Stem
The Stem is the foremost part of the hull structure — the upright or raked member at the bow where the shell plating from both sides of the ship meets and is joined. It forms the leading edge that parts the water as the ship moves ahead.
The stem may be a formed steel bar or a shaped plate structure. Its shape defines the bow form: a raked stem, a vertical stem, or a stem faired into a bulbous bow below the waterline. The stem takes the loads of head seas and any contact, so it is a strongly built part of the hull.
The stem is the cutting edge of the ship, shaping how it meets the sea and taking the pounding of head seas. Its form is a naval-architecture choice that affects resistance and seakeeping, and structurally it must be strong enough to take heavy slamming and minor contacts.
What is the difference between the stem and the bow?
The bow is the whole forward part of the ship; the stem is the specific structural member at the very front edge of the bow where the two sides of the hull meet.