I agree with a most of what you sad with an exemption of beam factor. You s=
Why a wide boat is more prone to capsize eludes
" Well, wide boat, with a relatively flat bottom shape with a lots of fo=
rm stability (let's say last generation open 60's), tends to
heel much more on the face of the wave than narrow boat with rounded or dee=
p V bottom with a little form stability. (For example
Marco Polo of the L. Francis Herreshoff). Once heeled to say 45 degrees wid=
e boats offers huge bottom area to wind and waves and
narrow boat does not. In case of capsize, Marco Polo keeps positive range o=
f stability somewhere to 170 degrees or so. Most oft wide
boats loose positive stability somewhere around 120 - 130 degrees.
--- In firstname.lastname@example.org, "bubblede" <gerd@j...> wrote:
> Hi Edward
> I would be very carful judging the seagoing value of any boat by the
> CSF, and I am actually quite surprised to find Brewer quoting it on
> his otherwise very useful page.
> What the CSF basicaly does is to put preconcieved, half-a-century
> old traditionalist ideas into a "formula" as justification for
> excluding "modern" boats: give me a goold old fashioned narrow heavy
> boat anytime... and so on
> Why a wide boat is more prone to capsize eludes me.
> The advantages of heavy displacement as such in capsize conditions
> are also unclear to me - sure I understand the difference between
> kicking a football and a bowling ball, but in the chaotic conditions
> in which capsizes occur there are many other factors that play a
> much larger role, and anyway the foot that kicks us then is large
> enough not to hurt even if our boat was made of lead. _any_ boat in
> the sizes that we talk about can capsize - the question is how to
> avoid getting the final kick.
> What I am missing in all this discussion is hydroDYNAMICS. I believe
> that a boat in these conditions is first of all a moving, dynamic
> shape and volume rather than a mass.
> Some examples:
> - A wider body with an nice hull shape will give you a lot of volume
> laterally to lean on and with speed help you get the nose out,
> rather than get the decks knocked under which will then server as a
> very unfavorable lateral resistance to trip you.
> - in the most ugly capsize head over heels, volume forward might
> help preventing the nose to dig in.
> - capsize though rolling occurs mostly after broaching. A hull
> shape and plan that gives you lots of directional stability and
> control even when running under bare poles (and I do not meean a
> long keel), or even a lifting keel or centerboard that will move
> your center of lateral resitance aft and allow you to keep your your
> boat pointing downhill.
> - A Lateral plan that offers little resistance in deep solid water
> will allow the boat to bob away on the higher disturbed layer if
> lucky without tripping over it's own feet.
> So I think the displacement of a boat should be the result of the
> above considerations, combined with requirements coming from
> selected material and requirements as for useful cruising charge.
> At the risk of kicking off a big flame war here: I think that modern
> long-distance ocean racers are probably the "safest" boats around,
> as they are a) built to arrive and b) driven permanently at maximum
> speed and breakpoint. In similar conditions traditional boats have
> summersaulted while hanging on to sea-anchors, while these things
> (open 60's, whitbread, even 6,50m mini-transat...)just change the
> spinnakers for a hevy genoa and keep tobboganing down the waves at
> 25 knots ;-)
> It is true that they break a lot, take knockdowns and capsizes and
> do not always arive. But this is not due to the concepts as such but
> rather to the fact that these concepts are then pushed to the
> extreme limits of risk-gambling between winning and not arriving. So
> do Formula 1 cars - if you would take one of these cars where the
> drivers step out unhurt after 150 kmh frontal crashes and walk away
> from it, take a spin around the corner at 120 where your honda would
> slip at 65, there is absolutely no doubt that the F1 is by concept
> and design the safer car and there should be no problem driving
> one - very uncomfortably - to your office dayly ;-)
> The fact that they do breake more F1 per km than volvos station
> wagons does _not_ prove that volvo are better or safer.
> Sure, if I would take an open 60 for a day sail, I would probably
> manage to bring the mast down five miles out, and also would not
> want to live or sleep aboard for longer than a fortnight.
> But if today I would try to design a good safe cruising boat, I
> would look at these boats and see what allows them to stay in
> control under the most extreme conditions, rather than look