Actual J measurement of E34/E35-3 ??

[sailingdeacon]

(This post has been changed due to a mis-measurement) I recently measured my '87 E34 for a new sail and found the J is 15' as documented. The E35-3 also has the same 15' documented. I understand the measurement is from the leading edge of the mast to the forestay attachment to the hull.

This could effect not only the size of a sail purchased but the price. I have the distinct feeling that in the past I have paid for a sail at a quoted percentage (larger) yet not have received the expected size after the sailmaker measured the boat.

 

[Seth]

J measurement

You have to be very careful about this. How did you actually measure this? If you used the very forward face of the mast to a point equal in distance to where the headstay touches the deck, up vertically so that you make this a distance PERPENDICLAR to the mast, this "might" right, BUT the measurement WILL be affected by where the mast is located. In the IOR days, we used to move the mast around in the collar to "change" the J for rating purposes.

Also, unless changed for rating purposes, the spinnaker pole length will equal the "design" J measurement. Under IOR, the pole determined spinnaker girths, and the J determined headsail LP's.

In today's world, PHRF uses the "design J" and pole length for determining sail sizes, and my original sailplan shows a J of 15 feet.

All you will accomplish by building sails to 14.5 is ending up with a smaller sail than you are assumed to have by all of the racing authorities

If the pole is 15', you can safely assume that the "world" considers the J to indeed be 15 feet.

On a similar note, the "I" cannot be accurately measured by a layperson. In fact, there is not one, single, "I". IG, or foretriangle height, is roughly the intersection of the headstay and the forward edge of the mast. This is used to determine genoa sizes. The "ISP" is from the TOP of the spinnaker halyard sheave, and is always very slightly different. The BASE of I is technically the sheerline abreast of the mast. In reality, it is almost impossible to obtain this point precisely using a tape measure. All of these things can have an impact on IMS, AMERICAP, and IOR mesaurements.

For a cruiser, or PHRF racer, the default numbers we sailmamkers use are the DESIGN values from the sailplan. The value of an actual boat measurement is not that you verify the design values, but rather to verify the sails will physically fit the boat.

So, unless you plan on getting an IMS o Americap certificate, the I of the E-34 is 46 feet and the J is 15 feet.

Cheers all!

 

[Seth]

35-3

For this boat, the I is 46 and the J is 15.83

 

[sailingdeacon]

post deleted

 

[Seth]

sail sizes

If you got a 155% built to 14.5, then you actually have a 149.8% genoa. Your rating is based on a J of 15, so are rated for more sail then you are carrying. If the quote was for a 155% based on a J of 14.5, then you have what you paid for, but not what you want.
Regarding the 140, sounds like you got a little less than you paid for. Of course, this assumes you are measuring the sail correctly.
The % sizes refers to the LP (luff perpendicular), NOT the foot length. A "real" 140 for your boat will have an LP of 21 feet (1.4 X 15).

If you are racing, you have 3 choices: 1). Live with it for now. 2). see if your sailmaker can re-cut the sail (not likely, but possible).
3). try and convince your local PHRF that you are sailing with a smaller J, and you will never have any sails built to a J of greater than 14.5. They might buy it and give you a very small credit. The argument will be stronger if you also cut the pole down to 14.5 and have you spinnakers cut down accordingly.
I believe your track is JUST BARELY long enough for a 155. Often we end up with 152-153 on some production boats-which is close enough, and sometimes we add another foot of track so you have enough adjustment range.\
If it is important, contact me directly and I will pull the sailplan (when you confirm which boat you actually have), and I can tell you with certainty.

Seeya!





Hope this helps!`

 

[sailingdeacon]

post deleted

A well know sail maker just told me they always build to the actual meaurements of a boat, not the design specs. so....... consider me confused.

 

[Seth]

sails

Rich Brown was the in-house engineer, and that plan is correct. The J is assumed to be 15 feet by PHRF unless you convince them that your boat is different and all of your sails do not exceed the limits imposed by whatever J you claim. I wonder where your mast is located in the collar-is it all the way forward?

Let me clarify the sailmakers point: As I said, we use the actual dimensions to determine clew height, maximum luff length, etc. In the case of a custom boat or a PURE cruiser, we may often use the rough I and J as we measure them.

The I and J define certain limits of LP, spinnaker width and foot, and luff lengths. These would be considered "not to exceed" dimensions when compared to on-board measurements.

So, the answer for a production, PHRF boat is as follows:
We measure to make sure the sails fit, and we use the design numbers for the maximum size limits.
The only exception is in the case of a custom boat or when the actual numbers are hugely smaller than design. In this case you would make the case to PHRF that your boat is not standard and submit your measured values. For you, there is no point in this.
Tell you what-why don't you give me your phone # so we can talk directly and save some time? I'll send you a personal note