Air Circulation – Submerged Breathing
Nemo would also need an air circulation system for when he was both submerged and surfaced. This includes circulating the stored air from tanks when submerged for extended periods and moving the fresh air throughout the vessel while surfaced.
Ch 9: Aronnax describes the air vent above the compartment (Initial Cell) door.
I used circulation fans above the corridor hatches and vent panels, as described, to all compartments throughout the boat. These could pull air through most of the Nautilus’ length while the inactive vents above each compartment hatch would allow it to circulate based on open space alone. All the vents and fans could be covered for sealing against water, if necessary and controlled from the Wheelhouse, Salon or other location.
The history of ventilation on subs indicates that in Nemo’s time, little was available. However, Verne specified that there was a desalination system on-board for the drinking water which was also far ahead of its time.
Rather than reach too far ahead in my design with some sophisticated circulation system, I believe Nemo could have installed simple fans adequate to this purpose. He had electrical power for the fans, expansive air reserve containers for the supply, and pumps to refill those tanks. Since, for the most part, Nemo replenished the air simply by surfacing, he allowed the clean air to filter in through the hatches. Here is yet another reason to strategically place hatches in various places along the exposed hull. More on Hatches in that specific section.
There would have been two air release points on-board as well to balance the supply distribution and usage. One forward with the bow reservoir tank and one aft in the Mechanical Room with the air tanks held there. I’m keeping in mind that Nemo was an excellent engineer and would have easily thought this through.
I think the corridor fans and the compartment vent panels would have been distribution enough. Sliding panels could be used to close off the vents and fans in an emergency situation.
When on the surface, fans can be reversed by a switch in the Wheelhouse, similar to the button Nemo used to start and stop the drive motor, to expel fouled or stale air. Fans forward of the Central Staircase and Main Hatch would blow toward the bow, bringing new air from this central point to the forward compartments. The fans aft of the Central Staircase would do just the opposite. This technique would be reversed when using the on-board air reserves, bringing the air aft from the bow Air Reservoir and forward from the stern Mechanical Room air supply tanks.
Air Circulation – Special Research Notes
In the early boats, the ventilation must have been a taxing factor to comfort the on-board crews and maintain any efficiency. In the HOLLAND boats of 1901 to 1903, one 10 inch ventilator was provided over the fore end of the engine. Air to the engine was supplied down this ventilator and through the conning tower hatch. Two fans exhausted the battery tanks through two 3 inch ventilators on the hull, with portable extension pieces outboard; a third 3 inch ventilator with an outboard extension piece was fitted just forward of the conning tower for air supply. There could have been little circulation of fresh air except in the space between the conning tower and the main engine.
Air from the air bottles was to be the source of supply to the boat, if required, when submerged. H. C. Fyfe states that ‘on the first submersion trials of No 1 on 5 February 1902, her appliances for the purification of the air were used to maintain atmospheric conditions without any need of her cylinders of compressed air being requisitioned’. This statement is strange in that, as far as can be ascertained, air purifying plant works were not introduced until some time after 1902 in the A Class. What undoubtedly happened was that for the duration of this first dive the condition of the air inside the boat remained sufficiently satisfactory without the use of air from the HP (high pressure) storage bottles.
An air purifier was fitted for trials in one boat and later on, all the A Class carried an air purifying pump and plant. This practice continued in later classes. When A3 and A4 were condemned for further service in March 1912 they were retained for carrying out further experiments in air purification. An eight man crew was kept for each boat so that the trials were undoubtedly taken as covering a serious requirement.