Whisker pole

[surazo]

I'm seeking advice to improved my Spi .I have a perry 47 Ketch and I am seeking which is the lenght and a diameter for a whisker pole for my boat ,using a simetrical spinnaker .
I appreciate advice in this matter because when the extensibles tubes appears on the market any manufacturer said something clear for and old boat and sailor like me .
Thanks

[Jim Cate]

Surazo, the normal length of a spinnaker pole is equal to the distance from the front edge of the mast to where the forestay intersects the deck. This dimension is called "J" by designers and sailmakers.

For a boat of your size, a diameter of 3-4 inches (75-100 mm) is normal, depending on wall thickness... thinner wall requiring the large diameter.

And collapsible (telescoping) poles are not usually used for spinnakers... not strong enough... but ok for poling out a genoa if you are careful.

Jim

[UNCIVILIZED]

Originally Posted by Jim Cate

Surazo, the normal length of a spinnaker pole is equal to the distance from the front edge of the mast to where the forestay intersects the deck. This dimension is called "J" by designers and sailmakers.

For a boat of your size, a diameter of 3-4 inches (75-100 mm) is normal, depending on wall thickness... thinner wall requiring the large diameter.

And collapsible (telescoping) poles are not usually used for spinnakers... not strong enough... but ok for poling out a genoa if you are careful.

Jim

Technically, the "J" measurement is the distance drawn perpendicularly from the headstay to where that line would hit the base of the mast, at the deck.
Jim's definitely right though, on the fragile nature of whisker poles, especially on big boats. And that they're not viable for kite use.

On a boat that size, you'd need a 4" minimum (diameter) sized pole, & bigger would be much better. Also, given that you're not likely to be governed by any racing rules/bodies, you'd be better off with a "penalty pole". AKA one which is a few feet longer than your "J".
As the longer pole will get your kite out into clearer air, so that it isn't tucked in behind the main quite so much (when you're semi reaching - AWA forward of say, 115 or so).

Talk to your rigger, or a couple of them, for both length, & hardware recommendations.
And for most of your hardware, pole included, good 2nd hand stuff works fine, & helps in the wallet department, if that's an issue.
BTW, even if you have deep pockets, carbon fiber poles are real pricey. Doubly so, given their fragility. Albeit a Lot lighter, when it comes to handling.

Also, while it's tempting to cheap out on the end fittings, Don't Do It. They take a hell of a beating, especially if you go with jaw type fittings on the inboard end of the pole, & a ring on the mast. In addition to making the pole more difficult to handle.
LMK if you need tips on simplifying how to setup things for mounting/hoisting the pole.

Jaw fittings on poles get slammed on the inboard end with each wave cycle, so that on a mid-sized to big boat (30' & up), they die early deaths. As in, within a passage or two.
Bayonet fittings like on race boats rule, & if you must, then go with bell end fittings, as a distant 2nd choice.

If $ is super tight, get good end fittings, & make/buy a wooden, or wood/carbon pole. Heavier by a bit, but cheaper.
Laminate your square wooden blank, then cut it into an 8-sided, & then 16-sided blank, on the table saw. After which, out come the draw knife, & hand planes.
Or, you can do a hollow, bird's mouth joint type variant. With a bit of inner blocking... With, or sans, composite reinforcing.

Also, occasionally, you can snag an aluminum pole from a racer who's moved up to a carbon fiber one.
Riggers can be helpful in knowing who to talk to on this.

[Snowpetrel]

For a cruiser I would go for an overlength, lightweight pole. Don't shy reach with it, in anything over a light wind or you risk breaking the pole, but it will be much easier to handle all round in the light airs that we tend to use kites in and makes a good whisker pole for the jib. The major loads come on a pole when reaching in moderate to strong winds, or when broaching. Even strong downwind conditions are kind on poles as long as you don't wipe out, Something us cruisers try to avoid at all costs.

Of course ignore this if you intend to race hard. In that case the gear needs to be every bit as strong and heavy as uncivilized talks about.

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[UNCIVILIZED]

Generally speaking, I'd think that it only makes sense to have a pole capable of taking an occasional knock in moderately strong breezes. As often enough, they're used to pole out a jib when running downwind in "reasonable" winds.

Strong compression loadings aside, when, not if, someone or something goofs. Via zigging when they should have zagged @ the helm, or a control line gets inadvertently eased too much, then the load on the pole easily goes up by a factor of 3-4x. Or worse, it bounces off of the shrouds, or the headstay, etc. under load. Which, if it's overly light, such creates a beer can failure, in lay engineering parlance.

And not using a pole to hold out a jib, in a good breeze when going downwind, is akin to attempting to resist a Syren's call. Few to none can do such.
Especially as that's when you most need a pole to boom out a headsail, so as to balance out the main on a preventer on the other side of the boat.

When you're sliding down a wave, & the ride stops @ the bottom, & the AWS goes from 12kts to 21kts, the load on all of your gear triples. And yet, by most standards, these aren't strong breezes.
FYI, those figures are what transpires in only roughly 15kts TWS. Still well within what most consider reasonable winds for flying a kite.

Even if the TWS is 10kts, when there is an error going downwind with a poled out sail, the math of the load changes is a squared function, & things set up for gossamer breezes will fold.

If a pole will never, ever see winds N. of 10kts (AWS), then you can go with a light one. But what pact must one make with Neptune & Aeolis to ensure that that 2-digit wind speed limit is never breeched?

[roverhi]

Whisker poles are not made for the loads of a symetrical spinnaker. Doubt if there is an adjustable whisker pole that will work on your boat in any case. Would go with a spinnaker pole longer than 'J'. That will make wing out a Genoa better. On my much smaller boat went with a 3" pole that is 15% longer than the 'J' measurement. Pole has bayonet end on the mast which is a big improvement over the typical ring and jaw set up. Carried an adjustable whisker pole as well as the spinnaker pole on the trip to Hawaii. Good thing I did as the whisker pole pretzeled after a day and a half poling out the 135 genoa. Ran the spinnaker pole for the 12 straight days of the rest of the trip without a problem

[surazo]

Jim,thanks for your advice .Clear .Whish kind of end fitting do you suggested for a traditional Whisker pole?.

[surazo]

Hi,thanks for your clear explanation and suprt Jim's explanation .I'm fel more sure about it .I 'm planning to use a aluminium tube of 3 " with with J+plus 2 feets in lenght but now Iam need advice about the end fitting .Cheaper but safer ,I found a lot of them and I rememeber in my previos sailboat I used a simple piston end .What do you think and suggest

[UNCIVILIZED]

For some (other) professional help in selecting your pole, & ends, I'd suggest studying the available equipment, as well as contacting:
Forespr, at Sailboat Products
Mauri Pro Sailing, at Spinnaker Poles | Mauri Pro Sailing
Annapolis Performance Sailing. APS - Spinnaker Poles & Accesories

Forespar is one of the industry leaders, when it comes to making spinnaker poles, their associated gear/end fittings, & whisker poles etc.
If you do bit of digging on their website, you'll see that for a boat your size, they recommend a 4", or 4.5" diameter pole, also.
I didn't make up, or look up those numbers earlier, it's simply an experience thing.

Part of the reason for this size pole, vs. a smaller diameter, is that IIRC, stiffness goes up with the cube of thickness (diameter). So a 4" pole is roughly 2.4 times stiffer than a 3" one of the same wall thickness. And a 4.5" pole would be about 3.4x stiffer.
As a comparison & reality check, look at the diameter of your boom. Then think about the size of a big headsail or spinnaker as compared to the main.

Bottom line, on a boat that big, it's not difficult for the loads on the sheets & guys to run into the 4-digit range. Which the poles have to be able to handle.
The formula for sheet load is: Sail Area (in sqft) x wind speed (in knots) squared x .00432
At 15kts, the load on a sail is 1lb/sqft, & at 22kts, it's 2lbs/sqft. And the loads on afterguys can get much stiffer than the sheet loads, due to the angles which they're lead at.
More info can be found here Harken

When it comes to pole ends. My preference on the outboard end, is to have the type of jaw with 2 types of built in release mechanisms. One which automatically snaps shut when the line it placed firmly into the jaw. As well as having a tripping mechanism which can be manually activated via a lanyard.
For the inboard end, I recommend this design UTS Automatic Socket End 4.0

Since budget is a concern, there are a plethora of chandleries which deal in pre-loved, quality gear. Good Old Boat magazine has a list of such, as do many other places.


PS: Can your boat & gear handle this? It's a Fav of mine :-)

https://www.youtube.com/watch?v=VWNpdQ37BBA#t=11

[Snowpetrel]

Nice video Uncivilised, I used to do that kind of stuff in dinghies, but not a keeler! But it does kind of make my point that we don't need a race spec'd spinnaker gear on a heavy cruising ketch. If any one is stupid enough to try setting a kite on a typical cruising boat in those sort of conditions they deserve anything they get. I guess my philosophy is to size it somewhere between a whisker pole and a spinnaker pole. this gives me a bulletproof whisker pole and longer lighter more manageable pole for the nice "gossamer" days when the spinnaker is worth pulling out of it's bag. My old 60mm (2 3/8") 5.5 meter pole used to cope with the kite on my heavy 34 footer up to 25 knots, as long as I was running reasonably deep. However I only used it in these sort of winds with a good crew aboard, and plenty of sea room to leeward to run off and blanket it if need be. I Never tried loading it up on a reach, by the time the wind got up to about 15 knots the genoa did a better job than the kite on a reach anyway.

But I agree that 3" might be cutting things pretty fine, depending on the J , and remembering that the boats a ketch so it should be a much smaller kite than the equivalent cutter or sloop.

The catalogs don't seem to give the specs for the whisker poles, but one site gives it as the #40320x series are telescopic with 3&3.5 inch and are rated to 46 footers and the #40520x are 3.5/4" sections and rated to 55 footers, with some allowance for light/heavy and longer or shorter J lengths.

Anyway for the OP I'd probably look at around the 3.5-4" (88-102mm) mark with 2mm-3mm wall. Ideally it's 6061 T6 (or 6063 T6) if you can get it. Make sure to put a pole protector where it might hit the forestay (or staysail stay), and be very careful about it bending around the staysail stay if you have one. And also beware of winching it to far back onto the forward lowers. Certainly a lovely part of the world you are in, I enjoyed my time in Puerto Montt very much.

[surazo]

Thanks to Uncivilised and to Snowpetrl .Now Im more clear about the Whisker pole .The video is amazing and I hope that not happend with a 22 tons sailboat .
Thanks again

[UNCIVILIZED]

Originally Posted by surazo

Thanks to Uncivilised and to Snowpetrl .Now Im more clear about the Whisker pole .The video is amazing and I hope that not happend with a 22 tons sailboat .
Thanks again

I've done milder versions of the "trick" in the video, on Maxi's, in much bigger waves. Let's just say that it's "exciting", & leave it at that

Glad that the links & info were of help. And most of the rigging & hardware companies are happy to talk to you. If they aren't, go elsewhere, as unfriendly folks usually aren't real good when it comes to customer service.

[Snowpetrel]

Just measured my new boats spinnaker poles. FWIW. 3.5 inch diameter, about 2.5-3k
mm wall and 5.2meters long. This is for an old racing boat, so they have had a very hard life. No signs of any breakages. Admittedly a smaller boat than yours at 40 feet and 8 tonnes, but the mast is about 15.5 meters off the deck with a 5.2 m J, so the kite might well be a similar size. This size pole makes a absolutely bulletproof whisker pole for headsails and I might well get another smaller longer pole for light airs.

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