i can help you there
first of all id like to direct you to
www.subguru.com and click downloads page
there you will find Kapitains guide to under ice oparations.
secondly to solve your problem right here right now id can tell you how to do it
1) decrease depth to 30 meters and stop
2) when at 00 knots select 0000 on your depth gauge this will surface your ship
3) keep all masts and towed array in down retrived cause it will only snap them
4) do not speed up when surfaceing stay at a stand still
5) you can break any thikness of ice using this methoerd
i dont advise a fast assent nor an emergency assent under ice
to submerge do exactly the reverse well almost
1) set a depth 35 meters or below
2) wait till you pass 30 meters to move off
3) never raise or extend towed array wile surfaceing or submerging from the ice