Aluminium work boats are very popular in the Pacific North West of the US and British Columbia... There is a considerable amount of logging in the area, and you can get "deadheads" which are waterlogged logs floating just beneath the surface..
I am sure there are others making simular boats in the area, plus of course in BC as well...
Have a look at the exhibitors at Seaworks, there are a number of workboat builders exhibiting every June at the Southampton show. http://www.seawork.com/