5. Vessels, Net


			Accumulated
	Cost		depreciation		Net book Value
Balance, April 1, 2018	$	1,728,987,980	$	(189,876,147)	$	1,539,111,833
Other additions		1,213,621		—		1,213,621
Depreciation		—		(32,383,899)		(32,383,899)
Balance, September 30, 2018	$	1,730,201,601	$	(222,260,046)	$	1,507,941,555

Additions to vessels, net were largely due to capital improvements made to eight of our VLGCs during the six months ended September 30, 2018 and mainly consisted of the first installment on the purchase of scrubbers for four of our ECO VLGCs. Our vessels, with a total carrying value of $1,507.9 million and $1,539.1 million as of September 30, 2018 and March 31, 2018, respectively, are first‑priority mortgaged as collateral for our long-term debt (refer to Note 6 below). No impairment loss was recorded for the periods presented.