Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 41Get this manual
Installing OutboardThumb Screw Models Outboard must be fastened to boat transom one of two ways: 1permanently fastened to transom with thumb screws, and mounting bolts (provided)or 2secured to the transom using the optional outboard mounting kit (shown below)Should the outboard strike an underwater object or be steered into sharp turnfailure to fasten outboard correctly to the boat transom with mounting bolts or optional mounting kit could result in outboard ejecting suddenly off boat transom causing serious injury, death, boat damage, or loss of outboard1Optional outboard mounting kits shownmust be used Ifautboard will not be permane ntly fastened to the transom with mounting bolts