The single most important document in the design process is the Statement of Requirements (SOR). This is the document in which you, the client, write down exactly what you want the new boat to do. The needs and desires you lay out here will guide the entire design process.
The SOR can, on occasion, be very short: "I want it to be as similar as possible to my current boat, but with room for 4 to sleep on board" could be a perfectly good SOR. The trade-offs involved will come out for discussion during the preliminary design, but the goal is set- and all possible design options will be evaluated against that goal.
Usually, though, the SOR is longer and more detailed. If you want me (or anyone else) to design a boat that's ideally suited for your needs, I have to understand what those needs are- what you'll use it for, in what weather, for how long. And since boats tend to be a substantial emotional investment, I need to know what about them gets you excited- what you've looked at already, why you like or hate it, and what feelings you're hoping to capture in a custom design.
The following list of questions should get you thinking. You don't need answers to all of them at once, but working through them in the early stages of the design process should help you put your thoughts in order and give you a reasonable idea of what you're looking for. Honest answers help to ensure that your custom boat design will be a good match for your unique needs.
What will the boat be used for? (Short trips to the beach, or long coastal cruises, or big-game fishing, or watersports, or....)
How many crew? Any kids, seniors or disabled?
How much cargo?
For how many hours/days/miles at a time?
Describe the worst sea conditions (wind, waves and current) in which the boat will be used.
What's the coldest and the warmest weather in which the boat will be used?
How fast do you want to cruise? What about top speed, and how much speed are you willing to sacrifice when the boat is fully loaded?
Your current boats (if any)
What boats do you have experience on, or currently use?
Where have you cruised with them? What do you like about them?
What do you hate about them?
Why don't they meet your requirements for your new boat?
How much do you expect to spend building this boat? (Be realistic- the budget is the big deal-breaker for many people, but if it's accurately known in advance, the boat can be designed to stay under budget.)
Who will build the boat? (You, or you plus friends, or a local commercial yard, or a yacht yard somewhere else, or....)
If you're building the boat yourself, what materials are you comfortable working with? What sort of projects have you already completed? (e.g. if you like metal: can you MIG weld, can you form compound curves, can you cut and handle large sheets of half-inch plate. Or if you like wood: do you do rough carpentry, or cabinetry, or do you make violins, etc.)
Do you have a preferred construction material or technique?
How long do you expect the build to take?
Sailboats- any preference for rig type?
Powerboats- do you have a particular preference for inboards, or I/O, or jet, or outboard?
Will you need an auxiliary engine or trolling motor? How far/fast do you need it to take you?
Layout & Styling
What boats have you already looked at?
What attracted you to them?
Are there particular design elements that you really like about certain boats? (The galley layout, perhaps, or the view from the helm station, or the way the rig controls are laid out.)
What did you dislike about these boats?
What about your personal tastes for styling and layout? Is there a particular look or feel you want to capture?
List all the gadgets, gizmos and fixtures you want on board. This could be a long list! (Include everything you think you'll want: head, sink, fridge, nav computer, microwave, power windlass....)
Make a note of things you might want to add in the future- perhaps you'll want that elaborate nav system a few years later, even if it's too pricey now. If so, we can ensure that there's enough space, power and places to run the cables.
Constraints & trade-offs
Are there limits on length, beam, draught, bridge clearance, or weight? (e.g. must fit through a certain canal, trailerable with a Dodge Caravan, etc.)
What traits do you want to prioritize? (e.g. speed trumps comfort, or rough-weather ability trumps living space, or long-distance efficiency trumps dockside handling, etc.)