The service of towing is the employment of one vessel to expedite the voyage or delivery of another vessel when there is no immediate danger to life or the property apprehended. Towage is sometimes done for convenience purposes only, for example; when a pleasure craft has become disabled and needs delivery to safe harbor.

Salvage of a vessel is in order when there is an immediate need for service due to perilous conditions that require assistance by a salvor. Although a marine peril to the salved property is necessary to be considered a "valid claim" imminent or absolute danger of the vessel are not required. Context is normally the determining factor when deciding the nature of the services and the amount of compensation. This is why most salvors provide a "fixed price" or hourly rate for their services.

"The admiralty and maritime law of the United States has long recognized that the law of salvage rewards the voluntary salvor for his successful rescue of life or property".

If the salvor wants to do the job but does not know what the cost will be but will make claim afterwards, the final amount will be decided one of three ways -- negotiation with the owners insurance company; binding arbitration or, rarely, through litigation in federal admiralty courts.