The older, heavier, metal machines will work out well enough. I just read an article in "Good Old Boat" about using old domestic machines with thick marine cloths. He went to a used machine warehouse with material and thread and found ones that worked the best. He ended up with a White brand machine, a big old metal beast.

You can contact Good Old Boat and buy the January/February 2003 issue if they have any left. Heck, if you sign up for the free trial issue you might be able to get it for nothing.