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Old 01-10-2016, 09:25   #16
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Re: Sailing with or against current

Growing up at Deception Pass and navigating from here to Alaska for over 50 years, currents have been a major factor. Study a little Set & Drift. Sailed the San Juans in a Lightning with no engine when a teenager. Liked descriptions above especially effect on rudder.
When in the San Juan Islands remember "Flood North, Ebb South". Northern Gulf Islands the opposite due to Vancouver Island.
Look at tide tables. They will indicate current.
Take into account when docking. Look at current around pilings and buoys. Have had some interesting times at outer dock in Friday Harbor with strong current running parallel to the dock and wind blowing me off the dock.
Use the currents rather than fight them if possible.
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Old 01-10-2016, 11:51   #17
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Re: Sailing with or against current

An alternating (tidal) current has some effect on the apparent wind, in addition to the sea state. When beating across a wide body of water (e.g. the English Channel) in light or moderate wind, it is sometimes useful to time the tacks with the turning of the tide.

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Old 01-10-2016, 12:05   #18
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pirate Re: Sailing with or against current

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Originally Posted by Hydra View Post
An alternating (tidal) current has some effect on the apparent wind, in addition to the sea state. When beating across a wide body of water (e.g. the English Channel) in light or moderate wind, it is sometimes useful to time the tacks with the turning of the tide.

Alain
Yup.. Get there a bit quicker.
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Old 01-10-2016, 12:16   #19
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Re: Sailing with or against current

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Wind against current will produce bigger and steeper waves than wind with current.
Hit Dungeness Point with opposing current, and winds and get back to us on it

Lots of good points being brought up here. I had a motor yacht tell us about getting thrown 90 deg off course coming around Cape Flattery on a March afternoon, when why he was out then I do not know!

Tread carefully, mother nature is a bitch........( well sometimes)
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Old 01-10-2016, 13:05   #20
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Re: Sailing with or against current

I think for the benefit of the OP we need to get back to some really, really basic stuff!


A boat doesn't care if there is a current flowing or not. But the skipper should, because the top and bottom of pilotage is to stay away from hard stuff. Therefore accurate prediction of where one's boat will be X seconds or minutes from now is essential to safety, and PREDICTION, is what is affected by current.


All that's required to do the prediction is basic plotting skill. If you need to do it with chart and pencil, that's okay for a beginner, just to get the idea. But in reality, particularly when you are in close quarters, you need to be able intuitively to perceive the track (vector) you are on. Else the resultant noises could be both unpleasant and expensive :-)!


So, OP, if I were you, I would start with something really, really simple: If your course steered is due north and your speed through the water is five knots, and if the current runs due east, also at five knots, where, precisely, will you be OVER THE GROUND 12 minutes from now?


Just draw it out on paper: A square 5 units (scale miles) on each side. If you are now in the south west corner, 12 minutes from now you will be at the northeast corner.


Now, play with this idea using different boat speeds and different speeds of current until you get an intuitive understanding of how this works. Then get really sophisticated and do these exercises again positing different angles twixt the direction of the current and your steered course. Once you “get it” , and you can do the calculation of the “vector” in your head within milliseconds, your problem will go away.


What others have said about whirlpools and dead-ended yacht basins is all very true and absolutely essential knowledge, but to be sure that you never find yourself in such a fix, it's essentail to be comfortable with the calculation I've just laid before you.


Off the south end of Saturna Island the whirlpools are sometimes so powerful that at their centre there is a “hole in the water” - a depression deriving from centrifugal force acting on the water. If you let a smallish sailboat drop into that hole, she may not be able to climb out again under sail alone, and the whirlpool will then take you with it whereever it chooses to go. Even onto a reef. But whirlpools can be seen from quite a distance away, and if you understand the calculation I've laid before you, it's easy enuff to pick a combination of course and speed that'll keep you clear of them.


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Old 01-10-2016, 14:20   #21
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Re: Sailing with or against current

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Current will affect your tacking angles too. This can be used when racing. One tack is better when racing over current.
Look up lee-bowing a current and the advantage it gives you.

Think about your leeway; you have to consider that vector in the equation as well.
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Old 01-10-2016, 14:32   #22
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Re: Sailing with or against current

Having been sailing in British Columbia for over 30 years I consider myself a bit of an expert on currents. Nakwakto Rapids (which I have been through several times) at the mouth of Seymour Inlet are listed in the Guinness Book of World Records as being the fastest tidal rapids in the world - at 16 knots!

In open space, try to go with the current for speed and efficiency (there's no use bucking a 5 knot current with a 6 knot boat for any length of time). In tight quarters (like tidal rapids near slack tide) try to go AGAINST the current for control. Going with the tide in a narrow passage will turn you white very, very quickly. Sometimes, when I have had to do it, going WITH currents of four to six knots, I go through backwards, powering ahead with my boat speed just a little less than the current speed. That way I maintain control and at full power can "stop" the boat and crab sideways to miss the rock or make the turn. Tricky but fun. (God it's nice to have a steel boat!
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Old 01-10-2016, 14:40   #23
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Re: Sailing with or against current

Trente Pieds, et al,

You're right about visualizing your actual course over the ground. It is much easier when there are objects in front of a background to show you how much you're being swept, and then you can correct accordingly.

Many of the rivers here in Oz have leads to help keep you in the channel, quite useful.

Not sure where dmk sails, but he writes like someone from the US. I'm glad he's thought to ask, really.

Ann
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Old 01-10-2016, 17:27   #24
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Re: Sailing with or against current

Yep.

I got one of my golds this way: betting on the opposite side of the river, sailing the longer route but getting more lift on the eddies.

If you are local, you do not bet, you know. You get a home advantage.

Still, if you look at all early races of that Emirates Team NZ vs. The Better Lawyers AC, you will notice one local Kosecki proving me wrong.

Cheers,
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Old 03-10-2016, 17:08   #25
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Re: Sailing with or against current

There is a lot of good information in this thread. Many of these examples and instruction should be included in a CF sailing curriculum. I'm serious. There are some very experienced and talented mariners here that are decent writers too! Kudos! I'm impressed.

Concerning the topic at hand, the Gulf Stream and Hurricane Matthew should provide a few more examples of navigating in opposing current and wind conditions over the next couple of weeks or so. I suspect Youtube will have some new videos on the topic soon.

So in the spirit of sharing, I should make a contribution too. How about this example? It is about as basic and simple as it gets - real beginner's stuff... It's about being pinned against a fuel dock by an incoming tide in a strange marina. Everyone has been there, right?

An experienced sailor might have used the opposing wind to help fend the boat off the dock or elected to wait for the current to subside a bit - as I did. However, the marina wanted to keep the fuel dock open, so an inexperienced marina hand (at the instruction of the guy running the marina store and fuel dock) offered to take my boat to a visitor's slip for me so I could get some adult refreshments and a meal at the club.

I immediately accepted their offer. So this dock hand and his buddy grabbed my dock lines, boarded my old Watkins, fended off the bow and engaged the prop. The hand at the helm gave it way too much throttle and scarred the port side hull amidships to stern on the lag bolts protruding from the corner joint of the wharf deck. Ouch!

The damage was really pretty superficial, but it did get into the hull paint, the contrasting stripe and the gelcoat. Most owners would have exploded. But not me. Not this time. I didn't say anything. I just stood there with arms folded and scowled. The minimum wage guys were frantically apologizing as the crowd of curious onlookers grew. It must have seemed bad. Even the normally friendly and inquisitive liveaboard cruisers kept their distance. Eventually the manager showed up, surveyed the situation, looked at me and planted his face in his hand.

Remember, I agreed to let them move my sailboat. I know more than a few owners that would rather let strangers sit their children that move their yacht. But that little bit of wisdom landed me a free tab at the bar and diner that night. But that's not all. I also agreed to 1) keep my mouth shut and 2) work with him so the marina would not have to make another claim against their insurance. I didn't mention that the boat needed to be hauled anyway. This is called sailing in favorable conditions.

The manager called the owner and the owner came to the scene of the crime. You could tell he was barely keeping a lid on it. After he did the math though, he agreed in writing to a free haul-out, free repair, free epoxy paint and free bottom job. He also gave me the opportunity to upgrade some thru-hull fittings, my transducers and make a few other repairs while it was on the hard. He generously threw in a number of serviceable salvaged parts (from boat abandoned over slip fees) and a month free in a liveaboard slip after all repairs were complete. Yes, I cleaned up on this one.

This is why I advocate never sailing in conditions where the wind opposes the current if it can be avoided. You never know what can happen!
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Old 04-10-2016, 17:28   #26
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Re: Sailing with or against current

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I did not grasp that either.
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Originally Posted by boatman61 View Post
I use that technique to raise the hook without engine.. raise the main, centre the traveller and sheet tight..


Yes but this has nothing to do with current.


You need a boat that can ride ahead of it's own anchor using the current alone. I think some boats are better at this. The anchor shouldn't be on the bow where normally you find it, but instead adjusted to the correct location (a little back and to the correct side)


Currents greatly affect the sea state. I was able to travel at 10 knots for hours along the south african coastline. The waves were very small despite having steady 20 knots of wind in open water.

When I navigated the sacremento river, I found the current 2-4 knots it was enough that despite the dead air (0 knots of wind) There was enough apparent wind from it to keep my sails full tacking.

I was traveling faster than the current powered only by the current.
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Old 04-10-2016, 17:55   #27
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pirate Re: Sailing with or against current

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Yes but this has nothing to do with current.


You need a boat that can ride ahead of it's own anchor using the current alone. I think some boats are better at this. The anchor shouldn't be on the bow where normally you find it, but instead adjusted to the correct location (a little back and to the correct side)
Seeing this in the flesh.. so to speak.. would be an education indeed..
I get the point about boats sailing on their hooks.. and I can visualise how setting the rode further back would get her to sail further up.. however I still cannot visualise any progress being worth the effort of going nowhere fast..
I'd do what I do at the Tejo.. drop the hook and wait for the flood.
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Old 04-10-2016, 17:57   #28
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Re: Sailing with or against current

Quote: "Sometimes, when I have had to do it, going WITH currents of four to six knots, I go through backwards, powering ahead with my boat speed just a little less than the current speed. That way I maintain control and at full power can "stop" the boat and crab sideways to miss the rock or make the turn."

Precisely! Used to handle Dodds Narrows near Nanaimo that way in a 65 footer when on a tight itinerary. The tricky bit of Dodds is about three parts of a mile long and curvey. The slack lasts about 15 minutes and the current is typically 6 knots.

With the increased traffic these days, I'd be a bit wary, mainly because you "have to drive for the other idiot as well". In Dodds, the big threat is tugs struggling to position their tows as the come through. To offset danger from the increase in traffic volume, we now have VHF which we didn't then, and I'm really quite impressed with the way the commercial traffic calls "Sécurité" prior to entering Dodds.

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Old 04-10-2016, 18:17   #29
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Re: Sailing with or against current

Ann, et al, [who IS this guy "Al" anyway :-)? ]

dmk does indeed write like someone from the US. As a California Girl you'll agree that there is nothing wrong with being FROM the US ;-0)! But more to the point, he writes like a novice in the realm of seafaring. "A Yankee in King Neptune's Court" if I may (mis)quote a countryman of yours and a namesake of mine :-)

dmk wanted specifically to know about "conditions" (other than turning) where current needs to be allowed for. And someone already mentioned docking, I think. I think you should give dmk [and me ;-)!] a discourse on how you and Jim handle departing a dock when the current is setting you onto it. Throw in some wind if you like.

Cheers

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