Quote:
Originally Posted by Amgine  This is not true, as I understand naval architecture. A larger boat is relatively less likely to be capsized through wave action (it simply takes a larger breaking wave, which is relatively less likely), but a knock-down or broach is directly related to sail area and wind, not directly to boat length. (Although yes, I know, there is a resistance factor related to length, it is simply not a large percentage of the ultimate stability moment.)
The sail area, however does not [usually] increase linearly with the length of vessels. So, relatively speaking, a larger vessel is less likely to be knocked down in similar wind strengths while a linear increase should have the same likelihood. |
Well you can go sailing in your safe ping pong ball and I'll stick to larger vesselss. In point of fact, if I can suggest this, you might find a barrel, which by the way is bigger than a ping pong ball, both much more comfy and safer
.
I think your naval architecture may need some polishing up but I note you then go on to severely qualify your claims reagrding large sail boats being as prone to knock downs as small ones
.
While a smaller sail boat can be knocked down by sail pressure alone that is very unlikely to be the case in larger vessels - Joli has already said "A big boat stands up to it's canvas better than a small boat" and that is so - in other than small cruising boats knock downs are predominantly due to wave action (the term knock down is applied to both wind and wave action taking the mast to horizontal or below).
I recognise though that even very large internally ballasted vessels can be knocked down through carrying too much sail combined with wave action (which may be a broach initiated by large seas), the clippers being a good example of that but that when carrying very large presses of sail not typical of cruising yachts practice.
Following up on Joli's comment regarding standing up to sail, one will also find large cruising sail boats (and large ocean race ones too which will carry spinnakers up into gale force winds through the Southern Ocean) reefing at much higher wind velocities than smaller ones. If you can find some video on the internet of the large boats in the Whitbread Round the World races where the race boats were not of as extreme race type as today (and some have gone on to be converted to cruising vessels) you will see the very large sail areas they could stand up to in very heavy conditions in the Southern Ocean. I will concede that they had very strong crews but the sail areas carried are impressive and the boats could stand them.
Most knockdowns of cruising vessels of dangerous concern occur while under very small sail areas or none at all in heavy seas so are mostly caused by wave action unable to be resisted by the stability of the hull (which is closely related to displacement and its distribution). Size (displacement) matters, that is why an ocean going cruise liner has no concerns whatsoever of being knocked down and capsizing from wave action even in very large seas, while in the same seas a 30 foot displacement power boat, no matter of what seaworthy design and with GZ and displacment in whatever proportion, would have great concern over its safety.
Just as another example, one will find that in standards the larger the sail boat the smaller the Angle of Vanishing Stability allowed - that because of the greater inherent ability of larger vessels to stand up to conditions that may result in a knock down.