Submarine
I notice that there has not been a reply to your question.
May I suggest that you find where your nearest model boat club meet and have a chat with them - they are usually quite helpful - my own lot have given me advice about my building a Clyde Puffer.
There are some who have working submarines at Stoke Park Pond, Guildford - 10 am Sunday morning - if near to you do come and have a chat - help with plans, ideas etc ...
best of luck.
Tall Paul.
Romsey, Hampshire.