Useful Formulae - PBO 422 Feb.

[drawp]

Has anyone tried to apply the formulae shown on page 129 of PBO 422 February? For 'Capsize screen' where beam is 12ft & displacement is 7.68T, I get beam/(displacement/64)^0.33 = 24.2.
'Comfort factor' includes a mathematical symbol " .0.3 " which I haven't come across before.
Sail area/displacement ratio. Where sail area = 800sq ft & displacement = 7.68T, sail area/(disp/64)^0.667 = 3290.
Does this mean my boat will float upside down and sail backwards in a following breeze? What are the correct formulae? Does the 'expert' who wrote this article work for an A-levels Examination Board? I may not be very clever but I'm good at pulling up anchors!

 

[Strathglass]

Peter,
Go to http//www.image-ination/sailsalc.htm
and put your boat parameters in their boxes and you will get all the info calaulated for you.
Iain

 

[romany123]

Yes its great....got the site from on here a little while ago....Proberbly from you Ian


Dave

 

[Juggler7823]

The correct URL should be:
http//www.image-ination/sailcalc.htm


Roy

 

[Shanty]

Just did a couple of the calculations on the data you give. Your capsize screen figure is 1.86 (anything less than 2 is a good sign). Your sail area / displacement figure is 19.2 - tending towards the undercanvassed end of the spectrum. Couldn't do the motion comfort ratio - insufficient data.

It looks like the mistake you are making is using a displacement figure in tons - all three formulae need the displacement in pounds.

 

[drawp]

Thanks guys. Thought I was going mad. The first formula on the page asked for displacement entry in tons so I just continued. Happy sailing.

 

[drawp]

Thanks guys. Looked up the site www.image-ination.com/sailcalc.html. Lots of useful calculations in there.