dimensions & measurements

Cal folks: I was enjoying the information at the site cited by Jim Ives (http://www.sailboatdata.com/) and that prompted my question about the elusive "J" measurement. Or maybe it's about how you calculate % of foretriangle for jibs. I had assumed that J was perpendicular to the mast, which makes it more or less horizontal unless there's significant mast rake. The somebody--probably on this list-- said it was actually perpendicular to the luff or forestay. The sailboat data site uses the horizontal method. Numbers make my head swim anyway, but it would be nice to have the right concept. Is the perpendicular-to-luff measurement ever used in boat statistics? Chris Campbell

It is the distance from the tack to the mast. Actually, I think it is a boat (class) thing. My bast is 2 inches forward in the slot and nobody has ever hinted I should shorten my pole or cut my sails back because of that fact. The thing that is perpendicular to the luff is LP (Luff Perpendicular). That is used to measure the "size" of a sail as in 155%. That is LP/J. Allen On Mon, Aug 8, 2011 at 7:16 AM, Chris Campbell <cc… [at] lsnm.org> wrote: > ** > > > Cal folks: > > I was enjoying the information at the site cited by Jim Ives > (http://www.sailboatdata.com/) and that prompted my question about the > elusive "J" measurement. Or maybe it's about how you calculate % of > foretriangle for jibs. > > I had assumed that J was perpendicular to the mast, which makes it more > or less horizontal unless there's significant mast rake. The > somebody--probably on this list-- said it was actually perpendicular to > the luff or forestay. The sailboat data site uses the horizontal method. > > Numbers make my head swim anyway, but it would be nice to have the > right concept. Is the perpendicular-to-luff measurement ever used in > boat statistics? > > Chris Campbell > > >

Hi, Chris. The J is a fixed measurement (for a given boat design) of distance from forestay to mast at the base. That perpenduclar to luff number LP varies by sail. It is the percentage of the J for the sail (e.g., 130, 150). The measurement point for LP on a sail will change depending on how high or low the clew is. However, it is always a perpendicular from luff to clew. Cheers Charlie From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On Behalf Of Chris Campbell Sent: Monday, August 08, 2011 10:16 AM To: Ca… [at] yahoogroups.com Subject: [Cal_Boats] dimensions & measurements Cal folks: I was enjoying the information at the site cited by Jim Ives (http://www.sailboatdata.com/) and that prompted my question about the elusive "J" measurement. Or maybe it's about how you calculate % of foretriangle for jibs. I had assumed that J was perpendicular to the mast, which makes it more or less horizontal unless there's significant mast rake. The somebody--probably on this list-- said it was actually perpendicular to the luff or forestay. The sailboat data site uses the horizontal method. Numbers make my head swim anyway, but it would be nice to have the right concept. Is the perpendicular-to-luff measurement ever used in boat statistics? Chris Campbell ------------------------------------ Yahoo! Groups Links

Charlie, Are you sure of this J measurement? I thought it was the shortest distance from the front of the mast to wherever the forestay connects to the boat. Is this not correct? Regards, Wayne From: "Husar, Charlie [USA] (ASE)" <hu… [at] bah.com> To: "Ca… [at] yahoogroups.com" <Ca… [at] yahoogroups.com> Sent: Monday, August 8, 2011 3:01 PM Subject: RE: [Cal_Boats] dimensions & measurements Hi, Chris. The J is a fixed measurement (for a given boat design) of distance from forestay to mast at the base. That perpenduclar to luff number LP varies by sail. It is the percentage of the J for the sail (e.g., 130, 150). The measurement point for LP on a sail will change depending on how high or low the clew is. However, it is always a perpendicular from luff to clew. Cheers Charlie From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On Behalf Of Chris Campbell Sent: Monday, August 08, 2011 10:16 AM To: Ca… [at] yahoogroups.com Subject: [Cal_Boats] dimensions & measurements Cal folks: I was enjoying the information at the site cited by Jim Ives (http://www.sailboatdata.com/) and that prompted my question about the elusive "J" measurement. Or maybe it's about how you calculate % of foretriangle for jibs. I had assumed that J was perpendicular to the mast, which makes it more or less horizontal unless there's significant mast rake. The somebody--probably on this list-- said it was actually perpendicular to the luff or forestay. The sailboat data site uses the horizontal method. Numbers make my head swim anyway, but it would be nice to have the right concept. Is the perpendicular-to-luff measurement ever used in boat statistics? Chris Campbell ------------------------------------ Yahoo! Groups Links

Wayne, I probably did not say that well. By “at the base” I meant both the forestay and the mast. Yes, it is where the jib attaches at the forestay. I would suppose that on many boats, there is not a horizontal J measurement. I have never seen a picture that showed the J as other than horizontal, and I’ve seen the words “main deck” in the measurement. All of this ignores the fact that the mast may be on a doghouse. On the CAL 25, there is no doghouse, so I’ve never really thought about it. That said, the 100 percent sail area always has equations that would be for a right triangle (i.e., vertical mast and J meeting the mast at a 90 degree angle. Sure could get messy if one wanted to be precise. Cheers Charlie From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On Behalf Of Wayne Gillikin Sent: Monday, August 08, 2011 5:13 PM To: Ca… [at] yahoogroups.com Subject: Re: [Cal_Boats] dimensions & measurements (Charlie) Charlie, Are you sure of this J measurement? I thought it was the shortest distance from the front of the mast to wherever the forestay connects to the boat. Is this not correct? Regards, Wayne From: "Husar, Charlie [USA] (ASE)" <hu… [at] bah.com> To: "Ca… [at] yahoogroups.com" <Ca… [at] yahoogroups.com> Sent: Monday, August 8, 2011 3:01 PM Subject: RE: [Cal_Boats] dimensions & measurements Hi, Chris. The J is a fixed measurement (for a given boat design) of distance from forestay to mast at the base. That perpenduclar to luff number LP varies by sail. It is the percentage of the J for the sail (e.g., 130, 150). The measurement point for LP on a sail will change depending on how high or low the clew is. However, it is always a perpendicular from luff to clew. Cheers Charlie From: Ca… [at] yahoogroups.com<mailto:Cal_Boats%40yahoogroups.com> [mailto:Ca… [at] yahoogroups.com<mailto:Cal_Boats%40yahoogroups.com>] On Behalf Of Chris Campbell Sent: Monday, August 08, 2011 10:16 AM To: Ca… [at] yahoogroups.com<mailto:Cal_Boats%40yahoogroups.com> Subject: [Cal_Boats] dimensions & measurements Cal folks: I was enjoying the information at the site cited by Jim Ives (http://www.sailboatdata.com/) and that prompted my question about the elusive "J" measurement. Or maybe it's about how you calculate % of foretriangle for jibs. I had assumed that J was perpendicular to the mast, which makes it more or less horizontal unless there's significant mast rake. The somebody--probably on this list-- said it was actually perpendicular to the luff or forestay. The sailboat data site uses the horizontal method. Numbers make my head swim anyway, but it would be nice to have the right concept. Is the perpendicular-to-luff measurement ever used in boat statistics? Chris Campbell ------------------------------------ Yahoo! Groups Links

I made these various measurements on Papoose. They cannot be made directly. I placed a 2x4 2 feet above the deck as measured at the intersection of the deck and the hull and measured from there and added 2 feet to get "I". I used the Pythagorean theorem to get "J" I updated the new measurement page to include the official phrf definitions and a better sketch. I can't recall which boat we are talking about here but here is a page for a Cal-29-1 http://l-36.com/boat_dimensions_boat_phrf.php?boat=Cal%2029-2&i=37&j=12.3&p=31.7&e=12.3&dspl=8000&wl=24&draft=4.5&cbdr= Allen On Mon, Aug 8, 2011 at 4:30 PM, Husar, Charlie [USA] (ASE) < hu… [at] bah.com> wrote: > ** > > > Wayne, I probably did not say that well. By “at the base” I meant both > the forestay and the mast. Yes, it is where the jib attaches at the > forestay. I would suppose that on many boats, there is not a horizontal J > measurement. I have never seen a picture that showed the J as other than > horizontal, and I’ve seen the words “main deck” in the measurement. All of > this ignores the fact that the mast may be on a doghouse. On the CAL 25, > there is no doghouse, so I’ve never really thought about it. That said, the > 100 percent sail area always has equations that would be for a right > triangle (i.e., vertical mast and J meeting the mast at a 90 degree angle. > Sure could get messy if one wanted to be precise.**** > > ** ** > > Cheers**** > > Charlie**** > > ** ** > > *From:* Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] *On > Behalf Of *Wayne Gillikin > *Sent:* Monday, August 08, 2011 5:13 PM > > *To:* Ca… [at] yahoogroups.com > *Subject:* Re: [Cal_Boats] dimensions & measurements (Charlie)**** > > ** ** > > > > > **** > > Charlie,**** > > ** ** > > Are you sure of this J measurement? I thought it was the shortest distance > from the front of the mast to wherever the forestay connects to the boat. > Is this not correct?**** > > ** ** > > Regards,**** > > Wayne **** > > ** ** > ------------------------------ > > *From:* "Husar, Charlie [USA] (ASE)" <hu… [at] bah.com> > *To:* "Ca… [at] yahoogroups.com" <Ca… [at] yahoogroups.com> > *Sent:* Monday, August 8, 2011 3:01 PM > *Subject:* RE: [Cal_Boats] dimensions & measurements**** > > **** > > Hi, Chris. The J is a fixed measurement (for a given boat design) of > distance from forestay to mast at the base. That perpenduclar to luff number > LP varies by sail. It is the percentage of the J for the sail (e.g., 130, > 150). The measurement point for LP on a sail will change depending on how > high or low the clew is. However, it is always a perpendicular from luff to > clew. > > Cheers > Charlie > > -----Original Message----- > From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On > Behalf Of Chris Campbell > Sent: Monday, August 08, 2011 10:16 AM > To: Ca… [at] yahoogroups.com > Subject: [Cal_Boats] dimensions & measurements > > Cal folks: > > I was enjoying the information at the site cited by Jim Ives > (http://www.sailboatdata.com/) and that prompted my question about the > elusive "J" measurement. Or maybe it's about how you calculate % of > foretriangle for jibs. > > I had assumed that J was perpendicular to the mast, which makes it more or > less horizontal unless there's significant mast rake. The somebody--probably > on this list-- said it was actually perpendicular to the luff or forestay. > The sailboat data site uses the horizontal method. > > Numbers make my head swim anyway, but it would be nice to have the right > concept. Is the perpendicular-to-luff measurement ever used in boat > statistics? > > Chris Campbell > > ------------------------------------ > > Yahoo! Groups Links**** > > ** ** > > > > > **** > > **** > > >