Asymmetrical purchase from ispinnaker

[John D'Acunto]

I'm needing to replace  spinnaker. I was looking on Ispinnakers.com .  has anyone purchased from them before?  I think i should be ordering a Size 4 613Sq Ft. any advice is helpful.

[rob...@epogue.com]

Hi John,

The important dimension is luff length - from the fully hoisted spinnaker shackle to the tack point at the end of the pole. That measure on J/92 hull #14 is 501.75" - although your pole extension length, mast rake, halyard shackle and pole turning block on the pole could all change it a bit. If I'm reading their table right, size 4 will be a little bit small.

Nothing beats getting a local sailmaker's advice and guidance!

Robert

[Mark Camilleri]

My rated spinnaker is 84 square meters  which I believe works out to 904 Sqr feet

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Sent: Friday, November 18, 2022 5:19:04 PM
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Subject: [j92owners] Re: Asymmetrical purchase from ispinnaker

 

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[oldsa...@gmail.com]

The J92 I sail on has an A2 with an area of 804 sq ft and a luff length of 525”. Seems big enough!

 

Cheers

 

Rich

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[Todd Aven]

The measurements depend on the intended use of the spinnaker, which is typically coded as A2, A3, A4, A5, etc.  Odd numbers tend to be aimed at different reaching conditions and even numbers targeted toward maximum downwind VMG (running). Larger numbers are designed for stronger winds.  I'm guessing John wants an A2 (typical "all purpose" spinnaker if you're only having one). 

There can be endless debate about the best size and shape, which is not what I intend to spur here.  Just an understanding of how the measurements relate to the intended use.  Here are the numbers for an A3 and an A2 that I had at one point on Thin Man. 

I've seen A2's for the J/92 ranging anywhere from 84sqm to 93sqm (mine).  I ultimately replaced this particular A2 with a slightly smaller one which was a scaled down version of a very successful J/109 A2 design from UK. It measured in at 89sqm. The old one simply had too much leech and not enough luff.

For comparison, this A3 was an AMAZING reaching kite, but I couldn't sail lower than about 145 TWA with it.

Longer luff generally translates into better rotation of the spinnaker to windward leading to better ability to sail deep, at the cost of reduced performance when reaching. It's a trade-off. Longer leech gives more sail area, which is good for reaching (to a point, same as an overlapping genoa), but not much help when running since it's the luff that generates the power. 

	A3	A2
SLU	44.8	45.8
SLE	37.1	38.0
SF	25.0	27.7
SMG	21.3	28.7
A. Area (sq ft)	752.5	995.2
Area (sq m)	69.9	92.5

Long story short, a 613sqft spinnaker is going to be a disappointing sail for a J/92 A2. If you're racing, aim for 900-950sqft. If you're cruising 800-850sqft would probably be a good balance.

Best regards,
Todd
J/99 #24 Thin Man

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[mbda1961]

Hi John

We have an excellent large masthead A2 from Elvstrom. These are the dimensions: 94.30m2, SLU 14.90, SLE 13.00, SFL 7.80, SHW 8.23, STL 5.14. Definitely for racing not cruising. Together with a smaller, flatter, fractional A3 it makes a good combination.

Mike

[John D'Acunto]

Thanks everyone for your responding to my question regarding my 1993 J 92.  I'm new at using an Asymmetrical Spin.  Just blew one out a few weeks ago and looking to replace it.  I measured it with luff 45' Leach 41" and Foot 26"  Does that sound about right for a J92?.  Some of the measurements still confuse me.