Line tangled in props

Do not use a hose. If you use a hose long enough to get under the boat you will exhale into the hose filling it with carbon dioxide which you will then breath in. If you exhale into the water the hose will fill up with water. Overall a bad system. Why do you think divers spend so much money on equipment.

A mask and snorkel will allow more time for underwater tasks if properly used and is handy to keep on the boat.

There is a secondary air supply system called "Spare Air"(google it) which is a small air tank and regulator to be used if a divers primary air supply becomes unusable. I saw one last week at Anchor Bay Scuba on M-29. I can't remember the price but I remember looking at it and thinking the price was pretty reasonable. It does exactly what you asked about. If you were to use that system do not descend just stay with the bottom of the boat for the repair. You do not have to dive very deep at all to encounter physical changes associated with diving. That is why dive training is fairly extensive. Just a reasonable warning.

Of course another option is to call a scuba diver. I have been known to dive for beers in situations similar to yours.

I would recommend spurs from spursmarine.com.
A pair of shaft cutters is the better way to go.

It's cheaper to do what I did... Make my cousin dive down with a knife off of poor man's until the job is done. Too bad I didn't have my fish camera back then, I could have watched him doing all that hard work while drinking the cold one

I still wanna hear the story.