In the Sargasso Sea by Thomas A. Janvier

For a while after this black thought came to me I was pretty much beaten by it; but when I got steadier -- and had finished kicking myself for a fool because I had not foreseen it all along -- I perceived that the odds were not wholly against me, after all. I had, at least, a sea-worthy boat in which to make my venture, and therefore was as well off as I had hoped to be when I had set about looking for one; and if the plan that I had formed worked out in practice -- if I could manage to force a passage through the tangle by alternately working over the bow of my boat to break up the weed, and over the sides to pole my boat forward -- I was a great deal better off than I had hoped to be: for should I win my way to open water I would have steam as well as sail power at my command.

But while this more reasonable view of the situation comforted me, it did not satisfy me. The difficulty of working myself along in that slow fashion I foresaw would be so enormous that I very well might die of sheer exhaustion before I got clear of the weed-tangle -- which must extend outward, as I knew from my guess at the time that I had taken in drifting in through it, for a very long way. What I had been counting upon ever since I had found the launch was in having part of the work, and the heaviest part, done by her engine; my part to be the breaking of a passage, while the motive power was to be supplied by the screw. But of course if the screw fouled, as it certainly would foul with the loose weed all around it, that would be the end of my hopeful plan.