water based varnishes are the future...............
as a painter i can honestly say its just as good as oil based varnish it just requires 3 coats which is still quicker than 2 coats of the normal stuff when u think u have to wait for it dry forever.... with water based u can do 3 coats in 1 day and its has far less fumes
For all vivs i would suggest Ronseal Floor Varnish.It is water based and low odour.If you use yacht varnish it will take forever to off-gas and then when you add the heat it will give of fumes again.All the vivs i have built in the past 2 years have had ronseal now and i have never had a problem.3 coats will see you right for around 3-5 years depending on what you are keeping in the viv.