"I just saw a car with a boat on indicate to come out of the slow vehicle lane and then a couple of cars stopped. Then this white car hit the back of that and then just shot across the road," Letford said.
"He hit the front of my ute and I just turned really sharp which didn't do any damage to the front of my ute, and then hit me in the driver's door, and then crunched the back of the ute and then the boat pretty much went straight over the top of it.
"His car went underneath the trailer and it ripped my towbar in half. Half the towbar was on the boat trailer and half the towbar was still on my ute."
Letford stopped and checked in his rear-view mirror to check on his two-and-a-half-year-old son Knox who was still sound asleep and spotted his 6.1m Scorpion aluminium boat about 30m down the road.
He then jumped out of the car to thinking he had really hurt the other young driver whose car had landed in the middle of the road, but said he was already being helped by other motorists and had only sustained a few cuts and scratches.
"He was pretty shaken up. But he was alright, he wasn't hurt."
Letford said a car towing a boat indicated out of the slow lane and then suddenly three cars stopped in a hurry and at least two of them - a Subaru and Altezza - slammed into each other.
Letford was told by another motorist who had been following him that his boat had left the trailer and landed back on the trailer before hitting the bank.
The building company owner went to survey the damage of his boat called Hard Knox, named after his son Knox, yesterday in Thames where it was towed to and said it was most likely a write-off.
Both sides of the boat caved in from being hit by the bank or the car and there was a large hole at the front from hitting the trailer.
"The trailer is just a mangled mess. Both the wheels have folded down to the back of the boat."
Waikato Police posted on its Facebook page that the car hit another vehicle which in turn slammed into the one in front of it before losing control and skidding across the centre line hitting the ute towing a boat.
"The sheer force of the impact ripped the towbar off the 4WD and the boat on the trailer came free and rolled down the road before stopping in a ditch."
Police said there were no serious injuries and all the people involved were lucky to be alive. Police are still investigating.
"Don't be distracted while driving, pay attention to your surroundings and other road users and check your speed," the post said.