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Old 08-06-2012, 09:36   #136
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Re: Capsize Ratio's

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Originally Posted by sneuman View Post
Does it always deduct? I think it matters where the stuff is - yes, a lot of it is going to be above the waterline, but at least fuel/fresh water tanks often are below the waterline (my 90-gallon H20 is) and that, in theory, ought to increase AVS, no?
The HR curve is give FULL LOAD. I assume this implies full water and fuel tanks.

Yours is a good question. I only design small things hence my experience with AVS is limited to playing around with exceel spredasheets that calculate AVS. I would have to go into them and have a good look at the formulae.

My ad hoc guess is that it is NOT the waterline that counts but rather where the weight is placed relative to some kind of 'center'. I would guess this center may be located below (?) the waterplane as well as it can be a moving one.

So, to sum up, I would suspect FULL fuel and water tanks, located in deep keel (not in the canoe body) would help in achieving higher numbers. Tanks located in canoe body may add to stability initially but they may deduct from the AVS number. (These are my guesses, the proof would be in running a specific design thru the calculations and watching the outcome).

The above applies to some heavy equipment - we can move our anchors and chain to our bilges - but they will add to AVS only if it is a deep keel bilge - wineglass, etc.. Otherwise we might be adding to the boats stiffness (initial stability) but at the same time we could be deducting from the AVS.

Then again we have to realistically imagine how likely our tanks are to remain full in any extended passage. (We can fill an empty water tank with sea water but only if it is a split tank, we cannot fill en empty fuel tank).

What do you think?

b.
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Old 08-06-2012, 09:43   #137
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Re: Capsize Ratio's

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Originally Posted by sneuman View Post
Either way, the result is still the same: Mom & pop dial it back, thus diminishing the advantages of the faster boat.
In a way True, but in our condition, we're both Ex-Racers, Mom and Pop,
just the two of us, and when we want to, we can pull out all the stops and kick her in the ass and get where we want fast..
and even thou we're in our 60s, we can still make a "Fast Passage" if need be.

But would I ever advise anyone without a racing background to follow in our wake,
Dont think I would..

So again, the delima rises, after the choice of the boat has been made, are you the person that can handle the choice..
We know all sailing boats are NOT created equal, why should we assume all people are....
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Old 08-06-2012, 09:51   #138
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Re: Capsize Ratio's

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Originally Posted by sneuman View Post
Either way, the result is the same: Mom & pop dial it back, thus diminishing the advantages of the faster boat.
That is only true in what regard going upwind in nasty weather. In those conditions if you cannot or want to have the bigger pounding given by a superior speed, you can go at the speed of an heavy boat....but downwind and at any other sailing position or even upwind with good weather and less strong winds a lighter boat will be as comfortable and much more faster.
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Old 08-06-2012, 09:53   #139
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Re: Capsize Ratio's

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Originally Posted by Randyonr3 View Post
this issue of "Pounding" in a light desplacement boat is a by-product of its speed and not its design or weight..
its like compairing a "bunt" of a baseball compaired to a hard hit.. the bunt will deliver a thud where a hard hit will deliver a crack.. same ball, same bat, but the speed of the hit will change..
the same is true with a fast boat compared to a full desplacement heavy boat..
the by product of the faster speed will cause the pounding as the speed increeses over the water.. A full keel heavyweight wont pound because it wont go fast enough to deliver the noise....
our boat, weighing in at 24k will pound going to weather at 10 to 12 knots, but if we back it off to a speed of 5 or 6, she calmly rides the waves like a full keel heavyweight..
The difference is that I can turn her off the crest about 4 or 5 degrees and the pounding stops.. and the speed goes up..
If you're sailing the boat to the point its pounding, just turn off a few degrees, its better on you and the boat..
+1, slow her up to 10 or 20% faster than the heavyweight or bare off 5 or 10* so you are still sailing closer to the true wind than the heavyweight. Either will comfort the ride.
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Old 08-06-2012, 09:55   #140
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Re: Capsize Ratio's

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Originally Posted by Polux View Post
That's what I said you have implied

Can't you see it does not make sense?

It is common knowledge, based in many years of bluewater experience that Halberg-Rassy are very good and safe bluewater boats. I don't remember of a single one to have capsized and these boats are used extensively offshore.

Do you really think that someone that is going offshore with an Halberg-Rassy is asking for trouble?

...
+1!

I believe boats get into trouble offshore due to:

- skipper's inexperience,
- human error,
- equipment failure,
- lack of adequate maintenance,
- etc.,

way before they have any opportunity to present ;-) their AVS!

b.
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Old 08-06-2012, 09:57   #141
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Re: Capsize Ratio's

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Originally Posted by Randyonr3 View Post
In a way True, but in our condition, we're both Ex-Racers, Mom and Pop,
just the two of us, and when we want to, we can pull out all the stops and kick her in the ass and get where we want fast..
and even thou we're in our 60s, we can still make a "Fast Passage" if need be.

But would I ever advise anyone without a racing background to follow in our wake,
Dont think I would..

So again, the delima rises, after the choice of the boat has been made, are you the person that can handle the choice..
We know all sailing boats are NOT created equal, why should we assume all people are....
I'd say, then, that you and your better half represent one of those outliers I was talking about.

I'm also guessing that pulling out all the stops like you're talking about tends to be relatively short passages. Double-handed for much more than a few days -- even for a couple of hands that are relatively fit in their 40s -- and the fatigue factor starts to rapidly grow. Standing 12 hours of helm and at least part of the other 12 as deck crew starts to wear after a bit (especially for someone like me who finds it very difficult to sleep in that situation). That tens to even things out - the slow one now will later be fast, to quote a Biblical passage.

Again, I point to the annual Carib 1500 as well as my own experience on this.
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Old 08-06-2012, 10:33   #142
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Re: Capsize Ratio's

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Originally Posted by barnakiel View Post
The HR curve is give FULL LOAD. I assume this implies full water and fuel tanks.

Yours is a good question. I only design small things hence my experience with AVS is limited to playing around with exceel spredasheets that calculate AVS. I would have to go into them and have a good look at the formulae.

My ad hoc guess is that it is NOT the waterline that counts but rather where the weight is placed relative to some kind of 'center'. I would guess this center may be located below (?) the waterplane as well as it can be a moving one.

So, to sum up, I would suspect FULL fuel and water tanks, located in deep keel (not in the canoe body) would help in achieving higher numbers. Tanks located in canoe body may add to stability initially but they may deduct from the AVS number. (These are my guesses, the proof would be in running a specific design thru the calculations and watching the outcome).

The above applies to some heavy equipment - we can move our anchors and chain to our bilges - but they will add to AVS only if it is a deep keel bilge - wineglass, etc.. Otherwise we might be adding to the boats stiffness (initial stability) but at the same time we could be deducting from the AVS.

Then again we have to realistically imagine how likely our tanks are to remain full in any extended passage. (We can fill an empty water tank with sea water but only if it is a split tank, we cannot fill en empty fuel tank).

What do you think?

b.
I have saw many stability curves of the same boat in light condition and loaded condition.

On loaded condition the boat positive curve is bigger and the boat will have more stability but the AVS decreases slightly. The boat will resist more to a capsize loaded than unloaded. The max load is determined by the designer and one of the major points to establish it is a not bigger degradation of the AVS value.

The differences in AVS between a loaded boat and an empty one are normally smaller or equal to 5º. But as I have said, the AVS is not all because the loaded boat will have more stability and will be more difficult to capsize.
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Old 08-06-2012, 11:12   #143
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Quote:
Originally Posted by sneuman

I'd say, then, that you and your better half represent one of those outliers I was talking about.

I'm also guessing that pulling out all the stops like you're talking about tends to be relatively short passages. Double-handed for much more than a few days -- even for a couple of hands that are relatively fit in their 40s -- and the fatigue factor starts to rapidly grow. Standing 12 hours of helm and at least part of the other 12 as deck crew starts to wear after a bit (especially for someone like me who finds it very difficult to sleep in that situation). That tens to even things out - the slow one now will later be fast, to quote a Biblical passage.

Again, I point to the annual Carib 1500 as well as my own experience on this.
I don't understand the premise here. Why are faster boats more work?

I've done two 700 mile-ish offshore passages. One on a westsail 32 and one on an open 60 (but in cruising mode, not racing). Neither was physically demanding, really, other than raising the main on the open 60.

I was more worn out after a week of travel on the slower boat than four days on the faster boat.

And for me, tweaking a line every half an hour to keep the boat going isn't hard work, it helps kill the time. I guess some people might wait to charge a reef longer than others, but that is more about how much thought and cash has been put into sail handling equipment, not hull design.
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Old 08-06-2012, 13:32   #144
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Re: Capsize Ratio's

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Originally Posted by cwyckham View Post
And for me, tweaking a line every half an hour to keep the boat going isn't hard work, it helps kill the time. I guess some people might wait to charge a reef longer than others, but that is more about how much thought and cash has been put into sail handling equipment, not hull design.
But we shoudn't talk here about sailing in moderate weather (remember op capsize ratio thou we have slipped away some) instead of circumstances where capsize is a possibility. In a weather like that it's no more tweaking a line every now and then and it comes a matter of survival, anyway if you happen to be in a boat compromised with it's sea keeping abilities. I love hard weather but I don't have any desire to be in gale short handed several day's in a boat that doesn't tend itself a minute or two so I can have leak and get a cup coffee..
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Old 08-06-2012, 21:03   #145
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Re: Capsize Ratio's

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But we shoudn't talk here about sailing in moderate weather (remember op capsize ratio thou we have slipped away some) instead of circumstances where capsize is a possibility. In a weather like that it's no more tweaking a line every now and then and it comes a matter of survival, anyway if you happen to be in a boat compromised with it's sea keeping abilities. I love hard weather but I don't have any desire to be in gale short handed several day's in a boat that doesn't tend itself a minute or two so I can have leak and get a cup coffee..
There isn't anybody here who would disagree. The boat must always tend itself for a lot longer than a minute or two.

I did hit heavy weather in both boats. Anemometer was broken on both, so I can only estimate winds in the high 20s in the Open 60 and high 30s in the Westsail 32.

The Westsail 32 was probably overpcanvassed and her windvane may have had a line wrapped wrong, partially compromising its power. We were running at about 4-7 knots. It was a very uncomfortable night and we worked hard at the tiller "helping" the vane when she started to round up beam on to the breaking waves. We had to be ready at all times. It sucked.

However, I'm sure that if we had set the boat up better, we would have found a way to work less. Even so, we would have been beat up and drenched (cockpit was repeatedly filled).

We probably had less wind in the Open 60, but were still surrounded by thunderstorms as a violent cold front passed overhead. We were down to just the triple reefed main and no foresail. Windspeed is hard to judge as we were running at 15-22 knots, so apparent wind fools you easily. We were happy and underworked, enjoying the ride and chatting amongst ourselves instead of battling the boat and the weather. The autopilot was more than up to the job.

Now, the conditions were similar but not identical, and I truly believe either boat can weather a huricane if her crew know what they are doing (in fact, both types have). I just really, really disagree that a fast, racing inspired boat is somehow less comfortable or more work. If anything, it's often the opposite because it will have a good sail handling setup and will reduce passage times.
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Old 12-06-2012, 16:25   #146
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Re: Capsize Ratio's

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Originally Posted by cwyckham View Post
There isn't anybody here who would disagree. The boat must always tend itself for a lot longer than a minute or two.

I did hit heavy weather in both boats. Anemometer was broken on both, so I can only estimate winds in the high 20s in the Open 60 and high 30s in the Westsail 32.

The Westsail 32 was probably overpcanvassed and her windvane may have had a line wrapped wrong, partially compromising its power. We were running at about 4-7 knots. It was a very uncomfortable night and we worked hard at the tiller "helping" the vane when she started to round up beam on to the breaking waves. We had to be ready at all times. It sucked.

However, I'm sure that if we had set the boat up better, we would have found a way to work less. Even so, we would have been beat up and drenched (cockpit was repeatedly filled).

We probably had less wind in the Open 60, but were still surrounded by thunderstorms as a violent cold front passed overhead. We were down to just the triple reefed main and no foresail. Windspeed is hard to judge as we were running at 15-22 knots, so apparent wind fools you easily. We were happy and underworked, enjoying the ride and chatting amongst ourselves instead of battling the boat and the weather. The autopilot was more than up to the job.

Now, the conditions were similar but not identical, and I truly believe either boat can weather a huricane if her crew know what they are doing (in fact, both types have). I just really, really disagree that a fast, racing inspired boat is somehow less comfortable or more work. If anything, it's often the opposite because it will have a good sail handling setup and will reduce passage times.
So in essence you are saying that a boat twice as long as another boat is more comfortable (especially if the shorter boat is over-canvassed and not set up right)

duh

sorry, forgot the smiley
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Old 12-06-2012, 17:23   #147
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Re: Capsize Ratio's

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So in essence you are saying that a boat twice as long as another boat is more comfortable (especially if the shorter boat is over-canvassed and not set up right)

duh

sorry, forgot the smiley
Actually, yeah, I guess that's about right, isn't it. All this stuff about capsize ratios and new versus old designs gets pretty well swamped by a little bit of good seamanship and the actual length of the boat. Some designs are better for some things, but you shouldn't assume that a racing boat is hard to handle or uncomfortable or that a heavy cruiser's going to be comfortable no matter what.
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Old 12-06-2012, 18:49   #148
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Re: Capsize Ratio's

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Originally Posted by cwyckham View Post
Actually, yeah, I guess that's about right, isn't it. All this stuff about capsize ratios and new versus old designs gets pretty well swamped by a little bit of good seamanship and the actual length of the boat. Some designs are better for some things, but you shouldn't assume that a racing boat is hard to handle or uncomfortable or that a heavy cruiser's going to be comfortable no matter what.
yip, the Queen Mary (a cruiser) is probably going to be more comfortable than the open 60 you were on....
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Old 12-06-2012, 21:34   #149
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Re: Capsize Ratio's

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Actually, yeah, I guess that's about right, isn't it. All this stuff about capsize ratios and new versus old designs gets pretty well swamped by a little bit of good seamanship and the actual length of the boat.
Are you saying the folks that got rolled during the Fastnet in 1979 didn't exhibit very good seamanship?
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Old 12-06-2012, 21:35   #150
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Re: Capsize Ratio's

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Are you saying the folks that got rolled during the Fastnet in 1979 didn't exhibit very good seamanship?
No, No...

He's saying they should have had bigger boats
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