| Where can I find the Portsmouth modifiers? #250724 07/12/12 08:30 AM 07/12/12 08:30 AM |
Joined: Aug 2011 Posts: 774 Greenville SC bacho OP
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Posts: 774 Greenville SC | I am making a few modifications to my boat and considering a few more. I would like to work up the rating hits, but I cannot find an official list of them. Google just brings up a bunch of dead links. Maybe my search skills suck though.
Ps, in an open class do I need to take a hit for non factory sails as well as a hit for a different area?
Last edited by bacho; 07/12/12 08:35 AM.
| | | Re: Where can I find the Portsmouth modifiers?
[Re: bacho]
#250725 07/12/12 08:52 AM 07/12/12 08:52 AM |
Joined: Jun 2001 Posts: 3,906 Clermont, FL, USA David Ingram
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Posts: 3,906 Clermont, FL, USA | It's not the most intuitive navigation: www.ussailing.org -> offshore -> Portsmouth_Yardstick -> Portsmouth Yardstick Index -> Current Tables -> MH Modification Factors MH Modifiers To answer your question you take the MN hit "For non-class legal mainsail, of same sail area or less than class legal mainsail (formerly square top adjustment)".
David Ingram F18 USA 242 http://www.solarwind.solar"Do or do not. There is no try." - Yoda "Excuses are the tools of the weak and incompetent" - Two sista's I overheard in the hall "You don't have to be a brain surgeon to be a complete idiot, but it helps"
| | | Re: Where can I find the Portsmouth modifiers?
[Re: bacho]
#250732 07/12/12 12:41 PM 07/12/12 12:41 PM |
Joined: Jul 2004 Posts: 125 Clinton, Mississippi rattlenhum
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Posts: 125 Clinton, Mississippi | Ps, in an open class do I need to take a hit for non factory sails as well as a hit for a different area? Depends on what boat you're on. The underlying principal is that you follow class rules or take the appropriate modification. Some classes don't require "factory" sails to be class legal like Hobie does. If your sails are class legal with same sail area, there's no hit. If your sails are not class legal, use MN for same sail area or ML for greater sail area.
Jerome Vaughan Hobie 16 Clinton, Mississippi
| | | Re: Where can I find the Portsmouth modifiers?
[Re: bacho]
#250740 07/12/12 03:10 PM 07/12/12 03:10 PM |
Joined: Jun 2001 Posts: 3,906 Clermont, FL, USA David Ingram
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Posts: 3,906 Clermont, FL, USA | So, my boats (nacra 20) current rating is only valid as a one design?
If I wanted to change the area of all 3 sails and add beam, would it make for sense to have it measured and rated texel or SCHS(spelling) for the long run instead of basing off of a design that is very different from what it is today? The short answer is no. I've only seen one race in the US use SCHRS and that was the Tybee 500. Mark S may use Texel in the NE but for the most part nobody uses either system in the US so your measurement cert wouldn't do anything for you. Personally I think you'd have a ratings beater if you just took all the modifiers applicable in DPN. If there is a weekness/loophole in DPN it's in the modifiers which is the appeal of a frankenboat.
David Ingram F18 USA 242 http://www.solarwind.solar"Do or do not. There is no try." - Yoda "Excuses are the tools of the weak and incompetent" - Two sista's I overheard in the hall "You don't have to be a brain surgeon to be a complete idiot, but it helps"
| | | Re: Where can I find the Portsmouth modifiers?
[Re: David Ingram]
#250741 07/12/12 04:00 PM 07/12/12 04:00 PM |
Joined: Dec 2001 Posts: 5,590 Naples, FL waterbug_wpb
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Posts: 5,590 Naples, FL | cool! a Franken 20!
How wide are you going on the beam?
How much more sail area you going for?
Jay
| | | Re: Where can I find the Portsmouth modifiers?
[Re: David Ingram]
#250743 07/12/12 04:14 PM 07/12/12 04:14 PM |
Joined: Jun 2001 Posts: 3,116 Annapolis, MD Mark Schneider
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Posts: 3,116 Annapolis, MD | We have switched in the mid atlantic to SCHRS.... the ISAF measurement system.
I believe the Great Texas also uses SCHRS. The advantage is that it gets rid of the politics in PHRF/Portsmouth.
The OA decides what handicap rating fleet they will offer. If your area jumps to SCHRS... your franken boat would be run through the same rating formula as the stock Nacra 20. Very straightforward... no politics.
crac.sailregattas.com
| | | Re: Where can I find the Portsmouth modifiers?
[Re: waterbug_wpb]
#250745 07/12/12 04:48 PM 07/12/12 04:48 PM |
Joined: Aug 2011 Posts: 774 Greenville SC bacho OP
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Posts: 774 Greenville SC | cool! a Franken 20!
How wide are you going on the beam?
How much more sail area you going for? Well I am not sure how much I will do, I am still exploring options. At first I was looking at the Open 20 rules but now I have decided against them. I was talking with Randy Smyth about the open 20 and we (I mean he) came up with a sail plan for it. After deciding against the Open 20 we decided that the sails proposed for that class would still be a good choice and he did not see a good reason to go bigger. So my new sails will be a 214sq ft main and a 53sq ft square top jib. So 24sq upwind. I decided I wanted to try those out before deciding on how much spin area to go with. I think I would like to have at least 2 separate spin sizes. Beam, again not sure. It depends what options I can come up with for beams. If performance will sell me bare extrusions at a reasonable price, I think I would shoot for 10.5'. If they wont, it will be up to finding some used beams to splice which does not excite me. Carbon beams are not gonna happen. I want to explore all (if any) options with ratings, because I want to do this mostly just for fun. I love to tinker with things that are good enough left alone, but I want to keep it fair rating wise on both sides. | | | Re: Where can I find the Portsmouth modifiers?
[Re: Mark Schneider]
#250746 07/12/12 04:49 PM 07/12/12 04:49 PM |
Joined: Jun 2001 Posts: 3,906 Clermont, FL, USA David Ingram
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Posts: 3,906 Clermont, FL, USA | GT 300 was DPN according to the NOR.
David Ingram F18 USA 242 http://www.solarwind.solar"Do or do not. There is no try." - Yoda "Excuses are the tools of the weak and incompetent" - Two sista's I overheard in the hall "You don't have to be a brain surgeon to be a complete idiot, but it helps"
| | | Re: Where can I find the Portsmouth modifiers?
[Re: bacho]
#250747 07/12/12 05:28 PM 07/12/12 05:28 PM |
Joined: Sep 2002 Posts: 3,224 Roanoke Island ,N.C. Team_Cat_Fever
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Posts: 3,224 Roanoke Island ,N.C. | I was thinking of doing all of that stuff, plus curved boards, but couldn't justify the expense. The boards would be your biggest improvement with no handicap that I can find. Pricey but probably worth it. The N-20 always suffered from the fat hull and how quickly it got that way, the curved boards would help get that out of the water. I think your handicap would be 57.5 with the stuff you're talking about doing.
"I said, now, I said ,pay attention boy!"
The cure for anything is salt water - sweat, tears, or the sea Isak Dinesen If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most. E. B. White
| | | Re: Where can I find the Portsmouth modifiers?
[Re: Team_Cat_Fever]
#250748 07/12/12 05:53 PM 07/12/12 05:53 PM |
Joined: Jun 2001 Posts: 162 Dunedin Causeway, FL hobiephil
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Posts: 162 Dunedin Causeway, FL | The boards would be your biggest improvement with no handicap that I can find. MH Modification FactorsOTHER: Any other deviations from standard class configurations, including the addition of wings, can be assessed a penalty of AT LEAST 0.995. Multiple deviations may incur multiple penalties. Penalties may be greater than 0.995
Last edited by hobiephil; 07/12/12 05:56 PM.
| | | Re: Where can I find the Portsmouth modifiers?
[Re: hobiephil]
#250751 07/12/12 07:00 PM 07/12/12 07:00 PM |
Joined: Sep 2002 Posts: 3,224 Roanoke Island ,N.C. Team_Cat_Fever
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Posts: 3,224 Roanoke Island ,N.C. | The boards would be your biggest improvement with no handicap that I can find. MH Modification FactorsOTHER: Any other deviations from standard class configurations, including the addition of wings, can be assessed a penalty of AT LEAST 0.995. Multiple deviations may incur multiple penalties. Penalties may be greater than 0.995 Then the PN would be 56.9 with wide beams, big main, big jib, different spin (non E/P) and curved boards. Slightly slower (.4) than an RC-27.
"I said, now, I said ,pay attention boy!"
The cure for anything is salt water - sweat, tears, or the sea Isak Dinesen If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most. E. B. White
| | | Re: Where can I find the Portsmouth modifiers?
[Re: Team_Cat_Fever]
#250753 07/12/12 08:44 PM 07/12/12 08:44 PM |
Joined: Aug 2011 Posts: 774 Greenville SC bacho OP
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Posts: 774 Greenville SC | I was thinking of doing all of that stuff, plus curved boards, but couldn't justify the expense. The boards would be your biggest improvement with no handicap that I can find. Pricey but probably worth it. The N-20 always suffered from the fat hull and how quickly it got that way, the curved boards would help get that out of the water. I think your handicap would be 57.5 with the stuff you're talking about doing. Did you ever get a price from anyone on building some curved trunks? Just curious, not something I want to do. | | | Re: Where can I find the Portsmouth modifiers?
[Re: bacho]
#250754 07/12/12 09:12 PM 07/12/12 09:12 PM |
Joined: Sep 2002 Posts: 3,224 Roanoke Island ,N.C. Team_Cat_Fever
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Posts: 3,224 Roanoke Island ,N.C. | Trunks are easy, the boards are alot of work. F-20c or M-20(would probably come with the trunks) boards would be the easiest and most affordable, still pricey though.For the trunk you just pack the board out a bit, release film, then carbon over your pack. Slide it off the board and you've got a trunk.
"I said, now, I said ,pay attention boy!"
The cure for anything is salt water - sweat, tears, or the sea Isak Dinesen If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most. E. B. White
| | | Re: Where can I find the Portsmouth modifiers?
[Re: bacho]
#250767 07/13/12 09:25 AM 07/13/12 09:25 AM |
Joined: Dec 2001 Posts: 5,590 Naples, FL waterbug_wpb
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Posts: 5,590 Naples, FL | a 10.5' width on a 20' boat would make it pitchpole before heel over?
For some reason, I seem to think a boat wider than 1/2 of the LWL has some issue? Maybe some of you designers could chime in here?
Jay
| | | Re: Where can I find the Portsmouth modifiers?
[Re: waterbug_wpb]
#250770 07/13/12 10:30 AM 07/13/12 10:30 AM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
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Posts: 12,310 South Carolina | a 10.5' width on a 20' boat would make it pitchpole before heel over?
For some reason, I seem to think a boat wider than 1/2 of the LWL has some issue? Maybe some of you designers could chime in here? There is a point where the additional bow pressure that results from extra righting moment due to the width starts to become a concern....like on the wide supercats (11' x 20'). The additional width gives it better speed potential but it makes them more sensitive to proper downwind handling...and more sensitive to sailing downwind in waves. However, you can control that by being wise with how much leverage you put on the bows...if you're in danger of stuffing it with the kite up, get your crew off the wire and start moving your weight inboard = problem solved. The trick is identifying that you need to do this BEFORE the boat takes you all the way to the scene of the crash. There really is not much concern with this change in the upwind attitude of the boat. The 20 (at 8.5' wide) is one of the best ocean sailing cats I've ever been on. It will flat out eat waves and wind and you can sail with the confidence that as long as you can keep your weight rearward, the boat will not pitchpole (unless you're out in some REALLY crazy stuff). I think it would live and perform well at 10 or 10.5 feet but it's going to be less wave resistant. Oh, and BTW, I've got a spare rear beam (standard width) from a 20 that I don't need.
Jake Kohl | | | Re: Where can I find the Portsmouth modifiers?
[Re: bacho]
#250778 07/13/12 12:25 PM 07/13/12 12:25 PM | MN3
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Unregistered | seems like a too much work to me (impo) I would rather just sail it till I break it (or it breaks me), then get another | | | Re: Where can I find the Portsmouth modifiers?
[Re: Jake]
#250782 07/13/12 01:13 PM 07/13/12 01:13 PM |
Joined: Jan 2007 Posts: 139 Hernando, Florida Mlcreek
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Posts: 139 Hernando, Florida | However, you can control that by being wise with how much leverage you put on the bows...if you're in danger of stuffing it with the kite up, get your crew off the wire and start moving your weight inboard = problem solved. The trick is identifying that you need to do this BEFORE the boat takes you all the way to the scene of the crash.
Jake, coming off of the wire and moving inboard is best to prevent pitch pole? Aren't you taking the cantilever action of your weight off the hull, and loosing the counter balance effect by doing this? Please explain the principle.
Thanks
Forrest I-20
Last edited by Mlcreek; 07/13/12 01:30 PM.
Forrest I-20 USA 645
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