In this episode of DIY's Shipshape Boating, host John Greviskis shows you how to build a radio box out of 1/2" thick PVC foam, fiberglass cloth and polyester resin for your boat. Materials: Tape measure
Pencil
4 x 8 1/2"-thick PVC structural foam
Straightedge
Orbital sander
320-grit sandpaper
Razor knife
Stainless steel finishing nails (approximately 20)
80-grit sandpaper
Sanding block
Fiberglass chopped strand mat
Stitched biaxial cloth
Polyester resin
Self tapping screws
3"-wide throw-away brush
Fiberglass roller
Epoxy filler
4" plastic applicator
Random orbital sander
Denatured alcohol
Tack rag
Polyurethane paint
3/8th napped foam roller
3" Badger hair brush
3/8" Lexan or Plexi glass
500-grit wet/dry sandpaper
1/2" stainless steel machine screws
Washers
Nylon lock nuts
Drill - Find the two welded-in supports (figure A) on the anodized aluminum t-top (these double as a place to through-bolt a radio box onto).
Note: Decide how big to make the radio box. (Make sure your line of sight is not hindered.) Make sure it's tall and deep enough to give plenty of room around the VHF radio. - Take measurements from your t-top: width, height and depth. (Ours is 32" wide x 24" deep and the inside cavity to be 10" tall).
- Take your PVC foam and lay out the dimensions (there will be a total of five pieces: top, bottom, two sides and a back). Mark out the panels for the radio box out using a pencil and a straight edge (figure B).
Tip: You can also use wood. Follow the same directions. - Once you have marked the panels, clamp down the foam to be cut. Use a razor knife and a straight edge to cut accurate straight lines.
Tip: Try to cut each line in two or three passes with the razor knife. - When the cutting is complete, use masking tape and a sharpie to mark out what each piece is (top, bottom, left side, right side and back). Do not write directly on the foam -- use the masking tape and marker to mark.
- Using your stainless steel finishing nails to assemble the box together.
Note: To avoid corrosion, always use stainless steel nails. - Line the foam to one another two pieces at a time, and then gently push the finishing nails into the foam (figure C).
- Eventually, we are going to round over the outside corners for aesthetic reasons. So, recess the nails a little bit by taking out an additional finishing nail and flipping it over nail head to nail head. With a hammer, lightly tap it down inside the foam.
- Grab your sanding block and some 80-grit sandpaper and round each corner.
Safety Alert: Be sure to use a particle-dust mask when sanding. - Next, you need to laminate the box with a couple of different types of fiberglass over top of the foam. One is fiberglass is called "chopped strand matte" (figure D) and on the inside we will use a structural type of fiberglass cloth called "stitched biaxial cloth" (figure E). It's used to help hold the screws in.
- Mix up the two-part (one part base material and one part catalyst, which is a product to harden = M. E. K. P. hardener) polyester resin. Use this to wet the foam and the fiberglass.
- Grab a 3" wide throw-away brush and, first, wet the topside of the foam (simply paint the resin onto the part). Now tear some of the fiberglass chopped strand matte.
- Fiberglass the corners of the box by setting the glass in place, and -- again with the brush -- wet it with the resin until it's transparent.
- Grab the fiberglass roller. This will get the fiberglass to lay down flat. Also, roll out the air bubbles to the edge to make sure there are no creases.
- Cover the rest of the outside repeating the previous steps until the outside is complete.
Note: It takes the resin about an hour or so to completely cure. - After the fiberglass has completely cured, we need to clean up the fiberglass spikes. Rough the box up a little bit (use 80-grit sandpaper) in order to apply a wipe over top of it. Grab a 90-degree die grinder (figure F) along with a 36-grit sandpaper wheel on it. This is to remove the fiberglass spikes.
- Using a clean rag and acetone, wipe up the debris. Acetone evaporates quickly.
- Next, apply watertight polyester-based body filler over the top of the box. (This is also a two-part product consisting of a base and a hardener.) Mix this up according to the directions and, using a 4"-wide plastic applicator, put a thin layer of filler over top the roughed up glass. Cover the entire outside of the radio box (figure G). Wait for the epoxy to cure, which will take approximately two to three hours.
- After the filler has hardened, sand it smooth with 80-grit sandpaper and a random orbital sander. Then, switch over to 180-grit sandpaper to reduce the size of our initial scratches.
- Wipe it down with some denatured alcohol (NOT acetone because it will break down the body filler) and a clean rag.
- Tack rag (a sticky rag) the surface to pick up any remaining debris or dust.
- Grab the alkylyd primer (a type of enamel), which is a high-build primer with micro-balloons added, and prime the surface of the box (figure H) in order to make sanding easy after it is cured. (Also, prime the inside.)
Note: You can add some brushing reducer into the primer to make brushing easier. - Using 220-grit sandpapers and the orbital sander, sand the box until it's smooth. Then again wipe it down with denatured alcohol and a clean rag. Tack rag again.
Now that the box is painted, it's time to make the front cover in the next segment.
RESOURCES :
VHS Marine Radio Handbook
Model: 1892216477
Author: Mike Whitehead
(January, 2003)
To order this title from Amazon, click here.
Bristol Fashions Publications
Communications at Sea
Model: 1574091611
Author: Mike Harris
(May, 2003)
To order this title from Amazon, click here.
Sheridan House
The Motorboat Electrical and Electronics Manual
Model: 1574091492
Author: John C. Payne
Order this book from Amazon.com.
Sheridan House
Electronics Aboard
Model: 189221640X
Author: Stephen J. Fishman
(September, 2002)
To order this title from Amazon, click here.
Bristol Fashion Publications
The Marine Electrical and Electronics Bible
Model: 1574090607
Author: John C. Payne
(October, 1998)
To order this title from Amazon, click here.
Grafton Books
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