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Downhaul under spinnaker
by CapriSun. 11/12/20 09:41 AM
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Spin run #282341
04/04/16 10:31 AM
04/04/16 10:31 AM
Joined: Jan 2007
Posts: 139
Hernando, Florida
M
Mlcreek Offline OP
member
Mlcreek  Offline OP
member
M

Joined: Jan 2007
Posts: 139
Hernando, Florida
On a blowing spin run, which sail has the most effect on the main, the spin or jib? Of course the power is in the spin, but does it overpower the effects of the jib on the main?

Thanks


Forrest
I-20
USA 645

" There ain't enough rum in the drum!"
-- Have You Seen This? --
Re: Spin run [Re: Mlcreek] #282559
04/30/16 07:44 PM
04/30/16 07:44 PM
Joined: Mar 2006
Posts: 337
Arizona
AzCat Offline
enthusiast
AzCat  Offline
enthusiast

Joined: Mar 2006
Posts: 337
Arizona
I see that no one has chimed in your question, so I'll jump in here.

What is it that you would like to know? I think maybe the reason that no one answered is that the reasoning behind your question isn't clear. Are you wanting to depower a bit downwind?

The quick answer I guess would be that apairant wind has the greatest effect on the main.


Auscat MKV 444 A class
NACRA I-20- 440/CATHATKA
Re: Spin run [Re: Mlcreek] #282561
05/01/16 06:25 AM
05/01/16 06:25 AM
Joined: Nov 2011
Posts: 381
SE MI / NE IN
rehmbo Offline
enthusiast
rehmbo  Offline
enthusiast

Joined: Nov 2011
Posts: 381
SE MI / NE IN
I'll add my $0.02: Simple answer is the spinnaker has the most effect. By far.

I think there are a couple reasons:
1) Sail size: 21m^2 vs 4.2m^2.
2) Sail cut: the jib is cut very flat for tight upwind wind angles, while the spinnaker is deeper cut keeping attached flow at higher wind angles that are seen heading downwind.

So on the typical downwind run, I think the jib is mostly just enjoying the ride and has a very limited effect on the main's lee-side flow. That being said, every little bit helps, so the jib should be trimmed out with lots of camber. In my case, the top of the leach is almost completely open and not doing anything, but the mid and lower sections appear to draw a little bit - judge by telltales.


Jeff R

H18, C2 USA1193
cramsailing.com
crescentsail.com
Re: Spin run [Re: Mlcreek] #282562
05/01/16 06:53 AM
05/01/16 06:53 AM
Joined: Nov 2011
Posts: 381
SE MI / NE IN
rehmbo Offline
enthusiast
rehmbo  Offline
enthusiast

Joined: Nov 2011
Posts: 381
SE MI / NE IN
One last comment: An over-sheeted jib (one you forgot to release when you turned downwind) would likely be stalled and have a big negative effect, acting like a rock in the stream.


Jeff R

H18, C2 USA1193
cramsailing.com
crescentsail.com
Re: Spin run [Re: rehmbo] #282568
05/02/16 07:42 AM
05/02/16 07:42 AM
Joined: Dec 2001
Posts: 5,590
Naples, FL
waterbug_wpb Offline
Carpal Tunnel
waterbug_wpb  Offline
Carpal Tunnel

Joined: Dec 2001
Posts: 5,590
Naples, FL
Any thought on the minimum distance between jib tack and spin tack to avoid interference with the slot between the two?

I know we left the jib up on F18 (what is the distance between the two?), and wonder if the same could work with a larger F24 (measuring the gap shortly).

I'm guessing in my case the spin tack is too close to the jib tack to leave the jib up. I think the distance between the two tacks/luffs is less than 72 inches.


Jay


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