Inserting new ships...

I would like to know..

How hard it is integrating new ships like Converted Whale in campaign?

Can it be done smoothly, or I have to edit several files to make it works?

I've read different topics where problems occured like, the new ships are just floating stationnary, or they don't sink, or they just travel alone and not in convoy, etc...

Many people suggest me to integrate in IuB more ships but those problems I keep hearing just make me stay away from the matter.
A guide would be appreciated.

JonZ