Genoa and Assymetrical only speeds and handling

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SailorC
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Genoa and Assymetrical only speeds and handling

Post by SailorC » Sat Feb 01, 2020 12:40 am

How often do you sail with just your genoa (no main) and what kind of speeds are you seeing, and in what wind speeds and direction? Also, how are tacks and gybes with the 150%?
Same info flying your assym is also appreciated.

There was a 32 I saw for sale, a pretty old ad on 2hulls, that had a 180%! Sheets ran to the stern, very curious to know her speeds and how she tacked and gybed.

The self tacking jib is meh in anything light to moderate.

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thinwater
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Re: Genoa and Assymetrical only speeds and handling

Post by thinwater » Sat Feb 01, 2020 7:36 am

There is quite a bit of PDQ 32 trim stuff on my blog.

Genoa Upwind.You are not going to be able to point to windward with more than ~ 120% genoa. This is because you need to sheet up against the hard top, which means rolling up some genoa. With a 180, the sail shape with probably be horrible after reefing. http://sail-delmarva.blogspot.com/2013/ ... an-90.html

You also need inside tracks to tack through less than 120 degrees with a genoa.

I am not a fan of sailing with genoa alone for several reasons.
* Leeway. The sail is too far forward and you will have lee helm. Sailing to windward will be horrible and you won't be able to tack.
* Furling. In any sort of breeze the strain on the furling gear is much more, since you cannot blanket the sail behind the main. In light winds you need the main to GO.
That said, off the wind, reef the main first. The balance will be better.

Same with the chute. Getting it down, in anything other than very light winds, is a problem without the main.

Hoisting the main should be easy, and it makes everything else easier.

The self tacker is not just low on power, the balance is wrong. A genoa will tack better too (if 120% and inside track). I also modified my keels to improve speed, pointing, and tacking. Heck, I stretched the boat 2 feet.https://www.practical-sailor.com/boat-m ... -the-keels
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Re: Genoa and Assymetrical only speeds and handling

Post by Jwood1 » Fri Feb 14, 2020 3:42 pm

I agree with Thinwater. On his recommendation, I installed a 120% genoa when I replaced my sails. I bought a new main, genoa and spinnaker from Mack Sails. I can't imagine using a 180% genoa, that sounds unmanageable. I did this right after I bought the boat, so I never experienced the self tacking jib. I run the sheets to the aft cockpit winches. For a beam reach or broad reach, the sheets are run outside through the block on the outside track. For a close reach, I run them inside through a temporary block I rig at the midship cleat. I have tracks and blocks ready to mount for the inside sheeting as Drew describes in his blog, and this should really improve my windward performance.

I haven't used the genoa only, without the main, for reasons that Drew mentions.

When reaching, I do use my spinnaker only, without the main, and it works great. In light air, the main tends to block the air making it hard to fill the spinnaker. I've seen greater than 6 knots SOG with spinnaker alone in 12-15 knots of wind.
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thinwater
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Re: Genoa and Assymetrical only speeds and handling

Post by thinwater » Mon Feb 17, 2020 1:13 pm

I suppose I've always been something of a sail trim maven. I like to to feel the boat move to perfection. I suppose that is why I tweaked the sail plan and underbody.

Unless you are trying to sail with the AW aft of 120 degrees, the main should actually help the chute fill, by keeping the flow attached and in effect, pulling the air away from the leach. The main will not be all the way out; the traveller will be well down, but a foot or so from the stop, and the sheet allowing only limited twist. The tack of the chute should be attached to the windward bow using a bridle. The spin sheet should be eased enough to allow the chute to rotate to windward, just short of collapsing. You may need a down haul on the spin sheet to control twist on the chute (you want it breaking evenly, top to bottom.

Your goal should be apparent wind = speed over ground. That's less than windspeed, but not that much.

[Speed polar]
Image

[Sheet downhaul]
Image

[Bridle]
Image

[Keep the head off the mast, and let it rotate to windward.]
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[My first boat with a chute. Home made and designed, about 1975]
Image

I kinna miss my PDQ. But the F-24 is a riot in a breeze. Zoom. In real terms, not that much faster, but it feels way faster. The PDQ 32 is pretty quick, well handled.
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SailorC
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Re: Genoa and Assymetrical only speeds and handling

Post by SailorC » Wed Feb 19, 2020 4:09 pm

Thank you both very much!

My buddy has the shorter rig with stock main and self tacker. Like a lot of people going to catamarans it's partly due to health problems. Thus, looking for easier handling, smaller loads and lines and climbing on deck, etc. So we were talking about solutions to still get decent speed out of running one sail only.

When we took her out he had us raise and lower the main. He has considered a fuller, sq top main, but I'm afraid that would strain him too much hoisting and then having to go to the mast to drop and flake. We also unfurled the self tacking jib, as we all know, pretty useless (at least in light to moderate winds we saw and has been his experience). So then we discuss - what about getting a 150% and just fly that? Motor upwind, tension the main halyard/topping lift on the boom, then crack off with the genoa. Still be a 5kt - 7kt boat?

If anyone has 150% genoa only stats that would be great.

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thinwater
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Re: Genoa and Assymetrical only speeds and handling

Post by thinwater » Thu Feb 20, 2020 11:37 pm

Furling a genoa in 15-20 knots with no main is probably more vigorous than hoisting a reefed main and some jib. Certain, damamge is more likely. Same with a chute. If it's just for drifting in light air, then OK. But then you'll want the main if you want to sail past walking speed.

I've sailed main only many times, but I'm just not a fan of head sail only. Dropping the main in a blow is easy.

Estimating the speed is not that hard. As a first approximation, look at the reduction in sail area and reduce the wind speed to off set. For example, if the genoa is 1/3 of the sail area, then use windspeed =(1/3)^0.5. That means broad reaching in 10 knots is more like 4 kt boat speed, and less than that in 5-10 knots variable. You'd need 20 knots of wind to see a good solid 6 knots. A chute alone would be faster, but I don't fancy wrestling with a chute in even 15 knots without a main to cover it. It will also be hard on the chute.

Just sayin'. Some one will feel differently.
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SailorC
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Re: Genoa and Assymetrical only speeds and handling

Post by SailorC » Fri Feb 21, 2020 1:01 pm

Thanks Thinwater.
Back to chutes, and in higher winds. I think Sailing Impi here hasn't figured out. They have a heavy duty assym for heavier air and also a lighter one. The key is they use it on a bridle setup (much like yours) and attached by a Tylaska T12 snapshackle. Makes a lot of sense to me.

Note too...they are running no main. It's a much different catamaran (L440) but still...I think it's an excellent example of a boat running an assym like I'm thinking could be done by someone or double-handed. They have some other videos showing it flown during squalls. I think it's a great channel for any cat owners.
https://youtu.be/4XQoq9gOURw

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thinwater
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Re: Genoa and Assymetrical only speeds and handling

Post by thinwater » Sat Feb 22, 2020 1:02 pm

Yup, that's how it is done.

I wouldn't fly a chute in a squall on a PDQ32. That's a good way to break something, if only stretching out an expensive sail. Not worth it.
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