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Old 09-03-2008, 17:50   #1
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Spinnaker Flying Considerations

When flying a spinnaker on a cruising cat with no backstay some people completely drop the main and tension down on the topping lift to support the mast from behind. Others double reef the main and some leave the main all the way up for ultimate mast support.

I prefer to drop the main completely and tension down hard on the topping lift, but am concerned in winds around 18-25 knots that the mast will be under too much load and could fail without the main up.

Is a tensioned topping lift, without the main, enough to support the mast from behind while flying a spinnaker?

My mast has one spreader and two side stays and is rigged similar to many popular cruisng boats.

Keegan
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Old 09-03-2008, 19:16   #2
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With such a nice boat you'd think the manufacturer would have some input on this. Did you buy it new?
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Old 09-03-2008, 19:28   #3
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With such a nice boat you'd think the manufacturer would have some input on this. Did you buy it new?
manufacturers tell you not to speed your car but you do it anyway...same with boats.

Keegan
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Old 09-03-2008, 20:17   #4
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My winter car is an Audi S4 and my summer car is a Mercedes CLK550. The manufacturer designed both to go way-way beyond the the speed limit (which I do).
I really don't know what boat manufactures (like yours) provide for info on loads/stresses. When I was at the Miami Boat show last month I toured an Amel. I'm pretty sure they would fully brief their owners on sail tactics.
But again, I don't know for sure. Did you buy your boat new? It's a nice one!!
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Old 09-03-2008, 23:58   #5
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If you are sailing in winds of 20 knots with a spinnaker up and your mainsail furled, how do you take the kite down?
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Old 10-03-2008, 00:11   #6
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spinnaker

I leave the main sail up with 2 reefs. also aids the recovery by shielding as you retreave.

Regards Bill goodward
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Old 10-03-2008, 07:05   #7
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Quote:
Originally Posted by Keegan View Post
Is a tensioned topping lift, without the main, enough to support the mast from behind while flying a spinnaker?
Hi Keegan - I think the complete answer is boat dependent. But I don't claim to know the full answer for my own boat. I do like to fly the chute alone and in light air it's very effective.

Prudency dictates that some aft tension be provided if the mainsail and sheets aren't providing anything - once apparent wind (coupled with the seastate) is high enough that a reasonably knowledgable skipper gets concerned. But the mast is not taking all the force of the chute - it's also distributed to the hulls via the guys/sheets. (I won't claim to know in what proportion it's distributed.)

I replaced my topping lift with stronger Sta-SetX in part for this concern. I've adopted the conservative practice of making sure the main sheets are tensioned pretty tight regardless of how much main I have up anytime I'm deep downwind with the chute and apparent wind gusts to 10+. Running a double reef main works well, too.

In flat water my boat makes a bit more than 1/2 the true wind speed DDW with just the chute. So apparent wind is <10 when true wind is 20 and I'm making 10+ knots. This does not feel rig-threatening, and in fact, is very pleasant. All bets are off when you're surfing/overtaking waves and boat speed and thus, apparent wind, can vary a lot. In those cases the risk of collapsing the chute would motivate me to not use it in addition to the risk of straining the rig too much if the boat suddenly decelerated in the back of a wave.

Another option if not carrying any main is to run the main halyard back to some point on the boom.

But my thoughts keep coming back to these facts: My spi halyard is not as strong as my topping lift and the spi is not as strong as either one. Despite my prudent practices to provide some aft support for the rig, I bet something else will give first.

Dave
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Old 10-03-2008, 11:39   #8
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What size is your Chute and what is the Diameter and type of your chute halyard?The reason I ask is that I am in the process of replacing my cruising chute halyard which was just a spare before I got a chute. I would like to reduce diameter if I can. I don't have the other problem because I have a boomless main with a double backstay.
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Old 10-03-2008, 11:55   #9
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What size is your Chute and what is the Diameter and type of your chute halyard?
Hi Lancerbye - are you asking me?

If so, my (symmetrical) chute is 140 m2. My chute halyard and sheets are 14mm, garden variety yacht braid; guys are 12mm. Smaller diameters could be used with sexier lines.

Dave
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Old 10-03-2008, 20:40   #10
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This is interesting. Must be a whole different way of treating spinnakers when you have a multihull. Monohulls don't fly without the main up. Main provides sqft one side and spinnaker provides sqft the opposite side for downwind sailing. You blanket the spinnaker with the main in a take down.
Multihulls are supposed to be so much faster I would think that their downwind sailing would be broad reach to broad reach and a spinnaker would be kind of superfluous??
We have a club cat Wharram 23 so I'd really like to know the answer to this one. We don't have a spinnaker but have a light drifter than won't tack.
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JohnL
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Old 10-03-2008, 20:42   #11
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And for Rigamorale. Huh?
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Old 11-03-2008, 06:38   #12
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Multihulls are supposed to be so much faster I would think that their downwind sailing would be broad reach to broad reach and a spinnaker would be kind of superfluous??
Hi John L - I think your understanding is correct mostly for really fast multis, i.e., racing boats or those seriously meant for speed over comfort. Aside from modern cruising tris, most cruising multis cannot duplicate the downwind gybing efficiency because they cannot bring the apparent wind far enough abeam. They just aren't fast enough to make broad reaching gybes more efficient than DDW under a big symmetrical chute. Add to this the butt simple ease of flying big symmetrical chutes - no poles, fly 'em and forget 'em - makes DDW running on cruising cats especially appealing.

On my cat I gain very little by also having the main up when DDW. It's not worth the hassle. I expect other cats or those with smaller chutes could be different in this regard. But if the desired course is anything other than DDW, but still deep enough for a chute, having the main up as well makes a huge difference.

Even on racing cats, asymmetrical chutes started showing up in the late '80s - by my recollection. Maybe earlier. These beasts still avoid DDW but can go much deeper than without the chutes.

Just my humble opinion. Perhaps others have a different take.

Dave
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Old 13-03-2008, 09:34   #13
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Dave,

One day I'm going to have to have you over so you can show me how you fly your chute. I've got one, but never used it.

Doug
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Old 13-03-2008, 09:41   #14
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Is it a masthead kite or frac?
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Old 13-03-2008, 10:03   #15
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My spi halyard is fractional. Just a little above the (soon to be used) Code 0 halyard which is just a little above the genoa halyard.

Doug - perhaps we should rendezvous sometime. We're currently on the hard in Georgetown and will head to the Va. portion of the Bay sometime in May. Got to escape from Maryland before the long arm of the tax man commeth.

But I bet you will conclude "why didn't I do this earlier" after you fly that kite the first time. It would be fun to get together to do it, but believe me, you don't need any help. It's all intuitive once you figure out the running rigging. Perhaps describe your rigging set up and we'll go from there. Is yours symmetrical or asymmetrical?

Dave
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