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luff vs boom length
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adywind



Joined: 08 Jan 2012
Posts: 201

PostPosted: Fri Sep 28, 2012 8:50 pm    Post subject: Reply with quote

I see the point here, the things are interconnected. It looks like at this point we all agree that in general cambered sails being taller,slimmer, heavier etc are at a dissadvantige for early planing compared to the cammless ones . And we can assume that theoretically when comparing simmilar sails from different brands the shorter and fatter ones will plane earlier then the taller and slimmer. Theoretically,because the differences are usually so small that only a lab test could tell for sure . Correct me if I'm wrong.
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DelmarEdward



Joined: 05 Aug 2012
Posts: 23

PostPosted: Fri Sep 28, 2012 8:50 pm    Post subject: Reply with quote

thanks for all the replies, i kind of knew the question would evolve over time as there are maybe too many parameters to consider. Also, none of this is set in stone, as sail technology continues to evolve over time.

Your answers to my original question are helpful, it isn't that it wasn't valid but that there are many things to consider. I already have a large cammed sail, and wonder whereto go next. You know, larger, lighter, less cams? Are the cams too much of a pain in the ass and should be avoided?


sorry if i'm rambling, just got back from dinner with wife-large BBQ rib and chicken platter with several micrro-brews from Four Corners New London,nh.

Tomorrow- 8.5 Retro or 9.9NX at Seabrook after the rain stops.

thanks again.
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U2U2U2



Joined: 06 Jul 2001
Posts: 3056
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Fri Sep 28, 2012 8:54 pm    Post subject: Re: luff vs boom length Reply with quote

DelmarEdward wrote:
All other things being equal, and in lower wind conditions, would you want a longer luff and shorter boom, or shorter luff and longer boom length in a sail for early planing?


seems to me that he is asking which your prefer::

longer luff //shorter boom

OR shorter luff & longer boom

NOT

So, taller masts and longer booms makes the most sense for early planing in light winds and light conditions for the sail you picked.

which has both tall and longer

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zirtaeb



Joined: 03 Jul 2009
Posts: 2331

PostPosted: Fri Sep 28, 2012 8:58 pm    Post subject: Reply with quote

Seems to me he's asking us whether long boom short sails plane up earlier than short boom taller masted sails.
Nobody knows for sure. Current trend in Formula and Slalom racing sails is longer booms, shorter luffs. But it's a trend.
As for cams or not, it's an entirely different ballgame.
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isobars



Joined: 12 Dec 1999
Posts: 13873

PostPosted: Fri Sep 28, 2012 9:23 pm    Post subject: Reply with quote

U2U2U2 wrote:
the original question was longer luff or boom length preference

the discussion now involves cams and race VS non cammed sails, low end, top end early planing

The original inquiry was about earliest planing technology, not preferences. The other factors are technically relevant to that issue. Thus it would seem that the post the most people disagree with is the second one in the thread: "longer luff, shorter boom".


Last edited by isobars on Fri Sep 28, 2012 9:29 pm; edited 1 time in total
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DelmarEdward



Joined: 05 Aug 2012
Posts: 23

PostPosted: Fri Sep 28, 2012 9:28 pm    Post subject: Reply with quote

Yes, the original question was really would a 560 luff and 270 boom or a 580 luff and 255 boom plane earlier, all other things being equal.

I didn't mean it do drift to cam vs non-cam, which is a different story i know.

I've been doing some reading on foil design and it does seem it would be the one with the longer boom primarily because it can support a deeper draft (camber) while the flow stays attached, ie. not stalling. Just having the longer boom length wouldn't necessarily plane earlier if the camber was less, ie. the outhaul also pulled tight.

The topic drifted because as i think about the larger , and possibly cammed sail, i go between "it's worth it" and "no it ain't"

Knowing me, I'll probably end up with several different large sails, cammed and non cammed of various sizes, grow sick of the whole thing, chuck them all and from then on only sail on a Chinnook powerglide.

who knows.
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swchandler



Joined: 08 Nov 1993
Posts: 5699

PostPosted: Fri Sep 28, 2012 9:53 pm    Post subject: Reply with quote

Finally, DelmarEdward is getting to the heart of the matter in my view. The way I look at things, it's the foil that's important rather than whether it's a high aspect or low aspect sail design. Of course, our size and weight has a lot to do with it, but I think it comes down to it whether you like a flat versus deep foil down low in the boom area. For me, I like a flatter sail, but I have to recognize that some folks, particularly big heavier sailors, like a fuller foil.

When it comes down to cambered vs. non-cambered sails, things get a little more complex, especially when cambered sails can incorporate one or two cambers vs. quite a few more. From my experience, non-cambered sails are my current preference for easy rigging and durability launching in surf environments. But that said, nothing beats the upwind ability of a cambered race sail. If you really want to travel, or race for that matter, those cambers really are your friend, especially if the conditions are variable.
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U2U2U2



Joined: 06 Jul 2001
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Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Fri Sep 28, 2012 10:43 pm    Post subject: Re: luff vs boom length Reply with quote

DelmarEdward wrote:
All other things being equal, and in lower wind conditions, would you want a longer luff and shorter boom, or shorter luff and longer boom length in a sail for early planing?


I see that "would YOU want" has a different meaning than personal preference, when being read by some, in a sail for early planing.

my answer stands, what I want is a longer luff shorter boom, for earlier planing.

and all this cam, foiled discussion, is mute, cause all other things are EQUAL.

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U2U2U2



Joined: 06 Jul 2001
Posts: 3056
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Fri Sep 28, 2012 10:59 pm    Post subject: Reply with quote

isobars wrote:
U2U2U2 wrote:
the original question was longer luff or boom length preference

the discussion now involves cams and race VS non cammed sails, low end, top end early planing

The original inquiry was about earliest planing technology, not preferences. The other factors are technically relevant to that issue. Thus it would seem that the post the most people disagree with is the second one in the thread: "longer luff, shorter boom".


TO help you out a bit, 3 others have said what I did, Konajoe, Adywind and techno900, 3 said longer boom, jingebritsen, zirtaeb and Carl.
2 posted essay answers without a committment puffin & swchandler,
with bred2shread saying both tall and long,

Certainly NOT what you posted is supported " THAT MOST PEOPLE DISAGREE" with me.

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jingebritsen



Joined: 21 Aug 2002
Posts: 2378

PostPosted: Sat Sep 29, 2012 3:56 am    Post subject: Reply with quote

watch out for spread sheet comparisons. the drop clew makes that type of numbers crunching a trap. typically, as the luffs have gotten shorter, the roaches have been getting beefier, and the battens immediately above the boom have gotten longer. simple physics, if you shorten the luff, the area has to come from somewhere else.

different brands have their strengths and weaknesses. i've directly compared RAF vs cam. cams are more stable. more able to achieve higher top end speeds. even the two cam sails within the aerotech line do this.

the first prototype i tested a while back when we went from a narrower luff sleeve back to a larger one was significantly better than the previous models. the current rapid fire hole shots great, goes fast, and turns better than fully blown race sails.

if i sail against my typical tuning partner on the RF, he may get me in the straights, at times with his VMG, but i kill him in the corners and most times edge him out in slalom runs. for purely recreational sailing, light wind pumping, and overall versatility, i prefer the phantom. but that only sizes up to a 7.5. if you want larger, then freespeed, RF, or VMG are your choices.

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