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-   -   Pole size (http://www.cruisersforum.com/forums/f116/pole-size-18526.html)

miss-m 22-08-2008 03:52

Pole size
 
Calm down Gentlemen please.

We have an asymmetric spinnaker and a furling genoa. We would like a pole to help on the downwind passages. We have seen some quite cheap on ebay and juust wondered- how long should the pole be? I've looked for a set formula but cant seem to find one.

Any ideas gratefully appreciated. Thanks all

donradcliffe 22-08-2008 04:39

As with most things on boats, pole length is a trade-off, with ease of handling, storage, avoidance of breakage, and sailing performance as the parameters. Traditionally, most racing rating rules have assumed a standard pole length is equal to "J", or the distance from the mast to the tack of the genoa. This is based on using symmetric spinnakers.

If you are starting from scratch, a slightly longer pole, say 110-120% of J may be better for poling out the genoa, depending on the size of the sail. I have a standard pole and a 125% genoa, and I find the pole limits me from sailing wing-on-wing to apparent wind angles of less than 130 degrees unless I partially furl the genoa.

The asymmetric spinnaker can be tacked through the end of the pole just like a symmetric one, giving more power downwind. However, if you are sailing short-handed, you may find yourself using the poled-out genoa much more often, as it can be quickly and easily doused on the roller furler if the wind comes up.

GordMay 22-08-2008 04:45

The luff of an asymmetrical spinnaker is about 15% longer than the leech, and the sail has an airfoil shape. Many cruisers prefer an asymmetrical spinnaker because a spinnaker pole is not necessary to fly the sail. Usually, the asymmetrical spinnaker is tacked to the boat's bow fitting and used poleless as a very big genoa; the asymmetrical spinnaker is best used broad reaching and as tight as 75 degrees to the true wind. Using an asymmetrical, it is necessary to "tack" downwind (gybe at roughly 90 to 120-degree angles) to fly the sail successfully.

Demystifying the Asymmetric Spinnaker

http://www.monmouth.com/~nsnj/demystasym.htm
and
http://www.northsails.com/north_amer...4Questions.htm

Refining Your Downwind Sails
http://www.airforcesails.com/refinin...wind_sails.php

Cruising with an Asymmetrical Spinnaker
http://www.cncphotoalbum.com/doityou.../spinnaker.htm

Hud3 22-08-2008 05:00

Miss-M,

I have a Forespar "line control" whisker pole that's adjustable in length. The fact that it can be extended for use with the sail allows for easy storage and handling. I use it for poling out the genoa. Haven't tried it on the asymmetric spinnaker yet.

GordMay 22-08-2008 05:22

Generally, an adjustable Whisker Pole, about equal to J, or a little shorter (collapsed) extending to 120-125% of J will accommodate a range of sails & conditions.

Forespar on Whisker Poles:
http://www.forespar.com/resources2/t...eSeminar.shtml
and:
http://www.mauriprosailing.com/Fores...sker-Poles.htm

svHyLyte 22-08-2008 06:55

I would not recommend using an extendable whisker pole on an asymmetric. The tack line loads the pole at a relatively flat angle and the resultant loading can be quite dramatic—more so than the poles are designed for (I believe Forespar offers the same advice).

As an alternative, measure the distance from the mast to the point forward of the pulpit necessary to get a fair-lead from the end of the pole to the tack block and select a fixed pole on the basis of that length as a J dimension.

Coincidentally, most asymmetric's can be flown pretty effectively down to about 160º, one will find that gibing down-wind will allow one a much better VMG than will a dead run with the added distance being easily off-set by the gain in speed. Moreover, the yacht will roll far less making life far more comfortable for the crew.

FWIW…

s/v HyLyte :)

Hud3 22-08-2008 06:59

Quote:

Originally Posted by svHyLyte (Post 196715)
...most asymmetric's can be flown pretty effectively down to about 160º, one will find that gibing down-wind will allow one a much better VMG than will a dead run with the added distance being easily off-set by the gain in speed. Moreover, the yacht will roll far less making life far more comfortable for the crew...

That's been my experience. Plus, "tacking downwind" allows you to enjoy some breeze over the deck. More comfortable than sailing DDW.

miss-m 26-08-2008 08:56

Ok, we're getting there. Honest. Thanks for all your replies.
Next questions is: Does it matter at what height you put the ring on the front of the mast?
Does that make sense? We can't have a track which the pole stays on permanently, so we're fitting a ring. But how high/ low should we put it? Or does it really not matter and I'm overcomplicating the whole thing?? :) And also, there seem to be a never ending combination of ends for the pole- does it matter overly which ones we use?

Thanks again

cantxsailor 26-08-2008 11:45

I have a Tacker........
 
You might take a look at a product called the ATN Tacker. I have one and find it works well for me. I sail mostly solo and wanted a simple spinnaker system. Using the snuffer makes the whole process pretty easy.

I have nothing to gain from the sales of any ATN products I'm just a happy owner.

As for ring height I think the pole should be higher at the mast than the sail. If you have a track you can use multiple sails with differing clew heights.........martin


www.atninc.com/index.htm

Zach 26-08-2008 12:22

I read something interesting the other day in regards to pole height...

In John Guzwells Trekka Around the World, he talks about mounting the pole 6 feet above the deck, allowing the sheet angles to take some of the load from the pole and letting it be a bit more tame. Then again he talks about using nylon guys and sheets too... So I bet theres a bit of give/stretch that isn't seen in the stuff used today.

Don't know how well it scales up, as Trekka is only what... 20 feet long? :D But it seemed like a cool idea to cut down on some complexity.

Zach

GordMay 27-08-2008 02:52

Quote:

Originally Posted by miss-m
... Does it matter at what height you put the ring on the front of the mast...

Both Forespar & Mauri Pro address this question, as previously linked:

Forespar on Whisker Poles:
http://www.forespar.com/resources2/t...eSeminar.shtml

and:

http://www.mauriprosailing.com/Fores...sker-Poles.htm


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