Yay !!! You have finished building your boat! Good job sticking to it! Now you wonder if you have to paint your boat varnish or perhaps a combination of both.
The painting appears to be a much more durable substance than that of varnish. Varnish does do a good job to hide any rough surfaces, but the yacht bottom paint is more likely to protect the epoxy and the wood, which should ultimately be your goal. If you are torn between the two, then it might be a good idea to varnish inside the boat and painting out.
Image Source – Google
If you plan to store your boat in a place that is protected from the elements then varnish your boat is always a viable option. If, however, your boat will be outside without protection of nature, it's good to hold with paint again because of its durability.
If you are still unsure, find and talk to other boat builders and owners and know what they are doing; as a way to achieve peace of mind. Whichever way you go, always follow the manufacturer's instructions for best results.
The key to building a solid building is to have a solid foundation. The same can be said here. The key to having a great boat search is very dependent on your preparation work. Your deck surface should be as smooth as possible, so that the sand like never before sanded! It is best if you use a very fine steel wool to do.