The standard wisdom for making images of fireworks is keep your camera steady and use long exposures.
The f-stop number squared divided by the ISO speed should be about 0.6 (f8 at 100 ISO, f 16 at 400 ISO etc). Total exposure time is generally set to include some detail in the dimly lit foreground.
Fireworks photography is for the most part a question of timing and planned composition. Except for some variety in the fireworks, it is the same shot over and over. Next year you plan a different location, and repeat. Each year the goal is to produce the best shot possible according to plan.
The standard wisdom is also 'don't shoot from a boat unless you want squiggly lines'.
A friend called me and asked if I would like to join him on his boat to watch the Canada Day Fireworks in the Kingston harbour basin. Naturally I accepted. I jumped at the chance to make some squiggly lines!
Photography of fireworks from a boat is about painting with light, not about featuring a tourist destination. Boats move. Waves move boats. Wind moves boats and makes waves. As people move, boats rock. If the engine is running, the deck vibrates, and the helmsman steers. He is concerned with where the boat is going, not where your camera is pointed.
The following shots were taken with a Canon 5DII using a 24-70 mm EF zoom lens ('Secret Gem'), and set to ISO 400, f 16 , and bulb. All shots were hand held, using manual focus. Some of the shots were straight, some with focussing during the exposure, and some with zoom during exposure. In all cases the boat was in constant motion over rough water with a strong wind. I used panning techniques to keep the fireworks before the lens while shooting. Exposures varied from about 1/2 second to 2 or 3 seconds.
These shots are an example of what is possible if you disregard conventional wisdom. Naturally, many of the shots taken will be disappointing, but the more work you do, the better the results. All of these photos were taken during a single 1/2 hour show.
Squiggly lines are great!