Perhaps no question raises more debate among metal boat builders. Which is better, steel or alloy? In truth both are fine building materials with their own specific advantages.
Technically, both steel and marine grade aluminum are alloys. For convenience, marine grade aluminum is usually referred to as “alloy”.
The world demand for steel has begun to price steel out of the small boat building market. This analysis shows why.
Consider a 36 foot sailing yacht.
Weight budget in steel:
steel – 10,000 lbs cost $1/lb = $10,000
lead – 5,000 lbs
machinery and fittings- 5,000 lbs cost $5/lb = $25,000
total 20,000 lbs ballast ratio = 25%
resale value $50,000
Weight budget in alloy:
alloy – 5,000 lbs cost $3/lb = $15,000
lead – 5,000 lbs
machinery and fittings – 4,000 lbs cost $5/lb = $20,000
total 14,000 lbs ballast ratio = 36%
resale value $100,000
Both boats cost about the same to build. Steel is initially cheaper to buy, but because of the added weight of steel the mast, rigging, sails, winches, ground tackle, fuel tanks, engine, etc. must be bigger to carry this weight, making the boat heavier still.
Typically it is easier to weld a steel yacht, as alloy expands and contracts more during welding. This can be overcome by tacking/welding in the correct sequence and by tacking temporary stiffeners to the metal to limit distortion, but requires experience. Steel has similar problems with heat distortion but is more forgiving.
Alloy boats generally have the best long term resale value of any boat building material. Because of the high resale value it is difficult to find alloy boats for sale for less than the cost of building. This is the economic attraction of building in alloy.
Economically, you should only build if you cannot buy a boat of similar quality for less. Otherwise you are financially better off to buy and use the difference to feed your cruising kitty.