What kind of boat can sail closest to the wind?

Discussion in 'Sailboats' started by laukejas, Aug 29, 2016.

  1. CT249
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    CT249 Senior Member

    Cheers gggG

    Stumble, may I ask how much sailing you've done on or against a competitive Tasar or International Canoe? I picked classes that I own and sail and therefore have some reasonable gut feeling to go from.

    Despite being a Hobie, the Miracle 20 was basically a copy of the Hurricane 5.9 which was itself built on modified Tornado hulls, so it's not exactly a Wave or 16 and is a reasonable comparison to a Tasar in some ways. The Miracle 20 is generally considered to be faster upwind than an F18 (despite having very similar waterline length) and the Taipan, and in our experience was higher than a competitive F18, especially at low speeds where the "twistable" rig kicked in. It therefore seems to be a reasonable yardstick.

    I may add that we used to race against the world A Class champ and the national Tornado champ most weeks in an earlier cat (Taipan 4.9) with considerable success against the latter, so it's not as if we're always watching kooks sail old bangers.

    For the reasons gggGuest noted, IMHO the physics work in favour of the mono in this completely artificial scenario. L/B relates to wavemaking drag, which is of little relevance when trying to go as high as possible since speeds are low in that scenario.

    None of this really means anything, and the class that could be my #1 favourite of all time would do poorly in terms of ultimate pointing ability and in terms of short tacking up a channel.
     
  2. Stumble
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    Stumble Senior Member

    Very little with an IC, a good bit on the A. My guess on the A vs the canoe comes down to a few things.

    The A is longer (by a foot) narrower (when trapped by about 2'), and has more sail area (~43sq ft) at roughly the same weight. We also use a unirig instead of a sloop.

    I agree that it's a silly comparison, but I think these weigh in favor of the A-Cat.


    Trying to tack up a 50' wide river on the A.... It would be faster to get out and push. No question an IC would crush the A in those conditions, the cat would spend half its time sailing backwards trying to complete a tack.
     
  3. rcnesneg
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    rcnesneg Senior Member

    Stumble, the trick on the high performance high-aspect uni rigged cats is to keep the speed up at the ends, yes, even short tacking up a 50' wide channel. Fall off at the end, turn quickly through the wind, ease the sheet 1 foot, give the boom a hard pump to bring battens over, and keep the heading low for the first 5 feet or so to get some speed before you go high. With enough wind, it's pretty easy. I guess you probably know all this already.

    My home marina currently has 3 inches of water in it and a long(1200 ft long) channel that's 50-100 feet wide. Back when it had 3 feet, I would tack my way out. When it had 2 feet I had to paddle out or snag a tow. Believe me, I've tried to get out with the boards most of the way up. It won't do it. I haven't seen an IC or much of anything else tack out besides sunfish and lido 14s, and the lidos usually did terrible.
     
  4. messabout
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    messabout Senior Member

    Gentlemen, I am enjoying this discussion thoroughly. Way back in the day I had an IC and not long after that, an A cat that was frighteningly quick. For going up the narrow river I'd choose the IC without hesitation....even though the A was somewhat faster in a straight line. In light air it would be no contest. I claim that the IC would prevail but only if the wind direction was coming from somewhere near the pointiest ends of the boats. Not so much that the IC would point higher, but it would tack without losing much way whereas the cat would lose more. ....Alas if we are to reduce the race result to a tacking duel, then maybe something like a Laser could be best if the skipper were skilled at the art of roll tacking..
     
  5. Stumble
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    Stumble Senior Member

    That's a really good point. If the objective is to get up a very narrow channel <5 times the boat leingth wide then the boat that roll tacks is likely going to win no matter how high it points. And a slow boat may actually be an advantage, at least you would have time to get flow reattached, on a fast boat you would need to tack before the boat is back up to full speed.
     
  6. gggGuest
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    gggGuest ...

    And also means, getting back to the original thoughts behind the question, that the first and probably key thing for Laukejas to do to get his boat up the river faster is to really get roll tacking sorted out, since if you can readily tack without losing speed then having to put a couple of extra tacks in is not such a great hardship.
     
  7. Skyak
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    Skyak Senior Member

    Fast tacks are a great asset in racing and particularly in those conditions, but if he is not tacking trough less than 90 degrees in a 10ft mono (presumed mid single digit boat speed) there should be some easy pointing gains to be had.
     
  8. sharpii2
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    sharpii2 Senior Member

    I agree.

    For starters, he could go with a deeper dagger board. Then he could make a new sail out of Dacron. After that, he could invest in low stretch line for his halyard and down hold. Mike Storer has reported excellent result by doing these three things to his Goat Island skiff. He claims he can keep up with a Laser, even though sticking with a Balanced Lug. Of the three changes, I think the bigger (through being deeper) board is the most effective.

    As for the mono vs. multi argument, the multi may well beat the mono in smooth conditions. With deep enough boards, it should have little trouble going up wind. Hell, in the 70's, one light, spidery tri went 9 kts in about 3 kts of wind.

    But where I live, in the Great Lakes region, multis aren't that popular, especially in larger sizes. Of course, a big part of this is the cost of slip rental. They take up a lot of space. But another reason is the types of waves we usually get, the short steep kind. This will stop a multi in its tracks, if the skipper decides to pinch it. He may be forced to accept a close reach, to make it to windward. This is because the multi has a lot of whetted area for its displacement, so when it confronts an obstacle like a steep short wave, it quickly loses momentum, even though its sharp ended hulls part it smartly.

    Even the light mono I had, had problems in these conditions. It would try to go over the first wave, then through the second one, but end up crashing down on the third one.

    A heavier, sharp bow mono has a lot of weight for its ample whetted area, so even though its rig may be smaller in proportion to it than a multi is to its, it is better at maintaining its momentum.
     
  9. Fred Roswold
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    Fred Roswold Junior Member

    A monohull sloop with:
    a) Low wetted surface hull (narrow, possibly deep canoe body)
    b) Efficient foils (deep, thin, high aspect ratio keel and rudder)
    c) Flat, high aspect ratio sails, with inboard sheeting

    Many existing racing keel boats meet these criteria. A well designed racing keel boat will sail at a TWA of 40 degrees or less in moderate breezes. Fresher breezes will result in closer wind angles because the true wind component of the AWA is greater. In very light conditions the boat will seem like it is sailing close to the wind but upon tacking you find that it goes about in more like 90 degrees or 100, not 80.

    The best VMG for any boat is found by looking at the polars for the design, however if you sail close hauled and keep the tell tails flying, and don't crack off for that addictive speed, you will hit close to your best VMG. This does not work for a slower boat which does not meet the criteria mentioned above. For those types of boats you have to work it out by trial and error if you don't have polars. Do not rely on sailing instruments and try to sail to the VMG, you will overshoot constantly, both directions.

    Best windward ability has to be balanced against great downwind or reaching speed. Many modern boats with wider, flatter, hulls fly off the wind but pointing isn't always their strong suit.
     
  10. upchurchmr
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    upchurchmr Senior Member

    I'm a little puzzled about peoples comments about multihulls not pointing well.
    I use to hear that all the time back in the 70's when I had an old, worn, cheap Tornado catamaran.
    It outpointed at a higher speed than all the "racing" monohulls of the time.
    It was fun coming up from behind a J24, starting to leeward, and pointing so much higher that the guys would often request that I did not pass them to windward (cause I would spoil their wind and mess up their fleet race).

    It was funny in retrospect that none of them came up and told me how much worse the catamaran pointed. Actually they wouldn't talk to me at all.

    What are you guys talking about?

    Not every multihull points well, same as monohulls.
     
  11. CT249
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    CT249 Senior Member

    What are we talking about? Some of us are talking from fairly extensive experience in fast multis with nice sails, in which we can compare performance against people like world champions. If you didn't race against other Tornadoes then how do you know you weren't sailing it too high when you outpointed monos?

    In some conditions the cat could be powered up with full apparent wind and therefore able to point high when a J is still underpowered and going lower for power. Generally a J would point higher, especially in the light and heavy stuff; perhaps not so much in medium winds. And all these sort of discussions are murky unless we know that we are talking about competitive boats in each case.

    By the way, at my old cat club the cat sailors never talked to the kitesurfers or windsurfers, so there's no reason to think that anyone was biased or bigoted against cats. And many windsurfers point lower than cats and never get stressed or feel insulted if anyone points it out.
     
  12. Seafarer24
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    Seafarer24 Sunset Chaser

  13. fastsailing
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    fastsailing Junior Member

    "1) a boat that reaches it's best VMG when sailing very closely to the wind, that is, at low TWA"
    "2) I also wonder what kind of hull and rig would be best for sailing so close to the wind"

    1) A boat with efficient rig, meaning tall compared the rigs boats with similar righting moment usually have. A boat with very deep board or keel, which also has significantly more area than usual at the same time. All those are important to allow pointing high to the apparent, or tight apparent wind angle.
    A boat which has high drag at all speeds, not just after wavemaking resistance becomes significant, in order to keep boatspeed down at optimum VMG point in all windspeeds. It seems everyone else here either got the question wrong on that latter point, or made some error in their reasoning, because they all suggested a low drag boat, contrary to sailing physics. It is important to have the rate of increase of drag with lateral force low, and over all hydrodynamic drag high at the same time, only then the result is the kind of boat asked for in 1).

    2) This is not about only the hull & rig, but completely different boat for a different purpose. A boat that can sail upwind while pointing very high does not have to meet criteria of 1). It can have it's best VMG while pointing low, and still be capable of pointing higher than the kind of boat answering 1) when choosing to do so.
    The best boat for that would be a boat with best possible L/D both under and above water, making it very different from the boat type 1), having high hydrodynamic drag and therefore low L/D under water. Best L/D from a rig & sails means being tall, while having low parasite drag. Full wing rigs like used in C-class or AC50 or AC45 or AC72 catamarans is the best. Best aerodynamic L/D for all the boat means windage of the platform must be small compared to sailarea. This means large righting moment to allow using a larger sail area and a tall rig for the boat size (and therefore windage of the platform), which means waterballast is useful. Just keep in mind most of the weight of human bodies is indeed water, making it the best kind of ballast for C-cats to name one. Having a high righting moment also means higher proportion of hydrodynamic drag is related to producing lateral force, improving L/D under water as well. Foiling cats are at the extreme edge on this.

    And of course windturbine boats are the ultimate pointers, but most of the above is not written for them.
     
  14. fastsailing
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    fastsailing Junior Member

    "Fresher breezes will result in closer wind angles because the true wind component of the AWA is greater."
    Which means that if you want a boat that has its max VMG while pointing high, it must have true wind component of the apparent wind vector great at all conditions, not only when wavemaking resistance limits its speed. That means high hydrodynamic drag in all conditions, most easily done with high wetted area of a deep board or keel, but even wetted area of the hull helps, while being the exact opposite of a) in the quoted text.

    If on the other hand you want max VMG upwind, statement of a) can be correct (*), but it means best VMG is not achieved while pointing high if all hull drag is kept low, while the boat is still very capable of pointing high at reduced VMG.
    * = the requirement of being a monohull is not a necessary requirement, instead it's irrelevant to the criteria answering the question.
     

  15. fastsailing
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    fastsailing Junior Member

    Extensive experience sailing fast multis and monos has nothing to do with answering the question OP asked. It is definitely the kind of question requiring theoretical knowledge of sailing physics, because there is no reason to believe any real world boat would be optimized for the proposed target and hence nobody has practical sailing experience of what is required to achieve that goal. The extreme case of a windmill boat is a proof of that. No world champion would have come to that conclusion based on practical experience of racing mainstream boats.
     
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