Morgan Stinemetz
Moderator
Yes, I know.
Morgan Stinemetz
Morgan Stinemetz
Mike.Gritten
Member III
Cute, Morgan!
Mast length
I no longer have a sail plan (since I left sailmaking), but if you take the P measurement (from the top of the main halyard sheave to the mainsail tack, or lower black band if installed-should be even with the top of the boom), and then measure down to the deck where the bottom of the mast is, you will have the total length, except for the 2-3" from the top of the sheave to the actual cap at the top of the mast.
Does this help? I can find the P for you if you don't have it-
S
I no longer have a sail plan (since I left sailmaking), but if you take the P measurement (from the top of the main halyard sheave to the mainsail tack, or lower black band if installed-should be even with the top of the boom), and then measure down to the deck where the bottom of the mast is, you will have the total length, except for the 2-3" from the top of the sheave to the actual cap at the top of the mast.
Does this help? I can find the P for you if you don't have it-
S
Morgan Stinemetz
Moderator
Seriously now... The "I" length is essentially the mast length. It is a sailmakers' measurement from the base of the mast up to where the jib halyard exits the mast at the top. In the case of my own 1973 Ericson 27--which I assume is the same as a 1974 E-27--it's 32.5. As the jib halyard exits at the mast truck (top) on my boat it is safe to assume that is also the mast length. This is (of course) not the same length as mast height above the water, and it is important to know the difference. I can go under 40-foot bridges with impunity, but I will tell you that every time I do there is a serious pucker factor. Please understand, too, that a deck stepped mast's length will differ from the length of a keel stepped mast, but the two operative measurements ("I" and height above water) won't change. Now that is probably more than anyone wants to know about this, but I was such a smartass before that I thought that I owed a better explanation.
Morgan Stinemetz
Morgan Stinemetz
Not quite
Hi Morgan,
Not quite so.. The "I" is the dimension from the top of the jib halyard sheave (as you say) to the "BASE OF I"-NOT the base of the mast. "Base of I" typically is very close to the shroud bases, or chainplates, on the deck. This is true on all boats (in terms of the "base of I"). On all boats, the actual base of I is a line just below the chainplates (I am using the chainplates as a reference for this discussion), but is not a point on the boat which can be physically identified-it is only the engineering drawings. When we sailmaker types measure a boat for sails, we use the base of shrouds as a base of I-just so we can compare it to the sailplan we have at the loft. If this dimension is 1-2" less than the sailplan indicates, we can confirm we are talking about the same rig. We then take all of the other measurements (luff length, base of mast, track locations, etc.) to make the sail fit properly (we hope!).
In the case of the E 27 with a deck stepped mast, the "I" will be longer than the distance from the sheave to the base of the mast by roughly the height of the cabin top-something in the order of 12-14" I would think. The standard "I" is indeed 32.5 feet, but that should be a longer distance than from the sheave to the base of the mast (mast step on deck). In the case of a keel stepped mast, the overall mast length will be longer than the "I".
The ONLY time the it would equate to mast length (but there is no technical correlation) would be in the case of a deck stepped mast which had no cabin top or any crown in the deck (totally flat deck).
And there you have it..
S
Hi Morgan,
Not quite so.. The "I" is the dimension from the top of the jib halyard sheave (as you say) to the "BASE OF I"-NOT the base of the mast. "Base of I" typically is very close to the shroud bases, or chainplates, on the deck. This is true on all boats (in terms of the "base of I"). On all boats, the actual base of I is a line just below the chainplates (I am using the chainplates as a reference for this discussion), but is not a point on the boat which can be physically identified-it is only the engineering drawings. When we sailmaker types measure a boat for sails, we use the base of shrouds as a base of I-just so we can compare it to the sailplan we have at the loft. If this dimension is 1-2" less than the sailplan indicates, we can confirm we are talking about the same rig. We then take all of the other measurements (luff length, base of mast, track locations, etc.) to make the sail fit properly (we hope!).
In the case of the E 27 with a deck stepped mast, the "I" will be longer than the distance from the sheave to the base of the mast by roughly the height of the cabin top-something in the order of 12-14" I would think. The standard "I" is indeed 32.5 feet, but that should be a longer distance than from the sheave to the base of the mast (mast step on deck). In the case of a keel stepped mast, the overall mast length will be longer than the "I".
The ONLY time the it would equate to mast length (but there is no technical correlation) would be in the case of a deck stepped mast which had no cabin top or any crown in the deck (totally flat deck).
And there you have it..
S
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Art Mullinax
Member III
What if?
What if you took a 100 ft tape, attached it to your main halyard, hoist it to the top, then read the tape where it touches the deck??? Not a lot of guess work, no over my head calculations, don't have to lay the sails on the dock to measure, etc!
KISS, Keep It Simple Sailor.
Art M,
What if you took a 100 ft tape, attached it to your main halyard, hoist it to the top, then read the tape where it touches the deck??? Not a lot of guess work, no over my head calculations, don't have to lay the sails on the dock to measure, etc!
KISS, Keep It Simple Sailor.Art M,
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bigtyme805
Member III
When I first read this post I thought it was a joke. Then as I followed it I realized it was not. The Mast height is clear in the specs page of this website assuming you have the original mast (32.5). If you do not know if it is the original mast then you had better measure it. Since it is deck stepped measuring should not be a problem.
Don
Channel Islands
E27 Amigo
Don
Channel Islands
E27 Amigo
Mast Height Confusion
Boy, I never thought that such a simple question would generate so much discussion! All I was looking for was the actual length of the mast for a standard rig E27. I had measured mine (approx. 31 feet) and was just looking for confirmation that that was the standard rig. That appears to be the case.
The replies (the serious ones, that is) did serve one purpose though, as an education about the difference between mast length and "I". Many people seem to believe that I = mast length. As our sailmaker friend pointed out, this is rarely so since I is not measured to the base of the mast.
Boy, I never thought that such a simple question would generate so much discussion! All I was looking for was the actual length of the mast for a standard rig E27. I had measured mine (approx. 31 feet) and was just looking for confirmation that that was the standard rig. That appears to be the case.
The replies (the serious ones, that is) did serve one purpose though, as an education about the difference between mast length and "I". Many people seem to believe that I = mast length. As our sailmaker friend pointed out, this is rarely so since I is not measured to the base of the mast.
info
That is the great thing about this site-lot's of info gets shared! You are right that "I" has absolutely nothing to do with mast length, and as has been said in this thread, you can raise the main halyard and go right to the base, or use the "P" plus the distance from base of "P" to the base of the mast (if you don't have a long enough tape measure). The "I" dimension has absolutely nothing to do with mast length per se.
Just make sure I have beaten this horse to death, your comment about your sailmaker saying that mast length equals I "rarely" is not true. It is never the same. If the mast is deck stepped, "I" will be longer, if it is keel stepped, it will be shorter than mast length. The point being is that is no correlation between the 2.
Now, can we bury this poor horse?
cheers,
S
That is the great thing about this site-lot's of info gets shared! You are right that "I" has absolutely nothing to do with mast length, and as has been said in this thread, you can raise the main halyard and go right to the base, or use the "P" plus the distance from base of "P" to the base of the mast (if you don't have a long enough tape measure). The "I" dimension has absolutely nothing to do with mast length per se.
Just make sure I have beaten this horse to death, your comment about your sailmaker saying that mast length equals I "rarely" is not true. It is never the same. If the mast is deck stepped, "I" will be longer, if it is keel stepped, it will be shorter than mast length. The point being is that is no correlation between the 2.
Now, can we bury this poor horse?
cheers,
S
I have a '74 standard rig E27. I recently measured my mast length, while it was on the ground, with a 100' tape so no room for much error (possible droop in the tape over the length but very little since I laid it over the spar). The measurement was of the extrusion only, NOT including the sheave. I measured 31' 4". I would say the sheave is probably 6".
Oh, now I see this thread is from 2005! Wake up here! But now that I have renewed the topic, what I was really looking for are the mast and boom section dimensions, or "thickness". They're sort of oval shaped so I need x and y. I'm preparing some winter covers and such, and I am 30 miles from the yard. Trying to go only once but need to make some fittings so would like to know now.