What are I J P E and what do they mean to me?

[blt2ski]

Originally Posted by allene222

I just finished putting together a page with dimensions and sail area calculations for thousands of boats. Not a unique list but follow the link to a page specific to the boat with sail area calculations in addition to the boat dimensions.

Boat Dimensions

I better not use your measurements, My main should only be 173#, and it is 194#, the spin would be 123#, and phrf is 695 for a code 5, and 724 for a code 6. A 155% genoa is multiplied by 1.65 for 20'ish# more than should be........

The reason for the spin goofs, is there is ot ISP or JSP listed......Not sure why 1.65 is used for a 155........ And only adding 10% for a racing main, where many can get to upwards of 20%, 161x1.2 =193.2, on par with my 194# Code 5 max PHRF main.

Marty

[allene222]

sailboatdata.com is another excellent site. My data source is completely independent of them so it is worth comparing them as errors can show up on any of these lists.

Allen

[allene222]

Originally Posted by blt2ski

I better not use your measurements, My main should only be 173#, and it is 194#, the spin would be 123#, and phrf is 695 for a code 5, and 724 for a code 6. A 155% genoa is multiplied by 1.65 for 20'ish# more than should be........

The reason for the spin goofs, is there is ot ISP or JSP listed......Not sure why 1.65 is used for a 155........ And only adding 10% for a racing main, where many can get to upwards of 20%, 161x1.2 =193.2, on par with my 194# Code 5 max PHRF main.

Marty

The 1.65 is approximate and depends on a lot of factors. The main thing is that the area for a full cut sail would be 1.55 * J * sqrt(I^2 + J^2) / 2. But it would also depend on how high the sail goes, any leach hollow, the foot profile, lots of things. 1.65 is a common rule of thumb. Perhaps I should be more precise in the calculation but it is close. On my boat it should be more like 1.63 (close enough?). The 100% calculation assumes the sail isn't a blade but again just an approximation.

My main is 9.5% more than the triangle and it is a racing main in that the roach comes to the backstay although not exotic. So again, the formula is close.

Every boat is different. Use any data at your own risk.

Allen

[puddinlegs]

Great project Allen, but there are a number of problems with spinnaker square footages on several boats that I took a quick look at including my own boat, an Express 34. (you need to define builders... Alsberg Expresses are very different than the Canadian Expresses)

Racing Symmetrical Spinnaker = 1.8 x JSP x ISP = 150 sq ft

Racing Asymmetrical Spinnaker = 1.8 x JSP x ISP= 150 sq ft

Cruising Asymmetrical Spinnaker = 1.65 x JSP x ISP = 137 sq ft



I can tell you, all our symmetrical spinnakers are all much larger than 150 sq ft. That's even less area than our #4 jib. Am I not reading your information correctly?

[blt2ski]

Mark,

Probably the same reason my Jeanneau Arcadia has a spin at 124#, NO listing for the JSP or ISP. The program does not auto entry the P or J figure as the spin figure. Not sure HOW many boats are this way, but will swag a BUNCH!

Marty

[allene222]

Originally Posted by blt2ski

Mark,

Probably the same reason my Jeanneau Arcadia has a spin at 124#, NO listing for the JSP or ISP. The program does not auto entry the P or J figure as the spin figure. Not sure HOW many boats are this way, but will swag a BUNCH!

Marty

The bug is fixed (I hope). Try it now. The program was auto entry I and J, but not correctly. Hopefully it is correct now. I apologize for the error and thank you for pointing it out.

Please leave a comment on the page if you have any other suggestions for improvements or find any problems.

Allen

[allene222]

As I said before, there are a lot of sites with dimensions and all of them have errors as far as I can tell. It is best to compare them and see if they agree. While that doesn't guarantee accuracy, if every site is different, you know you have a problem.

I added pages using the PHRF database so there is now another source of data. Some of what is given on the PHRF database is different as well so there is additional information on it. I included definitions of terms as well on the pages. Hope you find it useful.
http://L-36.com/boat_dimensions_phrf.php