and e wrote: This is a bawdy song.

Oddly enough, by origin, it may not be, although it certainly is best known as one. Here is the Ballad Index entry, with what we know about the origin:

Christopher Columbo
DESCRIPTION: Columbo, that navigating, masturbating son-of-a-bitch, sails the world round-o, master and crew engaging in a variety of sexual practices on land and sea.
AUTHOR: A (clean) version was copyrighted by Francis J. Bryant (see NOTES)
EARLIEST DATE: 1893 and the Columbian Exposition in Chicago
KEYWORDS: bawdy sex humorous whore exploration | Christopher Columbus
HISTORICAL REFERENCES:
1451-1506 - Life of Cristoforo Colombo (who went by the Spanish name Cristóbal Colón), known in English as "Christopher Columbus"
1492 - first of Columbus's four voyages to the New World, which he never figured out was not the coast of Asia, because (although everyone knew the world was spherical) he used a blatantly wrong figure for its diameter and never thought to do an experiment to check the correct figure, which was known to everyone but him, He was indeed brave. He was also an extreme racist, so quarrelsome that his subordinates usually hated him, a credit-stealer, a money-grubber, and a bigot.
FOUND IN: Australia Canada US(MW,Ro,So,SW)
REFERENCES (10 citations):
Harlow-ChantyingAboardAmericanShips, pp. 55-58, "Christopher Columbus" (1 text, 1 tune)
Cray-EroticMuse, pp. 308-315, "Christopher Columbo" (3 texts, 1 tune)
Randolph/Legman-RollMeInYourArms I, pp. 502-505, "Christopher Columbo" (2 texts, 1 tune)
Hopkins-SongsFromTheFrontAndRear, pp 152-153, "Christoper Columbo" (1 text, 1 tune)
Shay-AmericanSeaSongsAndChanteys, pp. 207-212, "Christofo Columbo" (1 text, 1 tune)
Shay-BarroomBallads/PiousFriendsDrunkenCompanions, pp. 18-22, "Christoforo Colombo" (1 text, 1 tune)
Kinsey-SongsOfTheSea, pp. 173-174, "Christopher Columbus" (1 text, 1 tune)
Niles/Moore-SongsMyMotherNeverTaughtMe, pp. 106-107, "Columbo" (1 text)
Morgan/Green-RugbySongs, pp. 186-187, "Christopher Columbo" (1 text)
DT, COLOMBO COLUMB2*
Roud #4843
RECORDINGS:
Anonymous singer, "Christopho Columbo" (on Unexp1)
Arkansas Charlie [pseud. for Charlie Craver], "Oh Christofo Columbo" (Brunswick 410, 1930)
Billy Jones, "Christofo Columbo" (CYL: Edison [BA] 5008, prob. 1925)
Billy Jones & Ernest Hare, "Christofo Columbo" (OKeh 40397, 1925)
Andy Kirk & his Mighty Clouds of Joy, "Christopher Columbus" (Decca 729, 1936)
Old Ced Odom & Lil "Diamonds" Hardaway, "Fourteen Hundred and Ninety-Two (Christopho Columbo)" (Decca, uniss.; rec. 1936)
CROSS-REFERENCES:
cf. "The Good Ship Venus" (lyrics)
cf. "The Sailor in Nagasaki" (tune, according to Niles/Moore-SongsMyMotherNeverTaughtMe)
cf. "Christopher Columbus Sailed the Ocean Blue" (character of Christopher Columbus)
cf. "Christopher Columbus Was a Very Brave Man" (character of Christopher Columbus)
NOTES [171 words]: This song frequently borrows verses -- identifiable by their internal rhyme in the third line or "limerick form" -- from "The Good Ship Venus."
This would not pass muster as a history of Christopher Columbus' voyage of 1492. - EC
A distinct understatement.
Incidentally, it is not clear whether this was originally clean or dirty. The 1893 date cited above is for a clean version, of which John Garst writes, "We all know 'Christofo Columbo' as a bawdy ballad, but in the Robert W. Gordon papers at the University of Oregon there is a 'clean' version, 'Written and Composed by Francis J. Bryant,' 'Copyright, 1893, by M. Witmark and Sons. Entered at Stationers' Hall, London....
If you wonder how the chorus could be 'clean,' here it is:
He knew the earth was round, ho! that land it could be found, ho!
The geographic, hard and hoary navigator, gyratory Christofo Columbo."
Shay's clean version has the chorus
Oh, Christofo Columbo,
He thought the world was round-o;
That pioneering, buccaneering,
Son-of-a-gun, Columbo! - RBW
Last updated in version 6.5

File: EM308