 6.75 meters. Crush depth starts at 25 meters (Trident) / 20 meters (Nakki). In combat, the torpedo gunner's 150m underwater view is your primary sensor.

The calculator now models your submarine's forward speed (0–4 m/s, set in Step 0). The torpedo inherits the sub's velocity at launch:

Submerged speeds (wiki-verified): Trident surfaced 6.28 m/s, submerged ~4 m/s (7.8 knots). Nakki submerged 4.48 m/s (8.7 knots). The Step 0 slider caps at 4 m/s reflecting realistic submerged combat speeds.

All speeds in m/s, from Foxhole wiki Movement Speed table:

Moray torpedo: accelerates 4.2s over 40m, then cruises at 24 m/s.

Binary search solves where torpedo meets target, accounting for sub forward speed:

Fuse is the torpedo's traveled distance, rounded up to the nearest 10m. The Moray accepts 30–150m in 10m steps. Detonates on contact or at set distance.

The sonar operator and torpedo gunner sit at different positions on the Trident submarine. They observe different range and azimuth readings for the same target — a parallax effect caused by the offset between crew seats.

Toggle Step 1 to "Sonar Relay" mode to input the sonar operator's readings. The calculator converts them to the torpedo gunner's perspective using a coordinate transform:

Default offset: 15 m (sonar station ahead of torpedo tubes on the Trident). This value can be calibrated by aiming at the same stationary target from both seats and comparing readings.

The converted gunner range feeds into the firing solution (TOF, fuse, lead). The converted azimuth tells the gunner where to look — the target is not always directly ahead from the gunner's perspective.

The live tactical plot is rendered on a <canvas> element at ~60 FPS via requestAnimationFrame. It visualises the firing solution in real time:

Sweep radar: A 55-degree green glow rotates continuously (0.7 deg/frame), simulating an active sonar cone.

Range rings: Concentric circles at 30, 60, 90, 120, and 150 m, scaled to the canvas. The current fuse distance ring is highlighted in orange with a dashed style. A red detonation ring is also drawn at the fuse distance.

Target ship: Positioned by converting game-world coordinates (x, y) to screen space with centre at the submarine. The ship rotates to match its heading from target velocity. A dotted track line with an arrowhead shows the target's projected course, scaled by speed and TOF.

Torpedo path: A red gradient line from the submarine to the predicted impact point, with an arrowhead. A lead angle arc is drawn from straight-ahead (north) to the lead angle, labelled with degrees, using side-appropriate rotation (right = clockwise, left = counter-clockwise).

Impact zone: An orange circle at the intercept point, sized to the Moray's 6.5 m explosion radius scaled to the canvas.

Depth side-view inset: When target depth > 0 m, a small inset box appears in the bottom-left corner showing a waterline, depth fill, and a red bar at the target depth position (0–50 m scale).

Submarine icon: Top-down view matching the Step 0 diagram — ellipse hull with green stroke, sail, curved bow tip, and two torpedo tubes in brass. Identical tubes confirm no ballistics difference.

Live stats bar: Below the canvas, a 5-column grid shows the current fuse distance, lead angle, time of flight, depth, and hit probability — colour-coded as danger (red), warn (amber), or good (green).

The canvas auto-scales to its container and adapts layout for wide (landscape) vs. narrow (portrait) viewports, positioning the submarine centre slightly lower on wider displays.

Pressing FIRE takes a snapshot of the current state (range, speed, AOB, side, depth, sub speed) and runs the fire sequence:

The calculator computes the firing solution from the snapshot. The result is fixed — changing inputs mid-simulation does not affect the in-flight torpedo.

A full-screen red flash overlay and a centred "TORPEDO AWAY" text animate with a fade-out over 1.4 seconds via CSS keyframes.

The sonar canvas renders the torpedo in flight: a coloured dot (green for predicted hit, red for predicted miss) moves along the lead-angle path at world-scale speed. Three trailing dots behind it fade with distance. An expanding explosion ring appears at the impact point when the torpedo reaches ~98% of its travel.

The result is deterministic — no random dice roll. A shot hits if and only if the geometry is physically feasible:

The hit estimate % (from the Hit Estimate section) is displayed as a reference but does not control the outcome — it rates how difficult the geometric solution is. A 45% shot will always hit if the geometry lines up; a 97% shot will always miss if the target is out of arc.

After the travel duration (min 1.8s, max 6.2s, proportional to TOF × 430ms), the sonar overlay label updates to show HIT or MISS with the detail. The label pulses three times via CSS animation.

The sonar overlay label (top-left of the tactical plot canvas) updates with the result and compact commander notes. On HIT it lists factors overcome (high speed, running away, long run, sub assist); on MISS it shows the geometric reason and corrective actions (close distance, turn sub, reposition, slow before firing). On any control adjustment the label resets to "TACTICAL PLOT / LIVE".

Colonial 420St Regiment — Foxhole submarine operations. Built by the crew, for the crew.

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Contact: DM @yasoo24 or @Mcanaan on Discord for questions, feedback, or to contribute.