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The "J" on my 2004 26M measured up at (317.5cm) 125 inches..... I did my best to make that measurement as accurate as possible and Kadet mentioned he has 3 meter LP (TBC) ... Maybe the X's and the M" are different?

Neo wrote:The "J" on my 2004 26M measured up at (317.5cm) 125 inches..... I did my best to make that measurement as accurate as possible and Kadet mentioned he has 3 meter LP (TBC) ... Maybe the X's and the M" are different?

Yep just did a remeasure with a cheap tape and laser level and got 315cm or 124 inches for J on a 2008 , so an is different

Thanks for confirming that Kadet ... I was starting to wonder if my tape measure had shrunk

That's good information. Thanks to those who measured.

So we can make the following conclusion:



On the M, the flat-2D (geodesic) drawing shows the LP is 9.7" or 9.58'. That computes as 9.58/10.33 = 92.7% In the 3D sail, the LP might be be a little bigger because there is a 3D "belly" in the sail and because the luff is hollow, not straight as shown. . So let's call it a 95%, okay?

Clearly the published J dimensions are wrong on the M.
Could somebody please measure the J dimesnion on an X?
And could some owners of an X and M please measure the "I" dimension? See instructions below

It's a bit tricky to measure the I dimension accurately, but you can get very close by putting a measuring tape on the main halyard, and measuring vertically down to the level of the sheer line abreast of the mast. The sheer line is the joint between the hull and deck. Then measure the width of the boat at to the same point.

Judy

PS. Definition of geodesic is
adjective
1. of, relating to, or denoting the shortest possible line between two points on a sphere or other curved surface.
2. another term for geodetic.

Judy B wrote:Could somebody please measure the J dimesnion on an X?

See my post on the previous page, duplicated below.

Tomfoolery wrote:I get about 116.5 to 117.0 inches using a cheap little tape and a plumb bob made from sail thread and a link plate for weight. That's measured to a point on the deck where the forestay line would intersect the deck if it was extended all the way. The measurement would only be a little shorter if it stopped at the stem fitting pin, which is the low end of the range I gave. The high end is the projected point of intersection.

Sounds like the 9.7 ft you've been using is correct. I don't know where Mauripro's site got the J=10.0 ft.

Judy B wrote:you can get very close by putting a measuring tape on the main halyard, and measuring vertically down to the level of the sheer line abreast of the mast. The sheer line is the joint between the hull and deck.

I have measured this but with the Mast down. Is that OK? .... Mine is 724cm (285 inches / 23.75Ft) from the pin of the top shackle. Which looking at your diagram is dramatically different

Judy B wrote:Then measure the width of the boat at to the same point.

From gunwale to gunwale?
I'm curious to know how this helps?

All the best.
Neo

I always thought "I" was the distance down the front of mast from the jib halyard to the level of the main deck, why would we use the main halyard in a fraction rigged boat to measure for the jib?

On a trailer sailer the easiest way with the mast down is to just measure from the jib halyard block or furler halyard block down to the base of the mast.

Because I fitted a new alloy furler my sailmaker wanted these 2 values.

"I" was 7 Metres from mast base to the furler foils halyard block or 7.2M to the mast-hound attachment point.

I used the original factory mast-hound and I did not have a jib halyard block because from new the boat never had a hank on foresail only the factory CDI knockoff.

Or am I missing something Judy B?

kadet wrote:"I" was 7 Metres from mast base to the furler foils halyard block or 7.2M to the mast-hound attachment point.

The same (or similar) again YES!!

kadet wrote:I always thought "I" was the distance down the front of mast from the jib halyard to the level of the main deck, why would we use the main halyard in a fraction rigged boat to measure for the jib?

On a trailer sailer the easiest way with the mast down is to just measure from the jib halyard block or furler halyard block down to the base of the mast.

Because I fitted a new alloy furler my sailmaker wanted these 2 values.

"I" was 7 Metres from mast base to the furler foils halyard block or 7.2M to the mast-hound attachment point.

I used the original factory mast-hound and I did not have a jib halyard block because from new the boat never had a hank on foresail only the factory CDI knockoff.

Or am I missing something Judy B?

DANG IT. I meant to type JIB/GENOA halyard. Or if it's a CDI, the integrated jib halyard is the next best thing.

Judy B wrote:DANG IT. I meant to type JIB/GENOA halyard. Or if it's a CDI, the integrated jib halyard is the next best thing.

Hi Judy, on many Macs that's a CDI FF2 so the Haylard runs up and down the length of the Furler.
Need to take the measurement directly from the hound which is easy to do on a trailer sailer. But is it OK to do that with the mast laying down?

DANG IT. I meant to type JIB/GENOA halyard. Or if it's a CDI, the integrated jib halyard is the next best thing.

Now I'm really confused

My Sailmaker tells me that they are changing the LP of my new Jib so the sheets go back to the Genoa tracks."The LP has to be reduced slightly, otherwise the optimal sheeting point would have been behind the Jib tracks"
Is this kinda good or kinda bad?