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#288301 - 02/07/18 04:09 PM Re: Portsmouth or SCHRS ??? [Re: Ventucky Red]  
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Mark Schneider Offline
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The sailor is responsible for his rating.... If the RC made a mistake... you don't get to keep the trophy.... you are supposed to report it.... and correct the scoresheet.
Doesn't matter if its portsmouth, PHRF SCHRS etc. etc.

So, you make changes to your boat... you are responsible for correcting the rating if its warranted. You have to know your proper rating for the modifications you made.

Same principle in SCHRS.... the sailor is responsible to know his proper rating.

For your example... There are lots of options... He could get the measurement guidelines.... measure his own sail and calculate his rating. That is his measurement rating!

If the OA... says... Harry, you are blind... you can't read the rule... get somebody else to do it... Presto he has a third party rating.

The OA could say... Harry.... just get the numbers from the sailmaker.... the sails may have shrunk over time... but hey... its measured by a pro... if it matters to you get them remeasured. . So, he calls his sailmaker.... gets the numbers for his his non stock sails.... opens the calculator and crunches a new rating...

If he can't find the sailmaker... he can get any sailmaker to actually measure the sail using the SCHRS rules ... get a sail measurement certificate, crunch the numbers in the calculator and he has a measurement rating based on an even more authoritative measurement.

If the OA requires it.... (big deal race.....) He can go to a US SAiling /World Sailing sanctioned measurer and get an Official SCHRS measurement certificate.

The sail foot is 150 cm...... It doesn't change based on who is measuring it... What is changing is the level of authority which reports the rating to the OA.

This is no different then Portsmouth... you were supposed to report all modifications made to the one design boat that Portsmouth wanted. Calculate your rating and register your boat using it's proper rating. It doesn't get you off the hook if the scorekeeper did it properly or if he made an error... it was always your responsibility to enter with the proper rating and check it.

Remember, in Portsmouth the adjustments table was not allowed for important races like Area Qualifier regattas because the adjustments were just best guesses.

The OA sets the rules and level of compliance... the sailor meets the standard or not.
Can you be lazy and half butt it... sure...
The good news is that your decision only effects your fleet and racers... The decision on ratings does not effect anyone outside your fleet. the data are not collected so ... YMMV.


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#288304 - 02/07/18 06:18 PM Re: Portsmouth or SCHRS ??? [Re: Mark Schneider]  
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Originally Posted by Mark Schneider
The sailor is responsible for his rating.... If the RC made a mistake... you don't get to keep the trophy.... you are supposed to report it.... and correct the scoresheet.
Doesn't matter if its portsmouth, PHRF SCHRS etc. etc.

So, you make changes to your boat... you are responsible for correcting the rating if its warranted. You have to know your proper rating for the modifications you made.



In the case noted above we have many once a year racers show up... I am not about to tell them no you can't race after they drove 100 plus miles, paid for a hotel, and an entry fee..

With DP-N we can fix that right then and there with the published modifiers... I am not saying they are fair or accurate, but....... With SCHRS, not such an easy remedy... Joe Blow sailor may not have an interest getting all the "T's" crossed and "I's" dotted with being SCHRS compliant. I have directed a few people to the web site and told them to get the measurements form their sail makers so we can come up with a number..

Put yourself in my position.. how would you handle this situation.... a.) Tell them tough luck rules or rules you can't race b.) tell them those are non stock sails and there is a 5% penalty until you can provide a measurement. c.) Stick with DP-N.


Last edited by Ventucky Red; 02/07/18 06:24 PM.
#288309 - 02/07/18 11:21 PM Re: Portsmouth or SCHRS ??? [Re: Mark Schneider]  
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Just spell out the rules in your NOR.
Handicap racing is conducted using SCHRS. Each skipper is responsible for registering with their proper rating. (reference table on web site)

If the owner cannot use the stock table or calculate their custom rating using the web site and available resources. The OA will generate a rating for the weekend using best available information and their judgement.

The OA is NOT measuring any equipment.

Designate somebody who understands the ratings process to serve on a protest committee in the event that you get a ratings protest from a competitor This is NOT the person who generates the weekend rating. . Let your judge / PC chair know the standards. They may want to spell out restrictions on equipment protests.... (that is a judge call there)

The stakes for the event are low and so you don't need high standards with certified rating certificates.... Its just overkill...

So for your situation.. by all means... Plan B
I think you have the conversation with them...
Non stock sails... OK... same size?.... or did you go bigger?

Same size different shape? ... use the stock rating.. Bigger... go with plan B. Nobody wants to cheat... they want to race once a year and enjoy the event. They certainly don't want to feel like they are putting one over on their friends in the fleet. So tell them... we try to be fair AND we lean to the fleet side of fair for your spitball rating . We are not measuring YOUR STUFF... They choose to register with that rating, get their stuff measured or go home. .... Tell them how it works... if they care enough... next time... they will bring a number and perhaps some math on a piece of paper. If you really want to accommodate them... allow them to submit a measurement rating before Sunday racing starts.... (ask the judge about this one)

If they are into the competition and boat design optimization thing... they will do the work themselves and present a number. They will have had plenty of time to get their rating sorted out when they follow your NOR rules.

I go into these things believing that people want a fair game with minimal stress. In the SCHRS world... the responsibility has shifted to the owner here. Your OA is just backstopping them so they can go racing.

I will try to get together with Will and create some NOR boilerplate that you can use.

Mark




Last edited by Mark Schneider; 02/07/18 11:35 PM.

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#288310 - 02/08/18 11:26 AM Re: Portsmouth or SCHRS ??? [Re: Ventucky Red]  
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Originally Posted by Ventucky Red
Originally Posted by Mark Schneider
The sailor is responsible for his rating.... If the RC made a mistake... you don't get to keep the trophy.... you are supposed to report it.... and correct the scoresheet.
Doesn't matter if its portsmouth, PHRF SCHRS etc. etc.

So, you make changes to your boat... you are responsible for correcting the rating if its warranted. You have to know your proper rating for the modifications you made.



In the case noted above we have many once a year racers show up... I am not about to tell them no you can't race after they drove 100 plus miles, paid for a hotel, and an entry fee..

With DP-N we can fix that right then and there with the published modifiers... I am not saying they are fair or accurate, but....... With SCHRS, not such an easy remedy... Joe Blow sailor may not have an interest getting all the "T's" crossed and "I's" dotted with being SCHRS compliant. I have directed a few people to the web site and told them to get the measurements form their sail makers so we can come up with a number..

Put yourself in my position.. how would you handle this situation.... a.) Tell them tough luck rules or rules you can't race b.) tell them those are non stock sails and there is a 5% penalty until you can provide a measurement. c.) Stick with DP-N.



Frankly, I would be realistic and come up with a reasonable number on the fly for a local event that doesn't have any regional or national consequence. Being a hard butt exclusionist does nothing but hasten the decline of our sport. I would consider applying the relative DPN percentage hit for whatever modification counted to the SCHRS number. It might take a little math but probably gets them in the ballpark. I would also probably err a little on the conservative side with a harsher rating (but do it with some specific math so I have some consistency and people can blame the formula instead of me). If they want a better rating under SCHRS, I would explain that they would be welcome to jump through the SCHRS hoop to prove out their number but above all, communicate how you derived that number and be open about it - let 'em race.


Jake Kohl
#288312 - 02/08/18 05:26 PM Re: Portsmouth or SCHRS ??? [Re: Mark Schneider]  
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Home is where the harness is.....
So, I feel bad that Mark has been in here doing all the heavy lifting! I'm the technical rep for SCHRS in the US and I work with the World Counsel and Technical Committee on a variety of things; data review, areas of concern, changes to class rules, etc.

Mark has done a great job explaining how SCHRS works! I think one word that has been missed however (it was alluded to) is "Corinthian". The point is this, any class, any boat, someone can go out there and cheat. Unless you measure and inspect every boat on the water at every single race, someone could be breaking the rules, but do we do that? No, because it wouldn't make sense! There are a number of ways to say it, but, "is the juice worth the squeeze" is probably the one that most people will understand.

First and foremost, SCHRS will meet the needs of likely 95%+ of the sailors our there; guys like me who sail a Frankenboat are not in the majority. The semantics of "class legal", "stock" and "one design" could be argued for ages here, but... is the juice worth the squeeze? The point is, SCHRS states, "These rules are intended to allow a wide range of catamarans to race together. Boats from established classes with class rules must comply with their class rules and can use the ratings on the SCHRS list."

The other point in the SCHRS rules is this, "In case of doubt about any part of these regulations, the meaning, i.e. the spirit of the regulations governs." As such, lets just agree that, class legal is class legal. If you could take your H16, F18, A-cat, P19, N6.0, etc. etc. etc. to a nationals and race it without fear of being protested, you're good.

With that out of the way, 95% of the work is done! wink

Now, to the last 5% (that's a total SWAG guess, so don't hold me to it!). As Mark stated, the onus for how races are run is on the organizers. I might get myself shot by Jean-Claude for saying this, but... If the OA wants to use SCHRS, but allow sailors to measure their own boat, that is up to them. Again, Corinthian. As Mark said earlier, if someone shows up with a rating sheet that looks off.... like, a 20' boat listed at 4.9m, there's a problem. I would suggest that in cases where the OA wants to use SCHRS, but not require a full measurement certificate, the boat owner should provide not just a number, but a print out of their rating calculator spreadsheet with their entry. That said, boat owners should not expect that self developed rating to hold up for a larger race, or for SCHRS to approve it, because they won't.

I COMPLETELY DISAGREE that the OA's should throw ratings/modifiers out there on the fly... One of my biggest complaints (some people here will know what I'm talking about and this "major" race has yet to fix the problem...) is poorly developed NoR/SIs. Write the rules down clearly and unambiguously and publish them well in advance. If the OA says, "bring your own certificate", make sure the sailors know, fill out the #$@% spreadsheet, print a copy and bring it with you! Most of the people here aren't building their own hulls, they are taking an existing platform and changing the sails. There are >250 boats in the SCHRS table, surely almost everyone here can go to the table, take the published values and then fill in the blanks for sail measurements on the sail measurement form.

Although allowing/accepting self measured certificates induces a level of risk and reduces the integrity of the system, I think this is a more appropriate way to go than as Mark said, "PHRF'ing the number". If a racer doesn't like the measurement, they can go verify it themselves, but the rating formula and the integrity of the data that developed it remains the same. The other option is to use WAY outdated ratings from US PN and apply what are nothing more than WAG (not SWAG) modifiers. I'd prefer to put faith in people to honestly measure their boats than that.....

#288313 - 02/08/18 06:11 PM Re: Portsmouth or SCHRS ??? [Re: Mark Schneider]  
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Specific to the FL300 and the Buoy 44 boat. That was my boat and the experience of developing and racing it gave me a lot of valuable insight into both sides of this discussion.

First, the boat was officially measured for 2016 at the Islander just prior to the start. The forms were signed by Carla and submitted to SCHRS; I have the signed certificate and can assure you that it was not the same rating as a stock Tornado.

For 2017, I purchased a new spinnaker; besides the addition of rudder T-foils (does not affect rating on a boat with straight boards), the rest of the boat remained the same. The new sail was measured and a new ratings request officially submitted. Again, I have a signed copy of the certificate issued by SCHRS.

Overall, SCHRS did a very good job of rating this configuration relative to the N20c. There were times when each platform was in a more favorable range than the other, but you see that with any boat/race. In the end however, the race times supported the ratings for both platforms. We had several break downs, so we didn't perform as well in 2017, but I am MUCH happier that we raced under SCHRS instead of Portsmouth.

With regards to Portsmouth; the rating, once the modifiers were applied, resulted in the modified Tornado owing the N20c time! So, a boat designed in 1962 that is narrower, shorter and has pizza pans for dagger boards rates faster than a modern wave piercer with more volume, sail area and lifting boards??? Although the T did weigh less, that isn't enough to overcome the advantages that the N20c has in pure speed. This kind of handicap is the reason that we didn't run the boat in that configuration in the GT300; US PN over penalized the modifications and has not updated the F-18 to address development in that class. Note that there is still NOT a published rating for the N20c under US PN and that highlights one of its major problems; lack of support/updates over the past decade.

In that same line of thought, US PN relies on race data to develop ratings, once a new boat is released, it would take a year or more to come up with a somewhat "reliable" rating. SCHRS can rate it before it hits the water with a pretty high degree of certainty AND as race data is analyzed, make adjustments as necessary when anomalies are found. This is a good example of how SCHRS is handling the adoption of deck sweepers on the F-18, or foiling (among other changes) in the A-cats.

In the case of the changes to the F-18, the recent opinion of the SCHRS world council was to be careful to not make a decision that hurt the integrity of the system. In 2018, like every other year, data will be collected, analyzed and anomalies identified; the F-18 (along with a couple of others) will be under the microscope to determine if/how overall fleet performance was affected by the adoption of the new mainsail configuration. The data used for that analysis is from a much MUCH broader pool than is available in just the US. As such, the statistical significance is much higher.

SCHRS leadership is committed to ensuring the integrity of the system. A lot of work goes in to collecting race data, looking for problems and making sure that the system remains viable into the future.

If you have a few minutes and are curious, go read the annual world council reports available here: http://www.schrs.com/inc/SCHRS_Review_20180129.pdf

Previous reports are located on this page: http://www.schrs.com/news.php

#288314 - 02/08/18 07:35 PM Re: Portsmouth or SCHRS ??? [Re: Will_R]  
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Originally Posted by Will_R


I COMPLETELY DISAGREE that the OA's should throw ratings/modifiers out there on the fly...


The guy that does one, maybe two regattas a year, is going to quit coming to the regatta if you put hurdles in front of him that he really doesn't care about. It's just not worth giving somebody a negative opinion. Throw a piece of bubble gum at a wall and give him a number. Let him race, have fun, no fuss, and see you next year. Offer to point him in the right direction if he wants to build a real SCHRS number for his boat. It's worth the risk that that one boat runs away with all the prize money....

A few years ago, we had a serious resurgence starting with Hobie 16s in our area at local regattas. We had two situations with two regattas in one year where one had poor communication at one and another suffered one sour attitude that resulted in handicap and class issues and a bunch of Hobie 16s feeling like outsiders. They evaporated and we lost all momentum from a fleet that was on the cusp of outnumbering all other boats combined on a regular basis. It was dumb and I really regret that we weren't able to fix it. Kill the hurdles and tone down the seriousness at the low level regional regattas.

That said, I'm NOT talking about a major regional (or bigger) event - like the Florida 300 or whatever. Absolutely, everyone that is putting a lot of effort into a campaign for that event should expect a fair and refined playing field - real handicap numbers should definitely be required.

And yes, Portsmouth is pretty much static at this point. I don't think anyone can actually run the statistics to do a real refresh on a single rating and, even if they were able to, I doubt they're getting any event results submitted to them.


Jake Kohl
#288315 - 02/08/18 07:41 PM Re: Portsmouth or SCHRS ??? [Re: Will_R]  
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Originally Posted by Will_R
As such, lets just agree that, class legal is class legal. If you could take your H16, F18, A-cat, P19, N6.0, etc. etc. etc. to a nationals and race it without fear of being protested, you're good.

With that out of the way, 95% of the work is done!

On the other hand, if you sail a one-design catamaran not already listed in the SCHRS tables, you have a lot of work - and a lot of guesswork - to do in order to generate a fair and honest rating. Anybody who claims you can simply plug a few simple measurements into the SCHRS spreadsheet hasn't tried.

Quote
With regards to Portsmouth; the rating, once the modifiers were applied, resulted in the modified Tornado owing the N20c time! So, a boat designed in 1962 that is narrower, shorter and has pizza pans for dagger boards rates faster than a modern wave piercer with more volume, sail area and lifting boards???

With regards to SCHRS, I made an honest and good faith effort to measure my class-legal Isotope, and the official spreadsheet showed it owing the Goodall Viper F16 time! So, a boat designed in 1962 that is narrower, has a shorter mast, and shallow centerboards rates faster than a modern wave piercer with more volume, sail area, and a spinnaker???

I'd be happy to race under SCHRS handicapping if the system were anywhere near as simple to use or as accurate as its proponents claim - but it isn't.

Regretfully,
Eric

#288316 - 02/08/18 11:57 PM Re: Portsmouth or SCHRS ??? [Re: Isotope235]  
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Jake, reread what I said. The goal is to make it easy while maintaining as much of the original integrity as possible. How many 1-2 races per year guys aren't racing a stock boat? If they are putting forth the effort to get to a race and they don't have a stock boat, so long as the OA had set it up this way, run what you bring, but have the decency to take 30 minutes to measure your sails and fill out the spreadsheet. So long as the OAs put the info out in time, is it really that hard? Show me a list of boats that you see annually at races in your area that aren't included in the current SCHRS table. (That is both a challenge and... I could use the data if it exists...)

Eric, I heard about your case through the grapevine. I've gotten two measurement certifications for my own boat, have written an in depth slide presentation on SCHRS, assisted in developing a guide for boat owners to get a rating, deconstructed the equations and the spreadsheet and have even put it into MathCAD and replicated what the calculator produces. If you will get me data, we will figure out what is going on with the rating that you calculated.

In all honesty, the Isotope is one of the classes that was on my list to look into, but if you saw the comparison that I assembled which lists all of the boats in US PN and SCHRS tables, you would understand the size of the task at hand. Honestly, part of the reason that the rules require a recognized/certified measurer (in my opinion) is to make sure that measurements are both accurate and consistent. I'm not saying that you did it incorrectly, but if you're numbers are as you say... Something has to be going on there.

#288317 - 02/09/18 10:47 AM Re: Portsmouth or SCHRS ??? [Re: Will_R]  
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Originally Posted by Will_R
If you will get me data, we will figure out what is going on with the rating that you calculated..

The numbers I used were:
Crew = 1
WS = 113.60
AL = 4.880
WL = 4.496
BEAM = 2.234
CM = 14.567
VLM = 7.390
CJ = 3.730
VLJ = 4.983
CSPI = 0
TRAP = 1
B27 = Yes
LTM = 0.634
SH = No
LF = 0

Which generated a rating of 1.050 with the 2015 SCHRS spreadsheet.

I took most measurements from my boat, but some (like weight) are from the manufacturer. Sail measurements are from my sails according to Formula 40 (I didn't re-measure them from the SCHRS diagram). The Isotope class rules restrict total sail area to 185 sq/ft, but permit any ratio of main to jib area, and allow either square or pin-top mainsails. I figured there would be more variation from sail to sail than between measurement methods. After all, if other legacy boat sail measurements were taken from published sources, that should be ok for Isotopes too. Most of us are running 44 sq/ft in the jib and 141 sq/ft in the main.

#288318 - 02/09/18 02:48 PM Re: Portsmouth or SCHRS ??? [Re: Isotope235]  
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Home is where the harness is.....
Eric, do you have a copy of the class rules? I looked online and didn't find them.

#288319 - 02/09/18 04:06 PM Re: Portsmouth or SCHRS ??? [Re: Will_R]  
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Originally Posted by Will_R
Eric, do you have a copy of the class rules? I looked online and didn't find them.

I sent you a PM

#288321 - 02/09/18 05:46 PM Re: Portsmouth or SCHRS ??? [Re: Jake]  
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Originally Posted by Jake
[quote=Will_R]
The guy that does one, maybe two regattas a year, is going to quit coming to the regatta if you put hurdles in front of him that he really doesn't care about. It's just not worth giving somebody a negative opinion. Throw a piece of bubble gum at a wall and give him a number. Let him race, have fun, no fuss, and see you next year. Offer to point him in the right direction if he wants to build a real SCHRS number for his boat. It's worth the risk that that one boat runs away with all the prize money....



Bingo...

I would like to see SCHRS become the norm; however, as I stated earlier, not many folks are going to perform the gymnastics needed to get their boats in compliance should the have altered the sail plan etc... as they are the once or twice a year racers... And in our case many of them are Frankenboats.

I think this needs to be handled by each race committee noting on the NOR that you're using SCHRS for the rating system. And if you're not compliant with measurement to your modifications than a X% penalty will be applied until you can either a.) furnish a measurement certificate, or b.) measurements from your sail maker that can be plugged into the on-line calculator where an agreeable rating number can be assigned.

On another note, I agree, it really shouldn't be that hard to be in compliance. With most of the modifications that come into play are with sails many times going from a pin to a square top, getting the numbers from any sail maker shouldn't be that difficult. My question would be are the "reputable" sail makers of our community in tune with the SCHRS requirement for measurement? And, if so could/would they include a measurement sheet with the purchase of a new set of sails?

#288324 - 02/10/18 07:27 PM Re: Portsmouth or SCHRS ??? [Re: Mark Schneider]  
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Here is the latest SCHRS to PY chart I could find: https://www.schrs.com/pylookalike.php

Here is a complete reference for Portsmouth Yardstick: http://www.ussailing.org/racing/offshore-big-boats/rating-rules/#1471969539173-9c4d8bd4-7aff

These sources should help a lot to rate different boats.


Last edited by Mike Fahle; 02/10/18 07:28 PM.
#288328 - 02/11/18 07:39 PM Re: Portsmouth or SCHRS ??? [Re: Mark Schneider]  
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Ventucky Red,

The answer is yes. Glaser for example will include a F18 measurement form with their sails, they are certified class measurers on the F18 side and I would fully trust them to provide accurate sail area data to compute a SCHRS rating. Any of the lofts building A-Cat sails should also be capable of the same.

One issue with the SCHRS rating scheme is the mainsail area includes the mast. So you need to measure the mast area. That is pretty straightforward. It helps to look at the F18 measurement certificate which clearly outlines how to measure sails and the mast. The US F18 class website also has detailed photographs of sail measurement. Its about 1 hr for a 3 sail boat.

Jake,

I hear you, but applying DPN corrections to SCHRS doesn't work. We've played this game locally. Get your sail area if that is the change and run the calculator. It is easy because the numbers for almost every boat are readily available online, type those into the excel calculator and update the sail area. I do this for our fleet, maybe you can designate someone for your local fleet?

Eric,

Unfortunately SCHRS doesn't differentiate between pinhead or square top sails etc. They do have a sinking correction factor which I think you should use for the Isotope, and on the 2018 rating calculator this gives you a SCHRS number of 1.072, quite a bit slower than a 1 up F16 (1.041). Without this I get a number of 1.057, again relatively slower than a 1 up F16. I used a board depth below waterline of 0.56 m, the number for the Taipan 4.9 (which in stock configuration has very short and stubby boards). You didn't post a number from what I can tell, so that may be part of your ratings issue. Personally I feel the 1.057 number is a fair rating considering the following statement on the Isotope website:

"The Isotope Catamaran is a registered Formula 16 boat!
The hulls meet the 16ft LOA requirements of the Formula 16HP class. The strong points of the Isotope are that its balanced helm allows it to out point any other catamaran to windward. An Isotope meeting the One Design class specifications can be raced as a single handed Formula 16 boat. An Isotope with a spinnaker can be raced with crew in the Formula 16 one up class."

If the hull doesn't plane, maybe the 1.072 number is fair, maybe. How does the boat sail compared against a 1 up Blade, Falcon, Viper or Nacra F16?

-Sam


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#288330 - 02/12/18 08:21 AM Re: Portsmouth or SCHRS ??? [Re: samc99us]  
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I hesitate to resurrect this discussion, since I've already gone into details at https://www.catsailor.com/forums/ub...ds/%2Bschrs/Search/true/schrs#Post282859, but:

Originally Posted by samc99us
Unfortunately SCHRS doesn't differentiate between pinhead or square top sails etc.

Really? Then what is LTM (length of top of mainsail) for?

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They do have a sinking correction factor which I think you should use for the Isotope, and on the 2018 rating calculator this gives you a SCHRS number of 1.072, quite a bit slower than a 1 up F16 (1.041). Without this I get a number of 1.057, again relatively slower than a 1 up F16.

SH (sinking hull) is "only for HC14, HC16, Prindle 14 and 16". While I could get a fair number by claiming the SH adjustment, and omitting mast area from sail area, that would be illegal. SCHRS claims to produce fair handicaps without cheating.


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I used a board depth below waterline of 0.56 m, the number for the Taipan 4.9 (which in stock configuration has very short and stubby boards). You didn't post a number from what I can tell, so that may be part of your ratings issue.

Sorry, I inadvertently omitted VLB when transcribing numbers in my previous post. I measured VLB = 0.560 for the Isotope.

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Personally I feel the 1.057 number is a fair rating considering the following statement on the Isotope website:
"The Isotope Catamaran is a registered Formula 16 boat!
The hulls meet the 16ft LOA requirements of the Formula 16HP class. The strong points of the Isotope are that its balanced helm allows it to out point any other catamaran to windward. An Isotope meeting the One Design class specifications can be raced as a single handed Formula 16 boat. An Isotope with a spinnaker can be raced with crew in the Formula 16 one up class."

When the F16 class was first created, a number of existing 16 foot catamarans were grandfathered in, including the Isotope and the Hobie 16. Technically, both the Isotope and the Hobie 16 MAY race as F16 class boats. That doesn't mean that they actually are the same speed as a modern F16 design. If it did, then why does the Hobie 16 have a SCRHS rating of 1.193 rather than 1.050?

Does anybody really believe that 45 years of marine engineering, including the advent of computer modeling, CNC manufacturing, and the addition of spinnakers has yielded no difference whatsoever in boatspeed? I don't.

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If the hull doesn't plane, maybe the 1.072 number is fair, maybe. How does the boat sail compared against a 1 up Blade, Falcon, Viper or Nacra F16?

I haven't raced directly against against a Blade, Falcon, Viper, or Nacra F16. They've always been in "A-Fleet" whereas I sailed in "B-Fleet". The times I have sailed on the same racecourse, the A-Fleet boats were definitely faster. I have raced several times against Hobie 16s (1- and 2-up), Hobie 17s, and Hobie 18s. The Isotope is definitely faster than a Hobie 16, perhaps a little more than the US Portsmouth handicap indicates. Although US Portsmouth rates the Hobie 18 faster than an Isotope, I was often able to beat some H-18s around the course. I'd be willing to race boat-for-boat against a H-18. To claim that a 1-up Isotope is as fast as a 1-up Goodall Viper (which carries a spinnaker larger than the Isotope's main and jib combined) however, is ridiculous.

#288628 - 02/12/18 03:59 PM Re: Portsmouth or SCHRS ??? [Re: Isotope235]  
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Eric,

We can move this conversation over to the other thread if you prefer. I will briefly answer some questions here.

1) LTM = is length of the top of the mainsail as you state, so it does factor in and my apologies on misspeaking on that front.

2) I'm not sure the sinking hull correction applies only to H14's and H16's. I would have to dig into that more. Will probably knows the answer off the top of his head.

3) So I used the same VLB. I would have to look at the formulas directly but I don't believe SCHRS distinguishes between short stubby Tornado-like centerboards and narrow, high aspect ratio F18 like daggerboards beyond this number, i.e you could build a boat with very high VLB but super big chord and be slow.

4) I was quoting the Isotope class website, NOT the F16 class website when making that statement. I'm not arguing your point that 45 years of technology hasn't made a significant impact on boat speed, because it has, but the Isotope manufacturer is claiming the boat as a fantastic trainer for the Tornado (same statement made by the F16 class) and they are the ones claiming the boat performs as good or better than an F16!!!!

5) When looking at the SCHRS numbers, one big thing sticks out to me in general, and that is platform and sailing weight matter a healthy amount to the final number. I would weigh your actual platform if at all possible, as I suspect it is heavier than the 113 kg you have quoted (even the Blade F16's aren't really there). That could drive you back to a more 'fair' number.

6) SCHRS may not be creating a perfect number for your boat in a long downwind race, but take a look at the Taipan 4.9 numbers. I'm referencing that as I believe it is pretty similar to the Isotope in many ways (including design age). The big thing is they race without the jib in solo mode. Add the jib in and you drive the number from 1.097 to almost half, or 0.980. That may need some looking into on the SCHRS side as I doubt the boat is actually twice as fast with a jib as without.

Hopefully we can resolve your issue, and I'm okay with it being public because it is important for others to see the process and become familiar with it.

Last edited by samc99us; 02/12/18 04:03 PM.

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#288630 - 02/12/18 05:40 PM Re: Portsmouth or SCHRS ??? [Re: samc99us]  
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Originally Posted by samc99us
2) I'm not sure the sinking hull correction applies only to H14's and H16's. I would have to dig into that more. Will probably knows the answer off the top of his head.

Direct quote from the SCHRS calculator: "Sinking Hull (Only for HC14, HC16, Prindle 15 and 16".

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4) I was quoting the Isotope class website, NOT the F16 class website when making that statement. I'm not arguing your point that 45 years of technology hasn't made a significant impact on boat speed, because it has, but the Isotope manufacturer is claiming the boat as a fantastic trainer for the Tornado (same statement made by the F16 class) and they are the ones claiming the boat performs as good or better than an F16!!!!

Please let's distinguish between marketing hyperbole and reality.

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5) When looking at the SCHRS numbers, one big thing sticks out to me in general, and that is platform and sailing weight matter a healthy amount to the final number. I would weigh your actual platform if at all possible, as I suspect it is heavier than the 113 kg you have quoted (even the Blade F16's aren't really there). That could drive you back to a more 'fair' number.

Yes, SCHRS places a large performance factor on platform weight. Yes, the Isotope Class Rules specify a minimum weight that is unrealistic. 275lbs would be a more reasonable number, and I understand that most Isotopes weigh at least 280. Rather than trying to get a rating for MY PARTICULAR ISOTOPE, I was trying to get a rating for the class, and SCHRS uses the Class Rules for that. I can contact the manufacturer to try to fix the class rules. A 1.1% change in minimum boat weight yields a 2% change in rating. In racing against other sailors who weigh 25 pounds less than I do, I don't see that large a speed difference on the water.

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6) SCHRS may not be creating a perfect number for your boat in a long downwind race, but take a look at the Taipan 4.9 numbers. I'm referencing that as I believe it is pretty similar to the Isotope in many ways (including design age).
According to sailboatdata.com, the Tiapan 4.9 was designed in 1982. The Isotope was designed I'm 1962 - hardly the same design age. Please note that the Tiapan 4.9 was also billed as an F16 class boat but it does not carry the F16 rating. The Taipan 4.9 Solo has an SCHRS rating of 1.097. I'd be quite happy with that rating for an Isotope.

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The big thing is they race without the jib in solo mode. Add the jib in and you drive the number from 1.097 to almost half, or 0.980. That may need some looking into on the SCHRS side as I doubt the boat is actually twice as fast with a jib as without.

That's a point I've made before which has fallen on deaf ears. If I were to take a 40sqft jib off the Isotope altogether, and add a 188sqft spinnaker (the standard F16 size), then the Isotope SCRHS rating would go from 1.050 to 1.108. That's right - add 148sqft of sail area (a 58% increase) and the boat gets 5.5% SLOWER!

Looking at things a different way, if you sail an F16 class boat single-handed with main and jib, rather than main and spinnaker, SCHRS says it will be more than 5% faster. According to SCHRS, jib area is 9 times more important than spinnaker area. That makes no sense whatsoever. If it were true, then nobody would use a spinnaker at all!

#288631 - 02/13/18 05:21 PM Re: Portsmouth or SCHRS ??? [Re: samc99us]  
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Originally Posted by samc99us

Jake,

I hear you, but applying DPN corrections to SCHRS doesn't work. We've played this game locally. Get your sail area if that is the change and run the calculator. It is easy because the numbers for almost every boat are readily available online, type those into the excel calculator and update the sail area. I do this for our fleet, maybe you can designate someone for your local fleet?




You guys are either being idealist, argumentative, or you've never met a casual sailor that does one or two regattas a year on a franken boat. There's nothing wrong with taking what the relative % rating hit in Portsmouth for any of the modifiers and applying it to get some sort of roughly approximated SCHRS number so a casual sailor can pay your regatta entry fee and have a good time with everyone else. While we're taking everything so seriously, we're not noticing how utterly unattractive it is to an outsider.


Jake Kohl
#288632 - 02/14/18 03:37 PM Re: Portsmouth or SCHRS ??? [Re: Isotope235]  
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Eric,

The issue with how jibs are rated is a serious one and has been taken up with the SCHRS international committee, so your concern is not falling on deaf ears. One note on this subject is jib area is working for you upwind and downwind, so it is possibly twice as effective per area unit of spinnaker. That is unlikely really the case but it is a possible explanation as to where the number is coming from.

The weight penalty is a peculiar one, we will dig into that as well. I will say that at the top of the F18 fleet, 25 lbs easily results in the 2% change noted. There is a very detailed paper regarding this that was recently published including the statistics to support this.

Unfortunately at the moment there are a number of different F16 ratings (every manufacturer has one that isn't just the published F16 rating). I'm not quite sure what the solution to this is. If you have measured weights for the Isotope fleet and can generate an average, that would be more than fair I believe for the SCHRS rating.

Jake,

I was trying to be idealistic, because our local fleet did as you are suggesting for 2 years and it doesn't result in a 'fair' rating per SCHRS (see the jib vs. spinnaker area issue above). If your fleet is okay with this, then go for it. I just kindly suggest setting up a fleet SCHRS focal point that can generate ratings for the frankenboats given basic input data for future events. That is what we do locally-I run the ratings as I volunteered, it is fast for me, and my number doesn't change (F18's have been 1.000 for a while now). I will kindly generate numbers for other boats if they can provide the input data, or if I am at an event and not fixing the bottom of my daggerboards, I will help measure. I will see what I can do to become an approved measurer.


Last edited by samc99us; 02/14/18 03:40 PM.

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