Favorite rough weather technique

Discussion in 'Sailboats' started by gonzo, Nov 10, 2009.

  1. capt vimes
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    capt vimes Senior Member

    fanie
    watch:
    http://www.youtube.com/watch?v=n_jz708oeVI

    do not ask me how this guy on his small mono got in this kind of trouble with a broken forestay and such... just watch what happens to the mono and the cat (yes its not a sailing cat) - coming to aid the striken mono - in this breaking seas.... ;)
     
  2. Brent Swain
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    Brent Swain Member

    Scroll back, I posted it earlier. Do your research before asking stupid questions.
    Brent
     
  3. gonzo
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    gonzo Senior Member

    About 24 years ago I had a 34' Wharram. I got into an inlet when the tide was coming out and the waves were seven to eight feet and breaking. By the time I figured it out, there was no turning around. The cat surfed a wave all the way in. A monohull would have been in trouble.
     
  4. capt vimes
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    capt vimes Senior Member

    not necessarily...
    depends on the travel speed of the waves and the surfing/planning capability of the mono...
    -> see BeauVrolyks posts...
     
  5. Fanie
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    Fanie Fanie

    Now that is desperate :D

    Richard, you in a multihull would scare me too :D

    I think every tipe of boat have a wow in them. I just don't want to be hooked by someone because there's not enough space to fish from :D

    There are some really nice mono's too, just like to discriminate against them a bit ;)
     
  6. CT 249
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    CT 249 Senior Member


    Brent, about "Outside only steering stations are just bad seamanship, any way you cut it"

    How, logically, can you claim that ALL those who don't share your opinion are poor seamen? Maybe some people (and I'm not claiming to be one of them) can handle different conditions of cold etc without suffering impairment - certainly that seems to happen in other sports. And maybe some of them rely more on senses that are dulled when you are inside.

    As an analogy, last year's national champ in a class I sail suffers a significant loss of performance if he wears anything around his ears, because that's where he gets a lot of information about the wind. Being inside a wheelhouse is similar. Getting off a lee shore, or gybing in a gale, such information may be vital and much more important than staying a bit drier and warmer. So surely what suits you may not suit everyone in all conditions.

    As another analogy, some top Hobart crews can sail very fast after living for days on Mars bars and soggy sandwiches and sleeping on the rail. Most other sailors can't perform in such conditions. The point is that individuals vary and what they can take without losing performance varies. Therefore, surely, it cannot be a simple matter of 'get a pilothouse like Brent says, because he knows all and everyone else is just like him'.
     
  7. apex1

    apex1 Guest

    Well,

    Brent is Brent,

    and we others (the rest of the world) are the amateurs.

    We have to bear that............................
     
  8. BeauVrolyk
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    BeauVrolyk Sailor

    Magwas,

    You are right, that a boat has the same "potential" energy when at the top of a 10m wave that it does when hanging 10m above the ground. But, there is a significant and important difference in how you get down from 10m up. If your boat was dropped from the crane and dropped 10m it would then have developed a great deal of momentum that would be extracted from the boat during the relatively brief time it was crashing into the ground - a second or two at most. However, that's (fortunately) not the way one comes down a wave. (BTW, I will leave falling off a breaking wave out of this as that's not been what we're talking about.)

    When you surf down a wave you are primarily moving horizontally, being pushed forward by the wave, and only moving downward slowly. This is obvious, when you think about how "heavy" you feel while surfing down a wave. If you felt REALLY heavy all of a sudden, then you'd be feeling the force that the boat was absorbing quickly. But, that's not what it feels like at all. Rather, you feel a little heavier as the wave starts to lift the stern of the boat, which is perhaps a 10 to 15 percent increase in your perceived weight and proportional to your acceleration vertically - upward. Then, while surfing down the wave you'll feel forward acceleration and a slight lightening. This is because the wave is pushing the boat forward, along with the wind on the sails (if any).

    Once you reach the trough, if your boat is actually faster than the wave, then you'll feel the boat slow down and your body will gently try to fall forward. There will be a modest increase in your perceived weight again, I'd guess no more than 15 to 20 percent, and then you'd wait for the wave to pick you up again.

    The point is that your decent from 10m is over a long period of time and there isn't a "sudden" crash at the bottom of the wave. The drag of the water on the hull uses up a tremendous amount of the "potential energy" stored in your boat, due to its being lifted by the wave, and that's evidenced pretty clearly by the gigantic waves your boat will make as it slides down the wave. Imagine how big a motor it would take to get your boat to go that fast and you've got a pretty good way to estimate the amount of energy.

    Hope this helps.

    Beau
     
  9. BeauVrolyk
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    BeauVrolyk Sailor

    Richard,

    The difficulty most sailboats have with going against truly large waves is that the typically lack a motor large enough to guarantee steerage as they reach the top of the wave. There, where the wave is the steepest, the boat's rig is in the strongest wind (protruding far above that of a motor yacht) and the difficult of effectively pushing the boat up about a 45 degree slope is simply too much for most small yacht engines. Thus, most sailboats, when trying to power directly into the waves (when they are quite large), end up actually going backwards for quite a time during the period when they are near the top third of the wave. The only way to avoid this, and I have done it quite a bit with my old cruising yacht with the big engine, is to get going really fast - nearly full throttle - while in the trough of the wave, and almost completely cut power about a boat length from the crest of each wave. This is hard for most folks to do in really nasty weather.

    The goal of this approach is to make up for the fact that the boat doesn't really have a large enough engine by building up speed when you're not going up-hill (up the front of the wave) and burn that speed off to almost exactly zero when you're at the top so you don't fall off the wave violently. This requires that someone drive the boat on each wave, which is at least as much work as sailing it, that there be a helmsman who can execute this strategy, and that the crew be willing to tolerate the continuous racing and idling of the engine (pretty irritating actually). I did this for about five hours once while holding station next to a life raft that was hanging from a sea anchor and it was terribly irritating.

    Finally, the most dangerous point on a wave is as you actually go through the wave top. This is true regardless of surfing with it or trying to power towards it. Some waves are steep enough to actually break, and I don't mean just form a white cap here I mean really curl over and break as you see at the beach. When most sail boats try to power into these sorts of waves their greatest risk is being pushed backwards, as they reach the crest of the wave, and falling onto their sterns. I've watched this in video of a boat being pushed ashore here in San Francisco. The sailboat was powering directly into 20' waves and each time he reached the top of the wave the wave and the boat moved back towards the beach at about 10k. What made this much worse was that the sternward movement of the boat caused it to broach while going backwards and allowed the wave to knock the boat onto her side. Eventually, the helmsman was washed overboard and the boat and swimming sailor were washed up on Ocean beach.

    Hope this helps explain why I go down wind and adore lots of sea room.

    Beau
     
  10. apex1

    apex1 Guest

    Fully concur Beau!

    Steaming into it, is´nt easy with a motoryacht either. And controlling the throttle is a task too. (much easier with a CPP btw.)

    As for the wave crest, that is the most dangerous point for a motor vessel as well, too much windage make them behave like a sailing boat sometimes.

    A overpowered, lightweight, low windage boat, like Dashews "Windhorse" behaves much better of course and gives one a choice between heading into, or running off.

    At the end I like to repeat: avoiding weather is the best tactique! Weather systems are more or less well known, for different seasons in certain waters, one should plan far enough ahead to get not trapped (by own ignorance).

    Regards
    Richard
     
  11. BeauVrolyk
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    BeauVrolyk Sailor

    Claverton,

    I went to the web site you've referenced, thanks for that. I would like to point out that this is a web site promoting the product, not an independent source. That said, some of what he's saying does make sense. However, there are a number of factual errors. The entire discussion about the speed of the water is simply wrong. The movement of water in a wave is a well understood and well studied phenomena. If you'd like a quick example, have a look at a surfing movie. While the water that falls off the top of a true breaking wave is falling through the air, it doesn't have either the distance or the density to develop the speeds described above. All one need do is watch a really big (>20') wave at the beach.

    In a true breaking wave the water circulating up the windward side is pushed along by the wind on its surface (a small force, but significant over time) and the momentum of the wave (a much bigger force). Once the wave has been built by the wind over a long long period of time to the point where the wave will break at the top, the wave then topples over itself. You can observe this at the beach all the time. We have a Big Wave competition here in N. California at a place called Maverick's and we all troop out to watch the 30' and 40' wave with surfers riding on them. What we have at Mavericks, and what the poor racers had in the Fastnet, are waves in which tons (and I literally mean tons) of water is falling from the top of the wave and landing onto the down wind side. But, at no time does that water get to break the laws of physics. While the water is certainly very heavy, and its horizontal component (meaning how fast the water is going sideways) is just slightly faster than that of the wave, its vertical component is the same as if you'd dropped all that water off the top of a single story building. This means that the absolute fastest the water could be moving would be at the speed it would pick up falling about 12 feet. The water isn't falling the entire height of the wave, but only the height of the breaking crest. This is a speed of about 15 miles per hour. As an example, people jump off single story buildings all the time without hurting themselves.

    But, there's a second problem with this. Water is not solid. As a result, as it falls it breaks up into foam. Again, observe the top of a wave at the beach. The foam is billions of small droplets and globs of water that are trying to move through the air. The movement through the air is what breaks it up and as the water attempts to travel through the air it slows down. Of course it also speeds the water up, you see the foam moving along with the wave at the beach, but that foam is NOT ever going faster than the wave. If it were, the foam on the waves would arrive at the beach first, long ahead of the wave. It doesn't do this.

    On the basis of these simple observable facts, which you've seen at the beach, you know that this persons calculations are simply wrong.

    Finally, as with my earlier post, no one arrives at the water in the trough (not even a surfer trying to go "over the falls") all at once. Just as it takes a long long time to surf down a big wave, it takes a boat a long time to slide down a wave. If you watch surfers you'll see that the only way they can achieve speeds higher than the speed of the wave is to go across it - this is not something a boat will ever do, so we'll ignore this option. But, the surfer clearly illustrates that the surfer riding on the fastest part of the wave and the mass of water in the wave arrive at the shore at the same time. While the water at the bottom of the wave is certainly sitting still relative to the water falling from the top, the difference in speed is a maximum of the wave speed plus whatever gravitational acceleration the water from the top achieved. In the case of a keelboat, in dramatic contrast to a surf board, there is massive drag. As a result, the keel boat is going a fraction of the speed of the WAVE, not the water. Keep in mind that the wave has picked up a relatively stationary sailboat and is accelerating it forward. That acceleration takes a while, which is why the boat climbs the face of the wave at all, and at no time does the boat go faster than the wave.

    What you've really got is a boat that is about 1/2 way up the wave face, sliding down into the trough at about 1/2 the wave's speed. All things that fit perfectly with my experience in large waves surfing down them. Think about the waves that pass under your boat, they are going about four or five times your speed. Now, imagine making that wave a lot steeper and you might get going faster, now you're going at most half the speed of the wave, not twice it as the author of the web site you quoted cited.

    While gigantic breaking waves are terrible - we'll all agree - the danger is the weight of the water crushing the boat and the circular action causing the boat to roll over. It is not the speed of the wave or boat, and it is certainly not crashing into the trough.

    Best,
    BV
     
  12. BeauVrolyk
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    BeauVrolyk Sailor

    Fanie,

    I adore cats, tris are even better. But, that's because they are so fast that you can usually outrun the weather. I would NEVER turn around and try to go bow into big seas and wind with a multi. We were trying to bring a big cat up to San Francisco from S. Calif. and going over 15' waves with about 35 knots of wind the darn thing kept trying to fly as the wind got under the beams and decks. It was a wild experience. In a really bad storm, greater than 60k of wind, I think the thing would have easily blown over backwards when the wind got under that big broad deck as the boat crested waves going up wind.

    How do you stop that from happening? Turn around?

    Beau
     
  13. Fanie
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    Fanie Fanie

    There are different types of rough weather water, the waves aren't just always long waves.

    My favourite is the washing machine. A bit like some of the members on this forum, each wave on his own heading. Imo this is the most dangerous and tiresome water you can get into besides of course huge breaking seas and rogue waves.

    I have no advice on this except to get out of it. Other than that I think just common sense, good knowledge of how your boat will behave, and how your crew including yourself will behave.
     
  14. gonzo
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    gonzo Senior Member

    The Eastern part of the Gulf of Mexico has a nasty pattern. Waves come at several angles and create a very confusing sea. It is common to get rolled both ways by opposing moving waves.
     

  15. Fanie
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    Fanie Fanie

    Sorry BV, I had some visitors and had to bail -

    As for the catamaran flying over the waves, isn't that what one expect from a cat :D

    Ok, that opens another point of design. Maybe we are too fixed on designing all in the water only, but how about what's above it. I experienced a similar trait with the little tri in really strong wind, it is too light to bite and turn, instead the wind just blows the bow leeward.

    All racing cars and I'm sure racing boats too use the wind to enhance water (road) holding. Now in cruiser boats we don't need to race, the wind does.

    How big a difference would it have made if the design was so that it tends to push / suck the boat into the water instead of trying to lift it out - similar to what an outboard does when you trim the boat's nose down.

    This may be one way of improving water (road) holding of a boat. One can also possibly trim the trampoline so it sucks the bow down instead of the lift up.

    Any comments ?

    No, I cannot tell the wife to go sit in the front to keep the nose down :D Poor aerodynamics ;)
     
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