What is "Ocean" worthy?

[jon hansen]

thanks John. side note: the number one injury from that storm/race was acid burns from batteries that had dumped

 

[jssailem]

I would not doubt that, Jon. The failures that occurred in that race have greatly influenced the way we view boat safety.

 

[capta]

Capta, I'm grateful you made it through to tell the tale.

-Will (Dragonfly)

Wow, those guys that made that video don't seem to have ever spent any time on a sailboat, let alone one in a storm.
First off, to the best of my knowledge, 'rogue waves' don't happen in perfectly calm water. To be in the situation where one might meet such a monster, one would probably be in a storm and either running under bare poles or severely reefed, not anchored bow to wave.
Perhaps this could be a scenario for a tsunami, but it is the silliest 'rogue wave' demonstration I've ever seen.

 

[Michael Davis]

Wow, those guys that made that video don't seem to have ever spent any time on a sailboat, let alone one in a storm.

Hey!!! Now you're asking that all academics have practical experience!!!

 

[DrJudyB]

Capsize Screening # = Boat’s Max. Beam (feet) / Cube Root (Gross Displacement / 64)

In English: take the boat’s gross displacement in pounds, divide it by 64 and then take the cube root of the quotient. Now, divide the boat’s maximum beam in feet by the cube root figure. The resulting number should be 2 or less. In general, if the number is over 2, the boat fails the screen. If the number is under 2, the boat passes. Again, the formula is a very general guide, and does not take into account a number of other important design factors that might lessen — or increase — a boat’s tendency to capsize. Use the formula to get a quick idea of a boat’s stability, but also explore the boat’s full capsize characteristics before you decide to purchase it and set off sailing in open waters.

The capsize screening formula ignores a bunch of important boat characteristics, and furthermore more it doesn’t work worth a damn on small boats (with short LOAs) which are very beamy compared to their displacement. For small boats, it’s almost meaningless. You really need to look at the stability curve.

For example I have a custom built 19 footer with a Potter 19 hull, but with a custom rig and a retractable bulb keel. The capsize screening number is around 2.5, but the AVS is 103 degrees.

And the area under the curve when capsized mathematically represents the amount of work needed to right the boat. We did the modeling using a flat deck without any superstructure. In reality, the super structure contributes to righting, but we didn’t include it in the modeling software.

 

[Jackdaw]

I entered or looked up, rather, the data for my Mariner on the site jackdaw posted a link to. Here is the results.
"boatName=Mariner 19cb
LOA=19.167
LWL=17.75
beam=7
displacement=1305
sailArea=185
displacementToLWL=104
speed=5.65
sailAreaToDisplacement=24.79
LWLToBeam=2.54
motionComfort=8.25
capsizeRatio=2.56
category=racer
ppi=444
"description=Capsize Ratio: A value less than 2 is considered to be relatively good; the boat should be relatively safe in bad conditions. The higher the number above 2 the more vulnerable the boat. This is just a rough figure of merit and controversial as to its use."
I don't know what kind of range the Capsize Ratio has, but if 2 is the maximum for relatively good safety, a point five difference is 25%. That seems significant. On the other hand, if the range of reasonable values goes as high as 50, a .5 point difference isn't that much.
As a small boat, where and how equipment and supplies are stored can make a big difference to the actual values.

-Will (Dragonfly)

Will, your boat is a 19 foot long daysailer. Capsize ratio??? ;^) The notion of a 'capsize ratio' (and the implication that you would be out in those seas) should never enter your mind. NEVER be in that weather in that boat.

 

[Jackdaw]

Racing boats and yachtsman are going to go out on open waters. Various races have committees setting rules to limit the risks. Most of these rules came about after the 1979 Fastnet Race.

Here is what one group (after 5 years of investigation) developed.

CRUISING CLUB OF AMERICA

In the spring of 1980, the Cruising Club of America (CCA), which was preparing to run its biennial Newport-Bermuda Race took a long hard look at the Fastnet race and began to study what could be done to prevent such a disaster from reoccurring.

Five years later, a final report was issued and offers several broad conclusions that help illuminate what is safe and what is not in hull and yacht design.

The conclusions of the report, in brief, are:

- Larger boats are less prone to capsize than smaller boats.

- A dismasted sailboat is more likely to capsize than a boat carrying her full rig.

- A boat has an inherent stability range, ie., an angle of heel past which it will capsize. That stability range can be calculated from the boat’s lines and specifications.

- Some boats designed to the IOR rule, or any designed to be particularly beamy, may remain inverted following a capsize. Boats with a stability range under 120 degrees may remain inverted for as long as two minutes.

- Boats lying sideways to a sea, particularly light, beamy vessels, are more likely to capsize than boats that are held bow to the sea or stern to the sea. It follows, then, that boats that are sailed actively in gale conditions and breaking seas are more likely to avoid capsize than those left to lie untended, beam to the seas.

- The issue of whether or not a boat will capsize, and when and how it might suffer such a fate, is a key point for any sailor contemplating safe extended coastal or offshore cruising. By analysing a boat’s stability range, you can get a very good reading on how the boat will handle a gale at sea and how best to plan your own gale tactics.

The CCA committee that compiled the five-year Fastnet report came up with a simple formula to determine the stability of any yacht of a fairly standard type and of a size suitable for offshore sailing. The formula is as follows:

Capsize Screening # = Boat’s Max. Beam (feet) / Cube Root (Gross Displacement / 64)

In English: take the boat’s gross displacement in pounds, divide it by 64 and then take the cube root of the quotient. Now, divide the boat’s maximum beam in feet by the cube root figure. The resulting number should be 2 or less. In general, if the number is over 2, the boat fails the screen. If the number is under 2, the boat passes. Again, the formula is a very general guide, and does not take into account a number of other important design factors that might lessen — or increase — a boat’s tendency to capsize. Use the formula to get a quick idea of a boat’s stability, but also explore the boat’s full capsize characteristics before you decide to purchase it and set off sailing in open waters.
​

Those 'observations' are solid and as valid today as they were the day they were written. The notion of the 'capsize ratio', however was an attempt to apply a formula to determine what's safe, and really worked backward from what happened to contemporary designs. Be very careful applying to modern boats.

 

[Michael Davis]

Racing boats and yachtsman are going to go out on open waters.

And winning racing boats are usually pushing the envelope. Some Fastnet boats survived when their crews had abandoned them and were lost. I've always felt that you should step UP to your survival raft and that my boat would scare me to DEATH before it was in any danger ( unless I do something really stupid. )