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Old Jul 09, 2012, 10:05 PM
FROM THE MIND OF A MADMAN
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Aren't the sails made especially for mast with "pre bend ?
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Old Jul 09, 2012, 10:10 PM
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United States, MA, Wenham
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Quote:
Originally Posted by gpzy View Post
Aren't the sails made especially for mast with "pre bend ?
Yes,
Sort of..... But It's called Luff curve in the sails, not prebend.

Most Sails, (mine are, like I mentioned) have a luff-curve cut into them.
That means that the section that attaches to the mast is not perfectly vertical. The top & bottom are off of vertical to a certain degree (ask your sailmaker how much)
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Old Jul 09, 2012, 10:28 PM
FROM THE MIND OF A MADMAN
gpzy's Avatar
United States, CA, Los Angeles
Joined Apr 2007
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Quote:
Originally Posted by breakwater View Post
Yes,
Sort of..... But It's called Luff curve in the sails, not prebend.

Most Sails, (mine are, like I mentioned) have a luff-curve cut into them.
That means that the section that attaches to the mast is not perfectly vertical. The top & bottom are off of vertical to a certain degree (ask your sailmaker how much)
Got it.!
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Old Jul 10, 2012, 01:51 AM
Silly Old Fart
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New Zealand, Wellington, Masterton
Joined Mar 2006
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Thank you Breakwater, we are singing from the same hymn sheet after all
I can imagine that a wooden mast must be very difficult to get right but also allow a tremendous amount of tweaking.
Do you make your own sails?
Having a sailmaker with an understanding of wooden masted models would be essential.
There are a couple who come to mind on this forum.
Do you have pictures of your M sailing?
Cheers, Ian.
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Old Jul 10, 2012, 01:35 PM
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Mast Shape

An experienced model yacht sailmaker will be able to work with you to assess the unrigged shape of your mast and the deformation that it undergoes when shaped by backstay and jibstay tensions. With a knowledge of your average sailing wind conditions, a mainsail can then be designed with the appropriate amount of luff round to be efficient through the range of winds you encounter. After 43+ years at the sewing machine, I've covered the entire range of mast materials from wood, to aluminum, arrow shafts, carbon fiber, etc.. It is not the material but an understanding of the matching of the mast shape and the sail luff configuration that is the key to optimally performing model yacht sails. Rod Carr, CARR SAILS
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Old Jul 10, 2012, 09:29 PM
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Quote:
Originally Posted by CaptainBit View Post
Do you make your own sails?
Having a sailmaker with an understanding of wooden masted models would be essential.
There are a couple who come to mind on this forum.
Quote:
Originally Posted by RodACarr View Post
An experienced model yacht sailmaker will be able to work with you to assess the unrigged shape of your mast and the deformation that it undergoes when shaped by backstay and jibstay tensions. With a knowledge of your average sailing wind conditions, a mainsail can then be designed with the appropriate amount of luff round to be efficient through the range of winds you encounter. After 43+ years at the sewing machine, I've covered the entire range of mast materials from wood, to aluminum, arrow shafts, carbon fiber, etc.. It is not the material but an understanding of the matching of the mast shape and the sail luff configuration that is the key to optimally performing model yacht sails. Rod Carr, CARR SAILS
My Sails are, Um...
CARR SAILS! (4 suits of them atleast)
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Old Jul 12, 2012, 10:31 AM
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Quote:
Originally Posted by Dick L. View Post
In my circles (beach Cats) pre-bend was a set of spreaders pointing about 15-20 degrees (or so ????) toward the rear, with enough tension to put a bend into the mast prior to attaching the main. With the pre-bend, the center of the mainsail was pulled forward. Adding down-haul and out-haul flattened the sail tremendously. Then, when it really started to blow, mast rotation did not allow the tip to fall off which really powered up the boat for double-trap work.

On mine, (single-handed racing) I used straight spreaders and loosened them enough to allow the tip of the mast to fall off to leeward, and at the same time the center of the mast bowed forward - in effect also flattening the sail. Of course, we used fore-stays and side shrouds, and main-sheet tension handled the leech of the main, as well as acting as an adjustable "back-stay" of sorts.

Downwind, letting off on the main-sheet also allowed the mast to tip forward slightly, huge draft in the main and then broad reaching downwind to maintain apparent wind.

Dick,

Pre-bend in the model boating world is when the mast is bent the wrong way (mast tip forward) so that when backstay is applied the mast becomes straight. I believe the reason is to get enough load on the backstay to get forestay load. Don't forget that because the jib boom pivot is usually located back on the jib boom there is a pivoting action that applies jib leech load depending on the location of the jib pivot on the boom and how much backstay is applied.

As Rod Carr said, the need for prebend, how much, and all that stuff is what a sailmaker needs to know to make good sails. In many classes when a sailmaker has experience they can tell you how much pre-bend, if any, is required.
Of course all this depends on the mast characteristics.

Ted
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Old Jul 15, 2012, 10:46 PM
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I may want to unload my "Toad" M boat. It is a sweet looking, and sailing boat. I have lost interest in this boat for some reason. ? There are pictures of her sailing in Marblehead.
#98
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Old Jul 15, 2012, 10:53 PM
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I may want to unload my "Toad" M boat. It is a sweet looking, and sailing boat. I have lost interest in this boat for some reason. ? There are pictures of her sailing in Marblehead.
#98
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Old Jul 15, 2012, 10:58 PM
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Spot? I think was a Star 45. Bone? Toad? Majic Dragon? Really? I have a design clasic M from Central Park that would say... good night, see ya. By J.E. I have not unleashed.
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Old Jul 16, 2012, 06:56 PM
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UK RM Championship 2012

thought I would brighten up the thread with some more pictures from the UK Marblehead Nationals.
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Old Jul 16, 2012, 07:07 PM
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UK RM Championship 2012

A few skippers suffered radio gear problems me included with the salt water lake.
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Old Jul 16, 2012, 08:58 PM
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I have had a RMG look the same complete with smoke.. I also had a spare. Hate salt water. I was able to get it repaired with new electronics.
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Old Jul 16, 2012, 10:16 PM
Brighto?
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United States, DE, Newark
Joined Dec 2003
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Vintage M

I ran across this boat in an antique shop in Mullica Hill, NJ over the weekend. I took a good look at the boat and found that generally it was preserved but missing the rudder, deck hardware, hatch and rig. It was build in the buttock method and would need a lot of restoration work to make it nice. As typical of most unknowing antique dealers it was way, way overpriced for the condition and we could not come to an agreement on a sale. I guess it will sit there for another year.
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Old Jul 22, 2012, 03:47 PM
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19 Traditional, High-Flyer, and Classic M-boats jockey for position at the start of the 2012 Nationals.

Some not in the photo..
Three of the Four "Varieties of M" all sailing at the same time.

Nine-Teen Boats.
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