Junkrigged Tacking Proa from Röda Möllan Sweden
Just not the Chinese lug rig ?
😉
Well, let’s face it. The traditional rig requires extremely stiff battens, so the sail is quite flat. But when the wind picks up, the sail takes on exactly the wrong shape—the front falls off the wind generating turbulence on the lee side on both tacks with one worse than the other.
And saying a sail is great downwind is no brag. Last time I heard, if you want great downwind performance, use a spinnaker—which is basically a modified parachute.
But, well, for light airs in crowded harbors the junk is king. Granted. I knew a guy in Honolulu with a 60 foot junk. He told me his fourteen year old daughter could handle the rig. That’s pretty impressive.
But it’s not for me. I don’t give a damn how easy something is to handle. I love the feeling of spray stinging my face. I love the singing sound of fast water ripping by your hull. Besides, In a really, REALLY fast boat, you are ALWAYS sailing into the wind. So for me, screaming windwardlyness trumps all. (Is that even a word? If not, It should be.)
And your take on the crabclaw….....
And your take on the crabclaw….....
Number 1 according to this
http://www.lukawskiyachts.com/mona/class.htm
Not sure of validity but interesting, Junk number 5 Rick
Tink
And your take on the crabclaw….....
Touché, Alex. You got me.
I’m building a five foot model right now specifically designed to see if I can get better windward performance from the claw. Can it be done? I do not know! I DO know the challenge is worth pursuing.
The sail I’m looking at is kind of a cross between a crabclaw and a windsurf sail—a long, elliptical cross section, yard and a shorter boom but with a straight leech so I don’t need battens. It’s a bit more triangular than a windsurf sail, not because that’s better, but because it’s lighter, simpler, and cheaper. I’m a practical cat, so I like that.
And just to let you know… “Oh, the cleverness of me!” (He says. Ironically.) I have this idea that instead of reefing, I can reverse the boom with the yard and get this total low aspect shape in ferocious wind. Does not a having a 200 square foot sail with a CE about four feet off the deck sound wicked cool?
We shall see. I believe nothing I have not seen for myself.
But yeah. The claw is worth pursuing and taming. This deserves another thread. You catch me at a stage where I am testing my epoxy skills and my lofting skills. Boatbuilding is not for the meek. And we who would break out of the box must necessarily face failed experiments.
Last, uh, OK. The crabclaw has a Romantic, aesthetic attraction. I admit it. At the heart of all things there may only be feelings, and all our logic and science is subservient.
Best,
Rick
Cheap monohull test hull isn’t exactly a benchmark…...
First up - mast placement is well forward. Ok on a dinghy but not ideal on bigger boats?
And your take on the crabclaw….....
Number 1 according to this
http://www.lukawskiyachts.com/mona/class.htmNot sure of validity but interesting, Junk number 5 Rick
Tink
I came across that page in my travels too. Not sure of the validity as well. Better to to take the same boat and test it with different rigs, and even that has liability, for each boat tends to have a rig best suited for its type.
Junk also has those romantic connotations….....
To some.
But for simplicity, cost and DIY - the crabclaw must win on a proa?
Take madness for example - the rig cost as much as the boat and was had at discount!
(Madness is for sale people…)
While not a cruiser , people are obsessed with speed potential of proa’s and reinventing the wheel…. Have weird boat - add weird rig!
I don’t get it.
For efficiency the jezzero.
For cost and simplicity the crabclaw.
Back to those pesky Chinese lugs - even Wharram and his slower cats gave up on them ages ago.
But - part of the fun of a proa is reinventing the wheel….....
Junk also has those romantic connotations….....
To some.
But for simplicity, cost and DIY - the crabclaw must win on a proa?
Who knows? I ask this same question. Only tests will tell.
Take madness for example - the rig cost as much as the boat and was had at discount!
(Madness is for sale people…)
That is exactly the situation I want to avoid.
While not a cruiser , people are obsessed with speed potential of proa’s and reinventing the wheel…. Have weird boat - add weird rig!
I don’t get it.
For efficiency the jezzero.
For cost and simplicity the crabclaw.
Back to those pesky Chinese lugs - even Wharram and his slower cats gave up on them ages ago.
But - part of the fun of a proa is reinventing the wheel….....
I think we actually completely agree. There has GOT to be a cheap, simple way. If that is re-inventing the wheel, then the fracking wheel need to be re-invented.
Crab claw can have advantages, and most of this has not been reported before. There are radically different rigs being called crab claw, the wharram style and the ontong java style, replicated on wakataitea, for example, have little in common. Although I don’t mean to dismiss the other, which the owners are pleased with, I only refer here to the wharram style which has a number of aerodynamic and handling advantages over conventional rigs.
1. The sails have an airfoil shape no matter how they are cut, because the leading edge is more vertical and normal to the airflow than the boom. The closer to parrallel the flow is to the spar the flatter the sailcloth becomes in the direction of the flow. No other sail is shaped by its spars like this, but it requires the upsweeping boom. Putting a jib in front of the sail ruins this advantage because such a sail is more efficient with the draft in its middle.
2. Tilting the sail down not only lowers it but flattens it (as explained above), so the sheet load can be reduced, just when it becomes excessive. When the tilted sail is undersheeted it doesn’t become too full because it’s supported by the spars. This is effective depowering when close hauled. By adjusting the sheets and tack controls the sail can be quickly tilted up and down to the gusts. This technique is not for use off the wind.
3. All compression is on the stub mast and all bending is on the yard; a structural advantage.
4. Ketch rig makes real heaving to possible, which is the most powerful technique in all sailing. Ketch rig is also optimal for self steering to weather with the mizzen acting as a steering sail and the larger main set for power. Only crab claw balances the area of a low ketch or yawl mizzen with a top heavy main resulting in an even, close to elliptical, vertical sail area distribution of the entire rig. Other ketch rigs have the preponderance of sail area along the deck.
5. The sails automatically flatten in higher wind speeds because of their exceptionally bendy spars. Jibs inevitably work oppositely.
6. Drag producing halyards, shrouds and mast are all limited to the lower half of the rig reducing weight and windage aloft. The short masts also create much less windage and weight aloft in storm conditions at anchor and at sea under bare poles, also when motoring (doesn’t apply to me). The mast on the windward side of the sail puts its windage in an area of reduced and aft shifted airflow.
7. The aft leeward shroud can be untied, passed between the yard and mast, and retied aft of the sail so that the mizzen can set directly out to the side of the boat with no chaff. This eliminates the adverse affect a mizzen has on steering when the wind is abaft the beam making the mizzen an effective sail on these headings. It is easily done with the sail standing, which is impossible with any other rig. This is an advantage of the utmost importance in real sailing.
8. When the halyard is released the sail can not fail to instantly drop.
9. An effective new mainsail can be easily hand sewn out of polytarp for less than $100, because the spars support and shape the sails. The whole rig is unbelievably economical for the self-builder, the long bendy spars being the hardest part.
10. A runaway halyard can be reinstalled from on deck with a ten foot stick.
Vortex lift is not generated unless the leading edge of a foil is tilted back more than 45 degrees in the direction of the airflow which obviously doesn’t ever happen to crab claw. Ironically leading edge attached vortexes are probably generated by the gaff on a wing sail over the sail’s head.
Reefing can only be done when the sail is completly dropped so has no advantage. It is easier and quicker to put up a separate smaller sail and this will have better shape and smaller, lighter, optimal spars. This switch is easier than changing jibs, and with the short mast results in a better, cleaner reduced rig than any reefed rig, since it carries no bare masthead up at the top.
Nobody should try something really unusual like crab claw unless they are willing to devote their life to experimenting, failing, modifying and analysing it. Definately not for today’s consumer cruiser.
From Glenn Tieman on Wharram builders and friends.
I know it’s a cat, but interesting none the less…..
Crab claw can have advantages, and most of this has not been reported before. There are radically different rigs being called crab claw, the wharram style and the ontong java style, replicated on wakataitea, for example, have little in common. Although I don’t mean to dismiss the other, which the owners are pleased with, I only refer here to the wharram style which has a number of aerodynamic and handling advantages over conventional rigs.
1. The sails have an airfoil shape no matter how they are cut, because the leading edge is more vertical and normal to the airflow than the boom. The closer to parrallel the flow is to the spar the flatter the sailcloth becomes in the direction of the flow. No other sail is shaped by its spars like this, but it requires the upsweeping boom. Putting a jib in front of the sail ruins this advantage because such a sail is more efficient with the draft in its middle.
2. Tilting the sail down not only lowers it but flattens it (as explained above), so the sheet load can be reduced, just when it becomes excessive. When the tilted sail is undersheeted it doesn’t become too full because it’s supported by the spars. This is effective depowering when close hauled. By adjusting the sheets and tack controls the sail can be quickly tilted up and down to the gusts. This technique is not for use off the wind.
3. All compression is on the stub mast and all bending is on the yard; a structural advantage.
4. Ketch rig makes real heaving to possible, which is the most powerful technique in all sailing. Ketch rig is also optimal for self steering to weather with the mizzen acting as a steering sail and the larger main set for power. Only crab claw balances the area of a low ketch or yawl mizzen with a top heavy main resulting in an even, close to elliptical, vertical sail area distribution of the entire rig. Other ketch rigs have the preponderance of sail area along the deck.
5. The sails automatically flatten in higher wind speeds because of their exceptionally bendy spars. Jibs inevitably work oppositely.
6. Drag producing halyards, shrouds and mast are all limited to the lower half of the rig reducing weight and windage aloft. The short masts also create much less windage and weight aloft in storm conditions at anchor and at sea under bare poles, also when motoring (doesn’t apply to me). The mast on the windward side of the sail puts its windage in an area of reduced and aft shifted airflow.
7. The aft leeward shroud can be untied, passed between the yard and mast, and retied aft of the sail so that the mizzen can set directly out to the side of the boat with no chaff. This eliminates the adverse affect a mizzen has on steering when the wind is abaft the beam making the mizzen an effective sail on these headings. It is easily done with the sail standing, which is impossible with any other rig. This is an advantage of the utmost importance in real sailing.
8. When the halyard is released the sail can not fail to instantly drop.
9. An effective new mainsail can be easily hand sewn out of polytarp for less than $100, because the spars support and shape the sails. The whole rig is unbelievably economical for the self-builder, the long bendy spars being the hardest part.
10. A runaway halyard can be reinstalled from on deck with a ten foot stick.
Vortex lift is not generated unless the leading edge of a foil is tilted back more than 45 degrees in the direction of the airflow which obviously doesn’t ever happen to crab claw. Ironically leading edge attached vortexes are probably generated by the gaff on a wing sail over the sail’s head.
Reefing can only be done when the sail is completly dropped so has no advantage. It is easier and quicker to put up a separate smaller sail and this will have better shape and smaller, lighter, optimal spars. This switch is easier than changing jibs, and with the short mast results in a better, cleaner reduced rig than any reefed rig, since it carries no bare masthead up at the top.
Nobody should try something really unusual like crab claw unless they are willing to devote their life to experimenting, failing, modifying and analysing it. Definately not for today’s consumer cruiser.From Glenn Tieman on Wharram builders and friends.
I know it’s a cat, but interesting none the less…..
To all that, quoted in full, I can only say, “Yep.” The crabclaw is a true seafarers’ rig, tested and proven across millennia and millions of miles.
But…
If to that we can edge up the windwardlyness to something like a sloop, well then, we would have the sail to end all sails on a proa, shunting difficulties be damned.
My think is that we just need a bit more asymmetry in the yard and boom relationship, that, and composite tech in the spars. It’s not a new thing; it’s what the Micronesians would have done had they access to advanced materials. This is an honorable contribution to an ancient art.
[EDIT: Just wanted to point up “today’s consumer cruiser.” Yes. Yes. Did I say “Yes?” Oh. Yeah. I did. The claw is not for the faint of heart.]
[I like that.]
[EDIT #2 Chris Grill has some awesome crab claw sailing sailing experience to be found here. Don’t know what happened to this guy at the end of his story, but his blog is worth reading. In the end, he figured out how to fly a lot of sail in big winds. The Claw takes some learning. This I grok. (That’s a Robert A. Heinlein reference. Look it up.)]
I think we should move the Crab Claw discussion to another thread, and leave this thread to discussions about Fredriks Akka.
New thread:
The Crab Claw - Wharram style
Cheers,
Johannes