London, England (CNN) -- Sailors who've been hijacked often say they never saw the pirates coming.
That's because pirates like to strike at dawn and dusk, when the light is lowest, sneaking up on ships in small skiffs at great speed.
"Sometimes it's not until the pirates have come over the helm that people realize they're under attack," Royal Navy Commander John Harbour told CNN. Harbour is with the EU Naval Force (EU NAVFOR) that monitors the Horn of Africa.
"They often fire a Kalashnikov into the bridge [of the ship] to scare the crew. Sometimes they will go further and fire rocket-propelled grenades.
"Once they think the crew have their heads down, they will throw grappling hooks over the ledge with ropes and ladders to climb on board," he said.
The very first piece of advice we give is to keep a good look out."
Pirate attacks worldwide are on the increase in 2009, affecting even amateur mariners, what do the authorities advise yachtsmen do to protect themselves?
Steer clear of pirate hot spots:
Of course, the most effective protection is to avoid high-risk waters like those off the Somali coast, particularly the Gulf of Aden. Already in 2009 there have been 102 pirate attacks and 39 hijackings in the region, according to EU NAVFOR.
In the past two weeks alone Somali pirates have seized a private yacht in the Indian Ocean, taking a British couple hostage, as well as a Greek bulk carrier. There have been at least two more attempted hijackings reported near the Kenyan port of Mombassa.
"Stay well clear of the area," warned Elaine Bunting of Yachting World. "That really is the most important thing. The risk extends all the way down to the Seychelles."
Pirate attacks are on the rise around the globe though, not just in the Indian Ocean.
In the first nine months of 2009, 306 attacks occurred worldwide, compared to 293 for all of 2008, according to the International Maritime Bureau.
In other piracy problem spots, such as the coast of Venezuela, the risk of robbery, not hostage taking.
Somali pirates "are very well organized and they are seeking a ransom. These people are under instruction not to a kill a hostage," Bunting told CNN.
Of course, sometimes the worst is unavoidable.
What to do if pirates attack:
Most important is not to slow down in the face of fire. Also consider evasive maneuvers, such as short cycle zag zags.
EU NAVFOR said this technique successfully deterred two pirate attacks already in November.
"At 15 knots the ship's own wake will become a deterrent," said Cdr. Harbour.
Swerving should amplify the wake, disrupting the pirates' assault.
Daniel Auwermann, Lieutenant Colonel in the EU Maritime Security Centre -- Horn of Africa also recommended non-lethal defensive measures such as activating the fire pumps, "as the water will spray onto the pirates' ship, making it harder for them to get on board."
Security firms also offer deafening horns, such as Proform Marine's L-RAD -- a long-range acoustic device that blares so loudly it can force pirates to retreat.
Erecting barricades such as barbed wire and netting can also be helpful in preventing pirates from getting on board.
Most important of all, though, may be notifying the Navy, transmitting Mayday signals and satellite messages as soon as possible.
What to do if pirates get on board:
The Maritime Security Center calls on crew members "not to offer any resistance, cooperate with pirates, not to use any firearms -- even if available and not to make any sudden movements around the pirates."
If a ship has a safe area, try to get as many crew inside as possible.
Finally, the center tells crew members that "if military forces intervene; keep low to the deck and cover head with both hands, with hands visible and empty."
Are you better off with a gun?
While most authorities do not advise firing back, some ship owners feel that carrying weapons is the only effective deterrence.
"I recommend conveying to approaching pirates that the vessel is fully armed and prepared to defend itself," said Michael Moore, a lawyer specializing in maritime law.
Moore said having weapons on board was fundamentally dangerous and that transporting firearms through international waters was difficult, but added that "a few warning shots will almost always result in the pirates turning back to await a safer target."
Choosing whether or not to carry weapons "is a personal decision," said Bunting, who has written about the dilemma of bringing guns on board. "It's not something we can recommend. It's really a big risk."
Dozens of incidents of self-defense have been reported this year. Last December the crew of a Chinese freight carrier managed to deter an attack by throwing improvised Molotov cocktails at approaching pirates in the Gulf of Aden.
The "absolute most critical measure is to register with the UK Maritime Trade Organization (UKMTO) in Dubai and also with the Maritime Security Center -- Horn of Africa," before traveling through the Indian Ocean said Graeme Gibbon-Brooks, CEO of Dryad Maritime Intelligence.
Once on the water, it is important to regularly report location updates to the authorities. Checking maritime security updates, avoiding the shore and using the guarded international transit corridor between North Somalia and Yemen can all further reduce risk.
"The trouble is that there are some situations, including the recent British hostage taking, where none of these deterrents is likely to work," Bunting said.
Anouk Lorie contributed to this report.