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how to modify mainsail to raise boom

In my advancing age, I have developed a sensitivity to the sun.
Therefore I am installing a bimini on my Sea Sprite 23. I purchased a
stock bimini and modified it so that it doesn't interfere with the
sheets or winches. Now I need to raise the boom about six inches to get
a couple of inches of clearance.

I asked two sailmakers and got two completely different answers on how
to do this.

One sailmaker said that I should cut the six inches off the foot. He
said modifying the head usually results in many problems, mainly
interference with the backstay. However, to me, it looks as though it
shouldn't interfere. The masthead assembly appears to keep the backstay
far enough from the sail. I can't get an exact measurement though,
since the mast is raised.

Another sailmaker said that I should modify the head to get the six
inches. My current mainsail has a headboard with a top width of 4 1/2".
He says that he will use the same headboard and re-taper the leach of
the sail from the top batten to headboard. The sail has four standard
battens.

Could you please give me your opinion on this? How would shortening the
head and raising the sail effect how the boat sails and its stability?
This method would of course mean losing much less sail area.

I use the boat mostly for coastal crusing.

I'd start with no modifying at all and hoist the sail with a "loose
bottom". In other words you don't shove the foot in the boom but you
only attach the bottom with the front eye to the reef-hook using a
4"of strong line and the the rear opening of the bottom end in the
normal way (sorry, English is not my native language).
That way you can hoist the sail a bit higher (assuming you have
sufficient room at the top of the mast. As a consequence the boom will
raise 4"at the spot you want it to for your bimini.

I do this for practically the same reason as you described and I'm
very happy with the shape of the sail.

On 9 Aug 2005 11:48:19 -0700, wrote:

Now I need to raise the boom about six inches to get
a couple of inches of clearance.
----------------snip
Could you please give me your opinion on this? How would shortening the
head and raising the sail effect how the boat sails and its stability?
This method would of course mean losing much less sail area.

Thanks Len,

But I already moved the front of the boom higher so that the sail now
goes to the top of the mast. I still need six more inches so that I am
a couple of inches above the bimini.

John

In that case it depends on how balanced you're now with a full rig at
say 5 bft. When you've got a bit of weather helm now, you'll probably
improve the balance (and thus the speed) when you take away sail at
the bottom...

If you are happily belanced now I'd choose to modify the top of the
sail, it's less loss of sail-surface. And probably cheaper than
modifying the lenghthy bottom.... Only thing is how does the sailmaker
make sure there'll be a adequate extension of the top part of the
sail, maybe an extra stiffener on the right spot to avoid "flapping
around" of the first yard(s) from the top ?

Regards, Len.

On 9 Aug 2005 16:10:56 -0700, wrote:
But I already moved the front of the boom higher so that the sail now
goes to the top of the mast. I still need six more inches so that I am
a couple of inches above the bimini.

Jere,

I don't understand how using the topping lift can get me more
clearance. I've always assumed that the topping lift should be
completely slack when sailing. Otherwise, wouldn't it adversely effect
the sail shape. Also, it seems that the thin topping line would
eventually break when the mainsheet is pulled down hard enough.

John

The most cost effective and efficient way to raise the boom is to cut it off
of the head. The amount of labor will quadruple if you cut it off of the
foot. Remove the six inches put the same headboard back on and re-fair it to
the top batten. In some extreme cases the angle at the top batten is too
severe and your sailmaker will need to fair it down to the second batten.

Andrew Scott
www.scottsails.com

wrote in message
oups.com...
In my advancing age, I have developed a sensitivity to the sun.
Therefore I am installing a bimini on my Sea Sprite 23. I purchased a
stock bimini and modified it so that it doesn't interfere with the
sheets or winches. Now I need to raise the boom about six inches to get
a couple of inches of clearance.

I asked two sailmakers and got two completely different answers on how
to do this.

One sailmaker said that I should cut the six inches off the foot. He
said modifying the head usually results in many problems, mainly
interference with the backstay. However, to me, it looks as though it
shouldn't interfere. The masthead assembly appears to keep the backstay
far enough from the sail. I can't get an exact measurement though,
since the mast is raised.

Another sailmaker said that I should modify the head to get the six
inches. My current mainsail has a headboard with a top width of 4 1/2".
He says that he will use the same headboard and re-taper the leach of
the sail from the top batten to headboard. The sail has four standard
battens.

Could you please give me your opinion on this? How would shortening the
head and raising the sail effect how the boat sails and its stability?
This method would of course mean losing much less sail area.

I use the boat mostly for coastal crusing.

Oops, I posted this message yesterday as a new topic by mistake:

Thanks to everyone for your advice. I had the sail altered by cutting
the six inches off of the head. The boat was sailing very well before.
After I try the altered sail out, I will report back on this thread
about what effect it had. It might not be for a week or so though.

Thanks
John