Pirates have been holding the MV Faina off the town of Harardhere
A Ukrainian ship freed by Somali pirates for a reported ransom of $3.2m (£2.2m) on Thursday is preparing to leave Somali waters for Kenya.
Pirates seized the Kenya-bound MV Faina, which is loaded with 33 tanks and other weapons, in September 2008
The ship needs to refuel and take on fresh supplies for the trip to Mombasa, expected to take three or four days.
Its captain told AP news agency the 17 crew members had received medical aid from the US navy and were well.
A number of warships from foreign navies had been diverted to the area to monitor the situation, in part to ensure that the cargo of weaponry did not get into the hands of Somali insurgents.
The head of the East African Seafarers' Association told the BBC that the MV Faina is expected to take on fuel, fresh water and ship stores before sailing.
"MV Faina is expected to dock Mombasa port mid-next week," Andrew Mwangura said.
"All crew members are said to be safe and in high spirits."
The intended destination of the vessel's cargo has been the subject of much dispute.
The Kenyan government says the tanks, rocket launchers and small arms on board belong to it; however, the freight manifest suggests the arms were heading for South Sudan.
Ukrainian intelligence officials say they have "100% confirmation" that the arms on a ship are destined for Kenya.
"The Kenyan Defence Ministry's authorities said they want to train their servicemen to handle these weapons at our bases," the head of Ukraine's External Intelligence Service, Mykola Malomuzh, was quoted as saying by Interfax-Ukraine news agency.
Analysts say the Kenyan government would be highly embarrassed to be found supplying arms to South Sudan, as this would be a violation of the peace deal it helped broker in 2005.
The Government of Southern Sudan, which is said to be beefing up its military capacity ahead of the 2011 referendum, has also denied ownership of the arms.
Somali waters, considered to be among the most dangerous in the world, are now patrolled by a fleet of international naval warships which provide escorts to ships sailing along the coast.
Last year pirates in the area collected an estimated total of $150m (£105m) in ransom.
A recent BBC investigation has found that it costs as much again to negotiate and deliver these ransoms.