Proa sailing with an A Class catamaran rig
Hello,
I would like to share my experience with my second rig on my proa, the use of an old (read aluminum, instead of carbon) A Class catamaran rig. If you do not know A Class catamaran, the modern version looks like this:
http://dnacat.blogspot.sg/2010_04_01_archive.html
This was after my adventures/experiments with a kitesurfing 12M2 kite. You can see details on this here:
http://proafile.com/forums/viewthread/225/
So I went from one extreme to the other; the attempt to use a rig with no heeling force (the kite) to the freaking tallest rig I could find!!!
The mast was pivoting on a pin smack in the middle of the main hull, with stay and back stay to both ends of the main hull, a strut to windward to the middle of the ama, made of an extended windsurfer mast AND 2 shrouds, going to both ends of the ama. I could rig the boat with the mainsail only, or add a jib.
My mast and main sail were bought locally in Houston, where I resided at the time. The jib was bought on line as a used sail from Bacon Sails, a gold mine for used sails of all shapes and prices.
http://www.baconsails.com/
I found out that Star jibs had the right dimensions for my rig and bought one; I found out that buying sails and rigs from competitive classes can be a good bargain; the fanatic racers will change a jib after 2 seasons of races, eventhough the sail is still “crisp” and has many seasons of sailing left in it.
Since I did not have a mainsheet traveler shaped like half a circle on the leeside of my main hull (it’s a proa, after all…) I ditched the boom and the vang system and replaced it with a wishbone. I bought a (very) used wind surfer wishbone, kept the key elements and pretty much rebuilt it, larger, with aluminum tubes.
I modified the mast to attach the front of the wishbone, and made up a halyard system, with cleat at the top of the mast to avoid the double compression on the mast. A Class rigs do not have a halyard, whatsoever. They have a hook at the top, and a ring on the sail. You tilt the boat, slide the sail in the track, get the ring on the hook, and yank the hell out of the downhaul; you see, a halyard is too much weight aloft…. Not so for me. My setup allowed me to cleat and uncleat the halyard at the top of the mast; so no more compression on the mast than the ring and hook system.
I also added reefs on the sail; you see, a 30 ft mast with a 28 ft luff main sail can be too tall, sometimes…
With that rig, I did the Texas 200 solo in 2010. You can see a few pictures of the boat during that race on the detailed account by Jim Michalak, a real small boat designer, not like me.
See here:
http://www.jimsboats.com/15aug10.htm#2010 Texas200c
This was day 2, Jim is right, I passed all boats; except that I got passed again on the last half mile in the narrow channel to the marina, with the wind in the nose, of course. You will notice the tone of his comments, half amused, half condescending…
During that same day, I passed by our world famous Skip, who took that short video of me.
http://www.dailymotion.com/video/xduffy_texas200-2010-proa-sailing_sport
Here are 2 pictures by Jim, at the end of the T200. He is right, I did not break anything during those 5 days; to his surprise… and mine!
http://www.jimsboats.com/1oct10.htm#2010 Texas200f
I still remembered vividly the year before, where it did not end up so well… See my account below.
http://www.texas200.com/2009/stories/laurent/index.htm
Finally, here is a small video with Kevin, where you see me shunting. Release the sheet, raise the old dagger board, start sheeting in the other direction, to stop the boat, lower the new rudder, sheet in, lower the new board, raise the old rudder.
http://www.dailymotion.com/video/x99q0t_lake-livingston-may-10-2009-shuntin_sport
It looks kinda sedated and easy, but let me tell you, with a main only, if there is a lot of wind, and some chop, it can be hell. I remember my last shunt in the T200, where after fighting for 5 minutes, paddling like crazy to get out of irons, and swearing in French (it actually helps, you know…), I finally got the boat moving again in the right direction…I’ll come back to that.
Cheers,
Laurent
So what did I like about this rig, and what did I not like so much?...
Potentially very efficient; it is coming after all from one of the most refined racing catamaran class…
Too bloody tall for my boat!!! If I capsized, I could not recover by the normal technique used on catamaran; I had to rig up a pole under the trampoline, deploy it perpendicular to the hulls and climb on it like a monkey to put my weight far enough from the boat to actually tilt the boat back up.
My wishbone set up was flimsy to say the least. So I never dared to yank it full tilt, to reduce the twist in the main sail to a minimum. I kind of regret of not trying the experiment, at the risk of exploding my wishbone… I like the wishbone set up though. If engineered right, you end up with a very lightly loaded main sheet. I should have rigged up a line from the clew of the sail, to the foot of the mast, as a vang, to pull down (and compress…) the wishbone to reduce the twist. Instead, the FRONT of the wishbone was on adjustable line; by pulling on the snotter lines, I could both reduce the depth of the sail, and the twist… to some extent.
Despite these limitations, with the help of my non-symetrical boards, I could really go high against the wind.
A good wishbone allows you to have a well shaped marconi rig mainsail, without the expense of a traveller track, etc…
It was too tall for my boat size; great in very light wind to catch the slightest wind, way up there, but above 12 knots of TWS, a handfull to deal with…
Cheers,
Laurent
PS: did I tell you it was too tall????....
A few more videos, with the A Class rig, and the Star jib. Sorry for the crappiness and over exposure…
http://www.dailymotion.com/video/x9a3bp_lake-livingston-may-10-2009-with-ji_sport
You can see the snooter line arrangement on the home made wishbone, a bit of the strut installation and another “feature” of the boat at that time. With 2 people on board, it is too low on the water, so as soon as I pick up speed a bit (around 9-10 knots), the nose dives a bit, just enough for the front rudder lower support to hit the slightest chop in a more or less continuous way.
Wonderful water brake…
A bit more of the same here.
http://www.dailymotion.com/video/x9a31y_lake-livingston-may-10-2009-with-ji_sport
So how do you fix the rudder support being too low, when the top one is already flush with the deck? Well, you cut your hull like a French baguette bread, lengthwise and horizontally, just below the lower supports for the rudders, all the way, and you add a 6” section in the middle… That’s how you do it!
But that’s another story…
Cheers,
Laurent
This is all great reading, Laurent.
I wonder if you ever had issues with your boat wanting to head up coming out of a shunt. Your A class rig seems like it might be a candidate for that kind of behavior when the boat is mostly still and the foils are not working well yet.
What are your thoughts about the schooner v. cat rig with an occasional jib on a proa? Do you know of anyone else who has tried both rigs on the same proa?
BTW when I said you had a way with words, I absolutely meant it as a compliment!
best,
Chris
Hi Chris and all,
Since Gargen asked me the same question, I will re-use my answer to him and edit here.
On top of the issue with the A Class rig that I described in my previous post, which is too high a CoE, too much rig inertia, very difficult to right in case of capsize, It’s shunting, with a mainsail only, on a sloop, with the mast on the centerline of the vaka that just top it of!
Despite what the video on the previous post may make you think, with any kind of wind above very light, I always had trouble shunting without ending in irons… or aback. Even if I had the new rudder in the water, the front rudder lifted, the correct dagger board in the water (the aft one, and my dagger board are non symmetric profile and MASSIVE), as soon as you sheet in the sail on the new tack, the boat rotates into the wind, before it gets enough speed for the rudder to actually “bite” and gain control.
In that case, a paddle is your friend; coupled with some fairly high level of rage, I could actually turn the boat back in the right direction, gain some speed and then everything behaved as planned again…. : )
I know that Russell Brown does not have this problem; I believe it is for 2 reasons: his mast being significantly to windward, when you start sheeting in on the new tack, the aerodynamic force on the sail does not apply so much on the leeside of the boat, but is most likely actually applied very close to the centerline of the main hull, so that “misalignment”, which in my case is a big contributor to the heading up effect, simply does not exist. The second reason might be that with a “skegged rudder”, when you turn the rudder, you effectively end up with a cambered foil in the water. I suspect that, as soon as there is some water velocity over that rudder, it will be much more efficient than a symetrical profile at the same angle of attack.
Less misaligned driving force, more efficient controls: no problem!
If you look carefully at the videos of Harryproa posted on the web, you will see that it is not so true for those boats…
The shooner rig changed all of that. I had experience on that with Kevin’s boat; you sheet in the front sail first.
That’s it. That’s the only thing you have to remember, the rest falls into place effortlessly.
My first experience with the Moth rigs was not all positive… I had to extend the original masts so they would slide into sockets I installed on my hull. They are rigged with shrouds on the windward side, but if I get caught aback, I should be able to let go the sheet and let the sail rotate to some extent to get back the control.
My first carbon fiber sock/epoxy work was under par… I still had inside the layers some dry spots I did not know about… until one extension broke right under the end of the original mast… I had that redone, and knock on wood, no problem so far… At least on that side.
The sail area, with both masts, is still the same than the A class with my small Star jib (yes, I like to scavenge classy rigs from other boats…). It’s about 16 sq meters.
The center of effort is waaaayy lower, even if the rigs sit a bit high on my hull; because I did not want to have too shallow an angle for the vang. Moth sailors are fanatic about their vang. Their mast sits on top of a “pyramidal tubular structure”, with the attachment for the boom right above the pin. The vang goes from the boom, to the bottom of the boat, at the foot of that pyramidal structure. They have a very horizontal vang, huge loads and up to 32 to 1 vang!!! So I am told. I did not want to make this type of stresses on my mast extension so I raised the boom, to open up the vang angle; It looks funky, but it seems to work.
And, oh yeah, I no longer need a pole extension to right up the boat if I capsize…
Over all, I am very happy with the change; I have been in pretty strong winds and rough beach start with Kevin as crew last year, and the rigs held strong; the rudders and the dagger boards trunks, not so much… But it is another story…
I have not seen any big loss of performance… But keep in mind that all of that is based on limited experience. In other words, I spend much more time fixing my boat than sailing my boat!!! Especially in the past year.
The only conditions where the A class mast would be superior for sure is ghosting conditions (very light wind) dead down wind. I sailed once against Kevin under those conditions in one of our Texas Proa Championship “races” (pompuous title to feel important; I thought about intergalactic proa championship, but it was a bit too much…). The fact that I had a much taller mast (and a stronger push from the beach for our “Le Mans” style start) made a big difference.
I am now based in Singapore. The boat came with me in the container; I am slowly finishing the repair of the trunks (open heart surgery; how do you remove and replace 2 daggerboards trunks on a completely enclosed hull? answer; with a lot of difficulties and occasional swearing in French does seem to help). I gave up on rebuilding the rudders blades and just ordered 2 new ones from Phil’s Foil online (now known as CCI). I have not sailed for the past 6 months, but I hope to be able to do so in the coming 2 months or so…
I experience the same easiness than Kevin for shunting. I have only 2 sheets, no jib like Kevin. I may need to be able to sheet the aft sail a bit more since it is in the wind drift of the front sail. I will look at changing the anchor point of the sheet to the ama (I have a 2 to 1 for the sheets, way enough). So one “strand” of the sheet pulls the boom horizontally to windward (with the end attached to the ama), and the other “strand” pulls the boom down, to the main hull. Sorry, I do not know the proper term; I am trying to describe the 2 different lines that make a 2:1 purchase.
This would be final tweaking, really…
I am impatient to get back on the water and sail again, in Singapore!!
Cheers,
Laurent
This was really interesting and helpful, Laurent!
I wonder if you have any other thoughts about mast placement once you are underway. There has been some talk about how the driving force from the rig should be to windward of the main hull in order to reduce the weather helm induced by the ama.
http://proafile.com/forums/viewthread/26/#78
http://proafile.com/forums/viewthread/76/
Have you noticed any bad habits from having your masts on the centerline of the main hull while underway, while the foils are biting? Are you getting much weather helm?
Given your experience with overpowered rigs, what do you think is the best way to calculate the optimal sail area? Scampi is going to be a cruising boat—I don’t want to EVER capsize if I can help it.
Thanks again for sharing your experience with us! Its much appreciated.
Best,
Chris
This was really interesting and helpful, Laurent!
<SNIP>
Have you noticed any bad habits from having your masts on the centerline of the main hull while underway, while the foils are biting? Are you getting much weather helm?
Given your experience with overpowered rigs, what do you think is the best way to calculate the optimal sail area? Scampi is going to be a cruising boat—I don’t want to EVER capsize if I can help it.
Thanks again for sharing your experience with us! Its much appreciated.
Best,
Chris
The answer to your first question is No, if you mean by bad habit the tendency to have too much weather helm.
My boards are assymetrical, like a true wing. I have 2 (yes…. more work during the shunt…) and they are placed aft of mid ship.
Since they have curvature and a small angle of attack, even if the main hull goes straight in the water, with no leeway, the board in the water creates some lift to windward, aft of mid ship. So I can sail with no weather helm, if I have the right amount of board in the water.
Actually, I had even some leehelm in some cases! The wind picks up, the boat accelerates, and the amount of board in the water generates more lift and gives a leehelm tendency to the boat; easy to fix though, just raise the board a bit…
I don’t know if there is an optimal way, but I used the Kelsall Stability Index and it seems to be on the ball park number… It is supposed to tell you at which wind speed, you will lift the ama, with full main and 100% jib. Derek Kelsall is careful by saying that many other factors come into play and it should be used as a comparison tool only.
You can find it here.
http://www.kelsall.com/TechnicalArticles/KelsallFormulas.pdf
WARNING: you have to modify the formula for a proa!
Derek Kelsall assumes of course that your boat is symetrical longitudinally, so your CG is on the centerline of your boat, either a catamaran or a trimaran. His numerator is based on the right arm of the boat: displacement x distance from centerline to leehull. In our case, the CG is (most often) NOT at the mid point between the 2 hulls. So to replace his “distance from centerline of the boat to centerline of the lee hull”, I use “distance CL to CL between hulls x % of displacement on ama”. that is how far the CG is, from the main hull.
For height of the center of effort to WL, I use half mast height plus a guesstimate of how higher than waterline is the mast step…
Obviously, that does not really work for a crab claw…
For my boat, with the A Clas rig, I found a wind speed of 11.7 knots. With the shooner rig, I found 14.3 knots. It does not seem like much of a difference, but it feels about right with my experiece.
Over the years, I tried to gather data on different proas, from forums, articles, web pages etc and define trends, based on length, displacement, etc… It is to be taken with a (big) grain of salt, though as some of that data is questionable to say the least (such as “claimed” displacement…)
Cheers
Laurent
Over the years, I tried to gather data on different proas, from forums, articles, web pages etc and define trends, based on length, displacement, etc… It is to be taken with a (big) grain of salt, though as some of that data is questionable to say the least (such as “claimed” displacement…)
Cheers
Laurent[/quote]
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Aloha Laurent & Michael / editor, As everybody is trying to gather that data, could it be an idea, to make an specific place for such data , sort of spreadsheet with known correct data. that would be most helpfull for a lot of Pacific proa fans !!!?? see also
cheers Sven
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