I have not seen an engine-driven pump that would do much good (if you mean driven from your boat engine) - they tend to have capacities much lower than an electric pump and they don't work if the boat's engine isn't working. Whenever I've looked into them I have come to the conclusion that an electric pump (or a spare) is a better option.
Absolutely. If water is coming in faster than the pumps can cope with then it is a clear Mayday - you can always cancel it if you plug the leak.
An extremely sensible post, and made me think that an easily accessible mask and snorkel is probably more useful in an emergency even for use inside the boat!
My boat came with what I assume is a winterising pipe and cock which has a hose lying in the bilge to place in a bucket. It had never occurred to me I could switch to this in an emergency so thanks for pointing this out. For all I know that's actually the purpose of the hose and my guess was wrong!
Bear in mind that my engine uses about 5l/min cooling water - so roughly 60 gph. A typical bilge pump will be rated around 1000 gph and perhaps achieve half that (500 gph) in a typical installation. So the engine is not going to make that much difference.
We have four buckets and a stirrup pump. No fitted manual pump.
I guess that depends on how your boat is built. Water would need to get over my saloon seats to flood the batteries. Every time my main bilge pump is activated in the central 800mm deep sump, the alarm is triggered. We only panic if the alarm doesn't stop.
This is extremely common, many production boats have them and the VSR under the bottom step. I'm not talking about the switch panel here, but the domestic/engine switches or 1-2-both ones.
Our shower sump is under our floor boards. It has a 2000 gph rule submersible bilge pump installed. It is one of our emergency pumps by vertue of it location. The top of the shower sump is about 10 inches below floor level
Those are in the engine room at head hieght with battery charger. Generator is mounted on a high plinth in engine room. All electrics associated are at high level. I assumed all builder would have considered these things but from what you say that is not the case
Far from the case, in fact I'd suggest it's quite unusual not to have electrical switches lower than head height. You've obviously been lucky from a flooding perspective, but many boats including mine don't have anywhere high and convenient for such things. Most engine compartments are tiny and have no space. Not sure whether I prefer no electric in a flood over no way to switch off in a fire, it's always a compromise on a boat ?
We have two Lavac loos. If we needed a manual bilge pump we can remove the suction end from the loo and use those. The pumps are Henderson Mk5 high capacity bilge pumps. They are there but I can't imagine a scenario where doing this would be useful. We generally sail with just two of us. We would rather leave electric pumps doing the work whilst we find and deal with the leak. Our main emergency pump is a Rule 3700gph, with a 1.5" hose, on a float switch under the saloon floor. This is higher than the main sump bilge pump, a 2000gph Rule pump.
Be really careful with that. Friend did the same and created a Syphon. We went to the pub and when we got back the water was above the cabin sole. No automatic bilge pump, no alarm. Lucky not to lose the boat