This isn't perfect. This is just how I think the ship would sink by the stern.
Titanic was sailing full speed through an ice field but hadn't encountered an iceberg yet.
The lookouts were looking at the horizon, not seeing anything until one of them rang the bell 3x and he immediately phoned the bridge. The officer on deck, turned around to see what the commotion was. A different officer emerged from the officer's quarters and answered the call. "What do you see?"
"Iceberg right ahead!" Shouted the lookout.
"Thank you." Replied the other officer and we went to go inform the officer on deck.
The officer on deck, immediately ran towards the wheelhouse just as the other officer informed him of the situation. "Hard to starboard." Shouted the officer. The helmsman immediately began turning the wheel.
The officer went to the bridge and used the telegraphs to tell the engineers in the engine room to slow down.
The ship slowly began shifting to starboard and the officers on deck were slightly counting in their heads. The Titanic's head missed the iceberg completely and the officers on deck were grinning when the iceberg hadn't punctured the ship.
The officers on deck waited until the iceberg was about midships and they believed that they were in the clear. "Hard to port." Shouted the officer on deck and the helmsman began turning the wheel.
Unfortunately, they made an error and the Titanic moved closer towards towards the iceberg and a few seconds later the iceberg struck the ship. The Titanic scraped her hull against the iceberg. The officers on deck felt the collision and immediately lowered the watertight doors. 1st class passengers, 2nd class passengers and crew all felt the collision and were roused from their sleep. The iceberg hit Titanic on her starboard side and opened 8 compartments to the sea.
Almost immediately, water began pouring into Boiler Rooms 2 & 1 and their coal bunkers, the Reciprocating Engine Room, the Turbine Engine Room, the fresh water tanks surrounding the electrical engines, and the propeller shaft tunnels. The iceberg hit and severely damaged the starboard propeller. The starboard propeller stopped spinning, leaving the port and central propeller to move the ship.
Captain Smith walked onto the bridge and he was informed of the situation. He quickly ordered that the ship should be checked for damage. Once the ship has been sounded and Captain Smith has been informed of the ship's fate, he then ordered the crew to prepare the lifeboats and the wireless officers were sending out distress signals. He just hoped that the engineers & firemen would give them enough time.
The Titanic was dead in the water since the Reciprocating Engines and Turbine engine compartments have been breached, and the engines have been stopped. The refrigerating engines short circuited, leaving the frozen cargo and provisions without power and it cut the power to the W.T.D in that area.
The stern slowly dips in the water as passengers came on deck and the 3rd class passengers were rushing towards the bow using Scotland Road since the crew refused to let them access the upper decks. Captain Smith was soon informed by his wireless operator that the Carpathia would be there in 4 hrs. Captain Smith just watched the activity going on around him with dread, or perhaps guilt since Thomas Andrews informed Captain Smith that the ship probably had an hour and a half to stay afloat.
Thomas Andrews wasn't sure how long the power would last until the water spilled over the bulkhead into the electric machinery compartment and knocked out the power. The emergency dynamos would kick in but they wont last long. Thomas Andrews realized that they wont be able to evacuate everyone or lower all the lifeboats in time. The musicians set up behind the 2nd funnel, near the compass platform and began playing music to calm the passengers.
The portholes on F Deck and E Deck slipped under the water as the crew managed to convince a few passengers into lifeboats as the lights flickered. Lifeboats 16 and 13 were the first lifeboats in the water and the portholes on F Deck imploded from the pressure and began flooding the 3rd class area on F Deck and down the stairs to G Deck. The 3rd class area on G Deck was flooded within a few minutes and the water level on F Deck began to rise and the water was pouring down the NO 6 hatch and flooded cargo hold #6.
The stern slowly sinks into the water as the rudder slowly disappeared from view. Other crew members opened the 2nd class gangway door on E Deck in hopes that they could fill the lifeboats with more passengers. Unfortunately, water began flowing inside the open gangway door and the crew members were forced to leave it open and returned to upper decks. The water began flowing aft due to a open watertight door and began flooding the aft 2nd class staircase.
Captain Smith sends an officer and a couple crew members to check the water level inside the ship and he watched as the crew set up lifeboats 3 & 5 and emergency cutters 1&2 were being filled with passengers. Portholes on F Deck imploded and flooded the 2nd class areas on F Deck and the provisions and refrigerated cargo began flooding shortly after. Emergency cutters 1&2 were lowered down the side of the ship while the provisions and refrigerated cargo was flooding.
Captain Smith stayed around the bridge and watched as the crew began lowering lifeboats 3&5 on the starboard side. Some time later, the officer returned without the 2 crew members and informed Captain Smith that the Turbine engine and Boiler Rooms 1&2 are completely submerged. The Reciprocating engines will be fully submerged in the next few minutes. Scotland Road, aft of the 3rd funnel uptake, is completely flooded. Boiler Room 3 began flooding when water began spilling over bulkhead H and the 3rd class aft dining room began flooding due to the water flowing from the 3rd funnel uptake.
Titanic seemed to have developed a 12 degree list as she sank by the stern and a 8 degree list to starboard. Captain Smith watched as crew and passengers tried to remain calm while others were freaking out. There wasn't enough time or lifeboats to save everyone and most of the people here would be dead before help arrived.
Lifeboats 14 & 9 were being lowered down the side of the ship as water began pouring over the bulkwark and flooding the aft well deck, flooding the 3rd class general room and smoke room. The 2nd class dining room began flooding shortly afterwards and water poured over watertight bulkhead N and began flooding the electrical engine compartment.
Passengers ran towards the bow while others waited for lifeboats. The poop deck started flooding and 2 crew members abandon the steering gear room and left the door open, allowing for the steering gear room to flood. The 2nd class enclosed C Deck promenade remained dry for a few minutes until the aft 2nd class staircase entrance on C Deck began flooding from the deck below. The 2nd class library, the forward 2nd class entrance, and the enclosed promenade began flooding shortly after. Lifeboat 7 was filled and lowered down the side of the ship as the 2nd class promenade on C Deck flooded.
Engelhardt collapsible lifeboats D&C were filled with passengers and some crew and lowered down the side of the ship when the emergency dynamos kicked in. Titanic's power was weaker and the wireless messages became scrabbled & unreadable. The 1st & 2nd class galley started flooding during the power outage. Some crew members went into the ship's interior to look for flashlights and other passengers/crew ran up any ladders or staircases they could find.
The electric cranes in the aft well deck disappeared from view as the 2nd class B Deck promenade began flooding. Lifeboat 12 was set up and filled with passengers as the 2nd class smoke room began flooding, while the peak tank became visible as it left the water. Passengers and crew stumbled up the aft Grand Staircase as it flooded on C Deck and others just returned to cabins or public rooms and waited for the end. Lifeboat 8 was lowered quickly down the side of the ship since the ship was leaning to port.
The staff of the A la carte Restaurant stood in the middle of the restaurant as the A la carte Restaurant and Cafe Parisian began flooding and they soon drowned inside the restaurant. Chairman Bruce Ismay quickly got into lifeboat 12, earning a look of dissapproval from a nearby officer. The aft end of the A Deck promenade began flooding as lifeboat 12 was lowered into the water. Thomas Andrews returned to the 1st class lounge and looked at the painting above the fireplace and waited for the end.
Lifeboat 4 was filled with passengers and lowered down the side of the ship as the Verandah & Palm Court cafe flooded and the A Deck promenade continued flooding. The aft Grand Staircase B Deck landing has been completely submerged and the water was slowly rising to the A Deck landing. Lifeboat 11 was lowered down the down the side of the ship as the 1st class smoke room began flooding.
The musicians began playing Nearer My God to Thee when they realized that the end was near. Inside the ship, the 1st & 2nd class galley was submerged up to the reciprocating engine casing. The forward 3rd class dining room began flooding a few moments later. Engelhardt collapsible lifeboats A & B were pushed off the officer's quarters and hook up to the davits. Captain Smith gave the call to abandon ship and locked himself in the wheelhouse and Thomas Andrews was seen in the 1st class lounge, not even trying to save himself.
The crew returned to the aft end of the Boat Deck to set up lifeboat 15 as the Boat Deck began flooding. The ship groaned in protest as the 2nd class entrance and the raised roof of the smoking room slipped under the water. Lifeboat 15 was abandoned since the Boat Deck flooded faster than they could cut the lifeboat free. The 4th funnel stayed attached to the deckhouse as the 2nd class entrance and raised roof of the 1st class smoke room disappeared beneath the water.
The dome of the aft Grand Staircase imploded and flooded the A Deck landing and the two cabins in the area. Lifeboat 10 was forgotten and abandoned as the aft Grand Staircase flooded. The reciprocating engine deckhouse and engineer's promenade slipped beneath the water as the stern dragged the bow in the air.
The survivors, in the lifeboats, couldn't believe what was happening. The Titanic, a dark silhouette against the horizon, was at a 40 degree angle. They could beams of light from the crew's flashlights, all over the ship. The third funnel, sticking out of the water, collapsed and hit the water hard. The ship groaned in protest at the weight of the bow and everything else. Cargo, coal, furniture, and anything that wasn't bolted down slid aft and began piling up against bulkheads, boilers, and cabin walls. Some passengers were clinging to Engelhardt collapsible lifeboats A&B which failed to get launched from the ship.
The waterline was close to the compass platform and the 1st class dining room and lounge flooded. Passengers and crew hung onto any stable structure they could and many more people were trapped inside the ship. The survivors, in the lifeboats, could hear loud noices coming from Titanic's interior.
The Titanic feeling the strain of gravity, split behind the 2nd funnel deckhouse, along the 2nd funnel uptake. The bow came crashing down and killed those that were in the water underneath the ship. Survivors heard what sounded like groaning metal and explosions deep inside the ship and they saw the bow temporarily right itself. The survivors hoped that the ship would stay afloat after all. and they heard the screams of people on deck.
The breakup was a clean break along the uptake. The Reading & Writing Room was destroyed and the aft gymnasium wall has been damaged. The A Deck promenade was severed from the stern promenade and the private promenades on B Deck were damaged, other cabins were destroyed or damaged. The forward end of the 1st class dining saloon was damaged. Crew quarters were destroyed along with more cabins. The 3rd class forward dining saloon was destroyed. The steam rooms of the Turkish Baths were destroyed, and the Turkish baths were exposed to the sea. Lavoratories, steam pipes, electrical wires, pipes from plumbing and other things were destroyed or severed.
The watertight integrity failed the Titanic as the breakup had ruptured WTB G, which damaged the coal bunker and WTD. Boiler Room 4 was exposed to the sea as the result. The 2nd funnel fell aft into the breakup when the bow hit the water and the gymnasium roof collapsed. The 1st funnel fell to starboard and damaged Captain Smith's quarters and destroyed Engelhardt collapsible lifeboat A and the steel bulwark.
The stern slipped beneath the waves, dragging the damaged bow upwards, with people, debris, belongings and other things spilling out of it. The stern and bow separated from each other and the stern began its journey to the ocean floor, leaving the bow behind. The BR 3 boilers became dislodged when the stern separated from the bow.
The bow rose to a 90 degree angle and stood still. The Grand Staircase & 2nd funnel deckhouse were submerged under the waterline. The bow seemed to stop at the forward expansion joint, leaving the officer's quarters, bridge & wheelhouse, the well deck and forecastle deck above the water, crawling with passengers and crew while others were trapped inside the ship.
Slowly, the Titanic's bow began slipping under the waterline. People jumped off the side of the ship into the water while others lost their grip, fell through the air, and they either landed in the water or hit the deck equipment or superstructure. The officer's quarters, wheelhouse & navigating bridge, and A Deck forward promenade slipped beneath the water. Captain Smith watched from the wheelhouse as the water, slowly engulfed the navigating bridge and surrounded the wheelhouse. He breathed one last breath before the windows imploded, filling up the small space and drowning Captain Smith.
The B Deck forward promenades disappeared a few moments later, followed by the well deck. The forecastle deck went under, leaving passengers and crew in the freezing cold waters, and they joined the dead in the water.
The people in the water were crying and screaming out for help, however, the lifeboats never came to help them. Over the next couple hours, people in the water began succumbing to the bitter cold, closed their eyes and never woke up again. The survivors in the lifeboats heard the screams and pleas for help as the people in the water tried to survive, but the screams were soon met with silence.
The Carpathia arrived a few hours later and picked up the survivors and made her way to New York. The Titanic sank in 1 hour and 50 minutes and there was around 520 survivors and 1688 casualties.
Notes: the two double bottom pieces. The aft double bottom piece was midway under the BR3 boilers and the aft coal bunker. The forward double bottom piece is halfway under the BR3 boilers and under the forward coal bunker.