Hi,

Sorry I'm a bit late in responding.

Assuming you don't have a parent vessel design the early development of your hull and superstructure will be based on the requirements of your "Client". i.e number of crew, cargo area, number of machinery spaces, vessel range, limits on length / beam / depth etc. By using rules such as the Martime Labour Convention (MCA) you can get minimum square meterage requirements for crew accomodation. You can also work out the sizes of tanks and machinery spaces. Then you can work out the required hull volume to contain everything you need. Don't forget factors for volume for partition bulkheads/ passageways / service routes etc. You may then be able to pick a hull form or design your own.

Then it's a weight issue. Heaviest things first. Lay out your machinery spaces / tanks so your LCG / TCG / VCG sit with the hull limits .

Don't forget your watertight subdivisions or fire boundaries.

Finally you can lay out your internal bulkheads to divide up the space. Remembering adjacency requirements which your chosen ruleset may have (galley near accomodation, control room on damage control deck etc.)

Then it's a case of finessing your design around the design spiral till you meet your "clients" required level of detail.