How to Build a Bottom Brush

by Paul Kamen, August 2003

Materials list:

One 10 ft. length of 1.5" Schedule 40 PVC pipe.
One 12 in. length of 1.0" Schedule 40 PVC pipe.
two 45-degree 1.5" elbows.
One 1.5" "T" fitting.
One 1.5" to 1" reducer bushing.
One wooden stiff bristle brush.
One small can of PVC pipe glue.
One 2" #10 machine screw with nut and washers.
Waterproof glue suitable for gluing wood brush head to wood brush handle.
Duct tape.
15 ft. 1/8" dacron cord (for lashing fender to pipes).
One 20"-22" boat fender.

All parts from Orchard Supply Hardware (OSH) except boat fender, which can be purchased from West Marine but I use the ones I find floating in the harbor.

Tools Needed:

Hacksaw (for cutting PVC pipe)
Drill (hand or electric, to drill hole for #10 machine screw in PVC and wood)
Screwdriver (to fit #10 machine screw)
pliers (or small wrench to fit nut for #10 machine screw)
Knife or scissors (electric hot knife is ideal)

Assembly Instructions:

Cut the 1.5" pipe into the following lengths:

20" (for pipe along bottom of fender)
4" (from fender to reducer bushing)
10" (two of them, for handles)
6'-4" (or whatever is left over, for long pipe from fender to handles)

Glue the parts together as in the photo. Cut off the bottom 12"-18" of the wooden brush handle, wrap with duct tape for a tight fit inside the 1" diameter pipe.

Drill through the 1" PVC pipe and wood brush handle and lock in place with the machine screw and nut and washers. This is important, to prevent rotation of the brush inside the pipe.

Glue the brush head to the brush handle with the waterproof wood glue. Otherwise it will rotate and start to unscrew at the connection.

Note: the photo shows two version, the MK-I and the MK-II. These instructions are for the MK-II. The MK-I is made with all 1" pipe and does not need the reducer bushing. However it was found to be too flexible, and the handle is a little too short, making it less comfortable to use than the MK-II. The MK-II also uses a larger fender to produce more upward force on the brush and better scrubbing action.