Fibreglassing styro

A few things to remember:

Don't try to do it with a single wrap of glass. Instead, cut long, thin triangles, and lay them on, overlapping each other, with the "thin end of the wedge" at the tip.

For particularly pointy cones, it may be helpful to snip the point off the triangles of glass, and stop your application an inch or so short of the tip of the nose cone. Then, after laying on the triangles all around the cone, roll a small "cap" cone onto the tip by making a small rectangle (2" high x 4" wide or so) of glass, brushing epoxy on the top few inches of the nose cone, and laying the top center of the rectangle right at the tip of the cone, and then smoothing each of the two ends around and down the cone.

+-----X-----+ (The point marked with "X" goes at the tip of the | | nosecone, and the side pieces wrap around and +-----------+ somewaht down on the opposite side)

If this rectangle-wrapping doesn't make sense in ASCII, simply imagine the shape of one of those ribbons people pin to their lapels to show support for one cause or another (red for AIDS research, pink for breast cancer research, yellow for supporting our troops, etc.).

Since styrofoam is quite "dentable", do multiple layers of glass, offsetting the overlap "seams" from layer to layer. Make sure to apply your rectangle tips from different sides, as well, to smooth out the coverage of the tip. Also, by offsetting the triangles, your glass fibers will be arrayed in different directions, which will increase strength and stiffness.

I generally use somewhere around a 6 ounce glass weight for this sort of work, as it only takes about 3 or maybe 4 layers to build up a very sturdy cone. "Crows-foot" weaves are preferable, as they conform better to curved surfaces without wrinkling.

If you have coupler tubing, use it for your nose cone shoulder. Wrap a scrap piece of your airframe tube with plastic wrap or wax paper, overhanging the end by an inch or two. Fold the excess into the end of the tube, and then insert your coupler tube to half of its own length. Force-fit the other half of your coupler onto the end of your styrofoam, and overlap your glass job down onto the exposed length of coupler. If you build up your glass thickness to the level of the airframe tube, you can make a nice even shoulder that will mate nicely with the end of your airframe tube. Once things are cured, you should be able to pull the completed cone, with coupler "base", out of the airframe scrap. If things get stuck, you can always simply slice the airframe scrap lengthwise, and peel it off the coupler.... The wax paper or plastic wrap should help.

Use good quality finishing (aka laminating or "boat building") epoxy to lay up your fiberglass. Don't use "fiberglass resin". In addition to stinking to high heaven, most fiberglass resins will attack styrofoam, leaving you with a melted mess instead of a nosecone. I am fond of System Three epoxies, although West Systems and Raka also make excellent stuff, from what I've heard. System Three has an inexpensive trial kit that is well worth the money -- see

for the details. I use the slow hardened when fiberglassing, as it gives me more working time.

Speaking of melting the foam.... When your cone is cured, you might try melting out the styrofoam using acetone (experiment with a scrap piece to see what I mean), and then epoxying any needed nose weight into the tip, along with a forged eyebolt with a washer and nut to provide a sturdy shock-cord anchor. Also, you might consider glassing the *inside* of the coupler to the inside of the cone, to strengthen it and its attachment.

Hope this helps,

- Rick "Poster board works good, too" Dickinson

Call around to some of the larger boat sales shops and ask if they sell epoxy and/or fiberglass for reparing boats. That's where I get the stuff locally.

There's also a local sailboat shop that's a complete West Systems dealer.

-Kevin