[muawiyah]

Actually, it doesn't explain that at all ~ rather the reverse. Fur traders used to leave central New York and arrive in central Saskatchewan in a year, and then buy furs and get back to central New York a year later ~ 2 year round trip just for really great furs.

A 2 year trip all the way around Africa ~ envision the riches they could pick up for a song.

I suspect the problem wasn't the duration, but the "take" as compared to the "risk". More than likely Phoenician boats could be seized by raiding parties along the shore with ease. Although Africans in Subsaharan Africa were fairly barbaric they were numerous and well versed in agriculture by the time the Phoenicians visited.

They might have let 'em skip on by on their first trip, but not the second!

Later civilizations weren't all that keen on sailing around Africa either.

Of Note: there are various seaworms that bore into and eat wooden boats WITH EASE. Columbus and others knew that when they went to America and prepared for the worst by taking tooks with them to build new boats. The earliest sailers going South discovered that problem I am sure.

Check out Teredo

[No Truce With Kings]

“Columbus and others knew that when they went to America and prepared for the worst by taking tooks with them to build new boats.”

Assuming you meant tools instead of tooks, that is not very impressive. The tools required to build a seagoing ship in the late 15th century consisted of an axe, an adz, a saw and an auger. That's all. A ships’ carpenter that sailed without those deserved to be keelhauled. (And yes, that is an anachronistic punishment at that time.)