Mine measured 39'3". i bought a main from the sail warehouse that was a 39" luff and it is fine. By the way they have a catalina 36  discontinued high performance main with full battens and a foot shelf for 1565.00 dollars on sale.  i have the same sail with standard battens and it is a nice sail. got it 2 years ago. paid close to 2400.00.

Mr KRABS
CAT 36 #2114

Rich, 
The "P" dimension is 39.0' for the standard rig and 41.0' for the tall rig.  P and E are luff and foot dimension for the mainsail.  J is length of the foretriangle and I is the height of the fore triangle.  These are the customary designations for a sailboat.  Racers know that and should not exceed the P or E dimensions.  The I and J define the for fore triangle.  The size of a jib is given as the LP (luff perpendicular)  which percent of the J dimension.  For instance a large genoa, the #1, is a 150% or 155%.  The working jib is typically 100% of the jib.  The #2 genoa is usually about 135%

LouBruska
Sojourn
1985 C-36 Mk1, Hull #495

Rich,

We’re a tall mast so I can’t measure or confirm.   I went with the recommendation from Dirk from National and the sail fit fine.    In general after working through the whole process I trust Dirks advice.  I suspect this 5” difference is accounting for stretch over the usable sail life (note that 1% would be just under 5”).  This would be a good question for Dirk.

In our case when the new sail arrived I rolled it out over the original sail and was surprised that it was both taller and longer by several inches.   After carefully looking at the original sail it was cut undersized.

I’d also add that if you are have the sail made with a loose foot, understand how the clew is attached to the boom.   National (and many other companies) uses a velcro strap around the boom.   The process works fine but it may be different that what you expect.

Good luck with your purchase.

Ray

I’m putting the mainsail on the boat this week (weather allowing).  Let me know if you have any questions or need a photo.

I got a main and jib from them last year. Happy with the sails but they put the insignia , draft stripe and hull number on the jib instead of the main. Make sure you check carefully when you get the sail.

Chuck Parker
C 36 Mk II 2072

I pulled the trigger on the 'offshore' main that the sailwarehouse had listed as a closeout.  Couldn't beat the price really.  Hope it was a wise choice.  Based on overall impressions of those who have first hand experience with this company and their sails I think things are looking good!