Yes they did!
Robin Law wrote a recent article about this topic titled "West Africa's Discovery of the Atlantic".^1 On the basis of early Portuguese accounts in the 16th and 17th centuries, he concludes that West African peoples created canoe-type watercraft, and at first contact with Europeans did not have sails, but were reliant on oar power (by the 17th century they adopted palm-woven sails). Nevertheless, these dugout canoes could be extremely large, with crews of 30 or more persons, and Law suggests that these canoes and other fishing peoples could travel out perhaps 14-18 km from the coast, but would stay within sight of land.
Law also wrote an earlier journal article^2 concerning the so-called "lagoon network" of maritime trade in the 400km littoral of mangrove swamps and periodic lagoons and river outlets between the outlet of the Volta river and the Niger delta. In the article, Law examines the seacoast-hinterlands trade networks and politics that existed at the outset of the Atlantic Slave trade, and is particularly interested in how the lagoon network may have facilitated the rise of Lagos as a major port.
Additionally, George Brooks^3 concludes that there developed a sea-borne network of trade extending from Cape Verde in Senegal to Cape Mount in Liberia, established as early as 700 AD but definitely before 1100 AD, trading in dried fish, Kola nuts, Malagueta pepper and perhaps other commodities.
Also, Paul Lane Peter Mitchell^4 makes the interesting case that in the period before the Portuguese entrance, there were human populations on the Canaries islands (off the coast of Morocco), and on Bioko island off the coast of Cameroon/Equatorial Guinea. The case of Bioko is interesting, because oral traditions indicate that there were several waves of conquerors/immigrants onto the island, which is within sight of the mainland. On the other hand, neighboring islands like Sao Tome, Principe and Annobon do not show evidence of human habitation prior to Portuguese arrival.
So, from the available evidence it appears that there was a maritime tradition present in West Africa, and there were trade networks that featured coasting voyages that stayed within sight of land.
1 "West Africa's Discovery of the Atlantic" by Robin Law in The International Journal of African Historical Studies Vol 44, no 1(2011) pp 1-25. https://www.jstor.org/stable/23046841
2 "Trade and Politics behind the Slave Coast: the Lagoon Traffic and the Rise of Lagos, 1500-1800" by Robin Law the Journal of African History vol 24 no 3 (1983) pp 321-348. http://www/jstor.org/stable/181898
3 "Ecological Perspectives on Mande Population Movements, Commercial Networks, and Settlement Patterns from the Atlantic Wet Phase (Ca. 5500-2500 B.C.) to the Present" by George E. Brooks in History in Africa vol 16 (1989) pp 23-40 https://www.jstor.org/stable/3171777
4 African Connections: An Archaeological Perspective on Africa and the Wider World by Peter Mitchell. 2005, Alta Mira Press. pp 296-299
further reading:
"Two Vanished African Maritime Traditions and a Parallel from South America" by Roger Blench the African Archaeological Review vol 29 no 2/3 (september 2012) pp 273-292. https://www.jstor.org/stable/23321048
"The Canoe in West African History" by Robert Smith in the Journal of African History vol 11 no 4 (october 1970) pp 515-533.
"Une histoire maritime africaine este elle possible?" by Jean-Pierre Cauveau in Cahiers Etudes Africaines vol 26 cahier 101/102 (1986) pp 173-235. http://www.jstor.org/stable/4392029
Portuguese in West Africa 1415-1670; a documentary history edited by Malyn Newitt. 2010 Cambridge University Press. Contains numerous translations of Portuguese accounts of West Africa from the first two centuries of contact. Includes numerous mentions of local "kings" and their "canoes".
The Rise of the Trans-Atlantic Slave Trade by Toby Green. 2012 Cambridge University Press. on pages 201 and 242-5, Green describes Mandinka peoples use of "war canoes" for slave raiding along the coast south of the Gambia river (in Guinea/Sierra Leone).