Capsize S

[Redrooster]

Hi all, totally new to sailing
Looking at a sailing data page. What does Capsizing S mean? I am guessing the force needed to capsize. What is a low mark and what is high. Racer compared to a Bluewater boat
Regards Red

 

[KompetentKrew]

SailboatData.com gives "Capsize Screening Formula" for at least some vessels. There is a "definitions" link nearby, which says:

Capsize Screening Formula (CSF):
Designed to determine if a boat has blue water capability. The CSF compares beam with displacement since excess beam contributes to capsize and heavy displacement reduces capsize vulnerability. The boat is better suited for ocean passages (vs coastal cruising) if the result of the calculation is 2.0 or less. The lower the better.​

It also gives definitions for SA/Disp, Comfort Ratio and S#, but I would ignore all of these if you are new to sailing. I would question how useful they are for any of us.

 

[onesea]

[Deleted quoted content removed]

It certainly gives an inside into some interesting opinions

“Generally, wind speeds over 20 knots (23 mph) are too windy for boating. At this wind speed, almost all-size boats will be greatly affected, and smaller boats may even be in danger of capsizing.”

“Windy.com weather forecast app
Capsizing’s number one reason is boats going out in the wrong conditions due to bad weather data. This app won’t let you make that mistake.”

Sometimes the internet is not the best resource available…

 

[William_H]

It certainly gives an inside into some interesting opinions

“Generally, wind speeds over 20 knots (23 mph) are too windy for boating. At this wind speed, almost all-size boats will be greatly affected, and smaller boats may even be in danger of capsizing.”

“Windy.com weather forecast app
Capsizing’s number one reason is boats going out in the wrong conditions due to bad weather data. This app won’t let you make that mistake.”

Sometimes the internet is not the best resource available…

Not sure what onesea is trying to say here. Over 20 knots is not too much for sailing. Our club tend to think cancellation of racing in sheltered waters if wind is over 25 knots. But in reality we often get caught out in more than 25knots.
Capsize means a lot different for an open dinghy compared to a keel boat with ballast and self draing cockpit. In the case of the open dinghy a heel on the boat will put the gunwhale under which takes on water so righting power from hull buoyancy is lost and boat slips to mast in water or worse. Dinghy sailors should be familiar with this occurrence and are prepared to right the dinghy climb aboard bail out and continue sailing. Not so bad with dinghy with sealed decks so no baling required.
For a decent keel boat with ballast in the keel and self draining cockpit much less concern. With a lot of wind and flat water the boat will heel over so naturally spilling wind from sails and also usually turning itself into the wind (rounding up) so also easing wind pressure on sails. So almost impossible to get any where near mast horizontal.
There is one exception to this if you have a large spinnaker up on beam reach. The spinnaker tends to hold the wind so hold the mast near the water. This has happened many times on my little boat. A bit alarming as boat turns out of control into the wind while some water pours into the cockpit and you are left standing on leeward seats. It all settles down of it's own accord pretty quickly. The mad sailor (me) might persevere only to have it happen again.
Now in big waves things are a little different. A keel boat beam to the wind can be tripped by a breaking wave. Firstly the righting force of the buoyancy of the sides of the hull is lost because the wave itself is sloping down then the wave water at the top can try to throw the boat to leeward when breaking but water lower down where the keel is can stop this sideways motion causing more heel of the boat to capsize.
From there you are relying on the righting power of the ballast keel and this ability can be described by various graphs and numbers.
So yes any sailor must be cognizant of weather and forecast. However any sailor of a keel boat of any size must be prepared for strong winds. This usually means a way of reducing sail area both jib and main sail to cope with rising winds. Generally it is the ability to sail to windward in strong winds that matters. So in 20 knots of wind in my little tender boat sail area would be reduced to about 50% of full sail. But yes being old and lazy I might cancel my participation in a race if winds were forecast much over 222 knots. However I regularly race in winds of 18 knots. (no I don't love it but it is good to get home and have survived a blow) Note force on sails of a boat increase dramtically with increase in wind speed. So 18knots is a lot gentler than 22 knots.
So if OP is considering buying a sail boat. I would recommend about 20 ft perhaps 25ft but do buy a GRP boat with ballasted keel and self draining cockpit. It should have decent self righting capabilities. ol'will

 

[KompetentKrew]

Not sure what onesea is trying to say here.

Boat Keep is probably a spam site they're trying to promote - original content is highly rated by search engines, so they advertise on freelancing sites and pay people to research and write articles on whatever subject they're trying to advertise to.

They're probably paying people from the developing world a penny a word to write this rubbish, so no wonder the author has no idea what they're talking about.

It seems a bit silly to try posting it here, but this kind of content is typically of such low quality that they don't even know how bad it is.

 

[MADRIGAL]

Not sure what onesea is trying to say here. Over 20 knots is not too much for sailing. Our club tend to think cancellation of racing in sheltered waters if wind is over 25 knots. But in reality we often get caught out in more than 25knots.
Capsize means a lot different for an open dinghy compared to a keel boat with ballast and self draing cockpit. In the case of the open dinghy a heel on the boat will put the gunwhale under which takes on water so righting power from hull buoyancy is lost and boat slips to mast in water or worse. Dinghy sailors should be familiar with this occurrence and are prepared to right the dinghy climb aboard bail out and continue sailing. Not so bad with dinghy with sealed decks so no baling required.
For a decent keel boat with ballast in the keel and self draining cockpit much less concern. With a lot of wind and flat water the boat will heel over so naturally spilling wind from sails and also usually turning itself into the wind (rounding up) so also easing wind pressure on sails. So almost impossible to get any where near mast horizontal.
There is one exception to this if you have a large spinnaker up on beam reach. The spinnaker tends to hold the wind so hold the mast near the water. This has happened many times on my little boat. A bit alarming as boat turns out of control into the wind while some water pours into the cockpit and you are left standing on leeward seats. It all settles down of it's own accord pretty quickly. The mad sailor (me) might persevere only to have it happen again.
Now in big waves things are a little different. A keel boat beam to the wind can be tripped by a breaking wave. Firstly the righting force of the buoyancy of the sides of the hull is lost because the wave itself is sloping down then the wave water at the top can try to throw the boat to leeward when breaking but water lower down where the keel is can stop this sideways motion causing more heel of the boat to capsize.
From there you are relying on the righting power of the ballast keel and this ability can be described by various graphs and numbers.
So yes any sailor must be cognizant of weather and forecast. However any sailor of a keel boat of any size must be prepared for strong winds. This usually means a way of reducing sail area both jib and main sail to cope with rising winds. Generally it is the ability to sail to windward in strong winds that matters. So in 20 knots of wind in my little tender boat sail area would be reduced to about 50% of full sail. But yes being old and lazy I might cancel my participation in a race if winds were forecast much over 222 knots. However I regularly race in winds of 18 knots. (no I don't love it but it is good to get home and have survived a blow) Note force on sails of a boat increase dramtically with increase in wind speed. So 18knots is a lot gentler than 22 knots.
So if OP is considering buying a sail boat. I would recommend about 20 ft perhaps 25ft but do buy a GRP boat with ballasted keel and self draining cockpit. It should have decent self righting capabilities. ol'will

Adding to ol' will's excellent summary of the effects of wind speed, serious dinghy cruisers manage wind of 20 knots quite regularly in unballasted centreboard craft. That said, cruising dinghies tend to be loaded with heavier gear than the average racing dinghy (anchor, provisions, spare parts, camping equipment, oars, and even outboard motors on occasion). The most important factor in avoiding capsize is the ability to reduce sail and choose a sail combination suitable for the conditions. This is also true for ballasted cruising yachts. There is a saying that "boats are stronger than crews". The goal of the cruising sailor is to make passage from one port to another, over distances small or great, and to arrive with one's vessel intact and the crew safe and happy. There are ways to do this in most sailing vessels in +20 knots of wind.

 

[MikeCC]

Unless you are going to so some offshore sailing or enter races where a capsize rating is required, probably not a big issue.

Capsizes are very rare in coastal sailing and you would be unfortunate to end up in a combination of circumstances leading to that.

Ballast ratio can also help give an idea of what might be a more stable boat in normal sailing. You'll also find comments here and elsewhere about the handling characteristics of many different boats.

Get out on as many different boats as is decently possible and see what you like. Go club racing to get a feel for when boats are being pushed a little bit.

 

[Stemar]

No moderately seaworthy monohull yacht is going to fall over under the effects of the wind alone. It will take a breaking wave bigger than the beam of the boat hitting you beam on to do that. That's not going to happen in any conditions you're going to want to be out in. Honourable exception made for racers who push things too far and trip over their spinnakers. As the wind builds up, the boat heels, spilling the wind, so reducing its effect. Uncomfortable and scary if taken to excess, but hang on and things will sort themselves out so you can reduce sail.

Cats and tris don't heel, so they don't benefit from the wind spilling, and over they go. Quite hard to do in a well-found cruising cat, but racers manage it regularly. When you see them flying a hull, they're on the ragged edge. Too big a gust or a half-second slow easing the sheet and over they go. They're also more stable upside down than the right way up

 

[jwilson]

Sorry Boatkeep, your article is simplistic, and in some places plain wrong. Only scanned quickly, but you say:- "If your boat is capsized in moving water, you will have less time to make sure you account for everyone and stop your boat from floating away. "

This is trash. Capsized or inverted boat and person in water move with the current at the same speed, except that a light dinghy at 90 degrees may have slightly more windage and go downwind faster. Current is irrelevant.

Also, if I'd never sailed dinghies in more than 20 knots I would have not enjoyed dinghy sailing nearly as much. It takes that to get many older planing dinghy designs planing really well.

 

[Pirx]

'boatkeep' is a spammer. He doesn't know anything about anything, just trying to push useless products. The important message from his post is "never buy anything from boatkeep"

 

[Dellquay13]

'boatkeep' is a spammer. He doesn't know anything about anything, just trying to push useless products. The important message from his post is "never buy anything from boatkeep"

boatkeep has dredged up a long dead thread to push his own article, and we all fell for his ruse