Hey Bruce,
Rack = rake. It's been a long day.
Tom
Bruce,
I was suppose to have a date tonight, but I hurt my back in the gym trying to get ready to race in a couple weeks. Couldn't go. Guess I just have " a nice rack " on my brain.
Tom
Tom and Les,
Ok,..14-15,...this is the point where my stock sail ( 160sf) is;
1. full downhaul,
2. max mainsheet,
3. outhaul max tight,
4. mast rotation ( check groove at mast base, not arm[it bends and gives you a false reading]) just forward of rear beam,
5. traveler out 6-8 inches,
6. dagger-board up 12 inches
7. and the top 3 foam battens are replaced with solid fiberglass one ( no power from top part of sail)
....you can get all this data from the f-16 forum here, Wouter and the Austrailian T-4.9 sailers actually have a database of past articles,..plus they are very responsive to help out,.....to date, I can find no I-17 database such as this.
8. At 15 +, down goes the stock 160sf sail,..up goes the Charle Ogletree 150sf Pentax,...6 inches cut off the luff,..head to foot.........the boat goes from handleing like a pitbull on a short lease,...back to a sweet sailing machine,...and just rips full throttle,.
.....never has the rudders done anything but be 'finger-light'.
9. Since I canot get you guys to come sail down here, and I do not have to sail against you 
...I gave you my research for the last 2 years,...90% came from the F-16 Forum gang.
10. a Aussie T 4.9 champ shared with me,..once I touch the mainsheet, I am changing the draft and shape of the sail, and am guessing as to what is going on,...all bad things in solo Uni sailing upwind.
Since then,....I never touch the mainsheet from max tight,..even in 30+ storm conditions,...I just travel down until the boat gets'happy'...
Again,....what are you doing with your boards?
regards,
Bruce
St. Croix
Hi Bruce,
The ARC 17 is a beginner's boat, no boards, a true beach cat. It does have "shared lift" between the forward half of the hull and an oversize rudder which in actual practice could be called a steering daggerboard. The objective of this hull design was to have a "beach cat" with a better underwater lift to drag than other boardless beach cats so it would go faster and a boat that would tack easily and quickly. These goals were acheived. The underwater part of the ARC 17 hull is a deep Vee hull shape forward which transitions into a round bottom shape at the transom. The deep Vee forward acts like a low aspect ratio daggerboard and provides 50% of the sideways lift force while sailing to windward. The other 50% of the sideways lift force comes from an oversized high aspect ratio rudder. The result is a much higher effective underwater aspect ratio lifting body and less induced drag due to generating side force than the full length assymetrical hull shapes. The other benefit of this hull design concept is that since the hull shape near the transom is round, it can slide across the water sideways with ease. When the rudder exerts a sideways force on the transom, the hull spins right around. On a beach cat hull shape that carries the hard corner and assymetrical hull shape right into the transom, when the rudder exerts a side force to turn the boat, the rudder and hull near the transom get in a fight. The rudder is pushing the aft end of the hull sideways and the hull is saying, "no, I am designed not to go sideways" and there is a large hull drag increase and the boat comes to a stop about half way through the tack. Now the jib must be backed to complete the tack and the boat backs up and this causes the rudders to have to be reversed as the boat backs up and finishes the turn. Now with no forward speed coming out of the tack, if the mainsheet hasn't been let out, the rudders stall and the boat goes into irons. What a complicated mess it is when tacking can be so simple with proper design.
Relative to the spinnaker:
With the effective sideways lifting part of the hull being in the front half of the hull, the ARC 17 handles a spinnaker very nicely, no lee helm. The 17 was my very first "shared lift hull design". The ARC 17 is the only boardless beach cat that will carry a spinnaker without lee helm for the above reasons.
Good Sailing,
Bill
Hi Bruce,
You asked "Please descibe this 'stalling' of the rudder upwind"...
I've never experienced this on a catamran but the same thing does happen when windsurfing, there it's call spin-out and it happens for the same reason - the "skeg" (which is like a fixed rudder) stalls... loses it's ability to develop lift and loses it's diretional stability. What does it feel like? It feels like you've lost your skeg, ie, like the rudder fell off... time for the warp factor six face plant if you're unlucky!
Jerry
Thanks, Tom.
I've heard the I17 handles spi well in heavy air but how the heck to you launch it when it gets that windy without going over?
Jerry
Jerry
Perhaps I oversimplified it when I said that boats designed for spinnakers...etc.
If the spinnaker has been properly developed you should have no problem, the boat I had in mind was a Dart 18, we've got loads of them over here, about 5 years ago the manufacturer just stuck a spinnaker on them, it was not good, the boat has skegs and as the boat pitched back and forward, the CLR would move back and forth making the boat want to luff one minute and bear off the next, add some rudders that were very swept back and the boat was very dificult.
Bill is right about pole length, but what that really means is the angle of the spinnaker luff, the more swept back this is the greater the lift, so, I suspect the problems encountered by your friend are more down to lack of developement of the overall package rather than just the spinnaker acting on the hull shape.
The fact is that with sufficient developement you can make anything work well. Just look at a Porsche 911, no-one would build a sports car these days with the engine behind the rear wheels, but 30 years of developement and it's a superb car.
Jerry,
For launching in heavy air..............
We just head a little lower after rounding " A " mark............... be a little conservative while setting in heavy air. Then after it's up, you can power up as you please. This is when these single handed uni's are so fun. You are driving the boat, setting the main, and handling the spin sheet at the same time don't forget downhaul, mast rotation, outhaul and boards.
Oh, speaking of boards, Bruce, with all that I just mentioned my boards usually end up all the way down even if I start with them up 4" to 6". I ripped out a couple a those well cushions when I first got the boat because I couldn't move the boards. Have been re-epoxying sections in as needed. Usually ends up a bit on the loose side though which I like in case I hit bottom. It's real pain hitting bottom with the spinnaker up and know one to go forward to wrestle with the board.
Tom
To continue, because of all that is going on with the spinnaker up, most of us have move our mast rotator line cam cleats back aft of the boards. Also, we have added a cam cleat for the spinnaker. While distance racing in " safe " conditions ( inside, not out in the gulf ) we lock in our spinnaker sheet, move to the back of the boat and trap out. We then control the boat with the main traveler/sheet only (mainly traveler). If the wind is up, the boat will simply fly!!! And the spinnaker will make this moaning sound.......on my boat anyway. It's great. Other guys have customized their boats in other ways. That's what makes the I17R so much fun. You sit around and try to figure out how to make things easier for yourself with so much going on.
Tom
ps. I have had some rather spectacular pitchpoles on this boat...............usually because I got tired and wasn't paying attention. This boat will work you!!
Tom
Hi John,
I just returned from sailing in the Tradewinds Regatta in thr Florida Keys. I saw many different types of boats with spinnakers. Most boats have poles that are too short. When the spinnaker fills, the bows dig and the skipper and crew head for the back of the boat. I think that the reason for the short pole is that the longer pole pushes the CE further forward and requires even more mast rake than we see today to get rid of lee helm with spinnaker. Now take the spinnaker down and the sloop rig CE is so far aft that it stalls the rudders. So what do you do??? Go with a short pole and small spinnaker and less mast rake and live with it. You can "get by".
A better solution is go with the long spinnaker pole that lifts the bows and move the centerboard trunk forward a couple of feet to trim the boat out with spinnaker. Now without spinnaker, this will automatically reduce the side load on the forward located centerboard and increase the side load on the rudder. Therefore downsize the centerboard until it is carrying the boat's original design point lift per square foot of board area and upsize the rudder until it is carrying the boat's original design point lift per square foot of rudder area. This puts the centerboard and rudder back to operating at their respective design point loadings which results in the these foils operating at their highest level of lift to drag ratio while the boat is sailing to windward.
The other scheme of raking the mast back and balancing the rudders and "live with it" is a second level of performance compromise, a slower boat to windward.
Bill
Bill
Yes I agree, I have always used the shared lift idea in my boats, both those I build and when I sailed T's and others, Whether the boards are forward or not, the same efect can be got with what ever size boards/rudders are chosen, its just about the position of CLR against CE of the rig, however with existing classes obviously board position is fixed.
With the boats we build, we go down the raking the mast back route to load up the rudders, and rake back the spinnaker luff, however we do have large rudders, one thing that compromises most boats that now carry spinnakers is that most class rules limit pole length to 80cm beyond the bow, I don't know why they do this, but Formula 16, formula 18, Formula 18Ht, Tornado and Formula 20 all do this, most manufacturer class boats just toe this line as well, hence the reason why poles are generally short on cats compared to skiffs, also skiffs have a neat way of getting around the lee helm problem, they sail them upright upwind and lean them to leeward downwind, the rig, and hull shape then creates a torque screwing the boat upwind which goes some way to balancing the leehelm effect of the kite way out front, cats obviously aim to fly a hull as much as possible so they can't do this.
I think the fact is that we are both singing from the same hymn sheet on what makes boats go well, we just have different ways of achieving this. Funny isn't it when you put time into developing things, even when you are on different continents and in different decades, you still end up in pretty much the same place, I guess now the internet is around it will stop all this repetition of work!!
Bill,
No doubt that having a longer pole gives you a more vertical component to the drive produced by the spinnaker. But I don't recall seeing any spin boats bury a bow even in the 15-20 mph breeze at Tradewinds on Sunday. It was the least of our worries on the Inter20 and never even presented the remotest of possibilites. I did hear tale of 6.0 driving under but they weren't flying a spinnaker. The inter20 does have a relatively short pole. My 6.0 has a 14' pole and a 28' hoist height and I'm less concerned about burying a bow with the spinnaker than without it. You do have an extreme angle on the luff on the SC17 and I remember remarking how similar the SC17 spinnaker angle looked to that of the Aussie style skiffs (not that there's anything wrong with that).
Would you agree that if your pole is too long that too much of the force generated from the spinnaker would be lost to lift? For example if you take this to the extreme and come up with a spinnaker flying with the luff horizontal - it would not provide any forward drive and would only lift the boat and provide a healing moment. Point being, if the luff is at too much angle, you would not be getting the full benefit of all that sail area. Hence, the less angle at which you attach your spinnaker (and still handle it without driving a bow under) the deeper you can drive it and the faster you'll get to C.
Jake
In regards to pole length, the problem is in how the classes are spec'ing pole length.
In simple terms, Tornado's and 6.0's have long bows so spec'ing the pole 80 cm in front of the bow gives you a long pole. F16 have a 4 ft shorter bows so you end up with a shorter pole. On a Wave you would end up with 4-5 ft pole, if you did this.
I tested pole length on a Wave and found you were into diminishing returns at 50% hoist length
The pole length is dependent on hoist height. If you have a one design class like the Tornado, you know hoist height, so you can spec a pole that works with the sails you tried
One of the reasons Tornado spec'ed like this is it can be enforced and it probably eliminates some of the really weird ideas without going into a detailed explanation of how to measure the pole. For example, if the rules said "the tack can be no more than 12 ft from the crossbeam when measured on the beach." I might try bending the pole so that it was 12 ft and nearly touching the water at rest but extended to 14 ft under load. Historically, with Tornados, unless you say you can't do it, somebody will probably try.
For boats like the F16 where there could be wide variations in optimum hoist height, I think the rule is too restrictive. It indirectly restricts sails, mast height, and mast placement. For example if I wanted to push the front crossbeam forward for some reason, I could have some real problems
Personally I feel bad idea's have their own penalties, I would open it up and keep my camera handy for the guy who tries to use his spare mast as a spin pole.
Also Bill is very right in one respect. I learned a lot about this in designing my own boat from scratch and knowing I was committing my own money and time to my theories. There is nothing like knowing you are committing your time and money to make you conservative.
I've got two bent H17 masts laying around that you could try and use.
I think it would throw the balance of your rig off though 
>>In simple terms, Tornado's and 6.0's have long bows so spec'ing the pole 80 cm in front of the bow gives you a long pole. F16 have a 4 ft shorter bows so you end up with a shorter pole.
This is wrong. The F16 rules specify that the pole can be 3.50 mtr measured along the pole. No 80 cm past bow or anything. And your explanation is of as well. Sure the pole is shorter in a F16 than on a say a F18 BUT its hoist height os proportionally smaller as well and the also the area is (proportionally)^2 smaller as well.
The F16 spi setup is actually the same as taking a picture from a F18 setup and then photoshop it to x % size. Therefor the lifting and pitching moments have exactly the same effect.
You guys are looking at boat design like a person that thinks only coins are money. Exchange the coins for a banknoted and this person think he has lost money.
THAT is cherry picking boatdesign.
>>The pole length is dependent on hoist height. If you have a one design class like the Tornado, you know hoist height, so you can spec a pole that works with the sails you tried
What is the difference to the F16 rules ? You know the hoist height here as well and just as the tornado the pole length is given.
>>One of the reasons Tornado spec'ed like this is it can be enforced and it probably eliminates some of the really weird ideas without going into a detailed explanation of how to measure the pole.
Yep that is why we, the F16 class, do it in the same way.
>>For boats like the F16 where there could be wide variations in optimum hoist height,
HUH !? Did you read the rules at all ? From the beginning the Hoist height of the spi is 7.5 mtr. above mainbeam.
>>It indirectly restricts sails, mast height, and mast placement. For example if I wanted to push the front crossbeam forward for some reason, I could have some real problems.
Sorry ? But now you go from bad to worse. Mast height is 8.5 mtr max + max 0.075 mtr for the crane. Mast placement ? Absolutely NOT ruled upon. You can even put the forebeam behind the rearbeam if you want to. This is really complete nonsense you're are writing up.
The only thing that ruled upon in a varying way are the sailarea of the jib and that of the mainsail. It allows some differences in area and lufflength so that the net power remains the same. So here you are right, but how does this qualify as "too restrictive ?" . Isn't that a bit meaningless when ALL other classes except A-cat are more restricted in this ?
>>Personally I feel bad idea's have their own penalties, I would open it up and keep my camera handy for the guy who tries to use his spare mast as a spin pole.
And you would also by one of these boats ?
>>Also Bill is very right in one respect. I learned a lot about this in designing my own boat from scratch and knowing I was committing my own money and time to my theories. There is nothing like knowing you are committing your time and money to make you conservative.
And Bill is the only one having done so since 1978 ?
Really !
Wouter
I'm afraid we are flying alright where we should be standing with both feet on the ground.
>>one thing that compromises most boats that now carry spinnakers is that most class rules limit pole length to 80cm beyond the bow, I don't know why they do this, but Formula 16, formula 18, Formula 18Ht, Tornado and Formula 20 all do this,
Formula 16 does not.
Formula 16 specifies a pole length of 3.50 mtr in front of the beam. This is 1 mtr in front of the bows. And no matter what skiff lovers say the cats beat them fair and square. A 49-er with spi has a rating about equal to a Prindle 16 without a spi.
>>hence the reason why poles are generally short on cats compared to skiffs,
I don't know about that, the 49-er spi tack isn't much further in front of the mast than the F16's. Same for 29-er and javelins (I think cherubs as well) and lets not even start on 505, 470 etc. Only the int 12 ft, 14 ft, 16 ft and 18 ft classes are unrestricted in this and have those massive poles. Look up those ratings if you have the time. Not very impressive. Only the 18's would impress a catsailor.
What am I saying here ? That I think it is funny that we are taking advice from a design concept that has yet to outperform Prindle 16's and Hobie 16's when having massive amounts of sailarea and almost no weights.
>>also skiffs have a neat way of getting around the lee helm problem, they sail them upright upwind and lean them to leeward downwind, the rig, and hull shape then creates a torque screwing the boat upwind which goes some way to balancing the leehelm effect of the kite way out front, cats obviously aim to fly a hull as much as possible so they can't do this.
This is not true. Take the 49-er again. Come to think of it I'm probably the only skiff sailor in this discussion group. Anyway. The 49-er has MASSIVE weatherhelm that is fully camouflaged by a balanced rudder. It is the reason why it is a non-kickup rudder setup. Leaving the beach and landing is a real pain in b*tt. And I know because I do it regulary. You can hardly pull in the main as that will weather vane the boat. It is also easy on the 49-er to overload the rudder and get a spin-out. Rapid and big turns need to be accompanied with significant mainsail sheeting. The RS 800 and laser X*1000 use kick-up rudders. Man ! do you learn to hate those. The rudder only needs to slip a little and all that weathelm is right on your tiller. Eventually we learned to lay the boats on their ear right after leaving the beach and to jam the rudder as far forward as we could and TIE it into place. And to top it out the 49-er may still have lee helm under spi. It is a BIG spi.
And one more point. I'm standing far more to the rear under spi than I do on upwind or even reaching courses. Does this imply a net lifting force of the spi ? Or that the spi actually presses the bow down that I push up again with my weight ?
Wouter
Hi Bill,
Regarding the migrating CE problem, why not design cat hulls with two sets of CB trunks rather than one "comprimise" position - shift the boards when spi is up, no need for oversized rudders, less drag? If you didn't want two sets of CB's you could use "rubber slats" to automatically seal the bottom of the unused CB trunks to keep flow non-turbulent there as they do on retractable CB windsurf boards.
Jerry
Hey Bill, John, and you other engineer types,
Check out that picture that MauganH17 has posted. The boards are WAY forward.
Tom
Bill,
thanks for the info on your new ARC17,......I went back to your site and looked at it alot closer......
.......looks like a great boat.
Of course,..I had to check out the ARC 27 too,.....definately on my wish list!.
regards,
Bruce
St. Croix
Jerry,
You are not with me yet. The spinnaker up causes a CE migration, we all agree. With spinnaker up lean the mast back to get the CE at or behind the centerboard to balance the boat, no lee helm. This is what is done today, we all agree. Now take the spinnaker down and the CE of the sloop rig is well behind the centerboard much closer to the rudder. Now the rudder is overloaded and prone to stall. This is what we put up with today.
Here's another way to solve this problem: With the spinnaker up and the CE moved forward, move the centerboard forward to bring the boat in proper balance. Don't rake the mast back. Now we are in good shape with spinnaker up. Now let's take the spinnaker down. The CE moves aft a couple of feet from where it was with spinnaker up. This loads up the rudder and unloads the forward located centerboard. Now, reduce the centerboard area the same percentage that the load on the centerboard has been reduced because of its forward location. This is going to be a number like 10 to 20%. The reduced load on the centerboard now falls on the rudder as an increase in load. Therefore increase the rudder area, rudder balanced, in direct proportion to the increased load it now carries. Now the centerboard is happy and so is the rudder and lee helm with the spinnaker up has been solved. The CE migration dragon has been captured and put in a cage under our control. This will place the centerboard immediately behind the main beam or if you feel bold and run a long spin pole and put the centerboard just in front of the main beam. As the centerboard is located further forward, it is becoming smaller in area and the rudder is becoming larger in area and the system is kept in balance on all points of sail. No more radical mast rake required and no more overloaded rudders with a hair trigger ready to stall sailing to windward.
Bill
Hi Bill,
Thanks, but I understood you the first time regarding how shared lift solves the CE migration problem when flying a spi. What I was asking was why an alternative approach wouldn't work just as well if not better. So, without raking the mast, when flying a spi, why not just move the daggerboard forward to a second daggerboard well to match the new CE? And when taking the spi down, why not just move it back to a more aft position? Although it would be an extra step during changing from upwind to downwind, it seems like it would give a balanced helm in all conditions just as well as the shared lift approach. I'm not a boat designer with your years of experience; I'm just trying to understand why this alternative approach is not used.
Jerry
OK Bill,
Explain something to me.
ALL Supercats, SCs and ARCs were and are sold WITHOUT A STANDARD SPINNAKER.
How long has Aquarius even offered the OPTIONAL SPINNAKER?
You told us that to make the ACR 22, you merely added two feet to the bows of the old SC20.
You have continually stated that a spinnaker boat MUST have daggerboards relocated and different rudders in order to handle the change in sail CE.
How is it that your boats are immune to that "Bill's law of physics"?
Is Aquarius selling unbalanced, poorly designed boats which need a spinnaker or unbalanced, poorly designed boats which aren't designed for a spinnaker?
Are your boats designed for spinnakers or not?
P.S. You never have told us the name of the other "boardless 17foot beachcat" that yours is so much better and faster than.
Wait a minute Bill...you moved the board forward to counter lee helm induced by the spinnaker and agree that the rudder loading is increased upwind. To that point you can make the daggerboard smaller but the rudder bigger. Somehow you conclude that the forward daggerboard placement also helps prevent rudder stalling upwind. But you just said the rudder loads are higher upwind now as a result of the daggerboard placement - did I miss something?
Supose we took an I20 and moved the boards forward as you prescribe (this boat runs very little mast rake and it's forward beam is very far forward on the boat). This would only make the windward rudder stalling problem more severe.
Hi Jerry,
Two daggerboard positions would work fine.
Bill
Hi Jake,
With the forward located CB and spin up everything is in balance and no lee helm. Now take the spinnaker down. The CB is still forward. Therefore the CB will be exposed to and carry less of the side load from the sail because the sail CE is now further behind it. What other foil can carry side load? The rudder! Now the rudder will carry its norman side load plus the additional side that the CB is not carrying because of its forward location. The next step is to match the CB and rudder areas to the loads they are carrying. Therefore relative to their base sizes, the CB can be made smaller and the rudder should be made larger. This results in the same effective CLR location as the base boat configuration but with the forward CB location, the CE cannot get in front of it, spin up, to cause lee helm.
Jake, the forward daggerboard placement does not help prevent the rudder from stalling. The increased rudder area helps prevent the rudder from stalling. The trem is called rudder loading and its units are force per unit area or for example pounds per square foot.
Bill
We're looking for solutions of problems that don't exist.
Why does Bill think that leehelm is a "dragon" ? Moreso than weatherhelm ?
Does any of you realize why a boat is setup for weatherhelm upwind ? It appears that the want for weatherhelm has become a dogma that must be satisfied at all costs.
-1- You have weatherhelm on big boats because that is the safety zone for them and because tacking becomes difficult without it.
-2- On smaller boats you have it in order to get some positive return on an item that otherwise only introduces drag.
On downwind the first point is useless; the safety zone here is to lee. How about weatherhelm when singlehanded doucing the spi ? You rather want the boat to track downwind then weathervane up. BLa bla bla Balanced rudders, bla bla bla. IT IS STILL WEATHERHELM ! Put your rudders sligthly of centre and you're gone.
Point 2 is totally mute on downwind legs. Good crews pull up their boards because alot of lateal resistance is really not needed on downwind legs. They leave a smaller area in place to keep some minimal sensitivity to steering. This moves CLR forward as well as on all boats the CLR component of the hull alone is forward of the daggerboard.
I can honestly say that I have never met a leehelm dragon while sailing a cat that was designed to sail with a spinnaker. And to complete it ; I never saw that dragon after adding a spi on other boats except the Dart 18 and a handfull exceptions as well.
I did experience the downsides of shared lift on the 49-er skiff and the downsides of long spi poles.
Excessive mast rake due to spinnaker then ? Nop, haven't seen it or even needed it on my own boats. Mast rake on Hobie 16 or even Taipan 4.9 then ? That is for other reasons and we can't really say that it is holding these boats back CAN WE, Bill ?
Spi pole length at 50 % of hoist height spi to prevent diving ? Great ! F16 runs poles of 3.5/7.5 = 47 %. What a difference those 50%-47% = 3 % makes ! That just doesn't fly with me. So I see really no need to put a longer pole on my F16.
What else was introduced to make the ARC-17 appear superior to all other designs ? Ohh yeah shared lift.
Massive tiller loads when the rudder kick up or when leaving the beach with the rudders trailing (unbalanced rudders !)
In my surf ? No, thank you !
Not using shared lift on other boats makes them slow or slower ? Hum, ARC-17 with spi = rating 70.2 ; Taipan 4.9 WITHOUT spi = 68.1 and to show that there are no ill feelings between us we'll just forget about those 26 % in more (main+jib) sailarea that Bill has put on the ARC-17.
I say that sums it up quite nicely. Thank God Bill uses shared lift on the ARC-17 or else it would be sailing of a rating of 75 and be looking over its shoulder for the fastest Hobie 16's I suspect.
A while back Bill also chastized all other designers for designing overweight boats and you'd expressed F16's were nothing special at 107 kg including all sailing gear !
Well, didn't he prove us all wrong by making the ARC-17 = 126 kg EXCLUDING the weight of the sails (min 8 kg) and spi package (min 5 kg). This puts you on a level with the 1976 Dart 18 design which is of equal length.
To daggerboard wells then : one for upwind sailing and one for downwind sailing ?
I will garantee you that you'll be at the leeward mark behind all boats that use only one daggerboard well.
How much time does it take to move the two boards from one well to another ? 10 seconds ? That is quite fast.
10 seconds that you could already be travelling at full speed under spinnaker = 50 - 100 meters less distance travelled ?
I can assure you that you will never be able to compensate for this loss even if the new position of the boards would make your craft more effecient.
As it is right now in the F18 a 3 second delay in setting the spi at the A-mark is enough to loose you 1 to 5 places in the field.
A lot of crews don't even readjust the jib sheet and outhaul of the main in tight racing as that takes to much time in which they can easily loose a tactical beneficial position. Most of the time they do that later in the leg during a lull or when the skipper has one hand free. Getting the spi up quickly is the most important thing. Repositioning the boards is not what you want to do if that delays the setting of the spi. That is even IF it would be necessary
BECAUSE
The balancing of the rudders that Bills shared lift needs to get rid of the weatherhelm feel on the upwind legs will ALSO remove the feel of the leehelm on downwind legs that other boats MAY have.
So the whole discussion comes down on wether having leehelm on downwind legs (not the feel of it as that can be taken away by balanced rudders) is a SIGNIFICANTLY bad thing performance wise ? If leehelm is assumed to be present, that is.
This does not appear to be the case. And untill a newly designed shared lift ARC F18 starts beating all other F18's on the course I think we'll be at a loss to proof that it does significantly influence performance in a bad manner.
Wouter
Jerry,
I let go of the tiller if I am going forward to adjust downhaul because holding the tiller while moving around on the boat causes me to veer all over the place. Occasionally, I will pull the mainsheet with both hands while on the wire, so I set the tiller down, sheet in, and pick the tiller up. I also put the tiller to rest if adjusting outhaul, mast rotation, or board position. Any one of these is a brief interlude of letting the tiller rest unattended.
Bruce,
I run my boards about 8" up all the time. If I thought I could afford the time, I might pull them another 12" when going downwind but for now, feel that it does not provide enough benefit for my "'round the bouys" racing to take my mind off steering the boat to go play with the boards up and down at A and C marks. I have not seen any difference upwind with my boards up 8" and all the other I-17R's with their boards all the way down.
Hi Wouter,
I saw a T4.9 at the Tradewinds Regatta two weeks ago for the first time. That boat looks like a great design. Did you design that one? It reminds me of Poison Ivy.
Good boat design has weather helm for two reasons: 1) From a boat performance point of view you always want weather helm. The daggerboard is always generating lift to windward. When the rudder is lifting in the same direction, the induced drag from the two foils is a minimun. If the rudder is producing lee helm, opposite the daggerboard, then the daggerboard must generate lift equal and opposite the sail side force plus generate additional side force to windward to overcome the negative side force the rudder is generating, lee helm. This situation, lee helm, makes the daggerboard work harder, generate more lift, which makes more drag. 2)Helm satbility. You want the helm to always to be pulling lightly in the same direction from the skipper for ease of handling. You do not want the helm to reverse between weather and lee helm, especially unexpectedly. This makes the boat difficult to sail well and it is draggy underwater; a slower boat results.
I'm not going to address the rest of your comments because I see an ugly attitude and your goal here is not to help anyone.
So long,
Bill
Hi Sam,
All SCs were sold without spinnakers. That was before 1992, 1978 through 1991. In 1992 the product name was changed to ARC products and spinnakers and self tacking jibs etc became an option or standard on all products, the 22, the 27 and the 30. See the Aquarius-Sail.com web site for this information. These products were/are designed with spinnakers.
>I'm sorry I forgot, the 22 also has the CB trunk located right behind the main beam to prevent lee helm with spinnaker up.
>I am saying that moving the CB forward is a better way to trim a boat out with spinnaker than raking the mast back which leaves the rudder overloaded and the CB underloaded sailing to windward without spinnaker. The boat will sail to windward like this but the induced drag from the CB and rudder is greater than it could be. The boat is out of trim sloop rigged.
>A boat with centrboards moved forward to accomodate the forward migration of sail center of effort due to the spinnaker and downsized boards to match the smaller side load they now are expozed to in this new forward location and upsized rudders to match the new increased side load they are exposed to due to the forward located centerboard HAS THE SAME CENTER OF LATERAL RESISTANCE as the boats original CB/rudder arrangement. The advantages here are: 1) that the centerboard is so far forward that the sail CE with spinnaker up cannot get in front of the centerboard and cause lee helm. 2) With spinnaker down the centerboard and rudder are sized to match the loads they are exposed to and this results in minimum induced drag from the CB and rudder, a faster boat to windward.
> At the recent Tradewinds Regatta I sailed an ARC 17 against several other boats for my first time in 25 years. We sailed poorly, went three times around the long course when I should have sailed two times around the short course, in the first heat. Then on Sunday my crew, who had never sailed on the boat or with a spinaker before, thought we shouldn't try the spinnaker in the 20 knot winds so we didn't. We still won the open class on corrected time and did finish a couple of heats first boat across the finish line. Our assigned PN was 70.2. That number is coming down as a data base is developed for the ARC 17 with spinnaker.
Good Sailing, Sam,
Bill