Oh, I know the answer because I replaced all plexiglass in Turkey. First reason is appearance. Mounting them on the inside gives a cleaner look because the fiberglass is not recessed for the plexiglass as it is with the front windshields. Second is also appearance. Note that the edges of the plexiglass are painted about 30-35mm inside and all around. This painting hides the ugliness of the adhesive. If you are replacing plexiglass, again pick a really good contractor. The port side windshield is complicated in that it is routed for a gasket. The routing and gasket on the top are inside and they are on the outside on the bottom and sides. If the windshield is cut wrong even by 1mm, it will leak. Also look closely at the port side windshield. It has a rounded edge in several places. If the contractor duplicates it exactly, you will be fine. Sadly, I believe most plexiglass guys are not up to this task. CW Bill Rouse, Admiral (Hon) Texas Navy Yacht BeBe Sent from my iPhone 1-832-454-9995 when in USA +1832-380-4970 Global Voice Mail +38 598 9700 896 GSM Croatia On Aug 25, 2014, at 19:47, "Ann-Sofie Svanberg kanalmamman@... [amelyachtowners]" wrote: I was wondering about the plexiglas windows, not the ones in the canvas part. /Annsofie SY Lady Annila Skickat från min iPad 25 aug 2014 kl. 09:37 skrev "yahoogroups@... [amelyachtowners]" : Although i do not know the answer to your question, I think it may be for two reasons. The job will look better and cleaner from the outside. The fused part between the clear and the solid fabric is hidden from UV damage. If I were having a new Bimini made designed to incorporate clear and solid materials, I would insist the clear be attached from the inside. I like the solid material which is polypropylene coated on both sides because it can be heat welded to itself and/or clear material, eliminating the need for seams which will either eventually leak or deteriorate because of UV. If you are having a new Bimini made and plan to have the seams heat welded, chose your contractor carefully. Before giving him an order have him give you an actual sample of his heat welding, including clear to solid, then hold him to the sample you approve. Hope this helps. Bill BeBe 387