helm (n.1) Look up helm at Dictionary.com
"instrument by which a ship is steered," late 13c., from Old English helma "rudder; position of guidance, control," from Proto-Germanic *halbma- (cognates: Old Norse hjalm, Old High German helmo, German Helm "handle"), from PIE *kelp- "to hold, grasp" (see helve).
Helm - the handle or tiller, in large ships the wheel, by which the runner is managed; the word is sometimes used with reference to the whole stearing-gear.
Rudder - that part of the helm which consists of a broad piece of timber, enters the water, and is governed by means of the wheel or tiller.
Tiller - the bar or lever by means of which the rudder of a ship or boat is turned.
[J.H.A. Günther, "English Synonyms Explained & Illustrated," Groningen, 1904]
helm (n.2) Look up helm at Dictionary.com
"a helmet," c.1200, from Old English helm "protection, covering; crown, helmet," and perhaps also from cognate Old Norse hjalmr, from Proto-Germanic *helmaz "protective covering," from PIE *kel- (2) "to cover, to hide" (see cell). Italian elmo, Spanish yelmo are from Germanic.