6. Vessels, Net


			Accumulated
	Cost		depreciation		Net book Value
Balance, April 1, 2017	$	1,728,769,295	$	(125,300,048)	$	1,603,469,247
Other additions		218,685		—		218,685
Depreciation		—		(48,653,225)		(48,653,225)
Balance, December 31, 2017	$	1,728,987,980	$	(173,953,273)	$	1,555,034,707

Additions to vessels, net were largely due to capital improvements made to one of our VLGCs during the nine months ended December 31, 2017. Our vessels, with a total carrying value of $1,555.0 million and $1,603.5 million as of December 31, 2017 and March 31, 2017, respectively, are first‑priority mortgaged as collateral for our long-term debt (refer to Note 7 below). No impairment loss was recorded for the periods presented.