I will update this page with pictures and more info once I complete the project. My boat is an A32 but it shares the same size hatches as many other models.
As per OEM, I’m using 2074 (15% grey) grey cast acrylic (Plexiglass or Acrylite brand). Cast acrylic is stronger and more scratch reistant than polycarbonites (like Lexan) and has a much lower expansion coefficient (less prone to leakage). All hatches are 1/2 inch (12 mm) thick.
I also have the DXF files for laser cutting the plastic:
File technical details:
– line color: RGB Red|
– line width (stroke): .01mm
– file format: AutoCAD DXF R14
25 1/4 inches square (641.35mm)
Corner radius: 2 inches (50.8mm)
DXF file: https://www.alohaowners.com/dloads/LargeHatchFinal.dxf
20 5/8 inches square (523.875mm)
Corner radius: 1 3/4 inches (44.45mm)
DXF file: https://www.alohaowners.com/dloads/MediumHatchFinal.dxf
11 1/2 inches square (291.1mm)
Corner radius: 1 1/4 inches (31.75mm)
Note, hinge and spring notches are included
DXF file: https://www.alohaowners.com/dloads/SmallHatchFinal.dxf
If you want to view or print these files, download “FreeCAD”. It’s free and works like a charm. Get it here: https://www.freecadweb.org/
Instructions (from a conversation with A & H):
There is only one product combination they use on OEM and rebuilds:
– Sikaflex 295 UV adhesive/sealer
– Acrylic edge MUST be primed with Sika’s 209N primer.
– Aluminum MUST be cleaned/prepped with Sika’s 205 cleaner/activator
Do not use ANYTHING other than the 205 cleaner on the aluminum bonding surfaces (alcohol, mineral spirits, etc will affect the bond).
Be SURE the Sika products are not expired. This is critical with the 209N primer. Expiry dates are marked on the products. It may be difficult to find fresh 209N.
The aluminum bonding surfaces should be free of any sealant and lightly sanded before using the 205 cleaner.
The easy/mess-free way to install the new lens is with 3M VHB tape. Use 1/4 or 3/8 wide on the lower flange to bond the lens in alignment and make it easy to fill the vertical gap with 295 UV. The tape will also keep the 295 from leaking out the bottom.
Be sure to remove an inch of the protective cover from the bottom (people have forgotten).
Be sure to prime the edge of the lens too (note that working time is short before the 295UV needs to be in place).
Drop the lens into place and press gently to seat it onto the VHB tape. The easy way to perfectly center the lens when dropping onto the VHB tape is to make shims to use on all four sides. Be precise as once the lens touches the VHB tape it’s almost impossible to remove.
Mask as needed and fill the vertical gap with 295UV. Use a gloved finger to smooth/remove excess. Lens should be slightly proud of the frame.
Close hatch and dog it down so proper alignment is maintained while the 295UV cures (at least a few days – a week is better).
It’s a precise process but it’s how the OEM does it and considering the cost and effort to replace a lens, I think it’s worth following.
Regarding VHB tape. Most production boats now only use VHB to mount fixed windows. It’s that strong. So it will also provide considerable adhesion to the new lens.