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Mainsail area on a sporty


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10 hours ago, crashtestdummy said:

Is there a point where a large, fathead main with relatively small headail is too much and makes the big slower upwind?

obviously, reaching and running with kites, it would help but I am thinking too big of a main would hinder upwind performance in all conditions

Commengs?

 

 

 

Yep there is a point around 12-15 knots where it’s starting to be too much . There are two boats I race with that have large square tops for light days and moderate top for heavier days . The larger squaretops on those boats are about 1.6 metres from luff to leech I think and the smaller ones 900 mm . Boats are 7 metre and 6.5 metre Elliotts 

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12 hours ago, crashtestdummy said:

Is there a point where a large, fathead main with relatively small headail is too much and makes the big slower upwind?

obviously, reaching and running with kites, it would help but I am thinking too big of a main would hinder upwind performance in all conditions

Commengs?

 

 

 

Are you talking about over powering the boat? or for another reason.

 

JJ

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23 hours ago, johnsonjay17 said:

Are you talking about over powering the boat? or for another reason.

 

JJ

50’ P measurement 18’ E measurement and small foretriangle.  Say 38’ I and 10’ 
 

is that too much power and not enough forward drive?   Seems to me like there is a crossover for sportys where you  would sacrifice upwind performance by having to big of a mainsail 

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35 minutes ago, crashtestdummy said:

50’ P measurement 18’ E measurement and small foretriangle.  Say 38’ I and 10’ 
 

is that too much power and not enough forward drive?   Seems to me like there is a crossover for sportys where you  would sacrifice upwind performance by having to big of a mainsail 

 At some point the loss of the slot effect will make the same area of sail faster with a larger jib smaller main. I just don't know when that occurs. Not sure we are there yet.

 

JJ

image.png

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The best main I had on my Elliott was a squaretop. Every other sail we tried left the boat underpowered. In the few cases where we were overpowered the main was still pretty easy to feather without reefing. We were fully powered up to about 12 knots, anything above that was a lot of twist or traveler down and expensive noises coming from the sail, but it was still fast.

 

IMG_20130803_131139_729[1].jpg

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On 12/7/2020 at 7:31 PM, crashtestdummy said:

50’ P measurement 18’ E measurement and small foretriangle.  Say 38’ I and 10’ 
 

is that too much power and not enough forward drive?   Seems to me like there is a crossover for sportys where you  would sacrifice upwind performance by having to big of a mainsail 

 

Something like this ?

CayuseoverallPic2.jpeg

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Putting more sail area up high will increase your center of effort. However, it makes the sail area more efficient as the lift distribution and the ratio of mast diameter to local chord at the top improve. It is difficult to give a general answer to this question, but I think a moderate square top will outperform a pinhead mainsail upwind in most cases, whereas an extreme fat head will have disadvantages. For example you need a lot of leech tension to keep the sail from twisting in light air, which will also close the leech which would be undesireable.

For some time in the 90s/early 2000s large roach mains were very popular, mostly for their elliptical shape. Nowadays everyone goes with a square top.

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2067200077_Cayouse15.jpeg.21be0fafa0266ec3423cf4c09b798df0.jpeg

26 minutes ago, neuronz said:

Putting more sail area up high will increase your center of effort. However, it makes the sail area more efficient as the lift distribution and the ratio of mast diameter to local chord at the top improve. It is difficult to give a general answer to this question, but I think a moderate square top will outperform a pinhead mainsail upwind in most cases, whereas an extreme fat head will have disadvantages. For example you need a lot of leech tension to keep the sail from twisting in light air, which will also close the leech which would be undesireable.

For some time in the 90s/early 2000s large roach mains were very popular, mostly for their elliptical shape. Nowadays everyone goes with a square top.

Agreed !

Since CAYUSE has no back stay, a square head main will fit perfectly; in the meantime the hi-tech fully battened main in the photo will do especially since I will be listing this boat for sale shortly.

CAYOUSE #10.jpeg

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5 hours ago, glass said:

2067200077_Cayouse15.jpeg.21be0fafa0266ec3423cf4c09b798df0.jpeg

Agreed !

Since CAYUSE has no back stay, a square head main will fit perfectly; in the meantime the hi-tech fully battened main in the photo will do especially since I will be listing this boat for sale shortly.

CAYOUSE #10.jpeg

Looks nice!  What is it/a little history on it/rating, etc would be nice.

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32 minutes ago, JimBowie said:

I assume that's a 1D 35 from Carrol Marine?

You have a good eye because the boat has a hydraulic forestay just like a 1D35, but it was custom built by Eric Goetz.

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https://www.reosportsboats.com/point-of-difference/

With the REO design, Andrew has created a boat with a small rig that excels in 15 knots or more, which is quite common in the Australian summer. With the mast about 30% shorter than a boat of its size would usually have the drag upwind in a breeze is reduced by a similar proportion. The resulting speed to weather in strong wind is quite amazing for a boat of its size.

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  • 2 months later...
  • 2 weeks later...

With these big fat tops don't you have to have split backstays?  I assume that most of these boats also have swept spreaders for some rig stability.

I've seen some older boats mod to a fat head.  With straight spreaders and split backstays you would need someone to be on the backstays all the time, right?

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29 minutes ago, Meat Wad said:

With these big fat tops don't you have to have split backstays?  I assume that most of these boats also have swept spreaders for some rig stability.

I've seen some older boats mod to a fat head.  With straight spreaders and split backstays you would need someone to be on the backstays all the time, right?

Depends. Some boats were designed with no backstay so it's fairly easy to adapt to a Square Top Main.

IMO - they work best on a stiff and stout rig. Carbon preferred. I wouldn't try it on on older thin walled and tapered aluminum section.

A couple of Hobie 33 w/Fat Head Main rig failures come to mind. I'm sure they'd be fine but the margin for error gets smaller.

Twin backstays are a good idea even if the boat didn't originally come with them. Not an issue if rigged correctly.

 

 

 

IMG_2496.thumb.JPG.8580e24df09a1b9f11381c6be0d9741f.JPG

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  • 2 weeks later...
On 3/11/2021 at 4:37 PM, Irrational 14 said:

 

Depends. Some boats were designed with no backstay so it's fairly easy to adapt to a Square Top Main.

IMO - they work best on a stiff and stout rig. Carbon preferred. I wouldn't try it on on older thin walled and tapered aluminum section.

A couple of Hobie 33 w/Fat Head Main rig failures come to mind. I'm sure they'd be fine but the margin for error gets smaller.

Twin backstays are a good idea even if the boat didn't originally come with them. Not an issue if rigged correctly.

 

 

 

IMG_2496.thumb.JPG.8580e24df09a1b9f11381c6be0d9741f.JPG

That is a great looking main.   What's the boat?  Who made the sail?   Columbia logo up there?   Switched from back stay to running backs?  Does that require a winch for the runners or are you able to wind up enough with cascade system?   

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Thanks FTH. This mainsail is on a Columbia 32 Sport (not the carbon version). Ullman Newport Beach was very keen on developing a sail w/me based on the owners input. Cooper Bros nailed it. Luff Curve/Leech Profile/Drag Reduction/Depower Ease, all targets achieved as planned.

It was a different direction than what they would normally do and we were all pretty happy with the end result. The fact that it could be made locally and in house was the key in case any re-cuts were needed. We chose a paneled sail exactly for this reason.

The boat had an extremely large roach main. Too large! All she did was tip over.  2005 called and they wanted their mainsail design back. The 2020 main is in fact less area than the original with a more effective head and less leech fat. Intermediate flutter battens placed in strategic locations for proper twist and control. Beauty!

The boat has a really stiff Southern Spars rig but I found it lacked proper headstay tension upwind since it had no backstay. I promptly added running backs, then tweaked it a bit more with deflectors at the hounds. This gets you to that sweet spot every time without the all the mast compression of normal runners and best of all, no winch required (well maybe sometimes but not much).

Most importantly,we can de-power very effectively. 2 Reefs and a very powerful vang and cunno config. No flogging, just invert the top batten with mega cunno and she's stable. Wap, wap. Requires a really, really strong main halyard though!

 

 

 

 

IMG_3605.jpg.33e43c057ebb6f7013439e2387e75f44.jpg

 

 

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On 3/27/2021 at 2:30 PM, USA275 said:

My thinking is the inverted top batten introduces a lot of drag

Some even argue that you can produce righting moment with an inverter top section...

Either way it's probably best just to reef (if possible), but don't tell that to sport boat owners. Hell, most don't have a reef. 

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