Yep. Sunday knocked the boat apart and stuffed it in the basement. Sunday night, and monday during the day we got snow. Its supposed to be 61*F for a high right now, it was 34*F all day yesterday. (sigh....) We didn't even have summer this year, two days it got above 90*F, and where was I? Setting trusses, and sheating a roof on a new house. Figures....
In February I'll be going to the bighorns snowmobiling again. That was fun, but the place we stay at is at 8500ft elevation, and most of the riding is that or higher. One spot I pulled out the GPS and we were at 96xx ft! Going from 1200ft elevation at home to that is rough on me. I sleep like a rock though.
We need volunteers to work the GC. I have rum.
Since I'm not going the Hobie Mega, I was planning on going to the GC, but then the remodel I'm working on got going later than I'd like, and I'm scheduled to be installing cabinets that week. That and I haven't sold the FXone yet, so no Viper for me yet.
Cheers!
WTF.
The cabinets will still be there when you get back.
1 week in FL during November will last you a long time during those dark misserably cold MN winter days.
As a bit of Bitsa update, where have we got to then, well not very far actually, I have been sailing a few times with the A mast and A sail, its an older design and the boat handles really well with it on, quite neutral and pretty much as expected.
With the A sail being an absolute pain to get and stay up the mast I changed the mast over to the Stealth mast and sail. A very much bigger sail and immediately causing problems. The COE of the sail is now so far to the rear that the boat sits heavy in the water at the rear and now drags the rudders which immediately caused a problem with the Stealth rudders and cassette box I had used. They sit too low down on the hull and the fat part of the cassette box was causing so much drag that the water was shooting around and up like a jet boat at speed. Not good. Anyway culmunated at speed with the Spinny up, pulling out of its threads 2 of the lower mounting screws and catastrophic failure of the smashing off of one rudder.
mmmm back to the drawing board, spent the last 3 weeks in the evenings making up faired in rudder cassettes and mounts so hopefully that will solve that problem.
Now this is where I'm hoping a few of you more knowledgiable types will offer their advise. I need to change back to the A mast and make a new sail. As a starting point in a new design what mast prebend should I start with and what camber and where abouts in the sail should I have that max camber. Get those starting points and perhaps I can create something out of the SailCut software. <img src="<>/cool.gif" alt="cool" title="cool" height="15" width="15" />
Out of interest, which Stealth main were you using Wayne? Was it one of the newer sq. tops or the old style big roach Landy?
Sorry to hear you had a problem, are you sure though that it was the COE causing the problem and not just extra power?
it was the later GP sq top. Yes and no to your question. The extra power once you get up to speed is really cool, The dagger boards and T foils do seem to level the boat up nicely. Its just when you tack and at low speed the vvvvvvery low volume sterns do dig in abit. Much more noticiable with the GP sail which is nearly 400mm deeper than the A sail.
If you put the A mast up it will not be a F16 then right? Unless you cut the mast, but that would be a shame!
Hi Wayne
I guess you have to do some major re cutting. An 'A' mainsail foot is approx 1.8m long and the Stealth's is 2.3m ish. So as you probably already found out the boom is sticking out beyond the transomes! Maybe you should turn the main upside down and have the mother of all fat heads ;-0
Seriously, I hope you do find a fix and if you need some measurements of the luff curve I recorded my Landy's prior to a re cut. From memory the max curve was 105mm but I have the measurements taken at each batten pocket end.
I was going to mention that a sinking stern could be attributed to your midships but that would probably be to polite for this forum at the moment.
Would using a F16 rig of any of the other F16's be an good alternative ? These sails are more rectangular shaped like th A-cat sail, with a foot that is 2050 to 2010 mm long. A good 200 to 250 mm shorter then the stealth sails for example.
Wouter
talking about homebuilding.. How is your BITSA (?) doing this year? Any experiences to share?
What foils did you use for Bitsa? (I think you named it Bitsa?)
Rolf, Bitsa was mothballed this season, there had been a lot of discussion going on about the jib and such like that I had become a little concerned that I had been going in a wrong direction with the eventual final spec for her, Main, blade jib and Spinny, that when an A Class platform came up ( I already had the rig and owning and sailing an A had always been one of those things to tick off in ones life ) I opted to run the A for a season ( known platform and rig )to learn about the mainsail and how to get the best out of them.
Intention is to now run the A rig back on Bitsa with a blade jib over the winter and next season just to see just what differnce a jib can make, it will give me a 14sqm main and 2.5sqm jib plus standard spinny.
Foils are still the standard late Stealths but at some stage I will need to rethink this as I've learned from the A just how small both the foils need to be. Perhaps at some stage in the near future some curvy things might appear but lets do one stage at a time.
Thanks Wayne, that is another good plan. Will be very interesting to hear about your experiment next season!
How did you like the A? What was different from the F16 and what was similar?
I am looking at foils, getting quotes etc. in these days. I would be very interested in your opinion on foils (daggers and rudders) for F16s!
Rolf, it really is what you are as a personality, do you like Ferrari sports style cars or American muscle hotrods, both achieve a desired goal, but just get there in different manners.
I do like the ease of use of the A, really easy to rig, 20 minutes max, and launch, everything about them is refined and subtle and yet fast across the water ( I've seen regular 19 knots of speed ). Upwind you can take on other boats and know you are going to be an equal if not ahead, tacking is dinghy like, mainsheet is light, uphauling from a capsize is a doddle, everything is about refinement and ease of use of the A.
But the F16 solo is really not much different in reality, a little slower, less refined upwind perhaps but still a damn good boat( I think aero dynamics of the snuffer and less developed rigs are the cause )and with a bit of tweaking of our class rules, would be pretty similar.
But where is the adrenaline factor
I'm goner scare you today
which the F16's do on a regular basis. Downwind the A is just a sled ride, safe steady and fast. Pop that spinny, heat it up a little and the F16's is a big grin factor. That one aspect has been the one thing that I missed from my F16. I am willing to forget the longer setup, forget the slightly heavier weight, forget the additional sail maintenance costs, just can't forget that one thing.
I think that the A is over penalised on handicap to the point of the rating as ludicrous ( is it faster around a race course on average than a F18, not a hope, so why does it rate higher than the F18 ), its costings are not nearly as high to run annually as I thought, its not as fragile as some make out and is a stunning little boat, but I enjoy for the moment Endurance motorcycles, mtbs, rally cars, the tougher less refined sports and not road cycling / track car racing, the well refined sports.
So for the moment its back to F16 style boats next year but my guess is at some stage health and mobility will dictate that an A may well be back on the cards at some time in the future.
As to boards and foils, go straight to the curved foils and be done with, it will complicate things to such a point as you will think why have I fitted them but with your Blade you are going to need all the help up front as you can get. Also there are a number of A reject boards about at the moment that with a bit of strengthening could suit the higher downwind speeds that our spinnies produce, it will take you out of class ( for the moment ) but they will offer something different. Alternatively what about some A straight boards, there are now quite a few sitting about, redundant. Rudders again A class of about 5 years ago, perfect.
Really?
I have basically a A-cat rig on my boat (but with spi). Going downwind in strong wind without spi is really adrenalin, with spi is safe in my opinion.
Cheers,
Klaus
Agree strong wind is good fun, but we can't alway guarentee strong conditions, the spinny is good fun in medium or light winds as well.
Hi Wayne,
great writeup, thanks!
I have never tried an A, but they are impressive. Even more so with a spin I would think. Add in the curved foils they are developing and it looks great!
Could I ask how old you are Wayne, as you wrote:
but my guess is at some stage health and mobility will dictate that an A may well be back on the cards
.
How did your experimental snuffer work out btw? That is really something to work on! Drag reduction.
About foils for our boats. I think we will want to measure them in as F16s. Curved foils are out of scope for now.
Installing A-cat foils is a real option.
Do you have any links to where I can find old A-cat foils?
As a gross estimation, foils needs to be about 2% of the sailarea. Would be interesting to compare current and 5 year old A-class foils to current F16 foils!
Klaus, I have shamelessly taken a look at your modified NACA0013 profile and unless we find foils we would buy, might use that one. Do you have something similar for daggerboards? And what about planform.. Would you be willing to spend a few minutes thinking about that?
I have never tried an A, but they are impressive. Even more so with a spin I would think. Add in the curved foils they are developing and it looks great!
Could I ask how old you are Wayne, as you wrote:
but my guess is at some stage health and mobility will dictate that an A may well be back on the cards
.
How did your experimental snuffer work out btw? That is really something to work on! Drag reduction.
Do you have any links to where I can find old A-cat foils?
As a gross estimation, foils needs to be about 2% of the sailarea. Would be interesting to compare current and 5 year old A-class foils to current F16 foils!
Yup owning and sailing an A is one of lifes sailing experiances, gotta be done. Unfortunately with the rate of development of the modern spinnakered boats with foils and the punitive handicap the A's incur, they sadly will become purely a class racing boat even more so than today.
I'm a
young at heart
54 but do acknowledge that time is fast catching up with the body and I'm just not physically able to do some of the more mundane things easily, that I could do when I was younger ( tying ones shoe laces as an example ). At the sailing club last night a few of us oldies joked we should buy a flying fifteen and join the real oldies.
The snuffer below the tramp is worthwhile looking at, to date I have never had a retrieve failure unlike the normal snuffer ring which seems to have the occassional hiccup. I think though to productionise it you would need to consider how to get it higher off the water. My greatplan had always been a Y beam with integrale snuffer and forestay, we have to make up weight to 104kgs, why not put it to better use in a stiffer boat + the front beam becomes part of the structure.
Try Hans Klok he would know most of the European A sailors, you maybe surprised just how helpful the A sailors are. My understanding one of the top A sailors is going to race an F16 next year so should be interesting.
I will take photos of the difference in size of the boards but I would guess that the A's are only around 1% of sail area, but very high aspect ratios to get the efficencies. The A seems to lack a bit of low speed drive sometimes ( sideways drift )but get up around 5 knots hull speed and its game on.
We are going out on a real tangent here Wayne, but I got to say this: Physically it should not be a problem keeping strength and flexibility until well into the 70s or even 80s.
I only have the theory myself as I am 40 this fall.. However I have been weighting more than 110kilos at 178cm. What I noticed was how weak I felt. Endurance was shot. Mobility/flexibility was poor and life was downright heavy. Getting my eating habits under control was the key for me. I feel almost like I did when I was 20 except for the long-term injuries I have collected.
Keeping active and eating properly is in my opinion the key to ageing with full use of the body. Of course the definition of
eating properly
is the crux with opinions, PR companies and scientists pointing in all directions while screaming that they are the only true prophet.
54 years is just the first half <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />
You lost me on the Y beam structure I am afraid. How would that look and at the same time reduce drag.
1% for each dagger x 2 = 2%? <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />
Rolf, at 40 I was invincible, at 50 it was oooh things are not the same as at 40, at 54 I'm worried about the speed of the rate of that change. You will notice a real differnce beteen 40 and 50's, I certainly have. Still trying to keep fit and enjoy the wilder side of life, sadly given up endurance motorcycle racing after finding the rate of recovery from injuries was affecting my work hours but do a bit of Mtbing, ski ing and now beginning to get to grips with http:/
Oh the Auscat Flyer 4s is listed as having 0.1 sqm of board area in the SCHRS listings, I think mine has even less as it has had the boards changed to high aspect ratio boards. mmmm.
Thanks Wayne!
I felt invincible and immortal in my 20s. In my 40tieth year I know I am very much mortal and subject to stresses of all kinds.
Guy who taught me mountaineering/climbing was in his 70s back then. 20 years later he is telling me that he is beginning to feel the age. Still active in off-piste skiing, climbing and ocean swimming through his 80s. Similar quotes from others with more experience who still are motivated and active give me hope <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" /> Avoiding flab and retaining max strength seems to be the key?
Snowbiking!! Now why is that more fun than skiing or snowboarding?? I mostly go backcountry with my snowboard and I have a problem seeing myself enjoy the ride down again on a snowbike <img src="<>/grin.gif" alt="grin" title="grin" height="15" width="15" />
A-cat sail area incl mast is ~13.94m2 with 0.1m2 of board area in total?
Higher AR should increase efficiency but some area is still needed. Would be very interesting to have some numbers on this.
At 40 I could diet moderately, do some walking, lift a few weights and see an immediate result.
From 60-62 I was not able to gain any measurable strength after a quick modest gain. No amount of work produced a weight loss. Only severe caloric restriction produced any weigh loss at all. Frankly, I'd rather be fat than give up cookies and milk.
Cheers!
I believe diet is the key to 90% of staying well as time passes. Diet is however a very controversial topic. It is so personal to many people and there is no best practice. Choose your poison <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />
Working out for sure helps this tender 40 year old.
Snowbiking came about for very different reasons. Two of my friends could no longer come sking with us due to a damaged knee and the other a car accident damaging his tibia and knee joint. Ski biking gives them an opportunity to join in with the fun and so we all decided to learn together. I've been skiing for a very long time so was quite keen to give it a go. After 6 days we were competant enough to tackle most slopes, the learning rate was quite fast.
yep, better live happy and short than long and sad <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />
Rolf,
basicaly board area depends on two factors:
* avoid stalling at low speeds (e.g. being manouvrable at the start line)
* avoid cavitation at high speed
Both depends on the force which the rudder or board has to produce. The force depends on the boat balance and leeward force from the sails. The leeward (or better sideslip) force of the sails depends on their efficiency and the righting moment of the boat. Since a A-cat has a higher mast and a more narrow platform the sideforces are considerable less (especially compared to a double handed F16). I know this from my boat: The board size is just fine double handed, single handed up-wind it is a bit too much so I can drop the traveller a bit to get a more reasonable sail angle of attack. It may be a bit cryptic what I say, so don't hesitate to ask if you want to know more details.
The foil which I posted here some time ago was for the Tornado (which is now history <img src="<>/frown.gif" alt="frown" title="frown" height="15" width="15" /> , like us human beings, boats don't get fitter with age...), where we had high speed cavitation problems (I am really not wondering, even todays Tornado rudder look like F104 sections for me, you know the aircraft they called a rocket with wings). Maybe you want to go with a bit more low speed focused section. Again, don't hesitate to ask. I have started a small report about foil design for boats, which I want to finish a publish hopefully soon.
Foil planform is as important as the section, but much simpler. You can go with all those fancy shaped boards, we have seen, but you can achieve the same with a simple trapez. You can achieve it even with a rectangular shape with some forward sweep, if you dare to do something others don't do. The basic idea is to have an elliptic shape. You can do this with an elliptic planform or with a trapez with a 0.4 chord ratio and zero sweep at 25% chord. If possible from a structural point of view, the rudder should have the same depth as the board. Don't stick too much about aspect ratio, absolut depth (draught) is more important than aspect ratio and a larger rudder can have less drag than a small one.
I personally think that a homebuilder can make a good foil only with a simple trapez planform, because the surface of the foil is only single curved (unless you have a buddy who has a CNC machine). Already a small change in thickness distribution will ruine the hydrodynamics (1% percent change in thickness has lot of effects, 1% is equal to 1mm on a board with 100mm chord).
Cheers,
Klaus
Wayne,
that makes perfect sense. Creative way to continue enjoying downhill skiing! <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />
Klaus,
thanks for writing up that info.
I always thought the ideal was to have ellipitcal pressure distribution over the foil, not neccesarily to have an elliptical foil. Reading what you wrote I think that is still valid.
Doing anything but a parallell sided rectangular foil is prone to errors without a CNC. I found this link which looks like my best shot with no CNC. Especially as a good friend offered to laser-cut templates on a CNC laser cutter.
http:/
Doing a cut after routing and then sanding/fairing before pulling off moulds is a real option. The same for rounding off the tip by hand at the bottom. Getting the proper section in that area will be hard. Dont know if the gains outweights the extra drag and loss of lift I will make with my unskilled hands.
I have done three sets of foils earlier by hand. Wood, plane and sand. Free hand.. None of them turned out really well. Partly becouse of design and partly becouse shaping wood by free hand is difficult.
Tornado rudders from Marstrøm was pretty good compared to my homebuilds. Yes, they did cavitate some times. Not a pretty sight when double trapeezing. I always thought the class overloaded the rudders with the mast rake. We sailed with less rake to overcome cavitation problems. They still happened, but not so often. Sheeting out a handful reattached flow.
I am really really surprised that you think the T rudders were designed for a speed much higher than obtainable by the T. With the amount of resources invested in producing a faster T around the course the foils is a very logical place to do research. The centerboards were of course very hard to optimize due to the class rules defining their planform.
When you mention forward sweep, you advocate installing the foil with a bit of forward sweep? Not seen that in a while <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />
The idea is to produce elliptical pressure distribution or to delay ventilation? Cavitation should not be an issue with a daggerboard operating in turbulent flow under the hull?
Looking at the
state of the art
daggerboards in the F18 class, they have gone for higher AR and shorter chord. I think the Wildcat from Hobie have daggers with an 180mm chord! Effective length when fully down 1130mm. Pretty extreme compared to older designs and probably a handful on the starting line.
What I really would like is to buy something ready made with reasonable performance for a reasonable price <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />
I have been unsuccessful in finding that and nobody is sending me plugs or moulds in the mail so it looks like I will have to shape something myself. A
good enough
planform that is easy to shape with a relatively robust profile (building in the garage, able to handle the starting line, tacks and jibes) with adequate lift and reasonable drag. Hmm, sounds like mission impossible..
I would be very grateful for any suggestions or help on this <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />
PS: I definately would prefer to live long and happily!
What is your diet like?
The Zlin Z42 is the classical example of a rectangular wing with near to elliptic lift distribution. The benefit is to have only one sort of rib, instead for each section at different rib.
state of the art
daggerboards in the F18 class
I would not take F18 as an example. Since the foil (and hull shape) is the only
unlimited
part of the boat, builder try to differentiate here, well I think that's why you put the quotes around it). At the end they have very different daggerboard and rudder length, so induced drag is not as good as one may think. I guess that shapewise A-cat (before c foils) is a better example.
Actually I think the foil looks like a section of a Mach 2 fighter aircraft from the sixties and hence totally unsuitable for a boat. They are very thin and pointy at the nose and this causes the early cavitation. I guess in the beginning without spi and single trapez it was fine, but once the boats got faster... My friend had an old (30y, Panthercraft I think) T. Later he bought some of this wood core rudders. Very beautiful, but as thin as the old once. So I didn't see evolution in the rudders.
I think I would ask a carpenter with a CNC machine to cut me the wooden core and laminate glass or carbon around it and sand and sand and sand... I don't have the talent to cut and carve it or cut and fill it (as in your link) by myself.
Other possibility, ask the carpenter to cut a female mold or cut your female mold from wax or foam with the hot wire method (not sure if it works for high aspect ratio). Or take an existing one and take a negative of it...
I don't like the female mold method because it is difficult to get a reasonable core or framework in the rudder. That's the reason why so many boards are heavy like stone, overcame the core weakness with extra skin thickness. If you have a wooden core you can go with glass and you are still lighter than many carbon boards.
From a structural point of view the ultimative boards are extruded aluminium: Topcat
You may ask the dealer for a price.
Cheers,
Klaus
Well Bitsa deservidly has been back on the water this year after quite a revamp. Back on with the A rig after the really unbalanced F16 low aspect rig created so much drag at the back, move the travellor foward to accomodate the much shorter foot giving me a chance to remove the gantry rudders at the back and go more conventional, fix the hole from the damage caused by the extra drag from the T foil / gantry, rejig the main sheet to a cascade system, and move the main sheet to the front.
http:/
So a very different boat. With the A rig on Bitsa is very well behaved, with almost neutral helm with just a touch of Lee helm when the spinny is really loaded up. I do like these A Rigs and despite being only 14sqm it is just as fast as the 15sqm F16 rigs. The class is really missing a trick here as A rigs are available secondhand with the early masts being more than strong and stiff enough to cope with the spinny + the development of sails and masts will always mean a steady supply of S/hand and huge amounts of development
I do like the very foward position of the sheet for the single hander.
http:/
Everything you do is facing foward out of the boat, and right where you want to be pulling from, out on the wire upwind your feet are locked on and if you pass the sheet foward of the rear stay, you can edge foward to the front beam.
I can only recommend the cascade system as being not only cheap to build, effective but buttery smooth.
http:/
The new rudders have been good, maybe a bit old fashioned in aspect ratio but do the job. I do need to be careful as they can be pretty effective brakes if you turn them too much in a tack.
http:/
So to sum up things then, yes I am pleased with the way the boat is beginning to shape up. In comparison to the new Nacra F16, it would seem pretty on par if not better upwind, just a fraction slower downwind and that I suspect is more the spinny rather than the boat. So no excuses, down to the skipper then
http:/