There are other ships that VSTEP can use, like static ships or AI ships.
I guess they have less requirements than a whole player ship with interior, collision model etc.
Anyway it all depends on what VSTEP will decide and what the game engine will support, and that's impossible to answer and predict.
When it comes to "Easy Boat Maker" there is no such program. Things become easy when you are able to use your tool and have a lot of experience and knowledge in 3D modeling and computer generated graphics. What limits that is your brain, effort, time and patience and especially learning curve and how fast you will learn it.
When you are sitting in front of your 3D modeling program then the program will not tell you how to make the boat, the hull, the funnel or anything. This is something you need to find out by yourself. That's what I have been doing the last 4 years in 3ds Max, finding my own techniques. These can only be used in 3ds Max and cannot be transfered to another 3D editor unless it has identical features.
To make a cylindrical funnel for example you start with a cylinder (3D primitive) and then you modify this primitive using modofiers like "Editable Poly" or any other useful modifiers or combinations of several modifiers to shape this cylinder into a funnel.
The same goes for the bow of a ship. You start with a cylinder, slice it 180 degrees, convert it into editable poly...make a new rectangular shape at the bottom and use this as a reference. Then you move groups of vertex points to shape the bow...etc. If I where going to share all my techniques then I'm sure that it would ended up like a 1000 pages long book. The bow example is maybe just 1 of 5 different methods you can use to make a bow in 3ds Max.
Before you start: You need a good 3D editor and 2D editor. Some are free, some will cost you a fortune.
1st you need to understand the 3D editor you are using it (you need to read the hated user manual, use tutorials, maybe read books, get help at user forums etc.)
2nd you need to try out many ways of 3D modeling and do a lot of tests and experiments and make a whole bunch of boats maybe before you are starting to get a feel of this.
3rd you need to know how to make textures and use a 2D editor (your 2nd program)
4th you need to know some about what game graphics is and how it works
5th you should really watch what other developers are making at this forum (http://www.shipsim.com/ShipSimForum/index.php/board,31.0.html)
6th you need to know what is required before you are thinking about sending the boat model to VSTEP (the guidelines (http://www.shipsim.com/ShipSimForum/index.php?action=dlattach;topic=11583.0;attach=37061))
This was a lesson for n00bs that thinks this is so simple...Now you know