displacement and a step change from the saddle tank type of construction to a double hull. She was a twin shaft vessel with two Vickers diesel engines, each of 1850hp, two main motors of 500hp and 352 Exide cells in two battery tanks.
The Nautilus, renamed N1 in June 1917, was designed by Vickers to have good sea-keeping qualities for extended operations in all weather conditions. Regarded by submarine officers as an exceedingly interesting experiment, Nautilus was laid down in March 1913 and, with an overall length of nearly 260 feet, was twice the size of any existing submarine.
The estimated cost of building Nautilus is given as £203 850 but, because of the extended building time, the changed that occurred, the increase in displacement and additions such as
