It’s back…The Super Cat 17 is back as the ARC 17 better than ever ARC-17 Web Page.…lighter weight…stronger construction (epoxy)…larger sail area sloop (257 sq/ft)…wider beam (8’-6”)…Spinnaker option (290 Sq/ft=26.94 m2)…Tom has definitely not been a sleep at the wheel.

My old 1981 Super Cat 17 was my all-time favorite boat…what I consider the ULTIMATE ALL AROUND BEACH CAT! Simple, fast, no boards, bomb proof! What more could you ask for? How about lighter/stronger/more sail/max trailer able beam/highest level of finish and hardware/Unirig or sloop configuration/Spinnaker option…Tom (and Bill Roberts)awesome job!

Bob Hall

Tom's also developed an interesting snuffer system for that boat as well.

thom

WOW. a 17' boat with 257 sq feet of sail? Upwind? My 6.0NA has a reputation for being seriously overpowered monster and it's 3 feet longer and has a measly 264 sqft of area (only 7 more!).

the link to the website is here: http://www.aquarius-sail.com/

Did I dream this, or did someone tell me that Bill designed the first snuffer system?(sorry if thats a name brand product infringement thing)

dave mosley
www.seacats.org

btw we are proposing to have a second annual supercat 20 Nationals, and would like to include the whole line of SC's and ARC's. I understand there was some talk of a national event to be held next year in Pensacola, is this right, and if so, would you consider letting the SEACATS run your event here in Columbia SC May 15-16th 2004?

Hi Jake,
There are two important parameters when it comes to a boat being overpowered or not with a sail plan. The first important number is sail area. The second important number is sail aspect ratio which is closely related to mast height.
Bill

Hi David,
Yes I did, and I have a US patent on it. In the mid to late 1960s I was sailing a Flying Dutchman. There I came up with the spinnaker launching and retracting system which has now spread to many classes and all over the world.
Bill

...this L I N K. It was filed [color:"red"]Oct 6, 1966[/color].

I find it incredible that this system was not widely used for all these years. I have seen versions of it for awhile, but not until the I20 did I really see it used on cats. Maybe others were using it, but that is the most prominant example that seemed to jumpstart it. I hope Bill's making a killing off of it, I know I sure love mine. I have sailed the Viper(20' monohull with open stern) and it has a molded in version, and I think the Laser 2 is doing something similar too.
Thanks Bill,
David Mosley

Anybody have a clue what this boat has for a Portsmouth number?

This fact is a proof of how conservative the worldwide sailing comunity is - even the most competitive ones. Multihullers have a reputation of being more open minded.

But I remember lots of IOR boats in the 70s using this system, with a big tube inside the cabin. After some time the system was abandoned. Maybe it is not so efficient for bigger spinakers, but the truth is I don't know the actual reason. I was too young...

Anyway, even the best engineering takes some time to replace traditional methods. When refrigerators were invented, it took a long time and extensive advertising for people to start buying. Sounds like a joke today, but it's true.

One reason why sailing evolves so slowly, is the small size of sailing related industires. Big industries and corporations are faster then individuals with regards to (profitable) inovations. Mass production turns small unit profits into interesting results.

Keeping with the refrigerators, Lokheed's representative in Brazil once told me the following story when he rented my apartment there:

A company (there) started to mold the foam insulation instead of just jam pieces of foam between the internal and external walls of the refrigerators, as was customary at that time. The insulation of the molded foam is far better then that of pieces of foam, so the insulation could be thiner and still more efficient. Then, a smaller engine could be used (cheaper and less power consumption) and the internal volume grew (more groceries inside a refrigerator that looks the same in the outside).

This inovation found its way into every industy in the world and also helped that Brazilian industry a lot - they owe some very popular international brands today.

Comercial planes also copied the same idea (to keep the heat inside) and that explains why the guy from Lokheed knew the story.

We need more people sailing and greater production volumes. Then, improvements will be introduced yearly, like in cars.

Cheers,

>>>Anybody have a clue what this boat has for a Portsmouth number?

It provisional Texel number = 100 with spi and 104 without (I have not taken into account the oversized spi as that will drop the handicap number but it remains to be seen wether the craft is really faster with such a large spi)

This leads to some "conservative DPN" to be expected at 65 (spi) and 67,5 ( no spi) under PN.

I used 8 kg's for the weight of the mainsail, battens and jib together and added that to the 136 to give 144 kg's overall no spi = 318 lbs. My smaller Pentex sails together are this weight and so this should be a good comparison. Weight of spi package has NOT been included in this. With it the ready to sail weight of the spi version will be 144 + 5 kg = 149 kg's = 329 lbs. Pretty standard for a 5.18 mtr. = 17 ft long 2,59 = 8'6" wide platform with an 8,76 mast. Fully fitted Hobie FX-one and Inter-17 are on either side of it within a few kg's (lbs).

Its jib is quite normal in size 4,74 sq. mtr. = 51 sq. ft. The remainder of those 257 sq. ft. = shy 24 sq. mtr. is all to be found in the mainsail and mast. WOW ! just 3 sq.ft less than the US I-20 main.

measure of aspect ratio of the mainsail = luff^2 / area = estimate 8.5^2/19,1 = 3.78 (other definitions are used as well but this is a good approximation)

Compare this to some other types :

A-cat = 8,8^2 / 13,95 = 5,55
US I-20 = 9^2 / 19,4 = 4,18
F18 = 8,5^2 / 17 = 4,25
F16 = 8^2 / 15 = 4,27
Prindle 16 = 7.37^ / 13,82 = 3,93
Hobie 16 = 7,33^2 / 15,21 = 3,53
Nacra 5.0 = 7,65 / 13.50 = 4,335

Bill, how does aspect ratio impact on being overpowered exactly ? You have me at a loss here.

Spinnaker area 27 sq. mtr. I-20's is 25 sq. mtr. Boats of comparable length and mastheight have typically 17-20 sq. mtr.

Aspect ratio spi :

ARC 17 = draw^2/area = 8^2(max !)/27 = 2,37 (probable 7,6^2/27 = 2.14)
I-20 = 8,3^2 / 25 = 2.75
F18 = 8,25^2 / 21 = 3.24
F16 = 7,5^2 / 17,5 = 3.21
ISAF youth trail boats = about 7^2/ 15 : 7,2^2 / 17 = 3.26 - 3.05
NA NE Nacra 6.0 with 250 sq.ft. spi = 8,5^2/32.5 = 2.22
Mosquito 17 = 6,38^2/16,9 = 2,41
Mosquito 15 = 6,38^2/14.2 = 2,87


Mosquito 15 was found to be faster in most conditions than the Mosquito 17 both in Aus as in South Africa. We all know how the NA NE N6.0 spi performs with respect to that much smaller I-20 spi.

More than a few sailors have noticed that smaller spis of higher aspect ratio are quicker than larger spis with lower aspect rations; in most conditions except a small wind range between light and medium winds. When the winds are light than the large area spi limps before the smaller spi does so; therefor the smaller spi is more efficient again in light winds.

For this reason I did not hit the ARC 17 with the kind of several Texel penalty for oversized spis. Remember the Tybee 500 where the NA NE had to give the US I-20 time on Texel handicap but where they were found to be about of comparable speeds.

The jib is pretty normal is aspect ratio and comparable to those of the newer boats with spi kits.

With this I think the estimates of the PN given are dependable; the old sc17 was DPN = 73. Quite an improvement.

Wouter

The old SC-17 with a PN rating of 73 was a ratings beater! The new one should be awesome. Even though it's a foot short, any chance of seeing this in the F-18 wars, either without boards or a version with?

Hi Joe,
For a first cut at a PN for this boat why don't we go to the US Sailing rules? The base PN for the previous SC17 was 73. The major changes between this boat and the old boat are in the sails. The mainsail is larger and square top and the boat has a spinnaker. The adjustment factors are as follows: 0.95 for the larger mainsail
0.995 for the square top
0.96 for the spinnaker
The boat without spinaker is slightly lighter than the old 17 but add the pole and rigging and sail and sheets and blocks etc and we are back up to the old 17's weight. The boat is 6 inches wider out of 8ft, or 6%, which will be hard to find in boat performance but the rules say wider boat so we better apply it. That is another 0.995. This brings us to a total adjustment factor of 0.9029. Apply this to the original 73 PN and you have an estimated PN for the new boat of 65.9 calculated using US Sailing rules. Looks like a fair starting point to me.
Bill

Bill… So what you are saying is that if the ARC 17 lives up to the 65.9 PN number it is going to be rated faster than all of these cats with Dagger boards…
Prindle 19 @ 66.4 original stock not MX w/o spinnaker
Nacra 5.8 NA @ 66 w/o spinnaker
Super Cat 19 XL @ 66.6 w/o spinnaker
18 sq Cat II Including Nacra 5.5, 11' beam@ 67 w/o spinnaker
Inter 17 Uni 30’ @ 67 with spinnaker
Taipan 4.9/F-16 @ 66.9 with spinnaker

If this proves to be true on the course, what a testimony for boardless cats.

Looking at the photos on the web site…there is a sequence of three photos where the bow is purposely driven down…was this to show the pitch pole resistance of the cambered deck? Is it to show how to motor up wind by utilizing the bows instead of boards? Both?

Bob.

Hi Seeker,
I appreciate your good wishes. I hope they come true. Only time will tell.
Don't jump to the conclusion that all boardless beach cats can carry chutes. Most boardless beach cats have non symmetrical hulls for the full length of the hull. Some others have a skeg well aft on a symmetrical hull. Either one of these hull designs have the CLR well aft on the boat. This leads to severe lee helm with the chute up. The ARC beach cat hull design has a deep vee hull shape forward to generate lift in the forward section of the hull and then the hull shape transitions to a round bottom at the transom. This means the rudder has to be oversized because it acts as the other half of the laterial resistance,LR or centerboard area, and rudder blade at the same time. So on the ARC17 the lift , the laterial resistance, is made up of a deep vee fore foot on the front end and an oversize rudder/centerboard on the aft end. The center of effort with the chute up will never go far enough forward to get in front of the bows on this boardless beach cat hull design.
The pictures showing the bows being driven down to and under the water (skipper and crew sitting forward) were taken to show the foregiveness of this hull design and high crown foredeck. A design with low bows and flat decks would have 'pitchpoled a long time ago'.
The ARC17 sails to windward best with the waterline half way up the bows. Don't forget on an ARC boardless boat, those rudders are working hard for you sailing to windward generating lift. A little less than half the lift comes from the bows. The rudders are much higher in aspect ratio than the fore foot of the forward hull, therefore the rudders make less drag than the hull for a required pound of sideforce.
In racing the boardless ARC17, it will struggle to windward but it will really scoot downwind.
Bill

WOW....been away for awhile. I saw the preview pics last year....now in production....wow...sign me up!

Bill, Wouter, Bob and All,

What a great time for innovation in singlehanded racing cats!

Reading this line of 'sailing minds' is very valuable,...especially the last post by Bill about the 'bow volume under spinnaker load' design.

...it was a good read!

..here is an idea,...make a 'Uni-rig open' portion of a large regatta,...allow the participants to sail other manufactures' design(, for example, Fx-1, T 4.9, N5.5, I-17, SC17, A-cat..etc)...kinda like a round robin, except on different boats,...the 'winner' would be a composite of 'all' types sailed.......since all these designs have their differences, sailpersonship would be the test..


....is that an idea,..or a dream...?

..congrats to your new 17 Bill,....where can we demo this???


regards,

Bruce
St. Croix

Hi Mr. Roberts

The SC 17 was the first catamaran I ever sailed. What a revelation it was. I have been a fan since.

The website mentions the rudders have a series 63 section. Are they designed to operate in the bucket upwind or does that happen only when reaching?

If not, maybe rudders with more area could be used (with mast rake) to give the boat a better drag angle racing upwind. It would be neat carry one set of foils to make it the ultimate beach boat and one set for racing around the buoys. That would be little extra investment to have essentially 2 boats.

What is the design displacement? The SC 17 I sailed on seemed better able to handle an extra passenger than many other cats it's size.

What is the design waterplane beam of the hull? Are the hulls any different from the original SC 17?

It is nice to see a new cat with a lower aspect ratio sail plan. Not all of us sail our boats around the buoys. Reaching fast is the best part of catamaran sailing.

If I was in the market for a new cat there would be no question which one to choose. I hope you sell as many as you can build.

-colin

Hello Colin,
Thanks for your comments. I will try to respond to your questioms in order.
The rudders are NACA 6300 series foil shapes. They are the same rudders as used on the ARC22, therefore they appear large in size for a 17ft boat but the large size is needed for reasons already mentioned. To operate in the "drag bucket" of a 6300 series foil the lift coefficient must be small. That means in general terms that the rudders are not working hard. But the rudders on the 17 are working hard going to windward. The time that the rudders can operate in the drag bucket is when the side forces are small and the boat speed is high, at a low lift coefficient. This point of sail is sailing deep downwind with the spinnaker.
I don't think two sets of foils, rudders, are necessary. The ARC17 already has large foils by industry standards. Smaller foils have been tested and that is definately the way not to go.
The design displacement for the ARC17 is 700 pounds. Now 700 pounds displacement for a lake sailing boat and 700 pounds displacement for an ocean sailing boat are two entirely different amounts of free board. You could take a foot off the bow height if the boat was a "small lake only" design. This extra free board for ocean sailing, SE coast of Florida, leads to more passanger carrying capability if that is the way you want to use it. Without the extra passangers, the extra bouyancy keeps the beams up out of the waves in the ocean.
The max hull width is 14 inches (at 2/3rds hull height) and it is the same as the old SC17 hull shape. The max waterline hull width is 12 inches.
This boat with its lower sail plan aspect ratio should be one heck of a beach cat drag racer.
Thanks for the good wishes, Colin.
Bill

Bill,
I went to the Aquarius site to look at the 17 and saw a new ARC 21 at 8.5' in width. Besides width, what is different about this seeming new design over the ARC20, which you state is able to be still ordered? (besides the variable width on the 20).
David
H20