[1] Outboards aren't going to work either, still props! (and heavy, and expensive!)
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[2]But you can't stop rope getting sucked in and clogging your impeller(s).
And you can't fortify the intake screen, you won't get 25 knots!
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[3] Does the weather allow for that, 25 knots all the time?
[1] Outboards tilt, so easy to address entanglement
[2] You just fit a riser onto the top of the jet casing, that comes to above waterline height, and have removable cap on it. Then you can access the impeller without significant water ingress. Lots of the lobster guys here have that set up.
[3] Mostly yes, we farm in a big Fjord system.