Hello everyone. I'm a new member with a question about a topic that is probably way too simple to be of interest to most of you, but I would really appreciate some help. Please excuse the fact that I don't use the proper jargon. I've only taken introductory physics (the kinds of classes that my engineer brother haughtily refers to as "physics for poets"), and that was about 40 years ago. Also, please bear with me while I set the stage for my question, because I think it makes a difference that I do. I'm an avid canoe paddler, and there's a paddling message board where several of us have been talking about something that we paddlers call "ferrying". Ferrying is basically the process of trying to travel straight across a river by pointing the boat at an upstream angle that's somewhere between zero and 90 degrees to the alignment of the current, and paddling forward, so that the actual direction of travel is directly toward the opposite shore. Ferrying can be done two ways, depending on the situation. Method #1 If your boat is floating in a sheltered eddy and you vigorously propel it out into a zone of very swift current, the boat's inertia will initially prevent it from drifting with the current, and so for a few seconds, the water rushes past the hull, which means that by controlling the boat's angle to the current you can steer it rapidly across the flow. It's great fun. This method of using the interaction of flowing water with an initially-stationary hull to propel the boat in what appears at first glance to be a diagonal direction works in the same way that a kite immediately flies upward in a strong wind when released at ground level (in this instance, the boat's inertia provides the same kind of force as the does the string of a kite). This type of ferrying can't last long, as eventually the boat's inertia is overcome, and after that it's just "along for the ride" within the stream of current, and that brings us to ferrying method #2. Method #2 When the boat is at equilibrium with the current, such as when crossing a broad river, ferrying is a simple matter of paddling the boat in a direction such that when you balance out the velocity of the boat as it moves through the water against the velocity of the current, the boat's actual direction of travel (relative to the river bottom) is straight across the river. Method #2 is simple, right? Wrong. There is not a single person involved with this discussion who understands that in Method #2, the boat is moving in a straight line through the water that supports it. Everyone says that as soon as you start paddling, the current "pushes on one side of the boat" and that's the reason that the actual direction of motion is diagonally away from the direction it is pointed. According to their reasoning, all ferrying situations are just as explained in Method #1 above (though their understanding of Method #1 is often still not quite accurate). According to their beliefs, you could perceive the direction of the current while paddling across a large river simply by watching or feeling the effect of it as it "hits the side of the hull". I tried to make the case that if one were paddling a boat among a pattern of free-drifting, floating markers, the boat's progress among those markers would be the same whether the water was stationary or part of a large, uniform, moving stream. No one believes that that is true. According to their belief system, the floating markers would float along and crash into the upstream side of the boat, as if the boat were somehow independent of the water which supports it. It just boggles my mind how something so incredibly simple is totally beyond comprehension to these folks, so the question is how best to explain the situation. I know there are illustrated "riverboat" problems online, but they never seem to deal with a boat who's true direction of travel is straight across a river. More to the point, for people who are already convinced that extremely complex hydrodynamic forces are at work propelling the boat diagonally away from its heading, typical river-boat examples using vector addition are seen as totally missing the point. Even examples of everyday experiences (like walking across the center isle of a bus as it cruises down the highway) are not seen as relevant by these folks. Now, all of them understand that your boat's speed relative to fixed objects is faster when paddling downstream than when paddling upstream, and they seem to know why, but it's very clear that none of them understand that exactly the same principle applies when traveling at other orientations to the current. This principle is perfectly clear when working with examples of adding vectors, but as mentioned, the real problem is helping folks see that vector addition isn't a case of "missing the point". I've given up on similar discussions in the past, but this time I want to take the next step if I can. What I'd really like to find, is a pair of animated videos that illustrate a boat crossing a river, with one frame of reference being fixed (relative to the river bottom), and a second frame of reference being the water itself as it moves downstream. That would show how, relative to the water that supports it, the boat moves in a straight line through the water in all situations. Other than this ideal video (which may not exist), a second-best option would be if some talented explainer of such things who enjoys a challenge were to join-in with the discussion! Otherwise, I'm all ears regarding ideas about how to make this more clear.