In recent years, many commercial towing and salvage firms have begun operating on many waterways primarily to offer assistance to recreational boaters. These firms have not replaced the Coast Guard for immediate distress, but they play an important role in responding to non-emergencies. If you find yourself stuck on the water, but not in immediate danger, the response to your situation will be governed by the Coast Guard Maritime SAR Assistance Policy.
In addition to responding to calls for help, many of these commercial firms offer service contracts that may be purchased ahead of time. The Coast Guard certainly cannot endorse any one firm, but if you are concerned about choosing a commercial towing service, the best thing to do would be to shop around among the various operators in your area, and to check with other boaters, marina operators, etc.