Power ten is a term used in the sport of rowing. It is generally used during a race.

It consists of bringing up the rating and power of the strokes during a race for ten strokes. It is used to 'push' the crew for a burst of more effort, say to inch ahead of a competing crew. It is increasing the race pace which is fairly punishing that little more, 110%.

The stroke or coxswain calls the power ten, either as part of a set race plan; say at the 1000 metre mark or as device to move into a move favourable position or to hold off crews coming from behind. Generally there would be a stroke or two warning before calling the ten, then, if there is a cox counting out the strokes of the blades to keep track. If there is no cox then the stroke may just call it either verbally or controlling the rating, ie rowing faster, pushing the crew until the end of the ten.

The calls or instructions a cox would use vary from country to country, an Australian cox would generally call "Bring it up for ten!"and then "Wind it down!" or "Bring it down!" to complete the ten. Some crews do not wish to let other crews know they are 'going for ten' so may use a code word. I had a crew that I had to tell to "Go ballistic!" As for counting the strokes, for me, this would differ for the level of the crew; a novice crew, every second stroke or if they were very new and nervous every stroke, but a more senior crew I would call the first, fifth, ninth and tenth strokes, giving the position within the race between counting.

An English cox uses a slightly different terminology. The power ten begins with 'Push for ten!', then count the stroke number from ten on even strokes and give a technical call* on the odd numbers and finishing the ten stroke by using the word consolidate. Now, apparently The Debutante is a pirate as "and if I were using it to get by or to push off of another crew, I'd normally call to 'Kill that boat in ten!' or 'Bury that boat in ten!'".

It is possible to go for longer than ten strokes, there are power fifteens but they would be used in the large boat like eights. As a general rule the cox and stroke would use the power ten sparingly, as doing to many could mean the crew do not have the energy to sprint at the end of the race. Over a 2000 metre course I would not expect a power ten to be used more than two or three times.

*A technical call is drawing the crews attention to things they need to focus on, like blade work and not rushing the stroke.

Information provided by the author after years of coxing and watching rowing.
English coxing information provided by The Debutante