You can lay the boat up on a soft bottom if you have a significant tidal range. The boat will either lay over on it's side as the tide drops or sit upright if the bottom of the keel
is flat. Did it once with the boat upright in Charleston. Ran anchors out either side and attached them to halyards to keep the boat upright. Don't know if the halyards really held the boat upright as it seemed to be very happy sitting on the flat of the keel
. Have laid the boat on it's side more times than I'd like to admit running aground. FWIW, purposely grounding a boat to do maintenance
is called careening. Before the days of travelifts and/or abundant marine
railways, it was the way that boats were maintained.