Bill,
If a factory stock Supercat is upgraded with a Sq top main and a self tacking jib, what, in your opinion, is the % increase in speed or in another manner of speaking the reduction of the PN. second question, is this the best 'bang for the buck' that you can spend on one of the older boats?
Regards,
Andy
Square top and self tacking jib?
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Bill Roberts
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- Location: Stuart, Florida
Re: Square top and self tacking jib?
The benefit of new square top sails depends on where you are coming from. If your present sails are the ones that came with the boat, built in 1985 or so, then new sails will show up as improved performance, maybe even as much as a point or two.
Adding a spinnaker, correct design, wil get you 2% points reduction in PN.
The primary reason for the self tacking jib is not to make the boat go faster. It is to make the boat more manageable with a spinnaker to help the crew out.
I developed the self tacking jib on the RC27. The self tacking jib is smaller in area than the original standard jib. When I first tried the self tacking jib, I was concerned that the boat might be slower with a smaller jib area. The thing that saved the day is that the longer luff, that's where the forward thrust acts from, compensated for the reduced area and things turned out to be no change in boat performance. BUT, it really made jibing the spinnaker easy and quick!
The thing that blows me away is that so many other classes have copied the self tacking jib and they have copied it wrong. This is crazy! They have made it more costly and heavier and it doesn't work as well as the ARC system. The subtlety got by them. The calculus went right over their heads.
Adding a spinnaker, correct design, wil get you 2% points reduction in PN.
The primary reason for the self tacking jib is not to make the boat go faster. It is to make the boat more manageable with a spinnaker to help the crew out.
I developed the self tacking jib on the RC27. The self tacking jib is smaller in area than the original standard jib. When I first tried the self tacking jib, I was concerned that the boat might be slower with a smaller jib area. The thing that saved the day is that the longer luff, that's where the forward thrust acts from, compensated for the reduced area and things turned out to be no change in boat performance. BUT, it really made jibing the spinnaker easy and quick!
The thing that blows me away is that so many other classes have copied the self tacking jib and they have copied it wrong. This is crazy! They have made it more costly and heavier and it doesn't work as well as the ARC system. The subtlety got by them. The calculus went right over their heads.
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Mac M
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Re: Square top and self tacking jib?
I have a 19XL with the straight track self tacking jib and an F16 with a curved track self tacker. I'm about to buy a SC20 and am considering adding a self tacking jib to it at some point. Which is the preferred straight or curved? Seems like the straight track would be cheaper. Also, anyway of putting a self tacker on a telescoping beamed 20?
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Kevin Keller
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- Boat Make/Model: SC-20, ARC22
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Re: Square top and self tacking jib?
Tom recommends the curved track for the SC-20, at least he did for me.
Dave Farmer built a small curved track for his telescoping SC-20 and I used to have more pictures of it but I do have one. It might have had to been taken apart to put it on the trailer. You can contact him and he might still have pictures of it. The one on mine, supplied from Aquarius, is much wider. Which I think is much better especially for going downwind.
I have included a picture of Dave's setup.
Kevin
Dave Farmer built a small curved track for his telescoping SC-20 and I used to have more pictures of it but I do have one. It might have had to been taken apart to put it on the trailer. You can contact him and he might still have pictures of it. The one on mine, supplied from Aquarius, is much wider. Which I think is much better especially for going downwind.
I have included a picture of Dave's setup.
Kevin
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Kevin Keller
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Re: Square top and self tacking jib?
OK, I just found another picture and I remember how he did it. He had the curved track that was attached to a metal bar that extended the width of the beam from inside of the hulls. The piece was attached to the beam by large hose clamps and could be fairly easily removed for trailering.
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Bill Roberts
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Re: Square top and self tacking jib?
I have a 19XL with the straight track self tacking jib and an F16 with a curved track self tacker. I'm about to buy a SC20 and am considering adding a self tacking jib to it at some point. Which is the preferred straight or curved?
There is a big difference between the straight track and curved track self tacking jib systems. The straight track as one can see is obviously straight. I consider the 22 self tacking track as straight because of the way it works. The 22 track is straight across the center and where it ranges sailing to windward. The ends of the 22 track are bent forward and down somewhat to encourage the car to run to the ends of the track. The sheet is eased at the same time. This is helpful for tacking downwind 'without spinnaker' when the jib needs to be trimmed very much outboard. With spinnaker, the jib is eased only slightly as the relative wind direction is well forward. The straight track works like this: The horrizontal component of the jib sheet tension between the jib tack and the car tends to pull the car to track center. The wind pressure in the jib sail at the clew corner tends to push the car outboard. These two forces are always equal and opposite at any fixed and stable position. Therefore increasing jib sheet tensions will move the car toward the center of the track and easing jib sheet tension will let the car run out. The subtle part of this system is to get that same jib sheet tension that moves the car inward or outward to trim the jib to the correct shape for the wind speed and point of sailing at the same time. This is acheived by adding a small 4:1 mechanical advantage pulley system between the car and clew corner of the sail. This makes the sail being trimmed with four times the jib sheet tension as the force tending to pull the traveller car to center. The force tending to pull the traveller car to center is 1/4th the force sheeting the jib between car and clew corner. Well how about that? The jib sheet tension positions the traveller car and trims the jib sail at the same time. By varying the mechanical advantage between the car and the clew corner sail, the car position and sail trim can be varied. What makes this work is that with the straight track, and the 22 track is close enough to straight, that with this geometry the jib sheet tension changes the sheeting angle off boat centerline and trims the sail correctly at the same time. With this system, as sheeting tension changes sheeting angle and sail trim change together in a coordinated way, in concert. In math we would say there is a d tension / d theta term which makes it all work.
I'm going to group the curved jib tracks together. The radius of curvature for the track is the distance from the jib tack to the jib track at the center of the track attached to the main beam at its center. With this geometry, as sail pressure pushes the sail to leeward, there is no change in sheeting tension. The d tension / d theta term is zero. The wind in the sail pushes the sail/car to the end of the track. Therefore another sheeting line is required to set the position of the car, more complication and something else to adjust when changing point of sail. Come in off the wire, Mr Crew, and reset the car position. Now, Mr Crew, where do you set the car for light, medium and heavy air when sailing to windweard? With the straight track, finding these positions is automatic, stay out on the wire. With the curved track you stumble and fumble in the middle of the tramp or don't worry about it.
Enjoy the straight track self tacking jib system,
Bill
There is a big difference between the straight track and curved track self tacking jib systems. The straight track as one can see is obviously straight. I consider the 22 self tacking track as straight because of the way it works. The 22 track is straight across the center and where it ranges sailing to windward. The ends of the 22 track are bent forward and down somewhat to encourage the car to run to the ends of the track. The sheet is eased at the same time. This is helpful for tacking downwind 'without spinnaker' when the jib needs to be trimmed very much outboard. With spinnaker, the jib is eased only slightly as the relative wind direction is well forward. The straight track works like this: The horrizontal component of the jib sheet tension between the jib tack and the car tends to pull the car to track center. The wind pressure in the jib sail at the clew corner tends to push the car outboard. These two forces are always equal and opposite at any fixed and stable position. Therefore increasing jib sheet tensions will move the car toward the center of the track and easing jib sheet tension will let the car run out. The subtle part of this system is to get that same jib sheet tension that moves the car inward or outward to trim the jib to the correct shape for the wind speed and point of sailing at the same time. This is acheived by adding a small 4:1 mechanical advantage pulley system between the car and clew corner of the sail. This makes the sail being trimmed with four times the jib sheet tension as the force tending to pull the traveller car to center. The force tending to pull the traveller car to center is 1/4th the force sheeting the jib between car and clew corner. Well how about that? The jib sheet tension positions the traveller car and trims the jib sail at the same time. By varying the mechanical advantage between the car and the clew corner sail, the car position and sail trim can be varied. What makes this work is that with the straight track, and the 22 track is close enough to straight, that with this geometry the jib sheet tension changes the sheeting angle off boat centerline and trims the sail correctly at the same time. With this system, as sheeting tension changes sheeting angle and sail trim change together in a coordinated way, in concert. In math we would say there is a d tension / d theta term which makes it all work.
I'm going to group the curved jib tracks together. The radius of curvature for the track is the distance from the jib tack to the jib track at the center of the track attached to the main beam at its center. With this geometry, as sail pressure pushes the sail to leeward, there is no change in sheeting tension. The d tension / d theta term is zero. The wind in the sail pushes the sail/car to the end of the track. Therefore another sheeting line is required to set the position of the car, more complication and something else to adjust when changing point of sail. Come in off the wire, Mr Crew, and reset the car position. Now, Mr Crew, where do you set the car for light, medium and heavy air when sailing to windweard? With the straight track, finding these positions is automatic, stay out on the wire. With the curved track you stumble and fumble in the middle of the tramp or don't worry about it.
Enjoy the straight track self tacking jib system,
Bill
Last edited by Bill Roberts on August 12th, 2013, 3:38 pm, edited 1 time in total.
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SC15Av8or
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- Boat Make/Model: SC15 / SC19
- Location: Richmond, Virginia
Re: Square top and self tacking jib?
Looks like I am going to have to upgrade my boats!!! 
I will be looking for a square top main for the SC15....along with self-tacking square top jibs for the SC15 and SC19. Then I will have to see if the budget can squeeze in the spin sails and rigging.
I will be looking for a square top main for the SC15....along with self-tacking square top jibs for the SC15 and SC19. Then I will have to see if the budget can squeeze in the spin sails and rigging.
Lifes 2 short for cheap GROG
SuperCat 15/19Av8or
SuperCat 15/19Av8or
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Bill Roberts
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- Location: Stuart, Florida
Re: Square top and self tacking jib?
Professional,
You can get the best and fastest sails from the factory or through the factory. Tom doesn't make the sails but he has worked with and purchased sails from various sailmakers. Tom selects the best and fastest sailmaker and that is who he gets sails from. There are cheaper sailmakers out there but they have no experience making SC and ARC and RC sails. There are all kinds of details that must be right to have an excellent sail. One of the most important is the luff curve which is highly influenced by the way your mast bends in concert with the cut of the sail. Bolt rope diameter is important. Bolt rope hardness is important. Headboard location relative to the bolt rope is important so that your halyard lock will work. Battens that naturally bend in the correct airfoil shape and have the right stiffness are important.
All of these things and many more are important. Tom gets phone calls all the time from boat owners who bought sails from XYZ Sailmaker and "the halyard lock won't lock" or "the bolt rope comes out of the mast" or "the sail won't go up the mast because the sailmaker put too much luff round on the sail and the battens are too stiff". The list of problems goes on and on and Tom gets phone calls on new sail problems that he had nothing to do with all the time. So think about this next time you buy sails. Do you want sails made out of good cloth or the cheap stuff. Do you want your sail sewn together with thread that is resistant to UV or do you want the cheap stuff that rots in the sun?
The choice is yours.
You can get the best and fastest sails from the factory or through the factory. Tom doesn't make the sails but he has worked with and purchased sails from various sailmakers. Tom selects the best and fastest sailmaker and that is who he gets sails from. There are cheaper sailmakers out there but they have no experience making SC and ARC and RC sails. There are all kinds of details that must be right to have an excellent sail. One of the most important is the luff curve which is highly influenced by the way your mast bends in concert with the cut of the sail. Bolt rope diameter is important. Bolt rope hardness is important. Headboard location relative to the bolt rope is important so that your halyard lock will work. Battens that naturally bend in the correct airfoil shape and have the right stiffness are important.
All of these things and many more are important. Tom gets phone calls all the time from boat owners who bought sails from XYZ Sailmaker and "the halyard lock won't lock" or "the bolt rope comes out of the mast" or "the sail won't go up the mast because the sailmaker put too much luff round on the sail and the battens are too stiff". The list of problems goes on and on and Tom gets phone calls on new sail problems that he had nothing to do with all the time. So think about this next time you buy sails. Do you want sails made out of good cloth or the cheap stuff. Do you want your sail sewn together with thread that is resistant to UV or do you want the cheap stuff that rots in the sun?
The choice is yours.
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Bill Roberts
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- Joined: November 17th, 2003, 9:13 pm
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Re: Square top and self tacking jib?
Hey Guys,
What's up? I write all this stuff up and explain everything and then I don't hear a peep out of anyone?
Do you all agree, disagree or what? Have any questions? I didn't mean to turn everybody off.
You guys and girls have purchased a beach cat from the technology leader in the beach cat business; first with the elliptical hull shape, first with the square top sail, first with the self tacking jib and also first in safety and the only beach cat that comes with a righting system and a water tight mast. Why does Tom use truss head phillips machine screws to attach rigging to the hull and to the mast"
Pop rivets will do. But they have a hole down the center that leaks and they losen up in fiberglass and make an oversize hole that makes a mess to fix. Quality, Quality, Quality is what it is all about.
Bill
PS Who influenced Harken to come out with the higher mechanical advantage mainsheet systems. Tom Haberman talked them into the 12:1 system for the 22 and the 16:1 for the 27and 30. Harken filled in the gaps and they are good sellers. This was all done long before these items were shown in the Harken catalogue.
What's up? I write all this stuff up and explain everything and then I don't hear a peep out of anyone?
Do you all agree, disagree or what? Have any questions? I didn't mean to turn everybody off.
You guys and girls have purchased a beach cat from the technology leader in the beach cat business; first with the elliptical hull shape, first with the square top sail, first with the self tacking jib and also first in safety and the only beach cat that comes with a righting system and a water tight mast. Why does Tom use truss head phillips machine screws to attach rigging to the hull and to the mast"
Pop rivets will do. But they have a hole down the center that leaks and they losen up in fiberglass and make an oversize hole that makes a mess to fix. Quality, Quality, Quality is what it is all about.
Bill
PS Who influenced Harken to come out with the higher mechanical advantage mainsheet systems. Tom Haberman talked them into the 12:1 system for the 22 and the 16:1 for the 27and 30. Harken filled in the gaps and they are good sellers. This was all done long before these items were shown in the Harken catalogue.
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Mac M
- Professional
- Posts: 232
- Joined: June 13th, 2012, 5:05 am
- Boat Make/Model: SC17
- Location: Lugoff, SC
Re: Square top and self tacking jib?
I try and get all my parts from Tom whenever possible. As a matter of fact I ordered some for the 82 SC20 I'm getting and got some direction on the upgrades I'm planning on doing to it. Look for an '89 SC19XL with the straight track self tacker and spin up for sale soon to finance the upgrades!
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Mac M
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- Boat Make/Model: SC17
- Location: Lugoff, SC
Re: Square top and self tacking jib?
Bill,
Would still like to know what you thought about how to upgrade the telescoping beamed 20's to a self tacking jib and spinnaker? Seems that switching to a solid beam would be ideal but rather expensive.
Would still like to know what you thought about how to upgrade the telescoping beamed 20's to a self tacking jib and spinnaker? Seems that switching to a solid beam would be ideal but rather expensive.
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Bill Roberts
- Expert
- Posts: 515
- Joined: November 17th, 2003, 9:13 pm
- Location: Stuart, Florida
Re: Square top and self tacking jib?
Pro,
This is easy.
First build a base to attach a straight track to. Attach a piece of Al bar stock, 1" by 1/4", to the front beam with SS hose clamps. Add spacers ~1/4" thick where the base stock extends over the smaller diameter beam. Attach spacers with machine screws, drill and tap; SS screws only. Place the traveller track over the base and mark attachment screws. Drill and tap. You can get all the parts you need from the factory.
Bill
This is easy.
First build a base to attach a straight track to. Attach a piece of Al bar stock, 1" by 1/4", to the front beam with SS hose clamps. Add spacers ~1/4" thick where the base stock extends over the smaller diameter beam. Attach spacers with machine screws, drill and tap; SS screws only. Place the traveller track over the base and mark attachment screws. Drill and tap. You can get all the parts you need from the factory.
Bill
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SC15Av8or
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- Boat Make/Model: SC15 / SC19
- Location: Richmond, Virginia
Re: Square top and self tacking jib?
Bill....
Is there a penalty for a SC15 with a self tacking jib verse one that has a stock non-self tacking jib ??
Is there a penalty for a SC15 with a self tacking jib verse one that has a stock non-self tacking jib ??
Lifes 2 short for cheap GROG
SuperCat 15/19Av8or
SuperCat 15/19Av8or
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Bill Roberts
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- Location: Stuart, Florida
Re: Square top and self tacking jib?
THE SELF TACKING JIB IS NOT A GO FAST THING!!!!!
The self tacking jibs are smaller in area than the standard jibs.
The self tacking jib is a jib sheeting system that makes it easier to
"jibe a spinnaker and jib" at the same time. It also makes it easier to
tack or jibe a boat/jib without spinnaker. It is a convenience thing.
It also opens the door for a one man boat with main and JIB to be
sailed very well. Previously all one man boats were unirig only because
the jib was so slow to tack. Look at the A cat. It would be much faster
downwind if it had a little high aspect ratio jib.
Now, this opens the door for SC17s and SC15s to be sailed and raced as a
one person boat with selftacking jibs. I'm sure right now that an ARC17
sailed by one person with main and jib is faster downwind than a $30,000.00
all carbon A cat.
Bill
The self tacking jibs are smaller in area than the standard jibs.
The self tacking jib is a jib sheeting system that makes it easier to
"jibe a spinnaker and jib" at the same time. It also makes it easier to
tack or jibe a boat/jib without spinnaker. It is a convenience thing.
It also opens the door for a one man boat with main and JIB to be
sailed very well. Previously all one man boats were unirig only because
the jib was so slow to tack. Look at the A cat. It would be much faster
downwind if it had a little high aspect ratio jib.
Now, this opens the door for SC17s and SC15s to be sailed and raced as a
one person boat with selftacking jibs. I'm sure right now that an ARC17
sailed by one person with main and jib is faster downwind than a $30,000.00
all carbon A cat.
Bill
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Mac M
- Professional
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- Joined: June 13th, 2012, 5:05 am
- Boat Make/Model: SC17
- Location: Lugoff, SC
Re: Square top and self tacking jib?
Bill,
I asked earlier about adding a straight track to a telescoping beam SC20 and you explained how to do it. Do you think that the telescing beam could handle spinnaker pole as well as the jib track? I have a mount (picture below, mount on the right) I got from Tom for another boat, but didn't end up using it. Would be drilling and tapping the holes through the beam be the way to go to mount it? My other option would be to buy a solid beam from Tom...
I asked earlier about adding a straight track to a telescoping beam SC20 and you explained how to do it. Do you think that the telescing beam could handle spinnaker pole as well as the jib track? I have a mount (picture below, mount on the right) I got from Tom for another boat, but didn't end up using it. Would be drilling and tapping the holes through the beam be the way to go to mount it? My other option would be to buy a solid beam from Tom...