From “Seaworthy Offshore Sailboat” by John Vigor
“Imagine a boat shaped like an old-fashioned flat iron-- almost triangular in shape, pointed in front and wide at the back. Now think what happens when that boat heels under sail. The bow end sinks slightly because it has little buoyancy; the stern end rises much more because it has excess buoyancy.
Now that the stern has less grip on the
water than the bow has, the stern tends to be blown downwind through the
water and the boat weathercocks into the
wind, pivoting from the bow. This is called griping [broaching].”
From “Rough Weather Seamanship” by Roger Marshall
“The stern shape is critical to the boat’s behavior. A boat with a large, fat stern and fine bow will tend to sail bow-down as it heels, which can cause the
rudder to
lift out of the water slightly and become less efficient. The boat may also be more prone to broaching in heavy
weather [...]”
From “Modern Cruising Under Sail” by Don Dodds
“If the stern gets too wide it can create turbulence; it also adds wetted surface when hard on the
wind at larger angles of heel. As I discussed earlier, stability problems have been blamed on excessive width in the stern.”
From “Seaworthy Offshore Sailboat” by John Vigor
“Designers of oceangoing cruisers try to balance the ends of a boat by keeping the submerged areas fore and aft roughly equal at all stages of heel. This results in a boat that is easily balanced by varying the areas of sail fore and aft of the
mast. Such a boat obeys the
helm easily and quickly in all conditions without excessive strain on the
rudder. It is a great
safety feature”
). 
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