I’ve read considerable good discussions about the affect of wind on a kayak, and design of the kayak to provide “good” handling in windy conditions.
What about the affect of current?
Wind pushes on the part of the boat that’s out of the water. That push, when it’s not neutral, is compensated for by the part of the boat that’s in the water, and by the paddler.
Current pushes on the part of the boat that’s in the water and has to be compensated for, or controlled, by that same part of the boat that’s in the water, and by the paddler, right? What are the considerations for good boat control in current? Similar to wind?
General comments are welcome.
I’m going to describe a specific example that I experienced, in case anyone wants to comment on it. I just took my first paddle in waves and current a week ago on Alsea Bay, Oregon. High winter water flows, relatively narrow bay, pretty high currents, rips from incoming tide counter to the outgoing river current. I was paddling the T180. Wind was steady at approx. 10 knots, so most of the affects should have been from current. I paddled all around the bay in every direction. The boat seemed to paddle neutral except for one situation. Skeg all the way down (for stability in 2-3 ft waves coming from multiple directions). Current from behind, coming from about 25 degrees off port side, I THINK. In other words, if the bow is pointing at 12 o’clock, the current was coming from 7 o’clock, I THINK. I had to paddle preferentially on the starboard side. The boat wanted to yaw to starboard. I could be wrong about the direction of current relative to my direction (I’d have needed to drop some orange die in the water to be sure, but didn’t plan ahead for that :^). I was wondering if having the skeg all the way down was my problem. Maybe the current wanted to pull the back of the boat around. Sort of like “current cocking” :^).
Anyway, I’d enjoy a discussion about boat control in currents for those who want to join in.
I’ve read considerable good discussions about the affect of wind on a kayak, and design of the kayak to provide “good” handling in windy conditions.
Current is a lot different from wind
There are cases where non-laminar flow or other types of turbulence will push on different parts of the boat in different ways (anyone with even minor whitewater experience can think of a ton of examples of that). Also, it seems likely that current direction and wave (and wind) direction, as in your example, would interact, but overall, this is a subject with too many variables and possibilities to discuss in general terms.
In general terms, a uniform current actually has no effect on boat handling. It only alters your true direction of travel. The fact that the water you are paddling through is moving has no affect on how your boat moves through that water. With a constant current, the only correction you should need to make is which way your boat is pointed, so that you maintain your proper course heading. Your actual course relative to which way your are aimed will be altered, but the handling of your boat, and your perception of it’s movement relative to the water will not change.
Think of an aiplane flying in a cross wind. The pilot does not need to make any adjustments to the controls to make the plane fly straight and true through the air. In fact, his intruments will show the same orientation of the plane to the air he is flying through, and the same air speed, no matter which way the wind blows. But if he looks at the ground going by, he can see that the crosswind is carrying him in a direction different from the direction the plane is pointed. It’s the same with boats. All the boat “knows” is that it is moving through water. Doesn’t matter if that block of water is also moving.
That’s all true with uniform current. Throw in turbulence and non-laminar flow, and you’d have to discuss it on a case-by-case basis.
One more thing
Your comment about dropping dye in the water to observe current flow reminds me of a discussion we had in physics class when I was in high school. Most people have the perception that you can determine current direction by doing something like that, but you can’t if you are observing the water from a boat.
Here’s the situation the old high-school physics teacher presented: Imagine you are in a boat in pea-soup fog, you have no compass, there is no wind, and you can’t see the shore. You are on a very wide river, flowing toward the sea. If you don’t get off the river very soon, you will drift out to sea and be lost. You need to figure out the flow direction so you can start travelling upstream, or toward one of the river banks. What do you do?
The answer most people come up with is to drop a marker in the water, and then note it’s position as you travel away from it in various directions. To the uninitiated it seams to make sense, but when you sit down and do the vector analysis, you find that it makes no difference which direction you go - your movement relative to he marker is the same in every case. The answer to this problem is that you are screwed. There IS no way to figure out what direction is upstream. You can’t detect a uniform current while you are in a boat unless you have some outside frame of reference.
But I thought …
Good point about the moving block of water. It did occur to me after posting, that to use the die to reveal current direction, I’d have to hover above the water in a stationary position relative to land, and poor the die over time (um, not practical). I didn’t think explicitly about the idea that the boat would be neutral in the moving block of water though. I see the point.
But I thought I’ve read about rudders (especially) and skegs being handy when paddling long distances in certain directions relative to CURRENT, not just in wind? No truth to that apparently, at least in a uniform current. Good, one less thing for me to worry about!
Great time for a GPS
Sometimes speed/course over ground is good to know! More so than speed through the water.
Doesn’t answer the main questions, but they are fun to play with to determine current direction/speeds.
There ya go.
Dye shmye. I could drop a GPS in the water to get an idea of direction and speed of the current. Just make sure it floats!
sounds like the scenerio where the current is behind you and off to port AND you have a skeg deployed the boat WILL go to starboard. Think about the skeg ‘catching’ extra pressure and pushing the stern round.
The whole business of boat ferry angles relative to current are even more involved and complicated than wind. This is even more reason to have a neutral, balanced hull. IMNSHO.
Depending on your angle to the current the paddler will be compensating with strokes to maintain a course. The statement “In general terms, a uniform current actually has no effect on boat handling.” would only pertain to paddling the exact direction of the current, perfectly parallel. Even a very slight angle to the current will have a huge effect on a hull.
A solid understanding of current comes early on to anyone who paddles whitewater, a highly recommended pastime for any sea boater!
playing in whitewater will develop an understanding of dealing with and working with the currents. Just Do It, (with safety precautions and backups in place) is sometimes a quicker way to understanding.
I’ve been enjoying playing in outflows from bays with my seakayak on ebbing tides. Timing is different with the longer boat but the techniques from shorter boat on whitewater pretty much apply.
So uniform current does have an affect on the hull? I suppose that would mean the boat has a tendency to stay stationary relative to land and the current is always dragging it along by water/hull friction. I can only think of two things that would resist boat motion in the current, three if I count paddling.
- Momentum, until the boat is moving at the speed of the current.
- Wind resistance.
After posting I was thinking that if the current was coming from behind and off port it would pull the stern to starboard and yaw the boat to port. Right? So in my scenario, if the boat was yawing to starboard, the current was probably from behind and off starborad. Or am I missing something?
whitewater vs laminar flow
No arguement from me about the whitewater issue. I’m sure the same is even true for tides during choppy conditions. But in laminar flow your boat can’t tell the difference which way you go, and neither can you, just like that airplane example, just like the foggy-river example, and just like a ship at sea. The only way going cross-currrent can requre corrective strokes to maintain a constant heading is if different parts of the boat are hit by currents of differing velocity, which is a normal occurrance in whitewater rivers. One thing a constant current CAN do is amplify the affect the wind has on your boat (it can also minimize the affect of the wind, depending on which way they move relative to each other, and your boat’s orientation). It also affects the formation of wind-driven waves, and that can be an issue.
But back to the general issue of current: If you were out in the ocean in a very fast current (some ocean currents are much faster than many typical whitewater rivers, but you can only observe that easilty in such instances were the current hits the stationary supports of an off-shore drill rig), you could paddle in any direction with no corrective strokes, and your boat would not tend to twist or turn, regardless of trim. That’s because your boat is in a big block of moving water. The boat (and you) can’t tell that the block of water is moving except if there is a fixed object to see. You’d be drifting sideways when going cross-wise to the current, but you wouldn’t be able to tell without a GPS.
Just a note, that when I took physics in college and we were discussing this very same topic along with vector analysis, the professor commented that some people have a really tough time getting a handle on this issue, and he was right. Heck, I’ve met people who swear you can drift downstream in a canoe and steer the boat where they want it to go just by ruddering. They don’t realize that the only reason they can do that is that they paddle once in a while and so they are moving at a different velocity than the river’s current. That comes down to the same principle as is being discussed here.
Aim upstream, learn to ferry, get a pair of objects to range off of, avoid skeg use unless you need it, accept some chaos, keep you hips loose, keep a blade in the water, learn as you go.
White water padding will push your sea kayaking skills nicely but watch “the dark side”. >;-) (Unless, of course, it’s where you want to be!)
Ferrying across a big river
Parts of the Mississippi and Wisconsin Rivers have currents nearly as fast as some whitewater rivers, but the degree of turbulence is quite low in comparison. When I ferry across those rivers, no corrective strokes of any kind are needed unless the wind is blowing. My actual heading is greatly different than the direction the boat is pointed, due to drift, but the boat is still slicing through the water perfectly cleanly, the same way as it does in stationary water. There is no side-slip whatsoever relative to the water. The only sideways movement is relative to a stationary object such as the shore or channel markers, and that’s not the same as actual “slip”. We need some airplane pilots on here to explain this topic better than I can.
Once again, turbulent water is a whole other issue, but there’s no one-case-fits-all way of addressing what happens in turbulence.
Definition - Ferry?
I’m not sure which way to lean relative to water flow if I “lean to ferry.” I probably don’t entirely understand the definition of “ferry.” I understand the word to mean to move across current toward shore. Thanks for any help.
Choppy conditions, that’s it.
Guideboatguy wrote “No argument from me about the whitewater issue. I’m sure the same is even true for tides during choppy conditions.”
I think you hit it. Conditions were choppy. There were actually two sources of waves. Wind waves from the bay and ocean waves coming from the mouth. The waves would be rolling over the current and pushing on the hull in opposition to the current. So now the current would be passing under the boat at some velocity, pushing on the lower part of the hull and especially the skeg.
I do understand about the large block of water, laminar flow, and point of reference. You explained it well. I’m a Chem E actually. In the case of waves and large uniform current maybe it can be thought of as waves rolling over a laminar sheet?
Peter had a good point too, which didn’t escape me, and I was aware of while out there. I really should work on not having the skeg down in that condition and learn to take the confused waves with loose hips. That was my first time out in that kind of stuff. At the end of the trip we practiced wet exits and rafting up rescues, which gave me more confidence about how quickly I could get back in the boat if I need to. (Though sitting in a boat half full of water is instable too, until it’s pumped out.) I’ll have more confidence and be looser over time. First I have to buy a boat. 98% probability the T180.
BTW, the rips, waves, current were all a blast. Whole different world than the lake.
you’re in the ‘hood give me a call. we can go out in the river and I’ll show you what’s really happenin’. Hands on!
Should have read your header more carefully.
Lean to ferry means lean down stream. Probably to compensate for the current trying to pull the carpet out from under you, in a manner of speaking.
Same principle as leaning in to beam waves (which I was thankful for knowing about at the time). Otherwise the low part of the wave moving opposite the net direction of the wave, as the leading water is swept up into the wave, will pull the carpet out from under you, then the high part will push you over.
Mostly type problem
What I typed was l e a r n to ferry. But yes leaning downstream can be relevant there, expecially on aggressive moves.
Picture a current coming fron the north at three knots. you are seeking to directly east across ths current. You might want to point your boat to about 30 degrees and paddle across the current. the 30 degrees will not be your course; the current will be pushing you south. But because the current will be pushing on your angled boat it will also be pushing you somewhat east Your paddling will be pushing you northeast and hopefully you can balance all of these forces to go straight east. It will require readjustment of the angle of your boat (ferry angle)
OK now up the current to 6 knots or more. there will be eddies delineating the places where the current is. It is always interesting when the stern of your boat is being held by a northerly current (the eddy current) while your bow is being pushed southward by the main current. Keep this time short by powering through the eddy line. You will adjust your ferry angle to about 20 degrees, even so you might want to be leaning a bit to the right as you enter the current fron the west. otherwise it might grab your shearline and flip you over like a pancake on Wolfgang Puck's grill.
This is a beginners view and I am little more than a beginner on this work. If you can handle somewhat rough water and can get to boston let me know in advance. There is no way to learn this except by doing. You must have good rescue skills to even consider this kind of stuff, even in the relatively safe spots I practice it in. Helmet a must as well. Roll highly recommended but folks took me before I had one.
On summer days I sometimes dance on eddylines with my explorer, first putting the bow in the main current and leaning one way, then turning and sliding the bow back into the eddy and leaning the other. great fun. I am still struggling to do this with some grace.
I was born and raised near Boston
in Holbrook. Little town near Brocton, Quincy, Randolf. Did most of my canoe paddling on Peter’s pond on the cape. No current :^). Love to try that with ya some day though.
I did learn some about ferrying, compliments of a discussion on PDXseakayaker. Also, vector math applies. Guideboatguy probably knows about that.
Yep on vectors
Cannot do real navigationin current without that stuff. Give notice before arrival!