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-   -   Overlapping versus Blade headsails which is quicker ? (http://www.sailnet.com/forums/racing/86724-overlapping-versus-blade-headsails-quicker.html)

bill@custardpie 04-27-2012 06:15 AM

Overlapping versus Blade headsails which is quicker ?
 
OK maybe this is a simplistic question but:

Scenario :

Beat to windward in a Force 3-4, flatish water, standard production 21st century cruiser/racer fractionally rigged

Dilemma:

If you have a choice between an overlapping 120% genoa sheeted around the shroud or a smaller say 100% blade jib sheeted to barber haulers inside the shroud.

Lets assume the blade will get you close to the speed the polar diagram predicts. Will you get anything more from the 120% genoa ?

Which do you go for ?

Irunbird 04-27-2012 08:38 AM

Re: Overlapping versus Blade headsails which is quicker ?
 
Not quite sure exactly what you're asking. Are you more interested in speed or pointing ability? These things will depend on more conditions than just wind strength- things like hull shape, keel length and ballast, number of crew (more hiking if you're racing, for example). If not pointing ability, and you don't mind a little more heel, I'd go with the 120% genoa, which really isn't that big compared to the blade... What we do on our J24 may be different, but if I have all of our crew (5 total) up to about 18 mph (about F4) of breeze we use the genoa (which is a 140%), and I just use a combination of traveller and backstay to keep the boat flat in the puffs. Wait till one of the mods (like Jeff) answer; you'll get more of what you are asking soon. I'm still kinda new at this.

Ray

Faster 04-27-2012 10:59 AM

Re: Overlapping versus Blade headsails which is quicker ?
 
Yeah, I think for any specific boat in specific conditions this would be a 'trial and error' situation.. you'll need to figure out which configuration ultimately gives you the best VMG to weather... and what works best in flat water may not work best in chop.

But, as Irunbird said lets wait to see what the 'H's (Jeff and/or Rich) might have to say.:)

RichH 04-27-2012 01:40 PM

Re: Overlapping versus Blade headsails which is quicker ?
 
Quote:

Originally Posted by bill@custardpie (Post 863966)
OK maybe this is a simplistic question but:

Scenario :

Beat to windward in a Force 3-4, flatish water, standard production 21st century cruiser/racer fractionally rigged

Dilemma:

If you have a choice between an overlapping 120% genoa sheeted around the shroud or a smaller say 100% blade jib sheeted to barber haulers inside the shroud.

Lets assume the blade will get you close to the speed the polar diagram predicts. Will you get anything more from the 120% genoa ?

Which do you go for ?

On a frac rig, most probably the blade will result in a faster sail plan output .... and enhanced pointing ability.

Reason: a blade 'can' be sheated INSIDE of the shrouds and without fouling on the spreaders .... and can be more easily adjusted to the defining 'slot open' distance. In F3-4 that 'attack angle' (tack to clew) is probably going to be somewhere on that 10 line offset from the tack.

If the 120 fouls with the spreader .... "no soup for you !"

Of course, you yourself have to do 'trials' with reference to correct 'slot open distance' vs. VMG once you get close to your final decision. When youre in this final stage of optimization, forget any so-called backwinding to the main ... simply finalize your plan based on speedo output and VMG.

sailingfool 04-27-2012 01:51 PM

Re: Overlapping versus Blade headsails which is quicker ?
 
Its pretty clear that any race boats, not constrained by class or formula rules to a non-overlapping headsail, use the largest genoas permitted by the wind strength.

In a serious race fleet beating to a windward mark in under 18 MPH wind speed, it is unlikely to be a single boat not flying a 150%, other than those boats whose rating/formula/class choses to exclude more powerful headsails. Maybe the more tender boats actually will drop to a 130%...

RichH 04-27-2012 11:00 PM

Re: Overlapping versus Blade headsails which is quicker ?
 
Quote:

Originally Posted by sailingfool (Post 864085)
Its pretty clear that any race boats, not constrained by class or formula rules to a non-overlapping headsail, use the largest genoas permitted by the wind strength.

In a serious race fleet beating to a windward mark in under 18 MPH wind speed, it is unlikely to be a single boat not flying a 150%, other than those boats whose rating/formula/class choses to exclude more powerful headsails. Maybe the more tender boats actually will drop to a 130%...

Thats not the current trend in maxis and other top class boats, especially with frac. rigs with square top mains, etc. The 'trend' is definitely going towards blades instead of large LP overlappers on FRAC rigs.

With mast head boats the only way you can adequately use a large LP is to shorten up the spreader length and usually to keep it inside that 10 tack-clew line.

Many of the one design fleets and 'development classes' are doing the same ...

bill@custardpie 04-28-2012 06:08 AM

Re: Overlapping versus Blade headsails which is quicker ?
 
The spreader length is an interesting point.

On a beamier boat the shroud would presumably hit the deck further out and the spreader would be longer as a result you can't sheet as close inboard. You don't get anywhere near the 10 degree sheeting angle.

So on an older boat(eg a 12metre, contessa, sigma 38 that sort of thing) which is probably not going to be as broad you can get away with the overlapping genoa and still make a good VMG. On a more modern design with a flatter broader hull (TP52, most modern cruiser racers etc) you are going to do better by going for a non overlapping headsail sheeted close to the centre line...

That would definitely explain what I'm see with our Hanse 430.

sailingfool 04-28-2012 11:31 AM

Re: Overlapping versus Blade headsails which is quicker ?
 
Quote:

Originally Posted by RichH (Post 864289)
Thats not the current trend in maxis and other top class boats, especially with frac. rigs with square top mains, etc. The 'trend' is definitely going towards blades instead of large LP overlappers on FRAC rigs.
...
Many of the one design fleets and 'development classes' are doing the same ...

I agree the blade has some current popularity as I day above:
"....other than those boats whose rating/formula/class choses to exclude more powerful headsails."

I cant say what the tread is or is not for maxis, but you see plenty of them still flying overlapping headsails:
2010 Photo Galleries
ANd certainly the VOR70s with their large square top mains, all carry large genoas.

So if you buy a new Swan 42 or J109 whose class headsail is a blade...you race with a blade when you race one-design. But we regularly see one design boats like the J105 or J109 coming out for a race, and we judge what fleet/rating they are racing at...if they are flying a blade, they are racing at their slower "one design" rating, if they are flying a 150%, they are racing at their faster non-one-design rating. Maybe the handicappers need to read this tread?

There are a number of benefits to a blade but I dont think that superior low to mid wind performance is one of them.

hellosailor 04-28-2012 12:20 PM

Re: Overlapping versus Blade headsails which is quicker ?
 
bill, I'd suggest you have to experiment because among other things it wil depend on the specific boat and rig. For instance, on a J/24 the spreaders may ship from the factory two inches longer than the class association requires. If you're on a stock boat, your 150 will hit the spreaders two inches before it needs to.

But if you cut the spreaders down to the minimum length (yes, take a hacksaw to your rigging!) the genoa now comes in two inches closer and you can point higher without tearing the sail.

Polars? Theories? A good set of polars should in theory tell you what has been found fastest on your boat. All well and good, but sometimes you need to check everything and then experiment. I'd bet the condition of your sails (main and fore) and the shape they take is going to affect that as well, so what works best on one boat, just may not be the fastest on the other.

rgscpat 05-01-2012 03:06 AM

Re: Overlapping versus Blade headsails which is quicker ?
 
Racers who have to race in mixed handicap fleets also have to consider handicaps whereas one design racers may be funneled into certain sail sizes because of class rules.


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