I recently spent a pleasant week on a small ship, actually a working boat, enjoying a cruise along the Norwegian fjords. Another photographer raised the question about getting a steady platform for a camera on a moving ship.
He had noticed someone using a tripod and questioned whether it would work. That chat got me thinking and I share a few thoughts. There are several challenges for photographers to overcome if they want sharp pictures on a moving ship; similar thinking can be applied to other forms of transport.
First we need to think about the movement of the ship itself. We had calm seas as we were mostly in sheltered coastal waters with kind weather and little wind. As a result the movement of the ship was a slow, smooth pitch and roll, perhaps rolling through a few degrees with a period of around ten seconds or so. The motion is slow because a heavy ship needs large forces to overcome the ship's inertia for it to be otherwise. Therefore, a modestly fast shutter speed of, say, 1/250 second or faster will handle the movement. As a result using a tripod will probably achieve little additional stability unless the photographer has other problems with hand holding a camera. It does suppose that the ship's movement is not so large that the photographer cannot hold a steady stance while working; in stormier conditions higher shutter speeds will be necessary and in the worst cases it should be accepted that only a few images will be sharp. These will usually be when the photographer has been able to make the exposure at the moment the vessel is effectively stationary as the motion changes direction; just like photographing a high-jumper at the top of their flight.
However using a tripod or resting the camera on the ship's structure, a deck rail for example, will bring another more troublesome cause of blur into play. Anyone who has been on board a ship, even a small ferry, will have been aware of the vibration from the engines. This is a small but high-frequency movement and is likely to challenge even a camera or lens's image stabilisation. By hand-holding the camera the photographer body will absorb and slow much of this high-frequency movement with image stabilisation (IS) coping with any residual motion. Many years ago, before IS, an aerial photographer acquaintance made the point that you have to keep the camera and even one's elbows off the aircraft structure to avoid the vibration taking the edge off sharpness of the picture. Apparently this is especially a problem in small aircraft with helicopters, at least I those days, being a particular problem. It seems to be good advice for photography from any moving vehicle.
Extrapolating these thoughts to other forms of transport brings other factors in to play. A large aeroplane is more like a ship, except in turbulence (when the photographer is likely to be concerned with other matters). Large airliner motion is generally slow and smooth but with significant background vibration. So the same approach to shutter speeds and avoiding the camera touching the aircraft structure so it avoids the vibration.
On the other hand, when photographing from a motor vehicle it should be realised that the motion is generally not smooth, slow or predictable as with a ship on smooth seas. The lower inertia of a car , bus or train means that its movement will be sharper and more violent especially when it hits a pothole or other road surface imperfection. As a result for sharp images a high shutter speed will be needed. However, the comments about vibration still apply even though the vibration may be less obvious than on board ship.
Of course these thoughts only apply where the photographer wants a sharp image. When the intention is to show the motion, to get a different effect then all options are open and the photographer will have to use their own judgement and experiments to determine what technique will achieve their desired outcome.
These are not carefully tested ideas but they are based on experience and careful consideration of the challenges. I hope they can form a starting point when shooting in these situations for the first time. At least with digital it is possible to do the necessary experiments quickly and easily to ensure that the chosen approach is producing the required result. Good luck.