Online Etymology Dictionary

rudder: O.E. roðor "paddle, oar," from P.Gmc. *rothru- (cf. O.Fris. roder, M.L.G. roder, M.Du. roeder, Du. roer, O.H.G. ruodar, Ger. Ruder "oar"), from *ro- "steer" (see row (2)) + suffix -þra, used to form neutral names of tools. Meaning "broad, flat piece of wood attached to the stern of a boat and used for steering" is from c.1300. Spelling with -d- for -th- first recorded 1440.
steer (v.): "guide the course of a vehicle," O.E. steran (Mercian), stieran (W.Saxon), from P.Gmc. *steurijanan (cf. O.N. styra, O.Fris. stiora, Du. sturen, O.H.G. stiuren, Ger. steuern "to steer," Goth. stiurjan "to establish, assert"), related to *steuro "rudder" (cf. O.E. steor "helm, rudder," Ger. Steuer and first element in starboard), from PIE *steu-ro- (cf. Gk. stauros "stake, pole"), from base *sta- "to stand" (see stet). The notion is of a stiff, upright pillar or post used in steering. To steer clear of in the fig. sense of "to avoid completely" is recorded from 1723. Steerage (1399) was the steering apparatus of a ship before the introduction of the deck wheel; meaning "section of a ship with the cheapest accommodations" first recorded 1804. Steering committee in the U.S. political sense is recorded from 1887.
tiller: mid-14c., "stock of a crossbow," from O.Fr. telier "stock of a crossbow" (c.1200), originally "weaver's beam," from M.L. telarium, from L. tela "web, loom," from PIE *teks-la-, from base *teks- "to weave" (see texture). Meaning "bar to turn the rudder of a boat" first recorded 1620s.
stern (n.): c.1300, "hind part of a ship, steering gear of a ship," probably from O.N. stjorn "a steering," related to styra "to guide" (see steer (v.)). Or the word may come from O.Fris. stiarne "rudder," which is also related to steer (v.).
pilot (n.): 1512, "one who steers a ship," from M.Fr. pillot, from It. piloto, O.It. pedoto, usually said to be from Medieval Gk. *pedotes "rudder, helmsman," from Gk. pedon "steering oar," related to pous (gen. podos) "foot" (see foot). Change of -d- to -l- in L. parallels that in odor/olfactory. Sense extended 1848 to "one who controls a balloon," and 1907 to "one who flies an airplane." The verb is first recorded 1693.
starboard: O.E. steorbord, lit. "side on which a vessel was steered," from steor- "rudder, steering paddle" + bord "ship's side." Cf. O.N. stjornborði, Low Ger. stürbord, Ger. Steuerbord. Early Germanic peoples' boats were propelled and steered by a paddle on the right side. Fr. tribord (O.Fr. estribord), It. stribordo are Gmc. loan-words.
row (2): "propel with oars," O.E. rowan (class VII strong verb; past tense reow, pp. rowen), from P.Gmc. *ro- (cf. O.N. roa, Du. roeien, W.Fris. roeije, M.H.G. rüejen), from PIE base *ere- "to row" (cf. Skt. aritrah "oar;" Gk. eressein "to row," eretmon "oar," trieres "trireme;" L. remus "oar;" Lith. iriu "to row," irklas "oar;" O.Ir. rome "oar," O.E. roðor "rudder"). First record of rowboat is from 1538 (cf. Du. roeiboot).
-able: suffix expressing ability, capacity, fitness, from Fr., from L. -ibilis, -abilis, forming adjectives from verbs, from PIE *-tro-, a suffix used to form nouns of instrument. In L., infinitives in -are took -abilis, others -ibilis; in Eng., -able is used for native words, -ible for words of obvious L. origin. The Latin suffix is not etymologically connected with able, but it long has been popularly associated with it, and this has contributed to its survival as a living suffix. It is related to the second syllable of rudder and saddle.