"How fast should my cruising sailboat be able to go in good conditions?"
"Absolutely nothing does more damage to more boats than water penetrating the deck core. Not hurricanes. Not inadequate ground tackle. Not electrolysis. Not leaking propane. Not anything."
A Ferrocement Hull has some tremendous advantages over other materials, but there are good ferrocement hulls and bad ones.
Whether its for keeping in the heat in cold climates or keeping it out in the tropics, Insulation can mean the difference between comfort and misery.