We took your son's intriguing idea first to Nova Scotia shipbuilder Philip Snyder. Besides being an expert on current timber construction techniques for boat hulls, docks, and wharves, Snyder has worked on a number of historic replicas, including Bluenose II, the modern-day successor to Canada's most famous racing schooner. It's true, Snyder says, that in the old days dock and ship timbers were fastened with hardwood spikes, more commonly called treenails (pronounced "trunnels"). But that was because the only available alternative - iron - broke down so quickly. Galvanized steel corrodes over time too, but much more slowly.

The advantage of galvanized steel for modern timber construction is its shear strength, or ability to resist breaking under lateral pressure - precisely the kind of pressure that is exerted by waves, currents, and (especially) winter ice. Since treenails have less shear strength, Snyder and longtime Muskoka dock builder Brian Umphrey, of MacTier, Ont., agree that your cribs will probably last longer with galvanized steel. Another fastening option, Umphrey suggests, is stainless steel. It's pricy - a 3?8" x 14" galvanized spike costs about 65 cents, while the same size in stainless will set you back $11.78. You might consider using a few, however, in areas where rot is likely to set in early.