Sigma are one of the better off-brand lenses and are generally a good product.
If you are looking at a 300mm lens, I think the only one they make is a 300mm f2.8.
That would be a good lens, but heavy and expensive.
For general photography, you wouldn't need to spend that much or carry that weight.
They also have a 70-300mm F4-5.6 zoom lens which would be a lot easier to carry and afford.
The only area it might suffer in would be low light photography, but at f5.6 or smaller apertures, it should be fine for ship photography.
For a bit more reach, their longer zooms are quite good and very popular.
I have a 150-500mm and it gives good results.