Welcome to AAPK. You are correct, the knife has a sheep foot blade and a marlin spike. The knife is generally called a Navy knife, or sailor’s rope knife. The sheep foot blade gets its name from its original use - it was designed for trimming the hooves of animals. However in this case it has been adapted for cutting rope, usually by laying the rope on a flat wooden surface and hammering the blade through it, using a belaying pin for the hammer.
The spike is a tool used for splicing rope and untying knots. The correct, but seldom used term is “marline” spike.
Marline
mär′lin, n. a small rope for winding round a larger one to keep it from being worn by rubbing.—v.t. Mar′line, Marl, to bind or wind round with marline.—n. Mar′linespike, an iron tool, like a spike, for separating the strands of a rope in splicing.
The knife’s bale, or ring, is often tied or hooked to a lanyard, which is in turn tied to the clothing of the user to help avoid it being lost overboard. Most sailor’s knives are 4 or more inches closed length, and the sheep foot blade having a strong thick spine to accommodate the hammering. I suspect your knife is a lighter weight version, known as a rigger’s or yachtsman’s knife. It’s not rare, nor is it high value. Probably from first half of 20th century, based on the handle covers which appear to be celluloid. For value estimate take a look on eBay for sold listings of “sailor’s rigging knives”, “marlin spike” or similar. Richard’s Sheffield was a maker of typically low-end knives, but might be of a little more value to a collector of such knives.
Ken
