If it is properly supported (cradle or good bracing on frames) - indefinate. The problem though is when the wood dries it will shrink, and will make the boat leak badly when put into the water
again. (this is for planked boats) You may also need to re-caulk a few spots if it comes loose when the wood dries out.
The wood will swell up over a few days back in the water, so as long as you monitor
it and have good pumps onboard the first few days, the boat will be fine.
One old shipwright said that he would put a lawn sprinkler underneath the boat to spray on the hull
24-7 for 3 days to a week before launching. This would help to re-wet the wood, and keep it from leaking so badly when launched.