If you are referring to the fixed plexiglass windows on the cabin, like the one over the chart table that also goes to the aft cabin, I recently called Catalina about replacing. I have one that is cracked, not just crazed. Those windows are custom sized to each boat during manufacture, and Catalina does not keep records of those windows.  Their recommendation was to remove it carefully, and take it to a local plexiglass shop and get a piece of same color and thickness. Then cut to fit and install. That is on my to do list for Troubador. 

Unless anyone one has a better idea, I think butle tape would work. 

Fyi, I have not figured out what to do about the black leeching down the hull from the fixed windows on the hull. 

http://selectplastics.com/
Try these folks they may be able to help you.

Hi,
I just home from doing the exact same project. You first need to remove the old window by slicing between the hull and the window. A cheap flexible steak or paring knife works well. I you have a buddy that can be on the opposite side you can saw it with a guitar string. Once removed you need to take it to an acrylic shop and have them fabricate it. The edge is beveled and kind of hard to do on your own. If you're brave or skilled you can order the acrylic online the color number is 2064.  I tried the select plastic route, but they told me it would be a 2-3 week turn around time.  A company called Shore Plastics in Philadelphia was able to fabricate one in a day for me.  
The bedding compound is Dow 795, which comes in a caulking tube.  I would avoid the butyl tape as some of it is exposed and the butyl remains sticky and attracts dirt.  Also, the color will show under the window on the outside. Another member Mark Kozy posted pictures of this process on his Picassa web.  If you do a search you may be able to find it.  It was hard to find on the search. If you want more detail you can contact me through email.   

Wally,
If nobody has an answer to your question, you could always drill a small hole in the old window.  Maybe 1/4"?  You could then measure the thickness, and easily plug the hole with a dab of caulking while the new windows are being made.  You're probably going to throw the old window out anyway?

Wally,
If you are using Shore Plastics in Philly, He used Chemcast acrylic sheet color 2064 thickness 0.220 for mine that he just did. Remember when using a template you also need the bevel on the inside edge. Even with using the old window as a template, I found I still needed to do some sanding to get the fit I wanted. I still have the old window from the forward/starboard side that I could probably get to him if that would be helpful. If you you need any further detailed help you can email/pm me and we could set something up to chat.

Larry

Hi,

If its a MK2 I have the templates for all four windows (fore and aft both sides).

You may have to do minimal sanding for an optimal fit, I did not on my boat.

I have made them for early C34s with screw retainers (as original-I do have an improvement for the screw install).  I have made them for MK1 and MK2 C36s and so far, no complaints.  Doing all four fixed lights is a long 2 day back breaking job (mostly from leaning over the side of the boat from the dock through the lifelines.  Lots of prep work and then just put 'em in....  The prep work makes the install pretty easy, I use 20+ sand bags to do all 4 lights simultaneously.

Sorry for not posting the photo essay on this website....don't know how.

Mark

If you need lights or some info you can reach me at: iamav56@gmail.com