The boats that come with VSK 5 have their colour scheme created by skin files. The original Nadeo Acc Boat skins kept are in a folder at the address Program Files\[your game version]\GameData\Skins\Boats\Acc. However your new skin files should be placed in a different place, which is Documents\[your game version\Skins\Boats\Acc. You will need to create the 'Acc' folder at this address.
Each skin is a zip file containing 6 dds files. These are hull.dds, sails1.dds, sails2.dds, spi2.dds, TeamMate.dds, and icon.dds.
Software. I use Photoshop so this site refers to this programme. To keep the cost down, you can use old versions of Photoshop or you can use other programmes, such GIMP (which is open source), but I dont have experience with this.
Photoshop needs a plug-in (dds.8bi) to enable it to handle VSK's image files (.dds format), which can be downloaded here. This downoad is for an installer which will place the plug-in in the correct place. For me this is C:\Program Files (x86)\Adobe\Adobe Photoshop CS5\Plug-ins\File Formats.
To make a skin, you should start by getting a template for the boat model (eg Acc). These are files with the parts of the design on seperate layers, which means it is easy to select part of the image to change. There is one for the Acc to download here .
A template has several layers - you can add more of your own and delete layers which you dont need (or just make them invisible). Individual parts of the design are put in different layers. For example, the mast, boom, deck and any writing on the hull are in their own layers, separate from the layers containing the hull itself. So you can easily alter the detail & colour of these bits, without the risk of affecting the rest of the design. Also because you can make the layers visible or not, you can see how things look with or without a particular effect easily. Once you are happy with the design, the layers are flattened into one single layer and the file is saved in .dds format, for zipping to VSK.
Set up folders on your PC to organise the downloads & skin files. Make a folder for Skins and inside it put folders for Templates and a separate folder for each skin you make.
Make the skin.