Their free-board was only the width of a man's hand, and they lay so low in the water that the men seemed to be crouched on the very surface.
The boatmen were paddling frantically. Their long spearshaped paddles flashed in the sunlight as they drove for the far bank. The leading canoe was already within a hundred yards of the Zambian papyrus beds.
The propeller of the Yamaha carved a lacy wake from the glossy green surface as Isaac swung the boat in a long curving trajectory to head off the leading canoe from the sanctuary of the reeds.
As the two vessels closed, Isaac made out the scarred visage of Sali . He squatted in the warped bows, turning his head awkwardly to glare back at them, unable to move without upsetting the delicate trim of the canoe.
This time we've got you, Isaac whispered, as he pushed the throttle forward to the stop, and the Yamaha shrieked.
Suddenly Sali rose to his feet and the canoe rocked wildly under him.
Water slopped in over the wooden sides and the canoe began to flood and settle. Sali shouted a threat at Isaac; a mask of fury and he lifted the AK his face was contorted into and fired a long continuous burst at the boat racing down on him.
Bullets slammed into the hull and one of the instrument gauges on the control console in front of Isaac exploded. He ducked, but held her on course to ram the canoe.
Soli flicked the empty magazine out of the rifle, and loaded another from his bandolier. He fired again. The bright brass cases sparkled in the sunlight as they were spewed from the breech. One of the rangers in the front of the assault boat cried out and clutched at his stomach as he tumbled to the deck, and at that moment the bows of the assault boat crashed into the side of the canoe at thirty knots. The brittle kigelia wood shattered, and the men in her were hurled into the river.
At the last moment before the collision, Sali threw the AK 47 aside and dived overboard. He tried to force his body deep beneath the water to escape the speeding hull. He thought he could cover the last few yards to the edge of the reedbed without surfacing and showing himself again.
However, his lungs were full of air and the buoyancy prevented him diving deeply enough. Although his head and body were angled downwards, his feet were only a few inches below the surface.
The propeller of the Yamaha was spinning at peak revolutions as it passed over his left leg. It took his foot off cleanly at the ankle and went over his calf muscles like the blade of a bread-slicing machine, shredding the meat down to the bone.
Then the assault boat was past, turning back steeply with Isaac spinning the wheel. She leaned out into the turn as he lined up the bows for the next canoe in the straggling line. He hit it without a check, steering into the fragile hull and spilling its crew into the river, driving it under and running on, swinging into the next turn like a slalom racer weaving through the poles.
The men in the third canoe saw them coming and threw themselves over the side an instant before the bows struck and then they were splashing and screaming as the swift green current carried them away.
Isaac spun the wheel back the other way, and the next canoe was dead ahead. The crew were shouting and pleading and firing wildly. The volleys of bullets kicked up fountains of spray all around the approaching assault craft in the moments before it struck and trod the shattered canoe under.
The remaining canoes had turned back and were paddling desperately for the south bank. Isaac overtook them effortlessly and smashed in the stern of the nearest vessel. He felt the engine check and shudder as the spinning propeller bit into living human flesh and then it surged forward again.
The last canoes reached the south bank and the poachers spilled out of them and tried to clamber up the sheer cliff. The red clay crumbled under their clawing fingers.
Isaac throttled back and turned the bows upstream holding the assault boat against the current. I am a Parks warden, Isaac yelled across at them. You are under arrest. Stand where you are. Do not try to escape or I will fire upon you. One of the poachers still clutched his rifle in his hand. He almost reached the top of the bank before the clay broke away under his feet and he slid down to the water's edge.
Sitting in the red mud, he threw up the rifle and aimed at the men in the assault boat.
The two unwounded rangers were kneeling at the rail, their rifles cocked and levelled. Bulala! Kill! Isaac snapped, and they opened up together, a massed volley of fire that swept the riverbank. They were hand-picked members of the anti-poaching unit, both good marksmen, and they hated the gangs that plundered the elephant herds, savaged their comrades and threatened their own lives.
They laughed as they shot the panic-stricken gang members off the bank.
They made a game of allowing them almost to reach the top of the red clay wall before bringing them flopping and kicking back into the river with a short crisp burst of fire.
Isaac made no effort to restrain them. He had a long-outstanding score to settle with these men, and a few years imprisonment was not enough punishment for their crimes. As the last of them rolled down the bank and sank slowly into the clear green water, he spun the boat and raced back across the river.
Scar-faced Sali was the leader. These others were mere brainless thugs and cannon-fodder. Sali could recruit a new regiment of them for a few dollars 4 head. Sali was the brains and the guts of the trade, and without him this day's work would count for little. Unless Isaac stopped him now, Sali would be back again next week or next month with another gang of ruffians.
He had to crush the head of the mamba or it would strike again.
He raced in close to the edge of the reeds on the north bank, to the spot at which he had rammed the first canoe. Then Isaac turned into the current and throttled back the Yamaha and allowed the current to drift them downstream, using bursts of engine to keep within a few yards of the edge of the reeds.
The two rangers stood at the port rail, and eagerly scrutinised the reedbed as they drifted by.
There was no telling how far the Zambezi current had carried the poacher before he had been able to reach the cover of the papyrus.
Isaac would make only one sweep from the boat for a mile downstream.
Then he would go ashore with his men and heat back along the north bank on foot to pick up any sign that Sali might have left as he dragged himself from the reeds on to dry land and tried to escape. Then they would follow him, for as far and as long as it took.
Strict interpretation of the tow gave Isaac no powers of arrest on the Zambian side of the river, but this was a hot pursuit of a murderer and a notorious bandit. Isaac was prepared to fight if challenged, and put a bullet through his prisoner's head if the Zambian police tried to intervene and take Sali away from him.
At that moment something caught his eye in the reedbed directly opposite the drifting assault boat. Isaac touched the throttle and held the boat stationary against the current.
A small area of reeds had been disturbed, as if something had been dragged through them, a crocodile possibly, or a large leguan lizard, except that clumps of reeds had been twisted and broken as though used as handholds. Crocodiles don't have hands, Isaac grunted, and manoeuvred the boat in closer. The disturbance must have taken place only minutes before, for under his eyes the flattened reeds were still straightening and rising into their original upright position. Then Isaac smiled thinly.
He reached over the side and snapped one of the reeds and held it to the sunlight. The smear of colour along its fibrous stem came a way wet and red on Isaac's fingers and he showed it to the ranger who stood at his shoulder. Blood, the ranger nodded.