You can usually start and run a small marinediesel for no more than 20 seconds, near idle, with no damage. Be sure it's got engineoil, obviously. when I worked with a mechanic, that's how we'd "test-fire" engines during spring commissioning, after changing fuel filters and priming.
See if you can remove the strainer for the raw water intake on the bottom of the hole..
If you can shove a hose right up it and wedge it in then get someone to turn it on as you fire up the engine..
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It was a dark and stormy night and the captain of the ship said.. "Hey Jim, spin us a yarn." and the yarn began like this.. "It was a dark and stormy night.."