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Go Back   SailNet Community > Out There > Racing > Overlapping versus Blade headsails which is quicker ?
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Thread: Overlapping versus Blade headsails which is quicker ? Reply to Thread
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Topic Review (Newest First)
05-29-2012 07:41 PM
Jeff_H
Re: Overlapping versus Blade headsails which is quicker ?

Thanks Rich...
05-29-2012 04:29 PM
RichH
Re: Overlapping versus Blade headsails which is quicker ?

ahhhhhh .... leech timing to perfection.

;-)
05-29-2012 03:44 PM
Jeff_H
Re: Overlapping versus Blade headsails which is quicker ?

Rich,

This is probably the other picture that you really wanted to make your point. Unfortunately we (Synergy and I) are not quite back up on a beat yet.

Jeff


[IMG]Photobucket[/IMG]
05-29-2012 01:37 PM
RichH
Re: Overlapping versus Blade headsails which is quicker ?

Quote:
Originally Posted by puddinlegs View Post
IMHO, self-tackers without a boom are pretty much useless, but I'm not expecting anyone to share my small thought on the matter.
Totally agree you. Without a (vanged) 'boom' or clubfoot there is no effective way to control 'twist' when the clew is outboard. This is usually always seen especially on cutter rigs with only staysl and reefed main flying ... without a means to prevent the clew from rising, the upper panels of the stay'sl will be unattached to airstream flow/stalling, the foot overtrimmed and only a small zone of the middle part of the sail 'actually' working ..... same thing with almost ANY jib when the clew is well outboard. Even with fore/aft fairlead, etc. adjustment, etc. to control clew height ... with a sans 'boom' arrangement the jib will 'naturally' become deeper drafted .... more powerful but 'slower' when the clew is well 'outboard'. FLAT is faster in most conditions (in relatively flat water, etc.)

In the olden days before the 'rules changes' ... a reaching strut or jockey pole was used to help control the 'clew rise'. The Hoyt Boom in this respect is perhaps the best way to do this ... but unfortunately is impossible to apply to an 'overlapping' jib/genoa.
;-)
05-29-2012 02:23 AM
puddinlegs
Re: Overlapping versus Blade headsails which is quicker ?

Quote:
Originally Posted by Jeff_H View Post

The problem with the Hanses is that they are surprisingly high drag for a modern design, and do not have all that much standing sail area. They are also limited by their next to useless self-tacking set up which means that the normal jib is very small (90% or so), and does not set as well as might be ideal. It sounds like you have a custom set up which may let you use a 105-109% headsail.

Jeff, having just seen a Hanse 47, we watched the owner's crew takes down the self-tacker (yes, it's a really odd set-up... from the track, to the base of the mast, up the mast, in the mast, back down the mast, back to the cockpit ) and hoist a standard jib lead to standard genoa tracks/adjustable lead cars on the deck while preparing to race. I'm sure the boat sailed much better with the standard jib than with the self tacker. IMHO, self-tackers without a boom are pretty much useless, but I'm not expecting anyone to share my small thought on the matter.
05-25-2012 12:31 PM
WDS123
Re: Overlapping versus Blade headsails which is quicker ?

OP mentioned he sails at his Polars with the Blade.


Question would then be can he sail better than his Polars with a 155 ?


I doubt it.
05-25-2012 12:03 PM
RichH
Re: Overlapping versus Blade headsails which is quicker ?

Simply look at JeffH's avatar ....

Youll notice immediately that the leech of the jib is (for the most part) operating in close proximity and 'just before' to the 'point of maximum draft' (POMB) in the main. What this positioning of jib's leech to POMB of the main is doing is yielding maximum 'bootstrapping' of two sails or which affects the best 'dumping velocity' from the jib to the main ... for maximum interaction flow between the two sails. Once the jib leech overlaps beyond or aft of the POMB of the main, aero-efficiency of the combo will start to rapidly decline .... although one can 'muscle' more speed (but not necessarily more 'lift' in direct proportion to the increase in SA) by increasing SA with a larger overlap.

I perceive this configuration is why the 'modern' frac rigs are generally carrying a lower LP jib and rarely a large LP jib ... for the combo of best boat speed AND pointing ability irrespective of 'sail area' considerations alone, ... also ignoring the geometry problems associated with sheeting angles on large headsails.

Whether this config. was determined aerodynamically or simply iterated by trial and error, it 'seems' to be in accordance with that which theoretically generates maximum aerodynamic conditions and output.
05-25-2012 09:56 AM
Jeff_H
Re: Overlapping versus Blade headsails which is quicker ?

I agree that there are some rigs where a #2 is necessary. Its one of my big gripes with the CCA and IOR era rig proportions where the 155's are too big once the wind gets over a certain point, yet the jib is the prime motivator so that you can't afford to go down to a #3.

The original poster is talking about a modern fractionally rigged boat, where you don't need the extra sail in a #2 since you can power up and down to fill the gap, and frankly, due to the rig geometry a #2's lousey sheeting angle becomes the limiting factor for the whole boat when going upwind.
05-25-2012 01:53 AM
SchockT
Re: Overlapping versus Blade headsails which is quicker ?

Quote:
Originally Posted by Stumble View Post
As mentioned above it really depends on the boat.

But typically a #2 (say 115-135) is the worst possible sail for any conditions. If you coukd ignore the spreaders and stay you could get a decent sheeting angle on them, but obviously you can't. This requires you to move the lead well outboard of the ideal sheeting angle. A 155 by comparison while having to go just as far outboard, also gets to come much further aft. So the angle between the centerline of the boat, and the line made from the tack to the clew is much smaller.

This is why most racing boats go from a 155 to the largest inside overlapping sail they can fly (typically a 115 or so). Not because reducing sail area isn't desirable, but because when you reduce area you also increase the sheet angle to such a point that it kills your pointing ability. And for most boats it is faster to be slightly over powered than to have to give up the pointing ability. Though there are boats this isn't true on, particularly very narrow for the leingth boats like an Olson 30, or Hobie 33.
That's not necessarily correct. In the area I race in, most boats have a #2 and they will shift down to that before they go with a #3. Perhaps it is because we are in a light to moderate wind area. There are many times when the #1 is too much power, but the #3 is not enough.

Tight sheeting angles on the headsail is not always what you are looking for, and the slot effect of overlapping sails should not be discounted.
05-24-2012 05:29 PM
Stumble
Re: Overlapping versus Blade headsails which is quicker ?

As mentioned above it really depends on the boat.

But typically a #2 (say 115-135) is the worst possible sail for any conditions. If you coukd ignore the spreaders and stay you could get a decent sheeting angle on them, but obviously you can't. This requires you to move the lead well outboard of the ideal sheeting angle. A 155 by comparison while having to go just as far outboard, also gets to come much further aft. So the angle between the centerline of the boat, and the line made from the tack to the clew is much smaller.

This is why most racing boats go from a 155 to the largest inside overlapping sail they can fly (typically a 115 or so). Not because reducing sail area isn't desirable, but because when you reduce area you also increase the sheet angle to such a point that it kills your pointing ability. And for most boats it is faster to be slightly over powered than to have to give up the pointing ability. Though there are boats this isn't true on, particularly very narrow for the leingth boats like an Olson 30, or Hobie 33.
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