5. Vessels, Net

	Cost		Accumulated depreciation		Net book value
Balance, April 1, 2015	439,180,669		(19,204,616	)	419,976,053
Additions	644,784,354		—		644,784,354
Disposals	(268,281	)	26,060		(242,221	)
Depreciation	—		(12,939,245	)	(12,939,245	)

Balance, September 30, 2015	1,083,696,742		(32,117,801	)	1,051,578,941

The additions to Vessels, net represent amounts transferred from Vessels under Construction relating to the cost of our nine newbuildings that were delivered to us during the six months ended September 30, 2015.

Vessels, with a total carrying value of $1,047.8 million and $416.0 million as of September 30, 2015 and March 31, 2015, respectively, are first-priority mortgaged as collateral for our long-term debt facilities (refer to Note 7 below). No impairment loss was recorded for the periods presented.