Marlene I own a hartley southseas whitch is a 38ft ferro. The hull was professionally built and plastered 1974 it has never shown any rust or seperation on the hull. The first time the hull was moved a crane lifted it without using spreader bars much to my horror but no damage was substained. Impact strength posted by hartley boats is for 38-40ft hartley construction method hull .75 inch thickness 30lb steel content per sq ftis as follows approx 8000 lbs per sq inch after 14days curing,11000 lbs sq inch after 28 days,19000 lbs per sq inch after 90days. As far as the wood problem epoxy resin sticks to ferro cement like sh!! to a blanket then you seal the timber the same and mastic them together.Fittings such as chain plates, bowrollers, anchor winches should have had plates welded in the frame before plastering. All that i need to do on haulout to the hull high pressure water wash down ,anti fouling 2coats,clorinated rubber paint 2coats So i strongly recommend that you only purchase a pro plastered hull. A good web site is
www.ferroboats.com Cheers Greg ..