parclan

Asymmetrical spin (only) takedown

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My son and I flew our Asym spin this weekend for the first time ever.  It is a small spin on my Bene First 375 - the kind with the saddle that buckles over the furled jib. 

Anyway,  it was the only sail up on a long, hot, slowish, slog with wind angle about 20 degrees off DDw. The TWS was about 12 knots. The take down did not go well for us, and the sail did tried to sein for shrimp. But we got it back in without incident or damage.

How do you douse the asymmetrical spin of it is the only sail up? No main sail to hide behind? 

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This may seem to go against instinct but with no other sails to cast a shadow, I would turn until the wind was forward of the beam until the sail was luffing and then lower it. This allows you to bring the clew in where you can reach it and the sail will be less loaded.

You should hustle though, you don't want the thing flogging or getting hung up on anything.

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Frankly I’d never fly a chute without the main up except maybe in VERY light air.

If you insist, you might try blowing the tack first which lets the sail stream out forward, and use the clew/sheets to gather it in and pull in along the sail foot until the sail is gathered enough to drop the head .

or get a sock for it

See this for tack blow and sock technique 

https://catamaranimpi.com/2018/02/13/the-beast/

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My boat is about the same size, I suspect your spin is a bit bigger. Blanketing it with the main helps. I have a sock and snuffer which also helps but the whole package of sail, bag, sock, snuffer and the extra halyard to raise the sock is big and heavy. If I were starting over I would look at a Harken top down furler. More money and it seems to take some practice, but once set up seems to work well on a friends boat that is larger than mine.

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Top down furler: advantage - easy. con - really slow to furl.  For short handed with a big sail it's a good and safe option, with enough hands the other advice here is good. With 2 getting the asym (or any spin) down will be a bit of an adventure, the furler being the least adventurous. Having the main up helps a lot. 

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A friend of mine bought top down furlers for his 37 footer. What a righteous pain in the ass. To begin with, they make the kite 3X larger to stow, which on a boat under 50' sucks. If you have one, it's like having a dead NBA center stuffed in a bag down below. Secondly, they're slower than f-k all to furl unless you have someone spinning a pedestal. You have to get the torsion line loaded up in order for the thing to begin twisting/furling. It sucks. 

Just hoist the bloody main and letterbox the damn thing and save yourself a shit ton of $$ and aggravation.

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So how do you hoist the main if you're already headed almost downwind? It requires heading up into the wind, and with the asym spin already up, thats a problem....

I think what we needed to do (better/more of) was dump the sheet all the way as we rounded up and just let it flutter aft until over the boat as we come into the wind. Then when as much of it as possible was fluttering over the deck, start dropping the halyard and gathering in as fast as possible, with the tack being released last - to keep it from going aft behind the boat all the way. if I can convince either of us to do it again, I may just try that approach.

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The real question is, "Why do you hate your mainsail"?

 

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2nd on having main up. This reminded of something years ago - 40'er new to owner, shake down cruise, coming back main and kite up, coming to harbor so dropping chute, blowing maybe high teens and the chute wraps on headfoil, hard, couple of spots and not going to pull out. Owner tells crew to get bosun chair and knife to go and cut it, we have 5 to 10 minutes before running out of water, while this is going on I finally convince the owner to gybe and voila, it unwraps  and we get it down.  It's always easier to get a kite down behind sails, for sure the main but the jib also helps (and if it is up or unfurled not going to wrap the kite).  I decided not to race with these guys ......

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1 hour ago, NoStrings said:

The real question is, "Why do you hate your mainsail"?

 

FWIW, I can sail much deeper with just the asym and no main, almost DDW, albeit a bit slower. Fairly confident the VMG favors a hotter angle and gybing though.

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Speaking of VMG... a sly old salt taught me this:

To break-ahead for loss of VMG off DDW:

If you come up 10 degrees, you have to go 2% faster;

20 degrees, 7% faster;

30 degrees, 15% faster;

40 degrees, 31% faster. 

As you see, it’s not often worth going DDW; you only need 2% gain in speed at 10 degrees higher angle

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Just blow the tack AFTER getting hold of the sheet.   Right after the tack, blow off about 10 ft of halyard then stop while you collect the bottom of the sail.   Be ready to dump more halyard as you get the sail shoved into the companionway.  The sail should collapse and/or flag out from where you are gathering it.

 You could start the engine to motor ahead downwind to reduce apparent wind.

--Kevin  

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Two relatively easy ways, 1. As already mentioned by several folks, dump/blow the tack, while holding sheet. Sail will stream away from boat. Then ease halyard as you take in sheet. Requires a long tack line. That runs cleanly.

2. Attach a retrieval line to the tack. Lead retrieval line to foredeck hatch. Dump the sheet, then ease the tack line as someone in vee berth hauls in on retrieval line. Once tack is in/near hatch, ease halyard. Make sure retrieval line is lead to leeward of headstay, above lifelines, and forward ofshrouds.  

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8 hours ago, Max Rockatansky said:

Speaking of VMG... a sly old salt taught me this:

To break-ahead for loss of VMG off DDW:

If you come up 10 degrees, you have to go 2% faster;

As you see, it’s not often worth going DDW; you only need 2% gain in speed at 10 degrees higher angle

thanks for posting that, Max.

I had never bothered doing the trigonometry on downwind VMG, but you prompted me to do a wee spreadsheet to make a crib card. 

I think the most interesting aspect of is that even heading up as far as 30° needs only a 15% speed gain to break even.  So in the lighter stuff even a 4ksb will probably benefit from coming up a long way

vmg.png.7fe63da3ccaf0df3bfa24b97ae497c29.png

vmg.png

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FWIW, twolegged, at 20 degrees it’s 7%. I’ve never run the calcs but I have notes from when the fella told me these numbers on two different occasions 

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5 hours ago, Max Rockatansky said:

FWIW, twolegged, at 20 degrees it’s 7%. I’ve never run the calcs but I have notes from when the fella told me these numbers on two different occasions 

Max, with respect, I think your pal made a rounding error on that one.  Or maybe he was deliberately rounding up?

At 20°, I calculate the extra distance as 6.417777247591214080957060222167% ... based on the formula (1 - Cos A) / Cos A

That's school trigonometry from my long-ago schooldays (before the days of recorded music :D) and my maths is well rusted.  So maybe someone with post 19th-century maths can check my formula

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Not to discount your efforts, as I am an engineer, but I trust my friend’s many years of experience and his history of race wins. 7 it is. 

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I think the difference may be that one person is using trig and a spreadsheet and the other is using trig and a sailboat. I could easily see leeway, sail efficiency, and other factors causing real-world adjustment to the theoretical numbers. 

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2 hours ago, IStream said:

I think the difference may be that one person is using trig and a spreadsheet and the other is using trig and a sailboat. I could easily see leeway, sail efficiency, and other factors causing real-world adjustment to the theoretical numbers. 

IStream, your comments suggest that you misunderstand the nature of these numbers.

These numbers are simply the boundaries of when a speed/distance tradeoff becomes positive.  They are not about how that speed is achieved ... so sail efficiency doesn't alter the calculation.   It's just one of the factors in how you may gain enough speed to make tacking downwind a worthwhile exercise

And when tacking downwind, leeway works in your favour.  So any leeway lowers the extra speed needed

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I have had success using a snuffer and can single-hand my asymm.

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On 8/2/2018 at 7:59 AM, TwoLegged said:

Max, with respect, I think your pal made a rounding error on that one.  Or maybe he was deliberately rounding up?

At 20°, I calculate the extra distance as 6.417777247591214080957060222167% ... based on the formula (1 - Cos A) / Cos A

That's school trigonometry from my long-ago schooldays (before the days of recorded music :D) and my maths is well rusted.  So maybe someone with post 19th-century maths can check my formula

My trig was also learnt in the past millenium though after recorded music but it is not rusty as I use it nearly daily and I agree with you... it is indeed (1 - Cos A)/ Cos A and for 20º it works out at 6.4% In my youth I've raced with somebody who had raced at a very high level and on downwind legs he used to  follow a course all over the place to catch puffs or get a tactical advantage and when I asked about it he told me that up to 10º the extra distance is negligeable which is indeed true.

I just have to say that once per year I teach some engineering and I gently poke fun at the students who come up with that many decimals. It goes along the line, "We have some very skillful people in this room who are able to tell us the force exerted by this slab / post / beam / whatever within 0.0001N (or whatever they've said/written) to measure this we would need a scale able to weight a microgram, we are talking buildings, I am a much more modest engineer and 3 significant digits will be enough for me" Everybody laugh and they stop doing it PDQ.

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On ‎8‎/‎2‎/‎2018 at 10:56 AM, IStream said:

I think the difference may be that one person is using trig and a spreadsheet and the other is using trig and a sailboat. I could easily see leeway, sail efficiency, and other factors causing real-world adjustment to the theoretical numbers. 

Yeah, the harder part is determining if that 6% speed increase is on account of the hotter angle, wind shift or increase, direction of waves, current, etc...

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29 minutes ago, Starboard!! said:

Yeah, the harder part is determining if that 6% speed increase is on account of the hotter angle, wind shift or increase, direction of waves, current, etc...

It don't matter how you're getting the increase.  It just matters whether or not you are getting it

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1 hour ago, Panoramix said:

I just have to say that once per year I teach some engineering and I gently poke fun at the students who come up with that many decimals.

touché, mon ami :)

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25 minutes ago, TwoLegged said:

It don't matter how you're getting the increase.  It just matters whether or not you are getting it 

Kind of, but if the speed only went up b/c the wind increased, then maybe the speed would have increased just as much or more staying on the original [shorter distance] angle?  Or maybe you just were not trimmed well on course#1. 

My point is that just being faster at different angle won't necessarily win. You should also know why you're faster too. Or else you're just chasing hotter angles and possibly giving up speed on what would have been a shorter course.

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how about "gybe" the boat (but not the kite)for a weather takedown?

Keep the sheet on, the kite's now backed up into the shrouds and the triangle, blow the tack, bring it down in a controlled manner? it "should" just fall onto the gatherer on the deck.

 

 

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13 minutes ago, Raz'r said:

how about "gybe" the boat (but not the kite)for a weather takedown?

Keep the sheet on, the kite's now backed up into the shrouds and the triangle, blow the tack, bring it down in a controlled manner? it "should" just fall onto the gatherer on the deck.

 

 

I think it's called a Mexican take-down, you want to unfurl the jib though so it traps the kite nicely over the deck.

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12 minutes ago, Starboard!! said:

My point is that just being faster at different angle won't necessarily win. You should also know why you're faster too. Or else you're just chasing hotter angles and possibly giving up speed on what would have been a shorter course.

If you are watching the knotmeter while you adjust course, you can usually see in a minute or two whether coming up has paid off.   There won't usually be much change in the wind in 2 minutes.

It's only when crew are slow to re-trim or there's a marginal chance of surfing that it takes longer to evaluate

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Can't believe no one has brought up the infamous Samurai Douse...

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not sure how the saddle thing might affect things.., but blowing the tack would probably be the best solution...

but i would use a trigger shackle and blow that if there was any breeze at all. This will really protect against it filling again, or shrimping, for any reason on the way down.

only downside is you will have to re-run the tapes to set again

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On 8/1/2018 at 12:07 AM, NoStrings said:

The real question is, "Why do you hate your mainsail"?

 

Yes, and if you manage broach with just the kite up, recovery ain't going to be easy.

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On 8/1/2018 at 11:28 AM, tiz said:

Just blow the tack AFTER getting hold of the sheet.   Right after the tack, blow off about 10 ft of halyard then stop while you collect the bottom of the sail.   Be ready to dump more halyard as you get the sail shoved into the companionway.  The sail should collapse and/or flag out from where you are gathering it.

 You could start the engine to motor ahead downwind to reduce apparent wind.

--Kevin  

+1 ^this^ 

I do it single handed on my J/109 using the autopilot.  Sail deep - almost DDW.   Haven't needed to start the engine.  The sail is depowered when the tack is released.

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On 8/1/2018 at 11:28 AM, tiz said:

Just blow the tack AFTER getting hold of the sheet.   Right after the tack, blow off about 10 ft of halyard then stop while you collect the bottom of the sail.   Be ready to dump more halyard as you get the sail shoved into the companionway.  The sail should collapse and/or flag out from where you are gathering it.

 You could start the engine to motor ahead downwind to reduce apparent wind.

--Kevin  

+2.

This video at 8:33 shows a single-handed letterbox drop.  Don't rush dropping the spinnaker halyard: add some drag to the spin halyard to slow the douse so you're not shrimping (wrap a few turns on the winch drum).

Here's a good video I saw at the Chesapeake Bay Shorthanded Sailing Society, although its using a symmetric, it's got lots of good ideas (I like the idea of dumping the spin halyard over the stern for extra drag and keeping the halyard free).

Like d'Ranger, I've mixed feelings about the top-down furler: it's definitely safer for singlehanding, but slow for the amount of effort you put into furling and dousing the furled up kite (the spin bag does get pretty heavy with the furler and torsion rope). Everything has its advantages and disadvantages.

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