# Spinnaker Size



## ncapener (Sep 1, 2008)

How are spinnakers sized for a boat? How do I determine luff, leech and foot measurements for my boat? 
I would like to buy a used one and need help figuring what works for my boat.

Thanks,
Neal


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## DwayneSpeer (Oct 12, 2003)

Do you want a spinnaker, genaker, or cruising chute?


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## ncapener (Sep 1, 2008)

DwayneSpeer said:


> Do you want a spinnaker, genaker, or cruising chute?


I would like to be able to measure for all three. Main goal is to get a used large downwind sail. There is slim picking and I probably get what fits size wise.

Neal


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## JimsCAL (May 23, 2007)

From Atlantic Sail Traders website:

"Measuring for a Spinnaker is very easy. The only dimensions needed are the I and the J measurements. Hoist a tape measure to the top of the mast with the Spinnaker halyard. If you do not have a dedicated Spinnaker halyard use your Jib halyard. Remember to tie a line to the halyard in case your tape breaks. Measure down to the top of the working deck, not the cabin top. This is your I dimension. Lower the tape measure. Now measure from where the forestay connects at the bow, back to the base of the mast. This is your J dimension. 

If you are racing, most PHRF organizations limit the maximum luff length of a Spinnaker to the I dimension. The maximum foot dimension is 180% of the J dimension.

If you are a Cruiser, there is a lot more flexibility to the size Spinnaker you can use. The luff length should be within 10% of the I dimension. The foot dimension can be anything, but ideally it should be from 160% to 200% of the J dimension."


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## tommays (Sep 9, 2008)

What gear do you have as a traditional spinnaker is gonna be the cheep part if the boat does not have all the gear to use it


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## mikehoyt (Nov 27, 2000)

You can look up these measurements on U Sailing site here http://offshore.ussailing.org/Assets/Offshore/PHRF/Critical+Dimensions.pdf


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## catamount (Sep 8, 2002)

tommays said:


> What gear do you have as a traditional spinnaker is gonna be the cheep part if the boat does not have all the gear to use it


Indeed, if you are looking to fly a symmetrical spinnaker off an articulated pole, you will need: (1) the pole, (2) some way to attach it to the mast, usually a car on a track, (2a) rigging for adjusting the height of the mast car, (3) a pole topping lift, (4) a foreguy or pole down-haul, (5) turning blocks for your guys (snatch blocks to the toe rail?), (5a) the guys, (6) turning blocks for your sheets (snatch blocks aft), (6a) the sheets, and this is all assuming you have an appropriate halyard (or two) already.

If on the other hand, you intend to fly the spinnaker tacked to the bow (typical of assymetrical spinnakers, cruising chutes, and gennakers, but can also be done with a symmetrical spinnaker), then you just need the halyard, a tack line and turning block on the bow, sheets, and turning blocks aft.

Good Luck!


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