Sinking Ships

[johndallman]

Originally Posted by tbone

(And we'd all want to hear about what sort of wacky campaign you've got that features multiple sinking ship escapes.)

Shipworms of Cthulhu!

[whswhs]

I wonder if the rules for moving around underground in Underground Adventures would have any applicability to moving around in a sinking ship?

[Pursuivant]

Shipwrecks are one of my interests and I've frequently considered how a shipwreck could be handled in GURPS.

As others have pointed out, the rate at which a ship sinks depends entirely on the ship and the conditions which caused it to sink. Dramatically, it also depends on whether you want the shipwreck to be an introduction to an adventure (i.e., an excuse to strand the party away from civilization with minimal supplies and equipment) or an adventure in itself. Basically, "Robinson Crusoe" or "Titanic" / "The Poseidon Adventure."

There's potentially a great adventure based around damage control to save the ship, or to get everyone off of it before it sinks (or, for submarines and spaceships, before the air runs out). Think of the U.S.S. Franklin or U.S.S. Lexington during WW2 as examples. The Poseidon Adventure is the classic Action film take.

Rules suggestions:

The vessel sinks/depressurizes/fails at a rate chosen by the GM. Realistically, this is based on the amount and type of damage it suffered, weather conditions, level of compartmentalization, cargo, and Size. The GURPS 3e Vehicles rule about sinking rate is an extreme abstraction.

Big ships with slow leaks or out of control fires can take hours or days to sink (e.g., SS Andrea Doria, USS Lexington CV-2). Ships with broken keels or massive holes below the waterline might sink in minutes (e.g., HMS Hood, USS Indianapolis), as might ships shattered by explosions (e.g., steamboat Sultana), or overwhelmed by rough seas (e.g., SS Edmund Fitzgerald). Fires aboard wooden ships or ships carrying flammable cargo can quickly get of of control, forcing those aboard to flee in a hurry even if the ship remains afloat (e.g., PS General Slocum).

Capsized ships sink or float depending on how much air is trapped inside the hull and the rate at which it escapes. Some capsized ships might survive, possibly with crew trapped inside, for days, while others might sink in minutes. Wooden ships or metal ships with large sealed internal compartments might also remain floating but mostly submerged for long periods of time (e.g., HMS Bounty replica). See "The Watch Below" for a SF treatment of a sunken but still floating ship.

Parts of ships which break apart might sink at different rates.

Roll vs. the lower of Leadership or Shiphandling skill roll for the (acting) captain when the ship encounters conditions which will inevitably destroy it (e.g., running aground in a storm) or takes fatal damage. Success means that they take proper steps to reduce the rate at which the ship sinks and get evacuation procedures organized in sufficient time. Failure means that problems occur, giving penalties to all skill rolls to properly evacuate the ship before it sinks. Critical failure means either abandoning a salvageable ship or refusal to abandon a doomed ship until it's too late.

People in a position to survey the damage might be able to make their own Shiphandling rolls to assess the situation for themselves and act accordingly. Proactive action by crew which supports the captain's correct decision to abandon ship might give bonuses to rolls to properly evacuate the ship. Actions by crew which undermine the captain's authority - whether good or bad - give further penalties or cancel bonuses.

Once the order to abandon ship is given Leadership rolls are required of the ship's officers. If there are passengers aboard, the ship's Stewards might need to make Leadership rolls in order to control them. Failed rolls mean that there is disorder, panic, or delays. (e.g., Costa Concordia). The severity of the problems depends on the number of skill rolls failed and how badly they are failed. Critical failure means that some or all people aboard try to save themselves, ignoring standard "abandon ship" procedures and chain of command.

Crewman skills are needed to quickly evacuate the ship's interior and to properly perform damage control and evacuation procedures. Crewman skill rolls are also needed to properly launch lifeboats, at a penalty if the ship is sinking quickly or takes on a severe list. Leadership or Intimidation skill rolls might be required to enforce discipline as passengers and crew get into the lifeboats.

Passengers who aren't familiar with ships, and crew who haven't been properly drilled in evacuation procedures, might need to make Fright Checks when the ship begins to sink. Fright Checks are required of everyone if the ship sinks as a result of battle damage, explosion, fire, or severe weather. Further Fright Checks might be required as survivors encounter people badly wounded or killed by fire or explosions.

If a ship sinks quickly or people remain aboard until it's too late Climbing or Crewman skill rolls, possibly based on ST and at a penalty, are needed to get off the ship. People who "go down with the ship" must make Swimming rolls at a severe penalty to get to the surface.

Contrary to popular belief, ships don't necessarily create vortices which suck down survivors when they sink. If the ship's screws are still turning as it sinks by the bow (lifting the screws out of the water) they can create currents which can batter swimmers or capsize lifeboats. In some cases, they can even destroy lifeboats or kill swimmers that drift too close.

Fires aboard ship can produce vast amounts of potentially smoke as cargo, stores, and painted surfaces combust. Smoke blocks vision as well as being dangerously hot and inherently toxic. Heat from fires can be transmitted through metal bulkheads or decks, damaging the ship's structure, burning people, and even igniting fires on the other side. Hot smoke vents upwards and outwards, meaning that crew inside a burning ship essentially have to travel up a chimney in order to get to the deck. Damage control includes closing off fire-filled areas if the fire can't be controlled in order to limit smoke and to starve fires of oxygen. Shipboard Firefighting uses Crewman skill rather than PS (Firefighter), although the two skills default closely to each other when fighting certain types of fires.


Commonly used skills:

Boating: To handle lifeboats once they are in the water. The same skill applies to modern life rafts, but only if they can be controlled. Otherwise, Crewman or an appropriate Survival skill is required.

Climbing: To get out of areas of the ship only accessible by ladders or by gangways which are missing or tilted at extreme angles. Climbing skill might also be needed to climb bulkheads or the ship's hull if it takes on an extreme list.

Crewman: To avoid hazards aboard the sinking ship, such as electricity, water currents, smoke, or fire. Crewman also lets you use standard safety equipment such as gas masks and life jackets.

Forced Entry: To force open doors or portholes which have become wedged shut due to damage. (Use Crewman to open or close them if they're undamaged.)

Jumping: To jump over debris or across gaps.

Throwing: To hurl lines to shore or to people aboard other ships using just muscle power. At the GM's option, Crewman or Lasso skill can substitute. Automated line throwing equipment uses Crewman skill.

Survival (Ocean): To survive at sea in harsh weather conditions, or for long periods of time, while in the water or aboard a small boat. This also includes the use of modern immersion suits, rescue beacons, ocean and surf rescue equipment, and similar gear.

Swimming: Both to safely jump into the water from the deck of a sinking ship and to climb aboard wreckage or rafts once in the water. Swimming rolls might also be needed to swim in rough seas, swim underwater to avoid oil slicks or enemy fire, or to get to the surface if you are pulled underwater by a sinking vehicle. Swimming rolls are also required to navigated flooded areas of a ship where it's too deep to wade. HT-based swimming rolls are required to stay afloat for long periods of time.

Edit:

Electrician, Mechanic, Etc.: Electrician, Mechanic, and similar skills are required to make actual repairs to ships and to deal with damage too severe for ordinary damage control. They might also be used to reroute damaged systems or to temporarily keep water from flooding vital systems. There are many cases where mechanics in the engine room died at their posts because they stayed behind to keep vital ship systems running until the very end, giving the rest of the crew to evacuate.

[Pursuivant]

Other ideas:

Angle at which the ship sinks and how fast it sinks plays a major factor in whether lifeboats can be launched. They're useless if the mechanisms used to deploy the davits aren't operational (i.e., electrical or hydraulic systems out) or if the ship is listing in such as way that lifeboats hit the ship's hull on the way down or enter the water end on.

Equipment like life jackets or helmets can complicate attempts to jump from a ship's deck into the water. During WW2, some sailors suffered neck injuries when they dove feet first into the water while wearing combat helmets because the water caught the helmet's rim. Jumping from a height into water isn't easy for those not trained to do it, so a failed Swimming or Sport (High Diving) skill roll means that the jumper takes falling damage.

Swimming rolls are required to avoid drowning after a bad dive or to climb aboard wreckage or floats. Penalties apply if the sea conditions are rough, and/or there's oil or debris in the water.

For modern ships, oil slicks can be a serious hazard. Ingested fuel oil is toxic, meaning that anyone who swallows water suffers 1d-3 HP to 3d Toxic damage over the next few days, depending on amount of fuel ingested. Oil on the skin interferes with the body's ability to retain heat, giving a -1 or -2 penalty to Survival rolls to resist cold weather or long immersion in cool water. Oil sticks to everything it touches, ruining clothing and any porous equipment. Removing it takes time, lots of soap, hot water, and scrubbing.

Burning fuel on the water's surface is potentially lethal to swimmers. Although ship's "bunker fuel" isn't particularly flammable, gasoline and similar products are extremely likely to ignite if spilled as a result of fire or explosion. Crew evacuating torpedoed oil tankers during WW2 sometimes had to swim underwater for dozens of yards to avoid patches of burning oil. Those who couldn't swim far enough burned. Anyone who surfaces in a flaming oil patch is effectively stuck in a Fire hex, but all damage applies to the head and upper torso.

Ingested seawater acts as an emetic and can be toxic in quantity. It also gives penalties to resist Dehydration. Spending long periods of time (more than about a day) in seawater can also soften and damage the skin, eventually causing painful sores or even making the skin slough off the underlying tissue.

Water conducts heat and cold far better than air. Spending time in warm water can quickly cause Dehydration. Spending time in cool water will eventually cause Immersion Syndrome (AKA Trench Foot - effectively equivalent to Frostbite) and Hypothermia. People in cold water die quickly - from Cold or Immersion Shock, surviving for a maximum of a few hours. Modern immersion suits greatly extend survival time. If you're a shipwreck survivor, your chances of survival are greatly improved if you can get out of the water, even partially. ST or Will rolls might be required to hang onto floating objects. Will rolls might also be required in order to continue floating rather than drowning.

In warm, sunny conditions, shipwreck survivors have to deal with sunburn due to light reflected from the surrounding water. Swimmers can get badly sunburned faces as a result.

[Pursuivant]

Damage Control

Crew, especially crew on naval ships, have assigned damage control stations as well as evacuation stations. These might be different from ordinary crew stations or ordinary battle stations.

Damage control consists of fighting fires, plugging leaks, and then restoring ship's systems to temporary functionality.

Shiphandling skill is needed to coordinate damage control efforts, possibly at a penalty for bad weather, lack of crew, and lack of internal communications. Inexperienced crew give penalties, as do experienced crews on a new ship who haven't had time to train. Experienced crews who have had time to train might get bonuses. For example, by late WW2, most U.S. carrier crews got very good at dealing with damage from kamikaze strikes.

Ship's officers can make independent Shiphandling or appropriate Engineering skill rolls to carry out damage control on subsystems, like power plants, HVAC, pumps, etc.

Pumps

On a damaged ship pumps are vital, both to pump water out of the bilge and to supply water to firehoses. Loss of pumps or the engines which power them are often a fatal setback to damage control efforts.

Wooden ships used one or more man-powered pumps with pump shafts made from hollowed out tree trunks. Depending on the size of the ship they might be manned by just a few men to gangs of 20 or more. Manning the pumps was exhausting, costing 1 FP per 10-15 minutes of work, so crew worked in shifts to man the pumps until the hull was patched. In some cases, crew had to man the pumps around the clock for days until the ship's hull was patched.

Repairs to a blocked or damaged pump shaft required one or more crew to wade or dive into filthy bilge water to deal with the problem. Swimming and/or Breath Holding skill rolls might be required to remain underwater long enough to effect repairs.

Modern ships use massive pumps, usually powered directly or indirectly from the ship's engines or boilers. These are generally very efficient at removing water from inside the ship and providing pressure for firehoses as long as they have power. Damage or flooding might knock out the pump motors, however, dooming the ship. Warships often have auxiliary pumps which work independently of the main pumps.

Ships assisting a stricken ship can contribute their own pumping capacity as long as they have hoses which can reach the flooded parts of the damaged ship. In a pinch, firehoses can be repurposed for this task.

Patching Holes

Sailors used any material available to plug holes below the waterline. Small holes were, and still are, plugged by driving softwood stakes into the hole. Large holes must be patched using more complex methods. Canvas sheets might be lowered over the side on ropes, with the ropes arranged so that a crew of men on the opposite side of the ship can work in tandem with the crew on the damaged side. The sheet is kept flat against the hull and maneuvered into place so it covers the hole. Aboard wooden ships, old sails and canvas hammocks were used for this purpose.

For larger holes or holes deeper below the waterline, patches must be held in place using internal braces. The patches are maneuvered into position by divers (Swimming/Breath Holding, SCUBA, or Environmental Suit (Diving Suit) skill) and then braced against a convenient bulkhead using wooden beams. In a pinch, rolled up mattresses can be used. In some cases, they are rolled up prior to being inserted into a hole so that they form a giant plug.

Often, plugging holes requires working in cramped and dark parts of the ship's hull, giving further penalties to skill. Maneuvering heavy supplies and equipment into place can be a task in itself.

Water rushing into a hole can create extreme currents which push people inside the ship away from the hole while sucking people outside of the ship into it. As long as you are braced, you can roll vs. ST rolls to avoid being sucked in or swept away. Free-floating swimmers and divers must make ST-based Swimming skill rolls instead, usually at a penalty. Getting sucked into a hole might drown a swimmer who can't surface for air.

People who get body parts stuck in a hole due to water pressure must make ST rolls to free themselves and will suffer damage to the trapped body part - either cuts from jagged edges of the hole or crushing effects from extreme suction.

Water rushing in from sudden holes in a ship's hull are effectively Slam attacks, which sweep anyone caught in the current along with the flow. ST ratings for gushing water range from ST 10 for a relatively small (e.g., fist-sized) hole to ST 20+ for larger holes well below the waterline of a large ship.

In extreme cases, high pressure jets of water inflict actual crushing damage. Crew trapped in suddenly flooded submarine compartments can be killed by the water pressure alone. Assume 1d to 6d HP of crushing damage per second of exposure. (There's also the possibility that crew trapped in air-filled areas of a sinking submarine's pressure hull are actually incinerated by the sudden air compression as high pressure water rushes in.)

[Pursuivant]

Power

Modern ships require power for most damage control activities. Water pressure is required for bilge pumps and fire hoses, while ventilation fans are required to vent smoke and contaminants out of the ship's interior.

A critical failure with overall damage control efforts might knock out power systems which otherwise could remain operational or allow smoke or flammable vapors to build up within the ship to dangerous levels (e.g., IJN Taihō).

Engineering skill rolls are needed to understand how damage to a power system or one part of the ship will affect other ship's systems, or to make plans to repurpose or seriously alter ship's power systems.

A good ship's engineer will understand the tradeoffs and long-term effects of "jury rigged" repairs, workarounds, and other abuses of ship's systems. For example, a starship engineer who says "I can overload the capacitors to give you one more phaser shot." also understands that those capacitors will be out of action for days after they are overloaded and that during that time the life support systems they normally facilitate will be offline. The ship's captain will know this too, but perhaps not to the same level of detail.

Mechanic skill is needed to make actual changes or repairs to a given mechanical (or integrated mechanical-electronic) system. Electronics Repair is needed to fix mostly electronic systems. Carpentry skill can be used to patch holes or install braces made of wood and similar materials.

Battle damage or boiler explosions can easily cripple some or all of a ship's motive systems, which in turn might knock out systems like electricity and hydraulics which are powered by energy from the ship's boilers. Mechanic skill is needed to make skilled repairs which allow damaged power systems to function or keep them running at partial power.

Electrician skill is needed to recognize damage to a ship's electrical power systems, to make repairs, and to isolate damaged electrical systems from undamaged portions. Even more importantly, it is needed to recognize places where damaged electrical systems or flooding have created further risks. Shorted electric lines can direct current into nearby metal objects, creating a potential fire or electrocution. Live current passing through areas flooded with saltwater can cause serious electrocution risks. Ships' electricians doing damage control wear electrically insulated, waterproof suits!

Ventilation

Modern ships also have HVAC systems which are vital in controlling spread of fires and smoke and to blow smoke out of the ship's interior. Air pulled into the ship via dorade boxes and is routed to interior areas, either passively or using fans. It is vented using dorade boxes on the other side of the system. Multiple ventilation circuits might exist based on the ship's level of compartmentalization.

Mechanic skills are needed to reroute or isolate parts of the ship's HVAC system, either to vent or block smoke or to prevent flooding. Engineer skill is needed to consider the effects of damage to the ship's ventilation systems as a whole and how fire or contaminants might flow through the HVAC system. During damage control efforts, failure to shut off or properly ventilate the HVAC system can be dangerous (see IJN Taiho, above). Good work by mechanics and engineers can vent smoke out of compartments and passageways aiding firefighting and evacuation efforts.

Balancing and Counterflooding
Damaged ships might take on a list as parts of its interior flood. An uncontrolled list can eventually cause a ship to capsize or become dangerously unseaworthy. To prevent this, damage control crew aboard compartmentalized ships might use counterflooding - flooding undamaged compartments on the opposite side of the ship in order to correct the list. This rights the ship but at the cost of making it ride lower in the water and potentially losing cargo or important ship's systems due to flooding.

The decision to counterflood parts of the ship is part of the captain's Shiphandling skill roll to coordinate damage repair. At the GM's option, counterflooding might give a bonus to damage control rolls, but at a cost of reducing the ship's speed, fighting ability, and seaworthiness in addition to loss of ship's stores, systems, and cargo.

In some cases, otherwise unoccupied crewmen might be required to stand as far opposite the list as possible to add their weight as a counterbalance. This might make them vulnerable to being swept overboard by high seas or blown overboard by subsequent explosions due to battle damage.

A list beyond the ship's rated angle of roll (assume 45 degrees port or starboard, 30 degrees to port or stern) might make equipment or cargo break loose. Moving on a listing deck or climbing a listing gangway is potentially hazardous - particularly if the deck is slick with water or blood. DX rolls might be required. Damage from shifting cargo or ships equipment can be extreme - treat these impacts like collisions or falls, assuming that the shifting object accelerates at just 10% to 50% of the rate that it would in freefall.

Reference
https://maritime.org/doc/dc/index.htm