Why does the verse specify "Ziknei Geval"?
Rashi: They are professional builders, like "u'Vnei Chirom veha'Givlim" (Melachim I, 5:32).
Who are "Machazikei Bidkech"?
Rashi: They fix your cracks, lest water enter.
Radak: They came to Tzor to strengthen the city's walls and buildings.
Malbim: They fix the boat. I.e. from them were Chachamim who enact and fix etiquette in the country.
Who are "Malcheihem"?
Rashi: The boats' sailors.
Radak: They are those who hold the oars.
What do we learn from "Hayu Vach"?
Rashi: They were around you, to sail to distant lands to bring merchandise to you.
What is "La'arov Ma'aravech"?
Rashi: It is an expression of a guarantor. All man's needs of living and his money are his guarantor and salvation of his life.
Radak: Merchandise is called Arov, and merchants are called Orevin, for they are guarantors to each other for their merchandise, buying and selling.
Malbim: Ma'aravech is security for merchandise taken on credit. Boats were guarantors for you (since all their business was via you). Also the trust to give to you merchandise on credit was not due to yourself, rather, due to others!
