Depends what you mean by better. The 17 degree deadrise will cut through the waves better than the 21. However the 21 will plane faster and will be more stable at rest. So better is dependant on the use you are planning.
To cut plexiglass you should use a handsaw and make sure it is a handsaw that can cut in straight lines. You should also measure out how you much you need and what shape you need.
Suppose the top face of the pyramid is ABCD with the square EFGH directly below it.Suppose AC and BD meet at P, the apex of the pyramid.Make a cut with a plane through P which is parallel to AB and goes through EF.Make a cut with a plane through P which is parallel to BC and goes through FG.Make a cut with a plane through P which is parallel to CD and goes through GH.Make a cut with a plane through P which is parallel to DA and goes through HE.The result will be the square-based pyramid PEFGH.
Cut it in half through its centre. Then cut each half into half. You will have four fourths.
Cut the square into two. Put one part on top of the other. Cut through both parts with your second slice. Stack the pair of slices on top of the other. Cut through all four with the third cut.
A boat or ship with a sharp bow and strong propulsion system can be used to cut through waves effectively. Additionally, specialized watercraft such as surfboards or jet skis also have designs that allow them to navigate through waves.
A sea saw
A Sandbar
A headline deck is formed when waves cut completely through a headline. This occurs when a wave has a significant portion of its energy intersected by the shoreline.
The ship's prow cut easily through the waves.
Mechanical waves, such as sound waves, travel through a medium like air, water, or solids. Electromagnetic waves, like light and radio waves, can travel through a vacuum because they do not need a medium to propagate.
Ocean waves, particularly powerful and consistent ones, can cut through rock formations over time and create a tunnel known as a sea cave. These sea caves are often found along coastlines where the waves have eroded the rock through a combination of abrasion and hydraulic action.
When waves cut completely through a headland, a feature called a sea cave is formed. Sea caves are formed by the relentless erosion of waves gradually wearing away the weaker rock layers of a headland. Over time, the waves create openings and cavities that can extend deep into the headland.
Humans use waves in various ways, such as for communication through radio waves, navigation through GPS signals, heating food through microwaves, and seeing objects through light waves (such as in optical technology). Waves are also used in medical imaging techniques like ultrasound and X-rays for diagnosing diseases.
How do scientists use seismic waves to study the Earth
Radio sound is heard through the use of radio waves, which are electromagnetic waves that can carry information from one point to another. These waves are transmitted from a radio station and received by a radio receiver, such as a radio or smartphone, which then converts the waves into sound waves that we can hear.
Wave-cut platforms are formed through erosion by the action of waves pounding against the coastline. As the waves erode the base of the cliffs, a gently sloping platform is created over time.