Stern platform and doors

Looking for your advice on something... I'm currently working on the reconstruction of a Doggersbank 50 (see picture), which will undergo the following:
- the hull will be lenghtened by some 3 meters
- a stern cabin will be added
- on stern a platform will be added, along with stairs going along the sides to enable one to walk from the now deck to the stern platform
- means of entering the stern cabin will be doors fitted on the stern platform; the cabin will have no communication with the rest of the cabins now on board.

Now, the platform will be according to preliminary stability calculations and design, some 30 cm above the waterline, and from that platform the person will enter the stern cabin.

I'm looking on advice what is the usual way such reconstructions are made. I know how to do the overall construction, but the layout of the stairs is troubling me. Is it better to do them as part of the structure, or to buy and fit them. Who sells such equipment, do you know?

Also, can anyone recomment manufacturers of stern doors which would be suit this purpose?

Build under the LR supervision.

 

Assuming steel construction I would make the stairs part of the structure, (more watertight volume down low is good).

Like this.........sort of.....



And see these guys for watertight doors........

http://www.manly.com/

 

Tad, thanks for answering,

you got it right! The stairs are just like something I had in mind - do you perhaps know where one could get some information on the construction details of such?

As to the doors, I'm still unsure of what are the Register's demands in view of having doors at such low height above the waterline. My stern platform (the fixed part of the hull) is some 30 cm above the waterline. I don't know if there are some considerations as to what type of doors they allow in view of that.

Do you perhaps have some knowledge on the subject?

My expectations is that the flooded compartment stability analysis will have to be done, but apart from that ...

Best regards
Luka