What is the difference between a pendulum and a pantograph wiper?

A pendulum wiper system consists of a single arm and blade working in parallel to create an arced sweep pattern, with the wiper motor shaft as the only pivot point, clearing glass in the shape of a slice of pie or pizza. Most cars have a pendulum style wiper system. A pantograph system has a double-arm for each wiper blade, and the blade pivots at the end of the wiper arm while the arm pivots on the motor shaft, creating a sweep pattern in which the blade stays parallel to the edge of the glass. A visual representation of the sweep patterns below shows the difference between the two. For tall, narrow windshields, the pantograph system is better, where a pendulum system may be preferred for wider, shorter windshields.

How do I determine the length of arm and blade I need for my windshield?

The first thing to consider when determining the length of your wiper arm and blade is to decide how much of the glass you want to be cleared. On most boats there is a section of glass that the captain never looks out of, whether it’s down low by the deck or up high overhead, so considering the captain’s line of sight when sitting or standing and driving the boat will determine what area of the windshield needs to be cleared. The next consideration is where the motor is going to be mounted, and how far that is from the are that needs to be cleared by the wiper. With those two measurements in mind, you can lay lengths of string or cardboard or something along those lines to estimate the lengths of arm and blade your windshield would need. You can also use tools from manufacturers and distributors of wiper products to help size the right system. With Imtra you can fill out our wiper questionnaire and we can use that information to recommend a system specifically for your boat.

How do I determine how big of a wiper motor I need?

The power of any wiper motor is entirely dependent on the length of wiper arm and blade that it is driving, so longer arms and blades require more powerful motors. Once you’ve determined the length of arm and blade required for your windshield you can select a compatible wiper motor with the necessary power.

Where do I mount the wiper motor?

Wiper motors can be mounted either above or below the window. The main determining factor in whether it is mounted above or below the window is the space on the interior of the boat to physically fit the motor where it can be accessed to wire it up and do any required maintenance or service. If you can’t fin the motor anywhere inside the boat, there are some options for externally-mounted wiper motors. If there is plenty of space both above and below, then the choice is yours based on preference or where the captain’s line of sight falls on the window.

Do windshield wiper systems work on forward-raked glass?

Yes they do, you just need to make sure the wiper arm you select has enough spring tension to keep blade on the glass, as gravity will naturally be pulling it off the glass.