If I did go with an independent sailmaker, it wouldn't be the most class-illegal element on my boat

When I race, I race open class, so class limitations mean little to me, plus, if I ever do resell my boat (which is unlikely since my heart and soul was poured into the thing over this winter) it would not be more than what I paid for it...

Maugan, I like your spirit, and I identify with your love for your boat. Best of luck raising the money for that new sail! Also, while the 17 class has seen a resurgence in the North East the past few years, the number of us sailing with jibs, and with squaretop mains is also growing all the time! Perhaps one day racing rules will be more "open" and there will be enough similar modified boats to have a "class" of their own...? Brian

Its nice to know that I have a fan

In the for what it's worth department...two other H17 sailors in our fleet had identical sail color vintages and each completely came apart some years ago while in a blow.

I'm finally at a point where I look at competitive sails similar to high performance tires. Eventually, they wear out and the newer technology replacements make me wonder how I could have driven on the old ones for so long.

Last season was my first with a Sabre square top. Even though my vintage '89 Hobie sail was not delamintated it was sagging. The differences with a square topped H17 are great. Upwind much more balanced with far more power up high. Off the wind, as long as you keep the leeward telltales flowing, no more being passed by every jib cat in the fleet.

I race portsmouth within the fleet and we use a H17X modifier amongst the 17s (square top, sport, classic uni)to sort out the class. Seems to work well.

My old sail...using it for those recreational days on the water so I can extend the useful life of the Sabre.

Would I ever go back to a stock Hobie sail only to race class legal? Not a chance! The 17 is a really great boat for the money with a lot of room for pushing it's performance envelope. So enjoy it!!

Sail fast, Tom G
H17 USA-190

Yep...had a 17 once. When they delam it happens real real fast. My sail went from perfect to a mess in a month. Now is the time to decide what class you want to sail and make it happen. If the 17 is your dream-buy a sail. If you are interested in other boats-now is your chance. An I-17R is light years ahead, but is a big hit to the wallet. How about a Nacra 5.2 or 5.8? You can get them for a song.

I've put way to much time and effort into this boat to just consign it to a write-off. I'm saving my pennies for a squaretop pentex from Sabre.

Not sure how a square top would work on a 17-might be a good thing as I found it underpowered (I am 200+). On the Nacra 6.0 NA I have run stock sails as well as a Sabre kevlar sqaretop with not much improvement. Most of the 6.0 guys that went to squaretops have gone back to pinheads beacause the PN hit was not made up for in speed. Again, these are very different boats, but having a new class legal sail can be a good thing.

I'm told the squaretop makes a big difference with the 17.

I'm eager to find out either way... I wont let the rating I get be an excuse for my finishing position.

It seems as though whether a squaretop would be an advantage or not would depend on a combination of crew weight and the conditions you mostly sail in.

My understanding of the squaretop is that it gives you a little more sail area and power in light air but depowers the boat in heavy air, because the top of the sail blows off (sort of like a Chinese junk). So if you are a heavy guy who sails in heavy air most of the time, I wouldn't think you would want a squaretop -- you would want to be able to take advantage of all the power you can get get. If you are a heavy guy who sails in light air most of the time, maybe the squaretop would be helpful. A lightweight guy, on the other hand, might really benefit from a squaretop in heavy air because of the way it depowers the sail.

Am I wrong?

you can tune the "blow off" of the top of the square head to your weight by using a combination of batten strength/tension, and mainsheet tension.

I'm sure that I'll have plenty of time in the next year or so it takes me to get the sail, to figure out how to tune it.

Actually, I found the square top to be more tuneable with a combination of batten tension (mine has RBS epoxy battens), downhaul, outhaul and mainsheet tension. Once you dial it in to your weight, the wind conditions and your sailing preference you can move out well.

As far as the PN hit mine was built to less than a 5% size increase so the adjustment is minimal..something like .005%, no big deal!

And yes the top of the sail does bleed the wind gusts but you have control over how much with your top batten tension.

One thing I do notice is the boat sails more balanced. Ever been on an upwind tack in heavy gusty winds with the stock Hobie sail...for me is was up and down..up and down...all gone now!

As with anything new there is a learning curve...remember your boat remains stock but you are changing the sail aspect ratio, the material and the design configuration. All of which has an affect on how your boat will behave. Learning was a good part of my first year..still continues but it is rewarding...Sail fast, Tom G

Via one of the sailmakers websites...these guys say it a lot better than I can.

Sail Shapes

It's rare in sail design when an innovation can add power in light air AND reduce power in heavy air.

Physically, these Mainsails feature an additional batten at the head placed at 45 degrees to the luff. This batten supports the 'Square Top' leech profile. Rather than the standard aluminum headboard, the square top is over 30% wider with a conventional stainless ring which replaces the headboard.

The additional sail area creates more power and efficiency. Some power is added simply due to the increased size. Efficiency is greatly enhanced as the 'Square Top' profile increases the effective aspect ratio which raises the lift coefficient for better upwind performance. Additionally, the added sail area is behind the mast turbulence zone which lengthens the effective luff for enhanced tell tale flow in the upper 30% of the Mainsail. The net result is more speed on all points of sail in light to medium air.

Depowering in heavy air is the second half of the 'Square Top's' advantage. All of the additional sail area is added behind the load path from head to clew. When excessive wind pressure is added, this portion of the sail behind the load path line 'hinges' open automatically which depowers the upper portion of the Mainsail. That's right, automatically. Even if the mainsheet isn't eased, the top of the sail depowers. In many 'marginal' conditions, reefing the main can be delayed as the sail conforms to the puffs automatically.

When reaching downwind with the Asymmetric Spinnaker, the 'Square Top' Mainsail is again a major improvement. By easing the mainsheet, the 'Square Top' automatically 'twists' open at the top 1/3 of the leech. This aligns the Mainsail with the apparent wind angle which is progressively further aft in the upper portions. Your first observation will be the steady leeward tell tale flow, even the ones at the top. In this condition, a standard 'pin head' main twists open in the middle where it has the most roach, leaving the top stalled and under-powered.


Squaretop / Pinhead

Why the new 'Square Top' Mainsail profile? Why do classes with a choice go 'Square Topped? It seems that everyone including A Class cats, to the latest rage in Europe, the Formula 18's, the Nacra Express, Super Cat 22's, and Farrier Trimarans are all winning with Square Top Mains.

Let's start with the obvious. Square Top Mains look bigger than Pin Heads. Sail area can generally be expanded by 7% with a Square Top profile. Just remember that, "Sail Area is King".

But wait, there must be something more than just area. The A Class and the Formula 18 Classes chose the square top without any additional sail area bonus. Yes, the advantages are in fact numerous and spread around the whole race course.

Upwind the Square Top essentially "stretches your mast length" by increasing you effective aspect ratio. This translates into enhanced lift to drag ratios which means more forward power, less hull flying, and higher pointing. In windy conditions a more dynamic advantage for the Square Top is it's ability to lower the center of effort. At first this sounds ludicrous. Is appears that all the added sail area is up high and should raise the center of effort. Actually excessive wind loads push on the square top aligning it with the wind which effectively makes it invisible to the wind. It's as if the Square Top automatically reefs the to portion when overpowered.

A Pin Head unfortunately depowers where the roach is largest; in the middle rather than up high. the result in high winds is the Pin Head must ease the traveler to reduce excessive hull flying which immediately hurts pointing ability.

In summary Upwind: The Square Top can point higher in light air due to the increased Aspect Ratio. In heavy air pointing is enhanced due to the lower center of effort which enables the traveler to stay centered. In all winds you can sail with more sail area while pointing higher.

Off the wind the Jib (and Asymmetric spinnaker) backwinds the lower portion of any Mainsail. This makes the bottom the Main 'see' apparent winds from well forward while the top of any main 'sees' the apparent wind much further aft. Due to the fact that the wind speed is greater at the top of your mast than the bottom the apparent wind is further skewed vertically along the Mainsail. It's no wonder that it's so hard to get the leeward tell tales to flow on the top of Pin Head Mainsails.

Square Top mains solve this dilemma by twisting at the top thanks to the excessive sail area in the head. By adjusting the Mainsheet, twist is easily manipulated. When combined with proper vertical camber distribution (your sail makers job), this makes the entire luff match the 'twisted' wind directions vertically. The bottom line? All your leeward Mainsail tell tales along the luff flow continuously.

For those of you that consume numbers, a sail with attached flow (leeward tell tales are flowing) has 180% the power of a stalled sail (leeward tell tales drooping or spinning). So, the top portion of a Square Top Main that enjoys attached flow is producing 80% more power than an equal sized Pin Head with stalled flow. So a Square Top is really bigger than life.

It's rare in sail design where an innovation can enhance performance in all wind speeds and wind directions. Why didn't we discover the Square Top long ago??

We did!

Or, as I referred to earlier, the Chinese junks. See attachment

Don't think you can call that a square head....the leech angle vs. the luff angle is not right. Would still have the same problems as a pin head (air flowing around the sail). Actually on first glance, I would expect it to be worse than a bermudan pin head (sounds like a bad disease hu?).

Or:

http://www.photoducoeur.com/_borders/starof46.jpg

Will, are you referring to Kevin's catboat or to my Chinese junk -- or both?

Sorry...I was refering to the "junk boat"

The lateen rig with proper sail shape, tension and support I think would do pretty well...except for the weight and windage of the upper most spar.

Will

Actually, that boat pictured has a sailplan that really is more effective than it seems. I remember reading up on the old America's Cup (or the 100 Guiney cup, I think it was called), and there's some way those things work that the top twists off or flattens as the sail is sheeted in higher breezes. I can't remember if they tightened the halyard or not, but some pictures clearly showed the top portion bleeding off wind in the gusts... Even with that old Egyptian Cotton sail material, it almost behaved like a modern mylar square-top...