Ballast Ratio - is this the best indicator?

[carrswood]

ummmm!
some good viewpoints.
and yes I understand where bosun higgs is coming from with his form hull & multihull comparison.

The comfort ratio is an interesting one. Maybe that would be a better overall indicator of a yachts seakindliness instead of the Ballast ratio. Cruising around in light winds is nice for most boats but it would be interesting to find a fair calculation that would indicate a yachts seakindliness/comfort in say 28+ knots

Tranona - out of interest what do you sail?

 

[Tranona]

Tranona - out of interest what do you sail?

An "old fashioned" long keeler, designed before all these statistics became important - and a Bavaria 37.

Not sure what that means - except that whenever I have looked at the design of yachts - or more properly how yachts perform in different roles I find boats with very different characteristics can be equally satisfactory. Also specific characteristics tend to come and go with fashion - and particularly through the influence of racing rules. So many of your "high ballast ratio" yachts from the IOR era actually have poor stability because the rules penalised stability! Just look at the keels with all the weight at the top and tapering away to nothing at the bottom - compared to my Bavaria (and many other AWBs) with bulbs at the botom.

Many of these boats are still with us, with owners proclaiming their "high ballast ratio" as a "good thing". On the other hand one of the most successful "blue water" yachts in the smaller sizes (from the same designer as mine) has a low ballast ratio but high stability (AVS) because of its hull shape. It is, like my smaller version, very comfortable in most conditions- more so than my Bavaria. But for general family cruising and living aboard give me the Bavaria anytime.

The current fashion is for lower ballast ratios because the hull forms that give the accommodation people want have high form stability and using less of the displacement for "dead" ballast allows builders to provide more boat for a given amount of materials.

Both styles of boat can be uncomfortable in a seaway - depends on whether you like your discomfort short and sharp or long and rolly! Or more realistically if you are like the vast majority of pleasure yachtsmen you rarely get into a situation where this becomes important. If however you seek out situations where you are likely to experience prolonged periods of adverse conditions, then it is clear you ought to choose a design that minimises discomfort from your perspective.

 

[Little Rascal]

The comfort ratio is an interesting one. Maybe that would be a better overall indicator of a yachts seakindliness instead of the Ballast ratio....

Nooooo!

It's just another one!

You have got to try and see the whole picture...

And you have to define more precisely what you are looking for - what does seakindliness mean anyway? Are you looking for 'comfort', reduced crew fatigue, initial or secondary stability, self-righting ability, high inertia in roll or pitch, ability to beat into a force 8, a 'dry' boat, a boat that doesn't slam in a seaway, a boat that doesn't 'submarine', something to cope with big waves upwind, something to cope with big waves downwind, something to cope with steep waves, something that can shorten sail easily, something that will cope with lying a-hull?

Seakindliness means different things to different people...

 

[Ubergeekian]

Don't know really. It probably depends a lot on the use you put your boat to.
Being landlocked I get great pleasure from going out for a couple of hours and sometimes ghosting about, or if it's more lively having a good thrash.

That's exactly why I have decided to keep the Hunter 490 I got from my father, based on Loch Ken. I can nip up there in fifteen minutes and have a play - basically I'm using her as a big, stable dinghy. I'm planning to refit the bunks and fit basic cooking facilities over the winter, but I'm not intending any long passages. Well, not yet, anyway. I'll have to take her over to the Isle of Man some time, and she'd work well in Ravenglass too.