jimi
Well-Known Member
How is this calculated?
STIX Ratio
- Thread starter jimi
- Start date
ChrisE
Well-Known Member
Well, you take your good and take it away from your bad. If your good exceed your bad then you go to heaven, if not then off to hell via Stix.
Yes, I know that it is spelt Styx but haven't a clue abt Stix.
Yes, I know that it is spelt Styx but haven't a clue abt Stix.
Lakesailor
Well-Known Member
Probably
Calculation
STIX is based on a variation of the Advance/Decline Ratio:
The STIX is a 21-period (i.e., 9%) exponential moving average of the above A/D Ratio:
Calculation
STIX is based on a variation of the Advance/Decline Ratio:
The STIX is a 21-period (i.e., 9%) exponential moving average of the above A/D Ratio:
BlueSkyNick
Well-Known Member
STIX is a short-term trading oscillator that was published in The Polymetric Report. It compares the amount of volume flowing into advancing and declining stocks.
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Interpretation
According to The Polymetric Report:
STIX usually ranges between +42 and +58.
If STIX gets as low as 45, the market is almost always a buy, except in a raging bear market.
The market is fairly overbought if STIX rises to 56; and except in a new bull market, it's wise to sell if STIX should go over 58.
Traders and investors should modify these rough rules to suit their own objectives.
In normal markets, STIX rarely gets as high as 56 or as low as 45, so rigid use of these rules of thumb would keep you inactive most of the time. For active accounts, the rules might be made much less stringent.
--------------------------------------------------------------------------------
Interpretation
According to The Polymetric Report:
STIX usually ranges between +42 and +58.
If STIX gets as low as 45, the market is almost always a buy, except in a raging bear market.
The market is fairly overbought if STIX rises to 56; and except in a new bull market, it's wise to sell if STIX should go over 58.
Traders and investors should modify these rough rules to suit their own objectives.
In normal markets, STIX rarely gets as high as 56 or as low as 45, so rigid use of these rules of thumb would keep you inactive most of the time. For active accounts, the rules might be made much less stringent.
BlueSkyNick
Well-Known Member
or is THIS what you were looking for? its a pdf file so can't cut and paste here.
ChrisE
Well-Known Member
Nick,
I think that this page describes what it is but not how it is calaculated. Here is an American boat designer's (John Holtrop) view on the subject. Still means booger all to me /forums/images/graemlins/smile.gif
ROLL PERIOD (T) = 2*PI*(I/(82.43*lwl*(.82*beam)^3))^.5
The roll period is based on the moment of inertia. The term ".82*beam" has been substituted for the waterline beam due to lack of data. Using ".82" results in a close match for the few boats with measured periods, but more data is needed (If you have measured roll data, email it to me and I’ll include it in my data base). Simply stated, a sailboat’s roll period, in seconds, is inversely proportional to its stability. Unstable boats have long periods, stable boats have short periods. The roll period is very easy to determine, you simply grab a shroud and push / pull until the boat is rocking over a few degrees. Then count the number of full cycles in one minute, and divide into 60. The general rule of thumb is that boats with periods less than 4 seconds are stiff and periods greater than 8 seconds are tender. The template value of 4.05 is near the stiff end of the range, indicating good static stability.
STABILITY INDEX = T / (beam*.3048)
This is another empirical term relating period and beam to stability. Values less than 1.0 are considered stiff. Values greater than 1.5 are considered tender. I like this technique because its simple, and includes the hull form, the center of gravity, and the roll moment of inertia, all in one easy to use package. The template boat again leans towards the stiff side, with a value of 1.1.
In summary, all cruising boats use a combination of CG control, form stability, and displacement to determine static stability. This value is then used to size the sail area so that a generous amount of capsize resistance exists under full sail and moderate wind conditions. This is a delicate part of a boat design. Too much sail area will require early reefing or high heel angles, to little and the boat will be a slug in light air. Dynamic stability is also important and closely related to the moment of inertia. A high moment of inertia helps survival in heavy weather. The roll period of a boat blends elements of static and dynamic stability and can be useful when comparing potential cruising boats.
While many other factors must go into selecting your ideal cruising boat, following the basic Stability Template is a good first step. The designs from these nine world class cruising boat designers have logged a great many sea miles. If your boat is similar, you can have confidence that it has at least some of the right stuff with regard to static and dynamic stability.
I think that this page describes what it is but not how it is calaculated. Here is an American boat designer's (John Holtrop) view on the subject. Still means booger all to me /forums/images/graemlins/smile.gif
ROLL PERIOD (T) = 2*PI*(I/(82.43*lwl*(.82*beam)^3))^.5
The roll period is based on the moment of inertia. The term ".82*beam" has been substituted for the waterline beam due to lack of data. Using ".82" results in a close match for the few boats with measured periods, but more data is needed (If you have measured roll data, email it to me and I’ll include it in my data base). Simply stated, a sailboat’s roll period, in seconds, is inversely proportional to its stability. Unstable boats have long periods, stable boats have short periods. The roll period is very easy to determine, you simply grab a shroud and push / pull until the boat is rocking over a few degrees. Then count the number of full cycles in one minute, and divide into 60. The general rule of thumb is that boats with periods less than 4 seconds are stiff and periods greater than 8 seconds are tender. The template value of 4.05 is near the stiff end of the range, indicating good static stability.
STABILITY INDEX = T / (beam*.3048)
This is another empirical term relating period and beam to stability. Values less than 1.0 are considered stiff. Values greater than 1.5 are considered tender. I like this technique because its simple, and includes the hull form, the center of gravity, and the roll moment of inertia, all in one easy to use package. The template boat again leans towards the stiff side, with a value of 1.1.
In summary, all cruising boats use a combination of CG control, form stability, and displacement to determine static stability. This value is then used to size the sail area so that a generous amount of capsize resistance exists under full sail and moderate wind conditions. This is a delicate part of a boat design. Too much sail area will require early reefing or high heel angles, to little and the boat will be a slug in light air. Dynamic stability is also important and closely related to the moment of inertia. A high moment of inertia helps survival in heavy weather. The roll period of a boat blends elements of static and dynamic stability and can be useful when comparing potential cruising boats.
While many other factors must go into selecting your ideal cruising boat, following the basic Stability Template is a good first step. The designs from these nine world class cruising boat designers have logged a great many sea miles. If your boat is similar, you can have confidence that it has at least some of the right stuff with regard to static and dynamic stability.
longjohnsadler
Well-Known Member
Presumably Jimi's trying to work out if he's 'stiff' or 'tender'.
BlueSkyNick
Well-Known Member
that's very interesting Chris, the only problem is that you are confusing me with somebody who gives a shyt !!
Jimi is obviously concerned about it, having been tossed about on his way to Cornwall. /forums/images/graemlins/smile.gif
Jimi is obviously concerned about it, having been tossed about on his way to Cornwall. /forums/images/graemlins/smile.gif
longjohnsadler
Well-Known Member
Looked over the Southerlys on the pontoon at SIBS.
No idea how they sail but had a nice feel to them - qiute distinctive.
No idea how they sail but had a nice feel to them - qiute distinctive.
ChrisE
Well-Known Member
Sorry, Nick, clearly the concerns of a Bennie owner /forums/images/graemlins/smile.gif
Colin_S
Well-Known Member
In my house it's pretty simple. If there's 24 in the pack we get 6 each but sometimes my daughter doesn't want any so the other 3 of us get 8 each. Sometimes not everyone wants 8 so maybe the dog gets some. Occasionally they don't all get used in one sitting so we may only have 4 each which leaves a few for the next day to confuse the ratio. Worse still is if we have a visitor as the sticks do not lend theirselves to fractions.
Do you break yours with your fingers before dipping or do you stick the soggy bitten end in the dip?
Do you break yours with your fingers before dipping or do you stick the soggy bitten end in the dip?
tome
Well-Known Member
It's a discrete method of measuring ladies up for trousers, but the detail belongs in the Lounge.
Lakesailor
Well-Known Member
That would be the "minus the wet bit" method then? /forums/images/graemlins/grin.gif
tome
Well-Known Member
Yes, take the wet from the dry and add 3 inches for turnups.
nicho
RIP
He gets tender after he's been stiff.....!!
danera
Well-Known Member
Basically it is intended as a guide to the seaworthiness of a vessel - a good explanation & worked example is contained in the book "Principles of Yacht Design". It's used by the RORC as entry requirements for offshore races.
The formula is dependant on length & seven? other multiplying factors which default to 1.0. These are horribly complex & consider stuff like the heel angle at which openings will flood, the weight of water in sails holding the boat down after being rolled, etc. You also get 5 points for being unsinkable! A spreadsheet for working it out is here http://boatdesign.net/forums/showthread.php?t=7572 but I can't get it to work.
The formula is dependant on length & seven? other multiplying factors which default to 1.0. These are horribly complex & consider stuff like the heel angle at which openings will flood, the weight of water in sails holding the boat down after being rolled, etc. You also get 5 points for being unsinkable! A spreadsheet for working it out is here http://boatdesign.net/forums/showthread.php?t=7572 but I can't get it to work.
Peppermint
Well-Known Member
Re: Thats an interesting question.
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