Capsize Ratio's

[barnakiel]

IMHO the 'amateurs' rant vs. Fastnet does not really apply here: an amateur racer will actually drive a boat far more competently than many a non-racer sailor.

Racing is a pretty specific mode of sailing where boat driving skills are learned up first and where they are promoted in a natural way. Most amateur racers are excellent sailors - with great feel for what the boat is doing and why, great driving skills and high levels of stamina.

I believe the extent of loss was party due to the fact that crews were racing in conditions that asked for calling the whole thing off and continuing sailing in a conservative way to minimize risks.

As with many cases when the weather comes from the ocean side - the organizers were not aware of how bad the wx was until they heard of the damage done - which was too late to take preventive steps.

Many complex factors, but 'racing amateurs' not truly one of them.

b.

[capn_billl]

As far as racer VS m&p's seamanship contributing to capsize. There are several factors. The racer will have full sail long after everyone else has reefed. The racer wil be pressing for the last .1 knotts long after everyone else has turned to survival mode. These two factors alone can contribute to increased capsizes during a race, but ultimately I think the boat design matters the most.

Take two theoretical boats, the Albin 30' and the newest 30' hyper racer make of mylar with carbon struts, and a wing keel. Both boats have the same hull speed. The racer has half the keel weight because it relies on reverse lift from the wing to counteract sail force. The lower wetted area allows the racer a few .1's of a knot more than the Albin under light air, and maybe even a whole knot more than hull speed in high winds from shallow flat hull that can somewhat plane.

Which of these two boats would you want to sail through a gale? Which is more survivable in a trans Atlantic? Which would be m&p's best choice for a long term cruise? Which is more likely not to repeat the fastnet disaster?

[Randyonr3]

Originally Posted by capn_billl

As far as racer VS m&p's seamanship contributing to capsize. There are several factors. The racer will have full sail long after everyone else has reefed. The racer wil be pressing for the last .1 knotts long after everyone else has turned to survival mode. These two factors alone can contribute to increased capsizes during a race, but ultimately I think the boat design matters the most.

Take two theoretical boats, the Albin 30' and the newest 30' hyper racer make of mylar with carbon struts, and a wing keel. Both boats have the same hull speed. The racer has half the keel weight because it relies on reverse lift from the wing to counteract sail force. The lower wetted area allows the racer a few .1's of a knot more than the Albin under light air, and maybe even a whole knot more than hull speed in high winds from shallow flat hull that can somewhat plane.

Which of these two boats would you want to sail through a gale? Which is more survivable in a trans Atlantic? Which would be m&p's best choice for a long term cruise? Which is more likely not to repeat the fastnet disaster?

WOW, this one dosent even deserve a rebuttle.....

[mitiempo]

Originally Posted by Randyonr3

WOW, this one dosent even deserve a rebuttle.....

I agree.

[Paul L]

Originally Posted by capn_billl

As far as racer VS m&p's seamanship contributing to capsize. There are several factors. The racer will have full sail long after everyone else has reefed. The racer wil be pressing for the last .1 knotts long after everyone else has turned to survival mode. These two factors alone can contribute to increased capsizes during a race, but ultimately I think the boat design matters the most.

Take two theoretical boats, the Albin 30' and the newest 30' hyper racer make of mylar with carbon struts, and a wing keel. Both boats have the same hull speed. The racer has half the keel weight because it relies on reverse lift from the wing to counteract sail force. The lower wetted area allows the racer a few .1's of a knot more than the Albin under light air, and maybe even a whole knot more than hull speed in high winds from shallow flat hull that can somewhat plane.

Which of these two boats would you want to sail through a gale? Which is more survivable in a trans Atlantic? Which would be m&p's best choice for a long term cruise? Which is more likely not to repeat the fastnet disaster?

An Albin 30 and a Melges 30 both have ballast to displacement ratios greater than 40%, with the Melges having its vcg much lower.

[barnakiel]

Originally Posted by capn_billl

1) Which of these two boats would you want to sail through a gale?

2) Which is more survivable in a trans Atlantic?

3) Which would be m&p's best choice for a long term cruise?

4) Which is more likely not to repeat the fastnet disaster?

ad 1) the racey one - it has one more storm tactic option,

ad 2) draw,

ad 3) the racey one, then hire a bungalow at destinations,

ad 4) draw, unless one design flawed.

b.

[cwyckham]

Ross Garrett's "Symmetry of Sailing" offers an interesting perspective.

He basically says that the static stability curve has very little to do with a yacht capsizing in real life. The sails will spill wind as you go over, so it's waves we need to worry about. Waves are dynamic, not static, so it's the roll moment of inertia we should be thinking about more than the static righting moment.

In fact, the really dangerous thing is breaking waves (not whitecaps that spill off the back, but waves that break forward like on surfing movies). Non-breaking waves only have a maximum slope of about 30 degrees and are not really a threat.

The danger of a breaking wave is that the boat is basically thrown down into the trough. It's like lifting the boat up and dropping it on its side from a crane. This simply breaks the boat (often the coach roof) and it starts taking on water.

From Ross Garrett: "...the form of the static stability curve will have little effect on the damage sustained... about 95% of the energy given to the boat appears as translational kinetic energy and only 5% into rolling it... The likelihood of damage is largely a matter of strength/weight ratio. The impulsive force on the coachroof is directly proportional to the displacement of the boat, so a light boat built well of strong modern materials is likely to fare best. On the off chance that the coachroof is damaged, a low centre of gravity will provide a good backup for survival by righting the boat quickly."

[TeddyDiver]

Originally Posted by cwyckham

so a light boat built well of strong modern materials is likely to fare best. On the off chance that the coachroof is damaged, a low centre of gravity will provide a good backup for survival by righting the boat quickly."

And if we omit the the fact that such boat doesn't really exist Ross would be right on the spot. However the fact is every ounce saved in one place is regularly found else where (in the keel bulb most likely) and there's no gain got in the end.. that is of course if the keel doesn't tear of as they sometimes do in boat's build of light modern materials. Thou that is not so much a flaw of the material, merely just the fact that race boat's are not allways meant to be sailed more than one or two races before they start to break apart

[Bash]

Originally Posted by sneuman

I highly doubt that. Fastnet and Sydney to Hobart typically bring out very top-notch offshore racers. This isn't Wednesday evening round the beer cans stuff.

Round the buoys? Even beer-can racers don't race "round the beer cans."

[cwyckham]

Originally Posted by TeddyDiver

And if we omit the the fact that such boat doesn't really exist Ross would be right on the spot. However the fact is every ounce saved in one place is regularly found else where (in the keel bulb most likely) and there's no gain got in the end.. that is of course if the keel doesn't tear of as they sometimes do in boat's build of light modern materials. Thou that is not so much a flaw of the material, merely just the fact that race boat's are not allways meant to be sailed more than one or two races before they start to break apart

?? A race boat is built as light as possible. They weigh a fraction of the weight of an old full Keeler of the same size, plus their center of gravity is lower.

Of much more interest to me, though are the implications for cruising boats. You want to be light and strong, not just strong.

[barnakiel]

Originally Posted by cwyckham

(...)

Of much more interest to me, though are the implications for cruising boats. You want to be light and strong, not just strong.

And do we have any cruising boats built of modern light and strong materials floating around? If so, which ones are they?

Boats meant for family offshore adventure, where carbon, kevlar and space age engineering have been applied not to gain competitive edge but rather to improve stability, sail-ability and survival-ability?

barnakiel

[TeddyDiver]

Originally Posted by cwyckham;

You want to be light and strong, not just strong.

Nothing against that but so far we can only dream such boat.

[barnakiel]

Originally Posted by TeddyDiver

Nothing against that but so far we can only dream such boat.

View Boat Photos - YachtWorld.com

Just one of possible takes, ten you get things like Shipmans, Martens, etc..

There are some strong and light boats around.

b.

[TeddyDiver]

Strong is relative term. Production boats, such as any boat for sale to public, has to be build compliant to some standard. The most common standard nowadays isISO 12215. Designing a boat is pretty much following the loadings given in these standards. Whatever the material.. when building from exotic materials the cost is the most limiting factor against over engineering. And in the end the old fashioned wood is stil today very competitive what comes to weight to strength ratio against especially when cyclic loading goes up from 10^5.
BR Teddy

[cwyckham]

Originally Posted by barnakiel

And do we have any cruising boats built of modern light and strong materials floating around? If so, which ones are they?

Boats meant for family offshore adventure, where carbon, kevlar and space age engineering have been applied not to gain competitive edge but rather to improve stability, sail-ability and survival-ability?

barnakiel

Not sure why everyone is assuming exotic materials. He said what is important is strength to weight ratio, not just strength.

Just about any modern boat will have better strength to weight than an early heavy cruiser made of inch thick solid hand laid up chopped mat.

We just know a lot more about glass in terms of workmanship and design.

A cored hull with a well designed lay-up and vacuum bag construction (or infused would be even better) is going to be much lighter and possibly somewhat stronger than earlier builds were. This will make it safer in breaking seas.