Sailrocket 2 set to launch

High Tacker (www.damsl.com)

Practical application of proa canted sail geometry on a cruising cat

See details at www.damsl.com

I think of my Catbird Suite as two proas leaning together so that sails can be canted in either direction, to windward or to leeward, take your pick for the conditions. She has A-frame mast and four sails so far, all on furlers, including mainsail, staysail, and a genoa on each bow. The mainsail and staysail are on soft furlers, so their tacks can be moved easily around to different positions on deck, because with the beam of a cat there are many possible and advantageous sail configurations in addition to the usual straight up and down-fore and aft plan.

Since I'm a lazy 70-year-old cruiser, and safety conscious, and my cat is pretty fast anyhow, I usually do the opposite of what the Sailrocket guys do. On a long passage-making tack, I attach the main and staysail tacks to the windward side deck and use those sails and the windward genoa so that I can go from close hauled through reaches to run and have the entire width of the boat to sheet down to, to various tracks and pad eyes, and thus maintain ideal sail shapes with no booms needed. The leeward genoa can be added without a whisker pole when close hauled or with a whisker pole for reaching and running.

In addition to having no booms bashing about, so that an accidental jibe is a non-event, there are built-in safety factors with sails canted away from the wind. The heeling moment is substantially re-directed downward, and since the sails themselves are "heeled" away from the wind, even though the boat herself is not heeled, there is some spilling of wind in gusts, so that the shock loading that would be experienced on a big cat with vertical sails is somewhat diminished. As cat sailors well know, big cats are very unforgiving in a gust, no heeling, so no shock absorbing and wind spilling effects. So everything about the rig must be much stronger than on a monohull. (Not to mention an A-frame with each leg stepped in a hull, rather than a single big mast in the middle trying to break the boat in two. A monohull rig on a cat just doesn't make sense to me. A cat is two boats in one, so why not take advantage of that. Uh, a proa is one and a half boats in one, LOL.)

Uh, I don't fly a hull, but if she ever did heel much, with sails already canted away from the wind, the increased spilling would be dramatic before the heeling became dangerous.

On the other hand, if you don't want to spill any wind, if you want to go faster instead, and with upward lift on the sails and thus upward lift on the leeward hull, a la Sailrocket, then you attach the mainsail and staysail to the leeward side deck and use the genoa on the leeward bow, so that the sails are canted into the wind, like Sailrocket or like a windsurfer leaning into the wind. Sorry I don't have any photos of this configuration. I haven't done it often, and when I did, I was too busy to take photos. In the sailing photos below, all sails in use are attached on the windward side. Hey, as I said, I'm old.

It is also advantageous in very light airs to have the sails attached to the windward side and thus canted away from the wind so that they set into proper aerodynamic shape by the effect of gravity when there's not enough wind to lift them into shape. You remember when sailing a little dinghy, when there is very little wind you move your butt over to leeward to heel the boat a bit so that the sail will fall into shape. So in very light wind, as soon as I unfurl a sail I'm away, while all those vertically rigged boats have sails hanging like so much laundry, all drag and going backwards.

For short tacking, I attach mainsail and staysail on the center line of the boat. The leeward genoa can be added and then when coming about onto the other tack, that genoa must be furled and the genoa on the other bow unfurled as it becomes the leeward one. The older I get the more often I think about getting electric winches, but then I don't short tack often using a genoa, just use the motors if there's that little wind. What the hell, a cat is too fast to be short tacking up a narrow channel anyhow.

A monster main could be added, but she does very well to windward without one, and she is superior reaching and running. She's a great motorsailer, too. But I shouldn't get too longwinded here. Read all about it at www.damsl.com

Cheers, Tom Bradshaw

 

High Tacker (www.damsl.com)

Practical application of proa canted sail geometry on a cruising cat

Oops! Somehow I managed to delete these photos from the previous post:

 

Sailrocket

Light winds today-thinking they'll sail tomorrow: http://www.sailrocket.com/

UPDATE: 10/13/11--light again-tomorrow wind.......

 

Sailrocket 2--It's a go!

Paul Larsen says today may be the day-"..have to do over 50 knots" before they commit to the $6,000 to get the speed sailing record guys to come down to their site. Good Luck Team Sailrocket!

video from the other day: http://www.youtube.com/watch?v=GYAzMIwKsJE&feature=youtu.be

Wow-did anybody else notice the leeway??!!!

 

Was that leeway or a slide on a turn? I wonder why they aren't using a cockpit canopy or at least a faired wind screen when the least bit of drag adds up at those attempted speeds.

 

Sailrocket 2

----------------
Good question-but if it was actually sliding...........

 

They would be losing lots of drive....Stepped hulls aren't designed to be fast sideways.... they may be trying out different degrees of lateral resistance. Or trying not to overload things when turning.

 

50.5 knots today, and SC foils are reported to be working.

Good forecast for tomorrow
so see what tomorrow brings.

Brian

 

Sailrocket

=================
Wow! They did it! Now for the record.... Thanks, Brian.
from the site: 50.83 knots/ 58.12mph

 

For those discussing "leeway", this boat is designed to have the main "hull" angled to the direction of travel. This is to reduce air resistance as it makes its runs. That is part of why it actually rides on 3 "pods".

As an engineer always looking for a better approach, this boat just impresses the heck out of me.

As I posted on the VSR2 site, the choices made for the new design are showing through. No other boat has had this combination of good natural stability and no foil cavitation. How many runs did it take for any other contender to push past the mid 40s?

The only known limits are structural, efficiency and wind availability. This round just feels different.

Speaking of efficiency, I hope all the data logging worked so that they can determine how well things are matching up with projections. I am betting that they will grab the record long before they reach the ultimate limit for the boat. Then Paul and his team will be in new territory, deciding how hard to push just to prove what VSR2 will do.

 

Thanks for the clarification, an interesting approach.

 

Sailrocket

Excerpt from Pauls blog today: http://www.sailrocket.com/

Hmmmmm...
Well it looks like ventilated foils aren’t going to give up all their secrets that easily. We went out today in what I would call ‘top-end’ conditions with gusts up to 31 knots. The first run wasn’t in winds this strong. It was pretty much a repeat of yesterdays 50 knot run. The boat felt great and I managed to use the whole of the course. We are still downloading data but we know it was another run between 47-48 knots with peaks over 50.

SMOKING. GREAT CONDITIONS, WING IN, SITTING LOW... BUT...Hmmmmm.

What’s going on here? I was sheeted in further and it was ‘solid’ wind. We really should be seeing continual solid progression, especially in these winds. I went again as the wind was hitting the 30’s. When the wind is gusting 30 it represents average winds more around 26-27. Helena sounded nervous as she called out the gusts. VESTAS Sailrocket 2 is made to sail in winds to 30 knots. I am only worried if it represents an ‘over speeding’ situation with crazy build ups of apparent wind. The apparent is what the boat feels and hence what will pull it apart. We aren’t there yet so I made the call to go for it and see what happens. I can always just ease the wing. I reckon on being pretty damned aware that I’m doing over 60! I discussed it with Alex as he is good at repeating my earlier plans and reasoning to me. The main reason for taking a bold step was to know for sure that we were over optimum design wind speeds of 26 knots average. If we still had a ‘glass-ceiling’ around 50 knots then we would know beyond all doubt that there was something we were missing. Raising the wing and launching the boat all went pretty well which is always encouraging. The comm.’s went down for the 87th time. VESTAS Sailrocket 2 accelerated like a scalded cat. I hit the course at pace and the acceleration came in brilliant bursts. I’m really starting to get comfortable with this boat... then BAM... she kicked and slowed. I figured either the wing or part of it had blown out. I pulled in arm fulls of mainsheet and there was nothing there. Obviously something in the new purchase system had failed for some reason. The middle section of the wing spun out to 90 degrees using its full-feathering range.



I put the rudder hard to windward to turn the rapidly slowing boat under the wing. Next I kicked up the main foil to allow the tail of the boat to skid around under the wing. The RIB was quickly up to me. As soon as they had me hooked up by the bow I went below decks to chase the culprit. It was nothing major. Simply a small string had failed as VESTAS Sailrocket 2 accelerated hard in the strongest conditions she had sailed in. I had replaced a single spliced string with a doubled up string of the same diameter but with two bowlines in it. It failed at the bowline. Typical, I should know better although I didn’t think it was that critical. Annoyingly it had happened at the peak wind of the day just as we were hitting 48.77 knots coming onto the course. I’m pretty sure we would have seen some higher big 'fun' numbers... but have no idea how high. It was set to be our biggest run. Once fixed we went straight back up to the top of the course and did another run. The wind was down to 22-25 knots. It was a real nice, clean run. I sheeted the wing in fully and the leeward pod leapt into the air. Not only does closing the wing-gaps in the wing increase the efficiency of the main wing, but it also increases the efficiency of the ‘wing-extension’ that sticks out the side. This purely gives vertical lift.

 

More progress

From the VSR2 site:

Hi all, just a quick one to say that we have punched through 54 knots, 62 mph and 100 kmh. The fun part is that we did it two up and VESTAS Sailrocket 2 was far from optimally trimmed. It was a wild ride...

 

54knots / 62mph!

Thanks ,PF--Fantastic!

 

Sailrocket smoking!

From Pauls Blog:

"The boat was smoking and I wanted to ride the gust to get the 500 meter average. Things were coming up quick. I eased the wing and bore away but VSR2 hardly slowed down. I was now out of runway and had to take evasive action so as not to hit the shallows at speed. At around 45 knots I swung into a hard right hand turn into the beach and wind. It was a long hard turn that the boat actually accelerated into as she smoked through her own ‘power window’. I knew I was in shallow water and started to try and release the main foil pin before we settled down to allow it to kick up but we slowed too quick. I felt the foil start to plough the thick mud and shell bottom. Not nice when the leading edge is a thin sharp edge as it is on this foil. We slowed quickly and stuck. I knew the situation wasn’t yet under control and could even escalate from here. VSR2 was floating and only the main foil tip was stuck. The grounding hadn’t been very hard so I doubted any serious damage. The RIB took ages to get to us as I tried to free the foil. I looked back at Adam and he was just wide eyed and looking at me for my response as to what had just happened. He had seen the GPS just in front of him. I was still concerned about the boat. As I tried to get things sorted I could sense Adam trying to draw my attention to the GPS. He wanted to know what the 53 number meant. I kept focusing on the boat but he persisted wanting to know what had just happened... how fast was that. “What had I just witnessed”? Eventually I jumped in the back cockpit and checked it out. 53.92 knots and a 50.05 500 meter average (54.4 on the processing and 50 even for the 500). It quickly dawned on me what had just happened. I told Adam that I had spent a great part of my life trying to sail on the fastest boats in the world... and in one ride he had been as fast as I had ever been. He was stoked. He had seen speed sailing at it’s best. He really hadn’t expected me to go that hard with him in the back. Neither had I really... but when your gust comes along... what are you going to do?

That was our first ever 50 knot average run... and it was all pretty easy. I had a 75kg passenger sitting up in the back waving and none of the extra aero aids onboard. The wing wasn’t fully sheeted in as the pod was already flying high and that would just make it go higher. I could easily see where another 5-8 knots would come from. VSR2 had beaten VSR1’s best ever run and she is still getting warmed up. I know now that we have a real contender. The kitesurfers are no longer the undisputed kings. They are the hunted. I know we haven’t done it yet but with every run our confidence grows. We were all buzzing as the thrill of a big run and what it represented began to sink in. The foil damage was only cosmetic. It’s one tough boat. Adam came to the breakfast table still smiling and was still buzzing as he got on the plane later today. He couldn’t have hoped for a better experience... short of going 60 of course."

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