Full Definition of INERTIA
a : a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force
Hobby horsing is movement around a rotational axis (the center of buoyancy) induced by wave motion. If you want to minimize movement you need a force to resist it.
In the case of a lead mine this force for resistance is provided by the boat’s righting moment which is a combination of hull
form and center of gravity.
You can’t change the hull
form but by changing how you load the boat
you can affect the ballast to displacement
ratio and in turn the center of gravity.
One of the reasons people run pipe for their chain out of the bow and down into an anchor locker
as close to the center of gravity as possible is to minimize the negative effect of reducing the ballast to displacement
ratio resultant from adding weight and increasing the displacement and thereby changing the center of gravity
Where inertia comes into play is that it affects the “feel” of the boat
. A boat with weight in the ends will “feel” smoother in it’s motion. But, because of it’s lower ballast to displacement ratio and raised center of gravity it will move more.
Much like a racing
boat with extreme deep draft
and a bulb keel
, the dismasted boat will “feel” like it has violent or jerky motion due to the enhanced stability curve and loss of inertia resultant from it not having a mast
because it will be much quicker to react to the forces of the sea acting against it.
Likewise a boat with weight in the ends will be more likely to bury her bow because inertia will make it want to dive down when a wave is trying to lift
it up. The other reason to keep weight out of the ends.