The nature of the Murrelet centerboard is not well understood. MacGregor Yachts states in the cruiser’s brochure that
A long, thin airfoil is far more efficient than a short, wide one. This is why racing sailboat keels are deep, and why sailplane wings are long and thin.
The competing hull forms in Murrelet (displacement in the bow and planing aft) bring up some interesting aspects in sailing the cruiser. Because the manufacturer built so many pocket cruisers, the best hull form and ballast configuration was extensively studied.
Boats can be split into two categories: the ones that dig holes in the water and the ones that travel on top. Race boats, runabouts, fast cruisers, sport fisherman and military patrol craft are part of the planing fraternaty.
James Boyd in his April 2005 Sailing World article (page 45) notes that the Vende Globe machines with canting keels also have water ballast. The question as to which is the primary ballast system on boats that have both may have been answered in that article.
John Vigor, a reviewer of “good old boats” in Twenty Small Sailboats to Take You Anywhere (1999 Paradise Cay Publications) lists the Alberg 30, Albin Vega 27, Allied Seawind 32, Bristol 27, Bristol Channel Cutter 28, Cal 20, Cape Dory 25D, Catalina 27, Contessa/J.J
Twin keels become more effective with increased angle of heel, while a single keel becomes less effective.
“No other nation has put so much faith in bilge (or twin) keels as the British. Other countries have flirted with them, but we became so enamored with the concept that they were the first choice for anything less than about 36 feet.”
Lady Washington
On the east coast of the United States the warming and cooling land mass does not create winds that fully overcome the ocean weather or trade winds that a very tall mast can capture. Hence, for some commercial sailing vessels following the same courses trip after trip, the taller masts were desirable even though the larger sails required additional crew to handle them.
According to Sailing Today, September 2000 page 83, Van de Stadt’s Dehler 25 sloop bested MacGregor Yachts by a year or so in the use of water ballast. The German Dehler 25s were produced from 1984 to 1991 and water ballast was reported in the US to be used for trailering reasons and cost savings.