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#11
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Well for starters, the apparent wind shift due to the "Current Wind"
(CW) would shift the Apparent Wind forward 45 degrees as soon as you cast off. Basically, you'd have little or no flow across the rudder when sailing with the current. Attempts at steering would tend to put on the brakes. A close haul course would not even be towards the dock you wanted to miss, but parallel to the shore. You'd have to hope to gain enough speed sailing parallel to the shore to maneuver just prior to reaching the first dock. If you managed to get the bow past the docked boat, you still might have to pivot the boat on it's keel with the helm to get the rest of the boat passed the docked boat. In that case, you'd have to again get the boat powered up again, and hope to coast around the next dock which is a further obstacle because it extends farther out. This is a situation of speed but no control. Chances are you would have lost all way with respect to the current, put on the brakes with the helm, and put yourself into the hole in the next dock. So missing the first boat would doom you for the second obstacle. If someone gave you a really major push off the dock with the boom, you might clear the obstacles by sailing down with the current. This initial push would give you some flow across the rudder, at least initially, and give you time to get the boat trimmed for speed. You would need to paddle hard to have any real hope to get out of there, because the course you'd want would be the other tack. Tacking in this situation is hopeless, unless you paddle very hard. The smart move is to swing the boat around at the dock and sail into the current which would give you flow across the rudder and helm response, plus more time and room to maneuver. In this case the apparent wind would not shift forward like the first case, but actually shift aft as the force of the current induced wind would actually help fill your sails! With a strong push off the dock to counter the current the boat would see a beam reach off the dock and with flow across the rudder, be able to head up to maintain that apparent beam reach, while putting some distance between the boat and the shore. Your course over the ground (COG) would be still be backwards! Heading upriver also gives you more precious time to clear obstacles. "Boat wind" (BW) would be with the CW in the first case, and oppose it in the second case. The CW would be slightly reduced but at least working for you instead of against you. The key to this whole problem is the effect of a dominating "Current Wind", and to a lesser extend "Boat Wind" on "Apparent Wind". It is easy to forget that the beam reach you see at the dock when you are tied up, will not be there when the current sweeps you along. What would you prefer, to try to clear objects while in irons, or to try to clear them while moving backwards, but powered up? Bart "Nav" wrote What's to stop you letting the stream take you past the obstructions while you add minor adjustmets using the wind??? Cheers Bart Senior wrote: You are in a difficult docking situation. You want to depart the dock and sail on a gorgeous day, but must leave now. Any later and you will lose your light, and have to cancel sailing for the day. You docked are on a river, facing down stream. There is a 5 knot ebb current and it is max ebb. The wind is coming directly across the beam of your boat and also directly across the river. It is blowing 6 knots. The boat is an Etchells keelboat, skeg hung rudder without a motor. Down current are two obstacles---both are docks that are parallel to the river. The closest dock does not project out as far as the second but has a motorsailer tied up pointed upriver that you must clear. If you clear the first dock, you still have to contend with clearing the second dock which extends even farther out into the river. If you can't clear that dock, you are trapped in a cul-de-sac and will collide with something, either the inside of the dock and pilings, which are free of boats, or else into the club house with your forestay and likely damage your rig, if not lose it entirely. Questions: 1. What is your strategy? What are all the factors you need to consider in planning this departure. 2. What can you do to insure you clear both docks? 3. What are your bail out options? |
#12
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I know I'm a little late here but anyway:
As pointed out by Nav: The current follows the coast and might almost take you past the obstructions. As Bart said: The apparent wind will shift once you are out in the current. First problem is to clear the dock: Turn the boat (as Joe and others suggested) Let the boat hang in the aft-most spring and the fore line, then ease the forward line a bit and the current will move the boat away from the dock. (That was my contribution) You can then hoist the sails, probably the jib first and then let go the lines at the same time, and start heading away from the dock into the middle of the stream on a close reach starboard tack. Keep a anchor ready, just in case. Peter S/Y Anicula "Bart Senior" skrev i en meddelelse . net... Well for starters, the apparent wind shift due to the "Current Wind" (CW) would shift the Apparent Wind forward 45 degrees as soon as you cast off. Basically, you'd have little or no flow across the rudder when sailing with the current. Attempts at steering would tend to put on the brakes. A close haul course would not even be towards the dock you wanted to miss, but parallel to the shore. You'd have to hope to gain enough speed sailing parallel to the shore to maneuver just prior to reaching the first dock. If you managed to get the bow past the docked boat, you still might have to pivot the boat on it's keel with the helm to get the rest of the boat passed the docked boat. In that case, you'd have to again get the boat powered up again, and hope to coast around the next dock which is a further obstacle because it extends farther out. This is a situation of speed but no control. Chances are you would have lost all way with respect to the current, put on the brakes with the helm, and put yourself into the hole in the next dock. So missing the first boat would doom you for the second obstacle. If someone gave you a really major push off the dock with the boom, you might clear the obstacles by sailing down with the current. This initial push would give you some flow across the rudder, at least initially, and give you time to get the boat trimmed for speed. You would need to paddle hard to have any real hope to get out of there, because the course you'd want would be the other tack. Tacking in this situation is hopeless, unless you paddle very hard. The smart move is to swing the boat around at the dock and sail into the current which would give you flow across the rudder and helm response, plus more time and room to maneuver. In this case the apparent wind would not shift forward like the first case, but actually shift aft as the force of the current induced wind would actually help fill your sails! With a strong push off the dock to counter the current the boat would see a beam reach off the dock and with flow across the rudder, be able to head up to maintain that apparent beam reach, while putting some distance between the boat and the shore. Your course over the ground (COG) would be still be backwards! Heading upriver also gives you more precious time to clear obstacles. "Boat wind" (BW) would be with the CW in the first case, and oppose it in the second case. The CW would be slightly reduced but at least working for you instead of against you. The key to this whole problem is the effect of a dominating "Current Wind", and to a lesser extend "Boat Wind" on "Apparent Wind". It is easy to forget that the beam reach you see at the dock when you are tied up, will not be there when the current sweeps you along. What would you prefer, to try to clear objects while in irons, or to try to clear them while moving backwards, but powered up? Bart "Nav" wrote What's to stop you letting the stream take you past the obstructions while you add minor adjustmets using the wind??? Cheers Bart Senior wrote: You are in a difficult docking situation. You want to depart the dock and sail on a gorgeous day, but must leave now. Any later and you will lose your light, and have to cancel sailing for the day. You docked are on a river, facing down stream. There is a 5 knot ebb current and it is max ebb. The wind is coming directly across the beam of your boat and also directly across the river. It is blowing 6 knots. The boat is an Etchells keelboat, skeg hung rudder without a motor. Down current are two obstacles---both are docks that are parallel to the river. The closest dock does not project out as far as the second but has a motorsailer tied up pointed upriver that you must clear. If you clear the first dock, you still have to contend with clearing the second dock which extends even farther out into the river. If you can't clear that dock, you are trapped in a cul-de-sac and will collide with something, either the inside of the dock and pilings, which are free of boats, or else into the club house with your forestay and likely damage your rig, if not lose it entirely. Questions: 1. What is your strategy? What are all the factors you need to consider in planning this departure. 2. What can you do to insure you clear both docks? 3. What are your bail out options? |
#13
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Bart Senior wrote:
1. What is your strategy? What are all the factors you need to consider in planning this departure. Walk the boat around at the dock to point upstream. Cast off and reach gently upstream at a speed slightly less than the ebb current. 2. What can you do to insure you clear both docks? Sailing 'backwards' against the current will keep the rudder working and provide good steerageway to maintain control of your position across the width of the river. 3. What are your bail out options? The nett slow downstream speed will make it easier to fend off. Be ready to drop the anchor if things get hairy. Could maybe sheet in to get enough speed to overcome the current, effectively providing brakes against your downstream motion. -- Wally www.artbywally.com www.wally.myby.co.uk |
#14
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6 knots wind and a 5 knot current???
CM "Nav" wrote in message ... | What's to stop you letting the stream take you past the obstructions | while you add minor adjustmets using the wind??? | | Cheers | | Bart Senior wrote: | | You are in a difficult docking situation. You want | to depart the dock and sail on a gorgeous day, but | must leave now. Any later and you will lose your | light, and have to cancel sailing for the day. | | You docked are on a river, facing down stream. | | There is a 5 knot ebb current and it is max ebb. | | The wind is coming directly across the beam of your | boat and also directly across the river. It is blowing | 6 knots. | | The boat is an Etchells keelboat, skeg hung rudder | without a motor. | | Down current are two obstacles---both are docks | that are parallel to the river. The closest dock does not | project out as far as the second but has a motorsailer | tied up pointed upriver that you must clear. | | If you clear the first dock, you still have to contend | with clearing the second dock which extends even farther | out into the river. If you can't clear that dock, you are | trapped in a cul-de-sac and will collide with something, | either the inside of the dock and pilings, which are free | of boats, or else into the club house with your forestay | and likely damage your rig, if not lose it entirely. | | Questions: | 1. What is your strategy? What are all the factors you | need to consider in planning this departure. | | 2. What can you do to insure you clear both docks? | | 3. What are your bail out options? | | | |
#15
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Yep, the current is strongest in the middle so you just have to stay
there and watch all the obstruction drift by. The wind is easily strong enough to add some direction control. Cheers Capt. Mooron wrote: 6 knots wind and a 5 knot current??? CM "Nav" wrote in message ... | What's to stop you letting the stream take you past the obstructions | while you add minor adjustmets using the wind??? | | Cheers | | Bart Senior wrote: | | You are in a difficult docking situation. You want | to depart the dock and sail on a gorgeous day, but | must leave now. Any later and you will lose your | light, and have to cancel sailing for the day. | | You docked are on a river, facing down stream. | | There is a 5 knot ebb current and it is max ebb. | | The wind is coming directly across the beam of your | boat and also directly across the river. It is blowing | 6 knots. | | The boat is an Etchells keelboat, skeg hung rudder | without a motor. | | Down current are two obstacles---both are docks | that are parallel to the river. The closest dock does not | project out as far as the second but has a motorsailer | tied up pointed upriver that you must clear. | | If you clear the first dock, you still have to contend | with clearing the second dock which extends even farther | out into the river. If you can't clear that dock, you are | trapped in a cul-de-sac and will collide with something, | either the inside of the dock and pilings, which are free | of boats, or else into the club house with your forestay | and likely damage your rig, if not lose it entirely. | | Questions: | 1. What is your strategy? What are all the factors you | need to consider in planning this departure. | | 2. What can you do to insure you clear both docks? | | 3. What are your bail out options? | | | |
#16
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Well just turn around then go down the river stern first! This really
sounds like a non-problem to me. The point is you don't need boat speed, just enough to give rudder control. The river is what is doing the work! Cheers Bart Senior wrote: Well for starters, the apparent wind shift due to the "Current Wind" (CW) would shift the Apparent Wind forward 45 degrees as soon as you cast off. Basically, you'd have little or no flow across the rudder when sailing with the current. Attempts at steering would tend to put on the brakes. A close haul course would not even be towards the dock you wanted to miss, but parallel to the shore. You'd have to hope to gain enough speed sailing parallel to the shore to maneuver just prior to reaching the first dock. If you managed to get the bow past the docked boat, you still might have to pivot the boat on it's keel with the helm to get the rest of the boat passed the docked boat. In that case, you'd have to again get the boat powered up again, and hope to coast around the next dock which is a further obstacle because it extends farther out. This is a situation of speed but no control. Chances are you would have lost all way with respect to the current, put on the brakes with the helm, and put yourself into the hole in the next dock. So missing the first boat would doom you for the second obstacle. If someone gave you a really major push off the dock with the boom, you might clear the obstacles by sailing down with the current. This initial push would give you some flow across the rudder, at least initially, and give you time to get the boat trimmed for speed. You would need to paddle hard to have any real hope to get out of there, because the course you'd want would be the other tack. Tacking in this situation is hopeless, unless you paddle very hard. The smart move is to swing the boat around at the dock and sail into the current which would give you flow across the rudder and helm response, plus more time and room to maneuver. In this case the apparent wind would not shift forward like the first case, but actually shift aft as the force of the current induced wind would actually help fill your sails! With a strong push off the dock to counter the current the boat would see a beam reach off the dock and with flow across the rudder, be able to head up to maintain that apparent beam reach, while putting some distance between the boat and the shore. Your course over the ground (COG) would be still be backwards! Heading upriver also gives you more precious time to clear obstacles. "Boat wind" (BW) would be with the CW in the first case, and oppose it in the second case. The CW would be slightly reduced but at least working for you instead of against you. The key to this whole problem is the effect of a dominating "Current Wind", and to a lesser extend "Boat Wind" on "Apparent Wind". It is easy to forget that the beam reach you see at the dock when you are tied up, will not be there when the current sweeps you along. What would you prefer, to try to clear objects while in irons, or to try to clear them while moving backwards, but powered up? Bart "Nav" wrote What's to stop you letting the stream take you past the obstructions while you add minor adjustmets using the wind??? Cheers Bart Senior wrote: You are in a difficult docking situation. You want to depart the dock and sail on a gorgeous day, but must leave now. Any later and you will lose your light, and have to cancel sailing for the day. You docked are on a river, facing down stream. There is a 5 knot ebb current and it is max ebb. The wind is coming directly across the beam of your boat and also directly across the river. It is blowing 6 knots. The boat is an Etchells keelboat, skeg hung rudder without a motor. Down current are two obstacles---both are docks that are parallel to the river. The closest dock does not project out as far as the second but has a motorsailer tied up pointed upriver that you must clear. If you clear the first dock, you still have to contend with clearing the second dock which extends even farther out into the river. If you can't clear that dock, you are trapped in a cul-de-sac and will collide with something, either the inside of the dock and pilings, which are free of boats, or else into the club house with your forestay and likely damage your rig, if not lose it entirely. Questions: 1. What is your strategy? What are all the factors you need to consider in planning this departure. 2. What can you do to insure you clear both docks? 3. What are your bail out options? |
#17
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![]() OooooozeOne wrote in message | BTW we travel the full length of this winding, hazardous stretch | often, right up to the top of the map, Point Clare. | | Keeps you on your toes, particularly at night. Can't see it as being all that difficult ... it's more than well marked. Do you turn on the engine like Nav does? ;-) CM |
#18
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![]() OooooozeOne wrote in message | Much of the shoreline has houses and the markers get lost in the | lights. Yeah... well really..after you've been in and out a few times how difficult can it be... knowing the Oz penchant for brews and all I can understand the confusion... a bit... but it should all be rather instinctive after a half dozen passes shouldn't it? | The fact that it's extremely shallow in sections and that there are so | many channel markers can be confusing. Nope... that I can't understand even at night... you folks have radar down there? Does the sweep turn counter-clockwise? ;-) | | Yes, we always go thru with the engine running and have often sailed | backwards thru the rip using the engine to steer. Cripes Ozzy... how strong is that rip current anyway? Looks like a stretch I'd love to tackle.... CM |
#19
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Nope... that I can't understand even at night... you folks have radar down
there? Does the sweep turn counter-clockwise? ;-) Radar?? What for, we rarely have anything but clear skys. G Interestin statement...... |
#20
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![]() OooooozeOne wrote in message | Radar?? | What for, we rarely have anything but clear skys. H-m-m-m-m-m.... didn't you state "Much of the shoreline has houses and the markers get lost in the lights.The fact that it's extremely shallow in sections and that there are so many channel markers can be confusing." Hello!!!??? CM |
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