Survival backstroke can get you out of trouble without using too much energy. Done on your back, with breaststroke kick, and either sculling hands or a gentler version of breaststroke arms.
It has the advantage of easy breathing, as the mouth and nose are almost always over water.
The disadvantage is you can't see where you're going, unless you turn your head often.
This swimming style is similar to an upside down breaststroke.
First, practice the leg kick while sitting on the edge of the pool. The leg kick is like inverted breaststroke. Use this three part sequence:
Using a float to support your upper body, do this:
The oar stroke consists of the opposite motions of the butterfly stroke, hence the alternate name: Moth Stroke.
Unlike the butterfly stroke you are swimming in a backwards direction. Move your arm in a circular motion akin to the butterfly stroke. The legs are however, kicked out like with breaststroke.
The Moth Stroke is not to be confused with the "slow butterfly stroke" which also can be alternately labelled as the "moth stroke."
If you have difficulty keeping your legs up while at the same time your arms reach forward above the water,
lie on a float to begin with, until you can do it right.
Lifesaving backstroke is the same, except you would be rescuing someone using the chin tow, so one arm would be supporting the casualty and the other is used for sculling.
Lifesavers use the breaststroke kick differently. The legs are somewhat lower, the knees are not pulled in as much because this would mean kicking the casualty. Instead, the lower legs do most of the kicking, in a rotation below the knee.
Your arms don't do much except the one supporting the casualty. The free arm might do a bit of sculling.
Once you've mastered this swimming stroke, you can increase the training level. Spread your arms sideways and swim lifesaving backstroke. It is about as hard as towing a casualty.
Hold your hands vertical to get maximum resistance. This gives you a similar workout to rescue towing, slows you down as much as a casualty would.
Next, add more and more clothes as you get stronger.
Wear a lifejacket and see what difference it makes.