Yes, for many, it's easy to forget how big things are in the Arctic.
Let me do a school-like exercise to illustrate the boat example.
- horizon being 3 miles away,
- the sea surface directly visible from the boat would be 28,3 square miles,
- which is 73,2 square kilometers,
- which is 73.200.000 square meters,
- each of which is getting ~490 W/m^2 of solar radiation incoming right now, 24/7, unless it's cloudy,
- rudely half of which is absorbed only because it's open water (ice/snow would reflect that much extra),
- so the whole area is absorbing extra 490*0,5*24*73.200.000/1000 = ~430.000.000 kWh of energy every day, i.e. ~1.550.000.000.000 kJ,
- and this much of energy is enough to melt 4.625.000 tons of 0C ice into 0C water (it takes 335 kJ/kg), if 100% of that energy would be spent to melt ice,
- even if only 10% of that energy is spent to melt ice somewhere, it's still 462.500 tons of ice melt (as a result of every sunny calendar day in this rather small area of Arctic, only).
So the fact it's open water instead of ice - will possibly result in more ice lost some place not very far from this "directly visible from a small boat" area (every sunny day) than dozens, or even hundreds, of cargo trains could move around.
This "visible from a boat" area - is something quite similar to a very large coal mine (by area). Now, one of largest US coal mines, which is Black Thunder coal mine, is said to produce "20-25 trains of coal per day", with the average daily coal production of ~214.000 metric tons of coal. It's an open coal mine, and it uses 6 world biggest dragline excavators (among other equipment) to operate.
The scale of processes in Arctic certainly dwarfes even most advanced and large-scale enterprises of human creation - it's a shame so many seemingly responsible people so often forget about it.