Glenn,

I just wandered up to the upper right corner of my computor screen in the Google box and punched in Lewmar replacement lens. It came of with several hits. Deffender Marine and Catalina Direct both list replacements between 29 and 32 dollars. Catalina Direct gave more detail and indicates they are matching the origanal color and have made the lens a bit thicker to give a tighter seal.

Steve,
The crazing of the lens is caused by U.V. damage. All plastics are to some extent affected by UV light, and transparent plastics are most affected because the U.V. can penetrate farther into a transparent plastic because the rays are not blocked by a U.V. blocking pigment. It is not a product defect.

Can anyone on the Forum define the problem? Particularly, what is crazing? Is it the development of faults within the plexi? Or are we talking about minute surface "cracks"? If the faults occur within the plexi, then they can't be reached by any sort of mitigation attempt. But if they are surface blemishes, they might be curable with a very fine polish.

I realize that crazing occurs as a result of UV exposure, but are there other factors? For example, does application of the wrong kind of cleaning material (Windex, for example) exacerbate the problem?

I have several hatches on my boat that need attention. And the boat is only 7 years old. See the attached photo of the hatch in the head.

I have 4 new lenses on the way right now from Select Plastics. They were the least expensive source I found and according to the owner, they make the one that Catalina Direct sells (don't know if that's true or not). They will also put a new "lens" in the Lewmar forward hatch, but you have to ship them the hatch ($$). They are also the ONLY source I found for the Lewmar Rollstop hinges. My boat is a 1991 and has the Lewmar forward hatch. The hinges have little (for lack of a better term) "ridges" built in which allow the hatch to be opened to several set positions. Over the years, these ridges round off and become useless. The new Rollstop hinges will allow me to throw away the stick I'm currently using to keep the hatch open. These folks were very nice to deal with, BTW, and Tony, the owner, seems to know everything there is to know about plastic & acrylic. And just for you Larry, here's a link to a discussion of crazing on their website.

[url]http://www.selectplastics.com/index.php/blogs/tonyd/crazing-acrylic.html...

Mike

Larry,

Crazing is something we see in aircraft windows with increasing regularity. Most aircraft windows are streached acrylic. Polycorbonate now available for our boats is reported to be more resistant to UV deterioration. Crazing is often first noted as surface crazing, you can feel this with your fingernail as the plastic ages it becomes more brittle as continues to gas off solvents. Surface crazing occurs due to UV exposure, heat, ozone in the atmosphere and chemical exposure. As the material embritlles further you may note deep crazing that can not be felt on the surface and can best be seen with a bright light shown at angle to the surface. Flexing, bending or impact can accelerate deep crazing also called stress crazing but, both are signs of material failure or internal fractures of the sheet. Some chemicals can rapidly accelerate crazing as they can accelerate the leaching out of solvents/plasicizers in the material. Salt effects the plastics like it does varnish by acting like magnifying glass when sunlight hits the crystal of salt on the surface of the glass, small scratches also concentrate the light and accelerate crazing.

Crazing is pretty much inevitable with our windows, keeping them clean and minimizing chemical cleaners and covering them are the best ways to preserve them.

It could be worse, on a Cessna Citation cockpit windshields they spray alcohol and hot engine bleed air on them for anti-icing, the heat and alcohol accelerates the window deteriorazation. Windshields for this aircraft run about $20,000 per side a scant $40,000 for a pair and roughly $22,000 for installation with freight, tax and paint, if you do not need side cockpit windows will set you back the price of a late model Catalina 36.

Mike, what a great link! Eloquent, concise, authoritative. Thank you. Now I understand.

Steve, I think what you're saying is that, with my marina directly beneath the approach (east wind) and departure (west wind) paths to PDX, there might be good reason to cover my plexi at the end of the sailing day. Seems to me there's a trade-off, though. The sunlight (Ha! When? What sunlight?) helps to control mildew, doesn't it, and so I would have to think twice about blocking it out.

Anyway, a good discussion. I learned a lot. But Mike, it appears you have an opportunity to help our continuing education on this topic. Would you consider photographing your lens replacement process and writing an article for our website's Maintenance section on this topic? You can email me separately on this at LCBrandt (at) coastpilot (dot) com.

Covering the hatches when the boat is not in use is an an excellent idea, and if my hatches weren't already completely crazed, It would be something I would consider. It would also help keep the upholstery from fading.

I recently noticed a nicely outfitted yacht in our harbor with fitted white sunbrella hatch covers. They appeard to have an elastic band that secured the cover under the hatch lid.

This would make a good home business for someone out there, there are a lot of boats out there with Lewmar hatches. . . .

I got this name at the Newport boat show from a fellow who replaces the plastic in the ports.

He is Tony D'Andrea at Select Plastics in Norwalk , Ct. Phone 203-866-3767. You can send in your ports to him and he will replace them.

He told me that it is possible to replace just the plastic or lens in some ports, and he can tell you which windows they are by the serial number on them, but others you wont be able to and get a tight seal. You may want to reach out to him.

The other disturbing piece of news is that if you do replace them, they will still craze (according to him ) unless you cover them, as someone suggested, with a sunbrella cover.

Chuck Parker

All,
The replacement lenses sold by Catalina Direct are Old Style Lewmar Size 1 (5X12). These are Lewmar Part # 360016099 (Smoke Grey Lens).
(Old Style Lewmar ports have the rotating latches and locking hinges)

On Tara, Catalina installed different ports than Catalina Direct carries (Old Style Size 2: 4x14, Part # 360017099). So I went to a Lewmar distributor here in Florida, rigginghydraulics.com to get the lenses. They sell the Size 2 lenses for $34.00 each and they arrived two days after ordering.

I just installed the replacement lenses for Tara's 3 opening portlights this week in less than an hour. It's easy if you have a very small flat-blade screwdriver, a 10mm socket or box wrench, a #2 Phillips screwdriver, and a set of allen keys (can't remember the size key I used).

Use the attached Lewmar Drawings to see the parts as an aid for disassembly.
1. Use the 10mm wrench to loosen each of the three lens retainers (you may need the allen key in the outer heads to keep the bolt from turning with the wrench).
2. Remove the three acorn nuts, thereby removing the lens. Take care not to drop any of the washers.
3. Use the small screwdriver to pry the caps off each latch.
4. Use the Phillips screwdriver to disassemble each latch.

Check all of the o-rings on the hinges and the latches).
Replace if worn or deteriorated.

Now install the new lens:
1. If it is a Lewmar product, one side of the lens will have a slightly carved out circle on one side. That will be the INSIDE of the lens where the latch will turn. The smooth side is where the o-ring will contact the lens. (Put the cutout side on the outside with the o-ring and you will probably have a leaky port).
2. Reinstall the latches, tightening each screw enough that you can still turn the latch.
3. Re-attach the lens to the hinges using the o-rings outside and the washers inside. Tighten each acorn nut with the wrench while holding the bolt head steady with the allen key.
4. Close the lens and twist the latches to lock.

That's all.
Sure glad I save the old Lewmar parts drawings; they are no longer available from Lewar's new website.

Just finished re-installing my old crazed lens...

A few months ago i ordered from catalina direct their "bettter" thicker lens. Disappointly the windows were too thick to close properly. From my experience having the right thickness is important.

Bottom line: don't be tempted by thicker is better lens. My replacements will be exact next time.

Jeff Cote
C36 MkI Hull#1065
Vancouver, BC