Join Date: Jan 2012
Location: British Columbia
Thanked 39 Times in 37 Posts
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There is no shortage of cruisers happily cruising in steel boats under 40 feet, some much smaller. The 40 ft minimum for steel is a myth.
3/16th plate gives you lots of room for corrosion, with little worry about strength. Light rust on 3/16th means nothing. It would take heavy flaking rust to become a structural concern. As corrosion doubles for every ten degrees rise in temperature, a boat in BC all her life is far less likely to have major structural loss of strength from corrosion, than one in the tropics..I have seen many steel boats plated with 1/8hth inch plate, rusted thru, when, had they been made of 3/16th, they could have had decades more life.
I never liked 1/8th plate, and seeing the Snowbird featured in Sea Spray Magazine in December 73, with 3/16th plate specified, was what first got me interested in steel boats . Cement hulls of the time were 12 lbs per sq ft, so the 3/16th plate at 7.5 seemed reasonable, especially if one used shape and the extra thickness to reduce the weight of internal framing. Being a steel worker all my life, I realized how much easier it was to keep 3/16th fair, and how much tougher it is. Corrosion forgiveness was an added bonus.
Brent Swain, Boat designer, Builder, and author of "Origami Metal Boatbuilding"
Last edited by Brent Swain; 01-18-2012 at 05:04 PM.