Companionway hatch windows-what are we using?

DDW

Super Anarchist
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I have swinging doors on removable hinges which swing outward. Just inside are removable swinging screen doors that swing inward. Both can be mounted at the same time and used at will. Outside of the swinging doors are slots for drop boards made from G10. These are installed when leaving the boat for storage (for security and to keep the sun off of the swinging door varnish) or theoretically in very heavy weather. The lowest drop board can be replaced by a step that forms a bridge deck. It has all worked better that any other boat I've seen. No windows but if there were I'd use a UV resistant grade of surface hardened Makralon or similar.

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Grith

Member
344
122
South Australia
My solution is three drop in tinted Perspex wash boards the top one with a fitted opening tinted perspex port light with fitted ultra fine fly screen.
The upper two boards have secondary overlapping tinted perspex water seals and all three slot into a three compartment lined vinyl storage bag attached to the starboard side cockpit seat to protect them when removed.
The lowest piece can be left in and stepped over if required.
The sliding roof opening is made of the same tinted perspex giving a sunroof type feel.
Just my yachts solution to the problem of security, ventilation and light.
Bottom photo viewed from the inside now with an additional hole cut in the bottom panel for feeding in an air conditioner duct. This hole has a black screw in inspection hatch plate to waterproof close it off as the portable aircond unit ( zero breeze mk2 ) is only for very occasional use.🙂
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If they are old it might be better to replace. Must order UV resistant material. Polycarbonate can be shaped with wood working tools and is very tough but even the UV resistant material clouds with sun exposure. Lexan (primarily used) is prone to cracking, more UV resistant and must be worked with special tools. When you leave the boat it is essential to cover all hatches and ports.
 

Startracker

Member
428
116
Van Isl.
Car headlights are polycarbonate. So proceed with a bit of caution following anything that fixes them. For example I use mekp on them. Does as good a job as an mek wash. I'll do that to remove yellowing and failed surface then follow up with a compound and wax.

Usually by the time it's as bad as yours the acrylic is failing internally. So a Polish will only buy you a bit of time and it'll haze faster as well. To check internally without a lot of effort, run water over both sides and look at bright light. Internal crazing means close to failure.

For design, Trevor Robertson has a clever design I'm going to copy. He posted it over on the Alajuela 38 forum.
 

Grith

Member
344
122
South Australia
A simpler method is to bevel cut all the joints so it acts like a shingle. When I've done it I never got a single drip below.
Yes definitely simpler but doesn’t add any rigidity to cope with a wave over the stern or deformation by age.
I had similar on a previous yacht and the much thinner beveled edge chipped when accidentally dropped during removal.
The bevels also moved apart in a high wind storm but have gone up in Perspex thickness since then on the new yacht.🙂
 

Steve

Anarchist
578
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duluth, mn
If they are old it might be better to replace. Must order UV resistant material. Polycarbonate can be shaped with wood working tools and is very tough but even the UV resistant material clouds with sun exposure. Lexan (primarily used) is prone to cracking, more UV resistant and must be worked with special tools. When you leave the boat it is essential to cover all hatches and ports.
I think you are confusing Lexan with Acrylic. Lexan IS Polycarbonate. Acrylic can also be easily worked with woodworking tools but it is better to order specialized drill bits that are readily available.
 

Steve

Anarchist
578
86
duluth, mn
Glass has the best clarity and remains so indefinitely, is stiff but is about twice the weight of the plastic options. Both the plastic options have their problems, Acrylic has the best clarity and is much stiffer than polycarbonate, is easily cut, routed and polished but is best drilled with the readily available specialized bits. t is prone to internal crazing. Polycarbonate is easily worked but it clouds easily and is not very stiff which is why it is not a good choice for large panels like deck hatches or drop boards.
 

DDW

Super Anarchist
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Both polycarbonate and acrylic are families of plastics, and come in a variety of forms. Lexan in particular is a branded product from GE, a version of polycarbonate. There are good and bad versions of both, UV and non UV resistant versions, scratch and non scratch resistant versions.
 

SloopJonB

Super Anarchist
70,197
13,334
Great Wet North
Both polycarbonate and acrylic are families of plastics, and come in a variety of forms. Lexan in particular is a branded product from GE, a version of polycarbonate. There are good and bad versions of both, UV and non UV resistant versions, scratch and non scratch resistant versions.

Correct but both Plexiglass and Lexan have achieved "generic word" status - much like Kleenex is the same as tissue paper, cellotape is Scotch Tape or Arborite is high pressure laminate.
 

DDW

Super Anarchist
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True, but my point was you really can't say "this" is better than "that without specifying what "this and that" are unambiguously.
 

Steve

Anarchist
578
86
duluth, mn
Correct, but as far as i know all versions of polycarbonate have one property which sets them apart from other plastics and that is that they are ductile, which gives them their outstanding impact resistance but also make them a lot less stiff than plastics such as cast acrylic for the same thickness. For uses such as windows and hatches, stiffness is a more important property.
 


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