It probably is Water Bonnet for the aluminum but they are out of business. Try
http://www.marineglassspecialties.com.They may have some or know where to get it.
GW used a type of glass the industry calls "school bus glass". It is not tempered. My local guys did not like drilling the hole so close to the edge.Maybe it could be drilled in the middle of a sheet before cutting.
Tempered glass is a better choice but it can't be cut. They cut untempered glass and put into a very expensive tempering furnace/machine. Glass shops don't have them so they send parts out.
Finding a shop that will do a small batch is a problem. Try
sales@jerseytemperedglass.com but I thought I used a Seattle company. It will make sense to have 3 or 4 pieces made because of setup charges and shipping.
I went with tempered. I you decide to go that way I'll see if the spares in the boat have an address. It's been 10 years. I think I ordered 4 and have 2 left.