"Our weapons are mostly designed to protect our state borders, not to wage war," the 32-year-old says as his boat bobs through grey mist enveloping the coast of Ukraine's industrial port of Mariupol.
"But if they attack, we will defend ourselves with every weapon we have."
Surkov's worries reflect that of Ukraine as a whole as it girds for a feared invasion from more than 100,000 Russian troops who have encircled the ex-Soviet state from nearly every side.
Ukraine's old navy stationed almost entirely in the Crimean port of Sevastopol -- practically vanished when Russia annexed the peninsula and took all its ships in 2014.
Military analysts say Ukraine now has just one major warship and a dozen or so patrol and coastal craft of the type captained by Surkov.
Russia has sent six more warships into the region for a week of naval drills involving dozens of navy ships starting this weekend.
Ukrainian military analyst Mykola Beleskov says Russia now has 13 major battleships in the Black Sea on Ukraine's southwestern coast that can enter the landlocked Sea of Azov on its southeast at any point.
"The situation is tense," Beleskov said.
Captain Surkov agrees.
"The presence of Russian patrol boats is growing," Surkov says. "They are whipping up tensions."
'Prepare for the worst'
Mariupol lies on the edge of the front line separating government-controlled territory from that overseen by Russian-backed separatists in the rebel stronghold Donetsk.
It came under repeated attack in the early months of the separatist conflict as the rebels tried to grab its port, vital for Ukraine's lucrative steel export, and establish a land bridge between Russia and Crimea.
Ukrainian forces were able to hold the line at a heavy cost.
The UN estimates that the entire separatist conflict has claimed more than 14,000 lives and forced 1.5 million from their homes.
Coast guards patrolling the waters off Mariupol today doubt they would be able to repel a serious Russian amphibious assault that might accompany any land invasion from Ukraine's east and north.
"The six Russian ships that entered the Black Sea region have weapons that can be used on land as well as at sea. They have missiles," border guard captain Igor Chernov said.
"We have to hope for a diplomatic solution," added Surkov. "But we have to prepare for the worst."
'Difficult to pull off'
Naval fores expert Nick Childs of London's International Institute for Strategic Studies said an amphibious assault on Ukraine would not be easy to pull off, even for someone of Russia's military might.
"There has been much attention paid to movements of Russian amphibious ships into the Black Sea to bolster forces already there," Child told AFP.
"However, amphibious operations would present hazards for Russian forces, and Ukraine has some coastal defence capabilities, including anti-ship missiles in development."
Ukrainian analyst Beleskov agreed that an amphibious landing would be "very difficult to pull off".
"We have good defences in Odessa and along the Black Sea coast," he said.
"If they limit themselves to an amphibious landing alone, we would survive."
But veteran Russian military analyst Pavel Felgenhauer said the Kremlin has been preparing such an attack for nearly a year.
"They staged an amphibious landing drill on the Opuk firing range in Crimea last April," Felgenhauer said.
"The plan is to concentrate a massive amphibious assault force of 10,000 troops in the first wave. The Ukrainians would never be able to repel that," he said.
"And then the second wave would come. An amphibious landing would be very hard to fight off because of Russia's superiority not only at sea, but also in the air."
The idea of a war of such scale breaking out at any time is leaving captain Surkov and his family feeling increasingly stressed.
He says he has spent almost all his time at sea since the start of the year because of the Russian war games.
"My wife is feeling nervous because I spend so little time at home," the captain says. "She is always asking me if everything is alright. But things are getting heated."