▁first ▁year ▁ice ▁to ▁a ▁maximum ▁depth ▁of ▁ 0 . 4 m ). ▁ ▁In vol ved ▁strength ening ▁the ▁bow ▁section , ▁ice ▁bel t ▁region , ▁fin ▁stabil is ers , ▁prop ulsion ▁sh aft line ▁and ▁the ▁prop ellers . ▁ ▁Al leg ations ▁in ▁May ▁ 2 0 0 9 ▁that ▁ice ▁strength ening ▁has ▁added ▁too ▁much ▁extra ▁weight ▁to ▁planned ▁disp lacement ▁( up ▁now ▁to ▁ 1 9 0 0 ▁t onnes ) ▁so ▁the ▁OP V ▁will ▁be ▁at ▁risk ▁in ▁Ant arct ica ▁because ▁ice ▁bel t ▁strength ening ▁is ▁lower ▁than ▁planned , ▁leaving ▁pl ates ▁above ▁vulner able ▁to ▁p ounding ▁by ▁blocks ▁of ▁ice , ▁and ▁also ▁not ▁have ▁the ▁cap ability ▁to ▁add ▁future ▁weight ▁by ▁installing ▁extra ▁equipment . ▁They ▁are ▁suitable ▁for ▁Southern ▁Ocean ▁pat rol s ▁now , ▁but ▁it ▁is ▁expected ▁that ▁future ▁weight ▁increases ▁" will ▁have ▁to ▁be ▁carefully ▁monitor ed ". ▁ ▁See ▁also ▁ ▁Prote ctor - class ▁in sh ore ▁pat rol ▁vessel ▁ ▁References ▁ ▁External ▁links ▁ ▁Ten ix ▁Off sh ore ▁Pat rol ▁V essel ▁A ker ▁Marine ▁design ▁review ▁Kam an ▁SH - 2 G ▁Se as pr ite ▁Hel ic opter ▁ST X ▁Canada ▁Marine ▁OP V ▁Sh ip ▁Design ▁Second ▁Navy ▁OP V ▁launched ▁ 2 7 ▁October ▁ 2 0 0 7 ▁G off ▁- ▁New ▁Hel ic op ters ▁selected ▁for ▁N Z ▁Def ence ▁Force ▁ 3 0 ▁October ▁ 2