We sailed two Alpha F14's against each other last Sunday in 3 club races, one with the new rudder system that we have just finished with T foils and the other F14 with the normal rudders. Very impressive, there was virtually no pitch with the T foils up wind or down with spinnaker whereas the other F14 sailed with the normal oscillations of the sea way, and with every "pitch" that the non T foiled cat made the T foiled one stepped just slightly ahead. Had one F18 sailing the three races and the T foiled F14 gave the F18 a head start at the beginning of each run and caught up by the bottom mark every time. Looking forward to results over an extended period of racing.
after seeing the AO 14's sail, I thought they would realy benifit from T foils to stop the Hobby Horsing I get on Altered which they showed more of. Very keen to try them on F16 also, look forward to seeing them in the flesh at the Sauna Sail, Hazelwood is a good venue for them goes deep reasonably quickly and stays that way, no weed.
They always seem to be mentioned re nose diving, but after much thought I think dampening Hobby Horsing up and down wind will be the major plus, no doubt they will dampen nose dives as well.
It is winter here so the club racing is treated more as "tuning" rather than “all out" competition, and the F18 skipper that sailed those races, although not in the "top ten" F18 sailors, does have many years of experience and sailed in multitudes of national events (always been a Hobie man) as well as at least two of the most recent Tiger worlds, so we are not looking at our results as "definitive", but yes, it was very interesting that the downwind performance/boat speed, of the F14 was greater than that of the Tigers on every downwind leg (and believe me he was trying , no 18’ sailor wants to be passed by ANY 14’ ever). The conditions were light with the wind only varying between 5 to 6 knots at the start of the first race ranging up to 8 to 9 knots throughout the course of the day, the water surface was smooth (no white caps) but with a relatively amount of undulations (lumpy) on the surface which caused a reasonable amount of "pitching" to all classes sailing. At the start of the racing I had anticipated that under these conditions, (which normally suits F18’s over F14’s) the advantages of the Tiger with it’s far greater sail area and longer waterline length, would let it simply “walk away” on every leg, but this didn’t eventuate, not just on one downwind, but consistently on every one. As I say it is interesting, but we will see what happens over a wider range of conditions and many more races before making any “claims”. No there is no secret or “black art” about the T foil system, ours is very similar to the first stocks that were on the Stealth, but our T foils have parallel leading and trailing edges (instead of the Stealth’s curved ones) apart from that there seems to be very little other variation that you can incorporate in the design of rudder T foils. It is very simple and straight forward making and attaching a T foil system, and basically you just take your “normal” rudder system off the cat and hang the T foil one on in their place then go sailing as per normal. The foils just look after themselves and you steer just like you always have but instead of the bow and stern rising and falling in opposite directions with the boat movement through the water, the hulls just go up and down vertically with the decks staying level instead of “pitching”. Great feeling though.
Re: "T" foils on F14
[Re: Wouter]
#76957 06/07/0601:14 AM06/07/0601:14 AM
As soon as I have taken some photo's I will post them. (perhaps video of the foils and of the cat sailing may be even more informative -banana foils next??)
I may be biased but hobby horsing has never been a problem on the 430. I purposely designed the bottom curve to among other things, avoid pitching. I don't sail a lot in lumpy conditions preferring lakes and 10 - 15 knotts of breeze but when it does get up I still don't see too much movement. I do however have issues with lee-bowing on occasions in 20k wind but I'm of the opinion that it's more a function of incorrect mainsail trim rather than hull form.
Re: "T" foils on F14
[Re: Berny]
#76960 06/07/0609:28 AM06/07/0609:28 AM
my understanding and opinion is that the rig will loose power and increase drag for each wave it passes over. By hobby horsing I think of short, fast, ocillations. But I think what Darryl describes is a slower cycle, where the boat still goes faster as the rigs movement is smaller and thus more efficient. That is the point I have reached so far, please enlighten me <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />
It seems to be the case Rolf, that by stopping the mast movement back and forth from a pitching hull, the airflow across the sail is obviously more stable and constant. When the mast "rocks" back and forth the airflow across the sail, when the mast moves forward, will effectively be faster, but as the mast moves backwards the effective airflow is much slower even to the point, particularly in lighter conditions, of "stalling" the sail until the mast once again moves forward. The more constant and even that the sail moves through the air the better. This must also apply to the hull movement through the water. We all know that to jump about on a cat will detrimentally affect its performance, so to stop pitching and “stabilise” the extremes of the hull movement must be “all good”. I, like most others, initially thought of T foils as being a simple addition to limit or stop the potential of “pitch polling” under extreme conditions or with the spinnaker “bear away”, but I am starting to feel that the “all round” beneficial effects of T foils may be far greater than just that of a “pitch pole” limiter. PS I am talking here more about the "natural" movement of the cat following the wave surface of the water as opposed to what we consider as a more violet rapid "Hobby horsing", although the stabilsing effect is the same for both conditions.
I probably confused the issue by mentioning pitching and h/horsing in the same context. I do understand the principle of rudder foils, what I'm saying is that hobby horsing is to some degree a function of rocker, in my opinion. It's my understanding that in the past, designers have tried to use monohull design criteria with catamarans which has produced boats with too much rocker. I concede that foils will 'smooth' both h/hosing and pitching, resulting from wave action. This, as Darryl already said, will keep the mast action and flow over the sail more stable which should reasonably result in better speed.
Re: "T" foils on F14
[Re: ]
#76963 06/13/0607:05 AM06/13/0607:05 AM
have attached a picture of the foils. Must say they where bigger than I expected.
AO F14 went well in the light stuff at the Sauna Sail, getting in front of my F16 a couple of times, upwind pointing with good speed was it's forte. They certainly didn't seem to slow it down in the light stuff as I had raced against it previously with out the foils in light wind and it was closer this time.
I think the Mossies with spinnakers spent more of the time racing with the AO F14 than I did, I think they came out on top though.
Must say it was hard for the smaller spinnaker cats though with 20 boats in the spinnaker starts Tornado, 10 x F18, 8 x F16. It was hard to get clear air.
They do look "big" in the photo Gary, (not so big in the "flesh" I think). No noticable drag in any wind strength though and they certainly stop the noses from "dipping" when the wind is up. I will post a report shortly on the weekend at the Sauna sail, BUT GOD IT WAS COLD THERE, (then again from all reports that weekend was bitterly cold across most of the southern part of the continent). That is one "unique" place to sail at Garry, unlike anywhere else that we have ever competed at. Ohh. you know that now that you have taken photo's of the "T" foils I am going to have to kill you! We have made these foils so that, using the same mold we can make the foils as an "L" foil by leaving off the outside blade of the T. Thats so that any cat that is at it's maximum beam width can still use them and measure to their overall beam. That isn't a problem for us as the Alpha is narrower than the maximum allowable beam of the formula
On Friday 9th June 2006, we drove from SA across to the Latrobe Valley Sailing club in Victoria to sail an Alpha Omega F14 in the “Sauna Sail” regatta. The trip was going well until we approached Melbourne at 5.30pm on the eve of a long weekend. It took us 2 hours longer to get through Melbourne to Morwell in the Latrobe Valley when going over, than it took us coming back. The traffic was “absolutely horrendous”. On Saturday morning we got to the club at 8.00am (through fog that slowed driving down to 5kms at times) to set up the cat in between fits of shivering. There was an excellent turn out of all sizes of cats as well as about 18 plus cats with spinnakers ranging from the F14 Alpha Omega, F16 Mosquitoes, F16 “Altered”, F16 Taipan 4.9’s, F18 Capricorns, F18 Hobie Tigers, F16 Cobra, and a Tornado (with kite). There were a total number of boats on the water of about 100, which led to some very “scary” close calls with very fast cats sharing the course with some very slow dinghy’s. Some of the buoy rounding’s, through the fog were “heart stoppers” (Thank goodness the water was about 22c as the wind felt more like 2c). The first race was sailed in a nice, light breeze throughout most of it’s duration of approx’ 5 or 6 knots, yet because of the low air temperature, the fog kept rising from off of the water and kept visibility quite low. All the spinnaker cats sailed as division 7 – same start, same course, and same finish. The first cat across the finish line was a Capricorn; The Alpha F14 was the seventh cat with kite across the line with several “Hobie Tigers” and the odd F16 Taipan, F16 Mosquito, F16 Cobra, etc following. Not too shabby a performance when every other cat in this division is larger with more sail power than the F14? I was very surprised at how well the Mosquitoes went with their kites, although for most of them, we found that we had an edge (particularly around 8 to 12 knots of wind), but there was one Mozzie sailor who sailed all the races outstandingly, I am not too sure if their current (provisional) yardstick of 80 really does them justice, I think that they are a faster cat than that. The second race (back to back) was started in a moderately better wind appearing out of nowhere shortly before the start (it seems to be symptomatic of the area that the conditions can change dramatically several times in one day, but I have never seen many other places where it will change completely so often over one days racing, local knowledge should be an advantage here). The second race was more frenetic than the first, due mainly to the faster boat speed of the cats, and the necessary avoidance of the slower dinghies. The same Capricorn crossed the line first and the Alpha F14 crossed in eight overall in the same division, (we finished behind, and with one cat between us and Garry on the F16 “altered” in both the first and second races) Everyone else now packed up their boats for the night, and went to their camp sites or heated motel rooms while we had to wait in the dark and cold for a protest from an F16 Taipan that had “made contact” with the Alpha while approaching from behind at a buoy rounding. It had broken the Alpha’s tiller extension, which made it quite difficult to sail the rest of that race. After about an hour the protest committee called the protest as indeterminable as there were no witnesses other than the two boats involved. We then gladly drove back to our Motel and sat in front of the heater for about an hour before all our body parts worked again. Next morning quite a few more cats and dinghy’s arrived to sail the three scheduled races for that day, including Greg Goodal with an immaculately turned out Capricorn. For this third race, the first starts (mainly small mono’s) started in a breeze of only about 3 knots, and they were sailing the first leg as a beat, but just prior to the start for the spinnaker cats, the wind swung ferociously and picked up to about 15 to 17 knots. This meant that the spinnaker cat’s start would be a “mad flat out” leg under spinnaker heading right through all the dinghies hiding in the rapidly returning fog. As the wind had picked up, the air temperature had dropped several degrees, with a chill factor that was “bone numbing”, and the resulting difference between air and water temperature meant that after a, “clear, good visibility” early morning, the “fog”, now rising off of the water, was creating really “pea soup” conditions These cats started and did one “scary” speed leg to the (windward?) mark under kites, then were told to restart as there had been too many boats over the line to pick out any of the many, individual premature starters so there was a general recall. Why no dinghies were cut in half on that leg, has to be put down more to good luck rather than good judgement. The cats restart was just as wild as the first, turning this race into a mad “speed” dash around the course as pretty much, most of the legs were sailed under spinnaker and rather than “full on racing”, great concentration had to be used, not to cut other boats in half, The Alpha faired much worse in this race than in the previous days, two races. Life can be tough (particularly at the start) when the wind blows hard, you are the smallest cat in the fleet, in conditions with very poor visibility, sailing in a group with everyone “on the edge” and no other thought than “going for it”. Greg Goodall on the Capricorn crossed the line first and the Alpha crossed the finish line towards the rear, although this placing is a little deceptive as the actual time difference between first and last, in this division, for this race, was not great, as the race itself was completed in very quick time. The fourth race, after a better start for the Alpha, and with three competitive legs sailed (the wind had moderated to about 10 to 12 knots, with the Alpha, at this time, sailing well up in the middle of the division), as it (the Alpha) was approaching the leeward mark under kite, the Tornado which had already rounded and was heading back on its beat, called a very late “starboard” on the Alpha. The ensuing sudden manoeuvres required avoiding a collision put the Alpha on its side. The luff of the sail somehow came free of the mast, and the skipper badly wrenched his shoulder. After righting the cat he had no option but to return to shore as, by having a “push up” luff on the mainsail it was impossible to reset the luff back into the mast while sailing without the skipper swimming out to the head of the mast. Not the easiest, or safest thing to do with an injured shoulder in “freezing” conditions. After coming ashore with a shoulder that was causing him a lot of discomfort, and the absolute bitterly cold conditions, I decided for him (and most importantly for my own freezing butt) that was enough for the day, so we packed up and went back to the motel. The next morning with the skipper still very stiff and sore, I decided that rather than go back to the club “for more of the same” (to us, that morning seemed even colder than on the previous day, if that was at all possible); we would pack up early and head back to Adelaide. All in all a weekend of mixed fortunes, the on the water results and competitiveness against much larger cats with much larger sail areas, and against skippers of quality with a lot of national and international success, was very satisfying. The few small misfortunes, Melbourne traffic on the Friday night, and the bitterly, bitterly cold conditions, we will put to the back of the mind. Still, all in all, an experience that we are glad that we have now participated in. Our thanks have to go to Garry (Altered F16) for all his help and his out going nature. His presence even made the weather seem to be not quite so cold, (my feet are still numb from the cold though). P.S. the "T" foils worked an absolute treat.
hope you have thawed out. I guess it probably was cold standing around on shore, as a sailor I didn't notice it that much, as the racing was HOT on the water in all meanings of the word <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />. One of the things that make spinnaker one up sailing so challenging is that you never stop working it certainly tries out my aerobic fitness, I often came off the water out of breath over the weekend, it kept me warm, until time for a shower then I got cold.
I think you forgot to mention the capsize in the race before the altercation with the Tornado, was it the result of a nose dive, I only saw the F14 over as I righted "Altered" from a nosedive then capsize, it was a huge gust.
You missed the best sight of the weekend Monday morning, when Greg did a full on cartwheel on the Capricorn pushing to hard after going back after breaking the start. It was one of the best I have ever seen on Flat Water <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />
There where only 3 Mossies with spinnakers there a bit dissapointing, but some of those that didn't turn up had good excuses, but after having at least 6 at last years F16 title it was a dissapointment.
I have followed this discussion of the T-foils, and have learned a lot, thanks for sharing. Now I have a question, or two, and forgive me if it seems obvious, but my actual on the water time is limited as compared with most others here. 1- How do you determine the placement of the T-foils? Do you simply get your boat to "feel" (feel being have boat speed and handeling characteristics maximized for all conditions in which you would normall sail)as you wish, then add the T-foils parrallel to the waterline? 2- I know that moving weight forward and back has effects on the boat, so do the T-foils negate this, or do they make weight placement more important, and possibly easier to feel when you have it right?
His only capsise was with the "bingle" with the Tornado, the Tornado came up on the Alpha “hidden” behind the Alpha’s spinnaker Gary, and called starboard at the very last minute, which made Antony have to manoeuvre in a split second otherwise there was going to be one hell of a “coming together”. It was a very near thing as it was and in the process Antony was “wrong sided”, wrenched his shoulder badly, and the Alpha went over side ways (ever so gently as it turned out), He had dropped the spinnaker sheets but couldn’t uncleat the main in time. The way that we have set up the T foils Rich is so that the foils are parallel with the deck line of the hulls, (fore and aft) which for us that makes them parallel to the ambient water surface (assuming that the water surface is flat) this means that when the hull is sailing “level” the foils are doing nothing. When the bow dips the foil is then travelling through the water but inclined downwards. This creates downward lift to the underside of the foils and pulls the transom down (or the bow back up). The reverse happens when the bow lifts. The resulting effect is that any and all pitching motion of the hulls is greatly reduced. It seems that with the foils the skipper doesn’t have to move his weight back and forth anywhere near as much on the boat with the foils as he would normally do with out them. Even having his weight “in the wrong place” doesn’t seem to induce any noticeable increase in drag We just placed the foils at the bottom of the rudders, but others have them a little up from the bottom, so their position (up and down) on the rudders is not critical as long as they are in the water.
Darryl the position of the foils on the rudder is more critical with your setup as you need to be able to lift the blades clear of the transome. Another problem might occure when raising 'kick up' rudders. The lower the foils are, the more drag they would cause as they are being raised, effectively neutralising steering. This would make it very difficult to sail in shallower waters where the rudders can't be locked down untill the water is deap enough. In that case they'd need to be up as high as is practical. A long-ish blade would also help.
Thanks for the reply. I guess I didn't state my first question with enough background, so let me explain that I have a homebuilt boat, (I picked it up from someone else) and the rudders were originally mounted at about a 30 degree angle off of the waterline. I have repositioned them to approximately 90 degrees from the waterline, but have yet to sail it as changed. So, I am assuming that I need to get the rudder rake situated first to an optimized "feel" then think about adding T-foils. Basically, the addition of the T-foil does not affect the weather/lee helm characteristics of the boat does it, or does that bring in a whole new rudder rake set-up?
Secondly, should the T-foil be at a right angle to the foil, when viewed from the end, or should it be placed parrallel to the rear beam in the case of canted hulls?