Here's how to make a boat bailer from a 2 litre plastic milk bottle. It's simple to make and works well. A suitable addition to a small boat.

Supplies

Empty 2 litre plastic milk container.

Step 1: Cut the Bottom Off a 2 Liter Plastic Milk Bottle

Cut off the bottom of a 2 litre plastic milk bottle.
Cut on a slight angle from the top downwards and outwards until halfway. Then cut straight down.

Step 2: The Design Benefits

The design is all in how the bottom is cut.
Study the photos. This cut gives the following benefits:

When the bailer is used to scope water out of a boat, the nose flattens out the 2 sides when pressed along the bottom of the boat. Making the scoop front twice as wide as a single side.

Each scope action can pick up over a litre of water. This will give a pump rate of over 30 litres a minute.

Step 3: Use It for Bailing Water

The bailer was tested in a bath tub giving 1.125 litres in each scope. With a pump rate of over 30 litres per minute. I have added it to my kayak. But have to conclude that a Kayak pump would probably be easier to use in a kayaks' confined space.This bailer is probably better suited in a dingy.