I close the three below the waterline when we leave the boat at the berth, but not while we are out. However, the engine intake sea cock is right beside the engine, and hard to reach anyway, without lifting floor and hunkering beside a hot engine. So, I set up a handle extension, and linked a long metal rod to the end of the extended handle forward, with a knob on it, so I can reach it from the forward engine room hatch, which is easy to get to. However, every now and then the damn handle works it's way off the seacock, always when it's the end of a days run, and if that happens I just say bugger it, I'm not getting in there next to the hot engine to turn it off...it'll keep until I'm back down there when the engine is cold. If your hoses and clips are good, it's no big deal, really. It's mainly an insurance thing.