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Old 02-12-2012
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The physics of a whisker pole....

Medsailor's latest hair-brained idea is to make my own whisker pole out of bamboo. It was an idea suggested by a resourceful friend of mine and has apparently already been done on a modern yacht with success. (see youtube video at the end of the post)

There is a store near me that has 1.5" very sturdy 12' long stock of bamboo. The "J" is 14.5' and I've heard that a whisker pole should be 1xJ or 1.5xJ dimension. That seems really long to me. I had some good luck messing about with a boat hook to keep a genoa from collapsing on my previous boat and it was about 2/3xJ.

Why are whisker poles supposed to be so long? What advantage will I loose if I only use a 12' pole? Anyone know the specifics?

Any advice about what ends to use? Traditional whisker pole ends start expensive and go all the way up to stupid for what they are. Unless/until I can find some at a swap meet, I'll be making my own ends, at least for the experimentation phase. Ideas include a single spike (like a boat hook end) to put through the bowline or clew ring, or a snap shackle, either fixed or on a short line.

Bamboo Whisker Pole Debuts at Carriacou Regatta - YouTube

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Last edited by MedSailor; 02-12-2012 at 09:01 PM.
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Old 02-12-2012
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Our spinnaker pole is 1xJ, expandable to about 1.5xJ. We are rated to carry a spin pole up to J, so I think that your pole would be no longer than J.

In the video, the flex on that pole in very light conditions is considerable. I'd be worried that it couldn't take much loading. Our aluminum pole is 3" in dia for a 13.25' J. I would also be worried about the ends poking holes into the sail.
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Old 02-12-2012
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Do you have a mast ring for a spinnaker pole already?

Spinn poles are generally equal to J length, and usually are far too short to use as a whisker pole for a 150% genoa. If your J is 14.5 feet, and you have a "150" the clew, when spread for max projected area is going to be more like 20-22 feet from the mast. If you have a furler then an extendable whisker pole will allow you to set it for the amount of sail you have out (within it's dimensional limits)

Using a spinn/J length pole on a big genoa is going to create a very rounded 'bag' of a downwind sail, it will prevent the clew from dancing around but it's not the most efficient setting for DDW with that sail. It would be like easing the outhaul on your main until the clew was mid boom....

Whether Bamboo is strong enough, it may well be but to be effective that's a long piece you'll need to stow somewhere - but you do have over 40 feet of deck so maybe that's no biggie..

It's probably cheap enough to try. While you should have a decent fitting for the mast end, a sturdy pin (thrust through the clew cringle) would probably do for the outboard end.
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Old 02-12-2012
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I am actually wondering the same thing...
One of the things I've heard of doing is having the boat end of the pole hooked to a shroud. This way the pole can be a lot smaller too.
I can't imagine too much force applied on that end...
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Old 02-12-2012
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Quote:
Originally Posted by Faster View Post
Do you have a mast ring for a spinnaker pole already?

Spinn poles are generally equal to J length, and usually are far too short to use as a whisker pole for a 150% genoa. If your J is 14.5 feet, and you have a "150" the clew, when spread for max projected area is going to be more like 20-22 feet from the mast. If you have a furler then an extendable whisker pole will allow you to set it for the amount of sail you have out (within it's dimensional limits)

Using a spinn/J length pole on a big genoa is going to create a very rounded 'bag' of a downwind sail, it will prevent the clew from dancing around but it's not the most efficient setting for DDW with that sail. It would be like easing the outhaul on your main until the clew was mid boom....

Whether Bamboo is strong enough, it may well be but to be effective that's a long piece you'll need to stow somewhere - but you do have over 40 feet of deck so maybe that's no biggie..

It's probably cheap enough to try. While you should have a decent fitting for the mast end, a sturdy pin (thrust through the clew cringle) would probably do for the outboard end.
Thanks Faster. The outhaul analogy is exactly what my visual brain needed... So it'll work with 1xJ but it will not be nearly as efficient as I would want....

I do have a ring on the mainmast up high and at chest level and even a little pulley for the topping lift. Aparently the previous owner was insulted enough by the offer I made that he took the pole with him. I plan on stowing my pole up the mast.

As for the flex in the bamboo, that is part of it's strength. It's strong but not stiff. The 12' sections are $9 so even if I end up with nothing but a pile of chopsticks on the fore-deck after a flying jybe, this should be a fun, and inexpensive, experiment.
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Quote:
Originally Posted by JSailer View Post
I am actually wondering the same thing...
One of the things I've heard of doing is having the boat end of the pole hooked to a shroud. This way the pole can be a lot smaller too.
I can't imagine too much force applied on that end...
Think again, the compression forces at the inboard end can be considerable when the breeze comes up, and especially when it starts going forward...

Older Amels had an arrangement there downwind poles were mounted on sort of braces on the shrouds... It was a pretty stout arrangement, but I doubt it shortened the length of the poles by very much, and I don't think you'd want to try mounting a pole onto a single shroud in anything but the lightest of breezes...

Forespar's website offers some great info on whisker poles here, you should really let this be your guide:

Whisker Poles

And for MedSailor, I don't like the sound of using just a "spike", or similar, at the outboard end... At least not on a boat of your size, that seems like it could be asking for trouble, especially when attempting to set it in a breeze... When I use my whisker pole, I really like to get it all positioned beforehand with a pole lift, foreguy, and afterguy... Then, unfurl the sail, and fine tune it all... That's the only way to do it, especially offshore or in a seaway, IMHO. Further advantage is, if you have to furl the sail for a squall, or a temporary change of course, you can simple leave the pole in position, ready to go again...

I whisker pole is definitely something worth spending some money on, and doing right, in my opinion... Short of adding an inventory of free-flying sails, few things will afford such a measurable increase in your sailing pleasure downwind, and making the best of lighter airs...

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Quote:
Originally Posted by JonEisberg View Post
Think again, the compression forces at the inboard end can be considerable when the breeze comes up, and especially when it starts going forward...

Older Amels had an arrangement there downwind poles were mounted on sort of braces on the shrouds... It was a pretty stout arrangement, but I doubt it shortened the length of the poles by very much, and I don't think you'd want to try mounting a pole onto a single shroud in anything but the lightest of breezes...
That makes sense.
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Originally Posted by JonEisberg View Post
And for MedSailor, I don't like the sound of using just a "spike", or similar, at the outboard end... At least not on a boat of your size....
Jon is correct, of course.. the "spike" type of end is usually found on rather small boats.. I was just trying to visualize the bamboo experiment.

Thinking further (always dangerous, I know...) a splintering bamboo pole under load might be a relatively lethal scenario to someone in the wrong place.

As with so many things boating, poles are the way they are for a reason and there may not be a true 'cheap and easy' solution.
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As with so many things boating, poles are the way they are for a reason and there may not be a true 'cheap and easy' solution.
SailingDog is that you? How did you get a hold of Faster's password???

I challenge the above assumption in general as a sad triumph of good marketing and lack of creativity over resourcefulness and ingenuity.

If I die by splintering chopsticks, it'll make for a very original epitaph.

As for , length mattering, I can see that a J length pole would be nice to have to be able to furl the sail up with the pole attached. I'm trying to imagine how one would do that with a 1.5xJ pole without going forward and shortening an extendable pole....

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Whisker poles should be strong/stiff enough so that when (not if) a held out genoa becomes 'backwinded' the pole will not fail due to 'buckling failure'. Buckling failure is vast 'multiplier' of a compression failure due to 'side deflection' of the middle of pole ... like how easy it is to break a yardstick or meterstick by simply holding it upright from the ground and applying a very slight amount of pressure on the free end .... the 'middle' greatly bows while the pressure is applied and it breaks at perhaps 10 times LESS than what it would fail in pure compression.
Ya need RIGID and STIFF if you ever want a spinnaker pole or whisker pole to 'survive' a compression.

Bamboo unless its large diameter bamboo is very vulnerable to buckling failure because its sooooooo 'flexible'.

Last edited by RichH; 02-14-2012 at 12:08 AM.
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