I believe inertia is one of the forces in effect here.  We can play with this!  So even a lttle weight hauled to the top of the mast will have an effect that will be felt, experienced as a slowing down of her motion and a resistance to get initiated into motion ( inertia).  I'm interested in how this would be experienced on a tender hull.

I have a slight problem with the Kasten explanation of roll inertia. He says its proportional to the 4th power of the axis. But I is to the 2nd power like it says here here.

                                                                  Stavanger, Thursday

I guess for smaller vessels we have two main factors that decide the comfort and safety: Natural roll frequency and roll damping

Last thing first: Roll damping is the boat’s hydrodynamic resistance against keeping on rolling after a wave has started it. My Alo 28, Johanna, with her round bottom seems to have quite moderate roll resistance. In Norway a lot of round bottom fishing boats have been retrofitted with long shallow roll-damping bilge keels. These have proven very effective and have made it much easier for the fishermen to work in a seaway, often with the boats hove-to. I doubt if these will be so effective on sailing vessels, and I know they rob some speed as well. Maybe sailboats with long keels have better roll damping than those with fin keels? And maybe wing keels or endplates on keels will help with roll damping? I don’t know. What is sure is that improved roll damping would make any vessel more comfortable. ( .. BTW, it would not surprise me if a single chine dory hull like Badger’s have better roll damping than a round hull...)

The positive effects of reducing the roll frequency have been well covered here. Now, in our sailboats we simply must have some ballast and some beam to carry the sails and both factors tend to speed up the roll frequency. It is therefore essential to have a mast which adds so much to the inertia, both from a safety and comfort point of view.

The good thing with a boat with heavy displacement and narrow beam and with a stout mast is that it will have a very slow roll. This is more comfortable and also adds resistance to being knocked down. On the other hand, any roll-resisting shapes of hull or keel will be less effective in preventing the big masses from rolling when it finally has started. The result is that such boats can roll a lot (albeit slowly) when the sea is in resonance with the boat, usually at some point downwind. I guess this is the downside of the heavy displacement boat: It is not easy to dampen any motions of big masses.

Lighter and beamier boats may be easier to knock down in a beam sea or when close-hauled, but may be more comfortable downwind. My 23’, 1.4ton Albin Viggen, Malena, was very good in a seaway, downwind. The combination of a fairly flat bottom, good directional stability and a full bow kept her from starting any tiring downwind roll in a seaway. I guess we could say that Malena’s roll damping to displacement ratio is good as she quickly settled down after ships had passed her. (Note: An un-balanced hull may add a lot to the rolling downwind, due to yawing...)

So I guess most boats have a point of sailing in which they thrive less well, and yes, any hull or keel shape which adds to roll damping should be preferred. Which is that??

Cheers, Arne.

Heavy displacement is safe though Annie, generally speaking but I think Beam is a very important aspect in regards to stability and motion.  Mine is extreme is this regard, 32 footer with 11 foot beam carried for most of the length.  Lots of volume and she's not shaped like a wineglass but more a champagne glass.  BBay has lots of weight and still has what I think is an unacceptably sharp motion in a beam chop or short beam sea.  Off Ranfurly last April I would not go forward as I thought it too "lively".  It was OK once hove to but under way not so great.  Not too bad under lots of sail but once reefed down the action deteriorated till  I was "white knuckling". 
We had winds gusting to 25 knots here tuesday so a bit of a chop and with the weight aloft it was truly remarkable how much slower her motion was.  So we have a real large lever here that we can use to control the motion of the yacht!  Why not try some weight aloft next time there's no wind and a chop or at anchor in a choppy location.
 I think its a great asset.

I agree - great article. Good luck with your experiments, Pete.