Complements from The Macgregor 26 Home page
MACGREGOR 26 WATER BALLAST SYSTEM
MacGregor developed this concept. It has been widely copied, and is now the standard throughout the trailerable sailboat industry. It makes it possible to have very light weight for powering and trailering,
and the heavy stability necessary for safe sailing. After launching, the transom valve is opened and a tank in the bottom of the hull is gravity filled with 1150 lbs of sea water. It takes about 5 minutes. The valve is then closed, trapping the water. Under power or sail, the ballast makes the boat stable and self righting. When the boat is floated back onto its trailer, the valve is opened. The car and trailer start up the ramp and the water drains out of the boat, leaving a trailering package that is lighter than most small powerboats.
You can also empty the tank while the boat is in the water. Under power, at about 6 mph, open the valve on the transom and the tank will drain in about 5 minutes.
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The above appears to say that it is possible for the boat to be without its water ballast (Which in the company's terms :-
"the ballast makes the boat stable and self righting." "the heavy stability necessary for safe sailing.)
The addition of +/- 10 people may have been a factor in giving an impression of stability - when in fact the opposite may have been the result.