On-Land search lights were more powerfull and yes they had longer light beams. In fact in RL they were more transparent than in the game.
It would be perfect if the game allowed to tweak the lenght of land based and ships mounted searchlights independantly. So there would be less debate about reality.
Not to mention the weather conditions also reflects on light beam visibility. And i guess it's already too real for the game to handle it, unless SH5 will do the trick
If you can trust on what you see here is one:
