Laminate Thickness And laminate stiffness Explained
To determine the number of fabric layers required to achieve a specific laminate thickness, divide the thickness desired by the single-layer thickness of the tape or fabric you intend to use.
| Product Code | Description | Fabric Weight | Single Layer Thickness* |
|---|---|---|---|
| 727 | 450g/m² ±45° Biaxial Glass Tape 125mm wide (Approx 13oz) as (441g/m2 = 13oz) | 450 | 0.4 |
| 729 | 175g/m² 0/90° Plain Weave Glass Tape 25mm wide (Approx 5oz) as (170g/m² = 5oz) | 175 | 0.17 |
| 730 | 175g/m² 0/90° Plain Weave Glass Tape 50mm wide (Approx 5oz) as (170g/m² = 5oz) | 175 | 0.17 |
| 731 | 175g/m² 0/90° Plain Weave Glass Tape 75mm wide (Approx 5oz) as (170g/m² = 5oz) | 175 | 0.17 |
| 732 | 175g/m² 0/90° Plain Weave Glass Tape 100mm wide (Approx 5oz) as (170g/m² = 5oz) | 175 | 0.17 |
| 733 | 175g/m² 0/90° Plain Weave Glass Tape 150mm wide (Approx 5oz) as (170g/m² = 5oz) | 175 | 0.17 |
| 736 | 332 g/m2±45o Biaxial Glass Cloth 1270mm wide (Approx = 9oz) as (305g/m² = 9oz) | 332 | 0.28 |
| 738 | 610g/m²±45° Biaxial Glass Cloth 1270mm wide (Approx = 18oz) as (600g/m² = 18oz) | 610 | 0.5 |
| 739 | 450g/m²±45° Biaxial Glass Cloth 1270mm wide (Approx = 13oz) as (441g/m² = 13oz) | 450 | 0.4 |
| 740 | 135g/m² 0/90° Plain Weave Glass Cloth 1000mm wide (Approx = 4oz) as (136g/m² = 4oz) | 135 | 0.16 |
| 741 | 200g/m² 0/90° Plain Weave Glass Cloth 1000mm wide (Approx = 6oz) as (203g/m² = 6oz) | 200 | 0.19 |
| 742 | 200g/m² 0/90° Twill Weave Glass Cloth 1200mm wide (Approx = 6oz) as (203g/m² = 6oz) | 200 | 0.19 |
| 743 | 280g/m² 0/90° 4H Satin Weave Tapered Edges 1000mm wide (Approx = 8oz) as (271g/m² = 8oz) | 280 | 0.22 |
| 746 | 260g/m² Woven Roving 1250mm wide (Approx = 8oz) as (271g/m² = 8oz) | 260 | 0.22 |
*Average of multiple layers applied by hand lay-up
Laminate thickness dictates laminate stiffness. Matching the thickness of the laminate you’re repairing will generally result in similar stiffness to the part you are repairing.
Fibreglass repair tips
This diagram above illustrates how we recommend laminating a repair after the damaged fibreglass has been removed. It is critical that the scarf angle is set at a minimum ratio of 12:1 and that the patch thickness matches the original laminate. Matching the original thickness ensures that the stiffness will be the same as the surrounding area, reducing the chance of a crack around the repair area.
Creating a scarf angle on the original laminate helps in many ways. It provides a substantial amount of surface area for adhesion and acts as a transition zone so that the difference in properties of the new and original laminate are not concentrated at one point. We suggest a minimum 12:1 scarf ratio between the length of the scarf and the laminate thickness. This ratio applies to both skins when repairing a cored laminate.
—Excerpted from Common Errors in Fibreglass Repair by Jeff Wright, Epoxyworks 38
Beveling Fibreglass in a Transom Repair
The fibreglass thickness determines the bevel length which is also the distance from the corner to the location of the cuts for removing the fibreglass skin. As mentioned, the cut line will be located to allow the outer edge of the bevel to end before the corner of the transom. The distance of the cut line (and the bevel) back from the corner is 12 times the fibreglass thickness.
A 12-to-1 bevel allows room for multiple layers of fibreglass fabric and epoxy across the cut line to restore strength to the fibreglass skin.
Layout the cut line the required distance from the edge of the transom. Remember to measure from the end of the rounded corners where they blend into the flat transom surface.—Excerpted from Repairing Fibreglass Powerboat Transoms by Tom Pawlak, Epoxyworks