Both of the skylights on my 2002 Hunter 356 are needing to be replaced. It sounds like they no longer manufacture this style, so does anyone know how to go about replacing them, can a replacement simply be cut out of a piece of plexiglass?
deck skylight replacements for 2002 hunter 356
- Thread starter Seneca
- Start date
Why do they Need replacement? Leaking? Weathered?
If leaking only you may be able to remove & rebed Only. I replaced my skylight a few years ago. Ordered rough cut cast acrylic from TAP plastics and used the old lens as a template to router a new lens. If you are not comfortable doing it yourself, have a local plastics guy supply & cut for you. I used 3 M heavy duty double sided tape to adhere the lens in place & back filled with Dow 795UV.
I replaced the four lenses on my deck hatches using modern polycarbonate that is UV and scratch resistant. I prefer it over cast acrylic but that is also a good material to use, and a whole lot less expensive. I used the Sika bonding system which is much stronger than the Dow 795UV system - but it depends upon how your lenses are mounted. You may not need that.
The reasons for my choices were based on my boats lens geometry and the fact I was heading off-shore. Your sailing needs may be different.
Totally agree with @BigEasy - you need to let us know why they need changing. I also used the old lenses as patterns and cut the new material using them as templates. It's not really hard to do - just a bit fussy. The hardest part, I think anyway, is getting the old lenses out in one piece and then cleaning up the surfaces where the new lenses will reside. You do need to be aware of space tolerances allowing for expansion and contraction between the lens and the frame.
dj
p,s, I'm attaching the Sika installation guide for your reference.
The reasons for my choices were based on my boats lens geometry and the fact I was heading off-shore. Your sailing needs may be different.
Totally agree with @BigEasy - you need to let us know why they need changing. I also used the old lenses as patterns and cut the new material using them as templates. It's not really hard to do - just a bit fussy. The hardest part, I think anyway, is getting the old lenses out in one piece and then cleaning up the surfaces where the new lenses will reside. You do need to be aware of space tolerances allowing for expansion and contraction between the lens and the frame.
dj
p,s, I'm attaching the Sika installation guide for your reference.
I am not a fan of Sika bonding system. Very expensive compared to Dow product because special cleaner and two primers are needed. The primers & cleaner are more expensive than the sealer! With the Dow product only one primer is needed. And, the most important reason for my dislike of Sika, after meticulous prep & installation, the seal failed in less than one year as evidenced by leaks. The 3/4" seal border discolored (mildewed) shortly after installation & was unsightly. Dow 795 seal is still leak proof after four years with no discoloration.
Cast acrylic is often recommended due to a lot of reasons. However, the mechanical properties are nowhere near that of polycarbonate. If you are interested, I could go through a detailed list of the pro's and con's of each. Just let me know if you'd like to...
I buy from Mcmaster as I can get individual pieces that are close to the size I need hence keeping the cost down - to a degree...
McMaster-Carr
McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
For comparison, here's the list for cast acrylic
McMaster-Carr
McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
Just picking a size, say a 12" X 12" 1/2" thick polycarbonate is about $97 and the same size for cast acrylic is about $40.
So there is a notable price difference, depending upon how many you need, that can really add up.
dj
I've heard this same complaint from others. Talking with folks in my boat yard, they all agreed that the Sika system is a much better system in this application. If you look at the adhesion numbers, the Sika system is at least an order of magnitude of better than the Dow product. I just looked and don't see the numbers, but I have them somewhere...sorry...
I've used the Sika system not only on my current boat but previous boats and have never had this problem. I've always had very good success. Don't know why. I will say I am meticulous in my surface preparation and in the application of each step watching very carefully the timing requirements listed in the application document I posted. I've never seen the discoloration mentioned so I can't comment. I've got something like 20 years of working with the Sika product and have never seen that adhesion problem with anything I've installed. I definitely want the added adhesion strength working with polycarbonate given the significant increase is that materials strength. I'll add in, I've only done this with polycarbonate, so I have no experience using cast acrylic. Could that be a difference?
For sure the various treatments needed are more expensive. I think it cost me about the same as the polycarbonate for two of my hatches.. sick..
I especially hate the fact once you open the activator, it has a short shelf life and you end up not using most of what you get. When I did my current boat, there was another person in the marina doing their hatches also so I gave them my open can of activator. I hate to see it just get thrown out.
dj
My complaint about adhesives, in general, is just that people sometimes use an adhesive when they really just need a sealant. That is, if a thing is meant to be bolted/screwed on, and does not require the adhesive for integrity, then no need for an aggressive adhesive. I die a little each time I go to remove a deck fitting to find it was bonded with some Mega-Bond 3000.
Skylights are a good example of where I would not want an adhesive, but instead, a good flexible sealant. For this application, adhesion properties are nearly insignificant. I would be inclined toward 3M 4000UV, or similar.
Skylights are a good example of where I would not want an adhesive, but instead, a good flexible sealant. For this application, adhesion properties are nearly insignificant. I would be inclined toward 3M 4000UV, or similar.
How are the skylights held in? In the OP's image, the skylight on the starboard side, the white framed one does not look like there are any mechanical fastening hold that lens in. I can't tell with the black one on the port side.
My hatch lenses simply float on the hatch frame. I absolutely need an adhesive.
dj
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Same with my application. The lens sits in a recessed area with no mechanical fasteners. Definitely need adhesive & sealing capability.
The skylights on Beneteaus are very problematic. Would have been better to simply place two Lewmar deck hatches for lighting the cabin interior & benefit of increased ventilation as compared to the fixed acrylic lens.
Well.... you used the word "longevity".... That's a bit of a problem word in this conversation. It's hard to know if the longevity of the polycarbonate is more than the cast acrylic. I'd say the modern polycarbonates may be close to on par with cast acrylic. But specifically longevity is probably the single advantage of the cast acrylic over polycarbonate - in terms of UV degradation.
Historically, it was hands down better, hence why it is still so often recommended. The older polycarbonate formulations were quite UV sensitive. You would get clouding in a few years compared to cast acrylic lasting 10 or more years. I had a boat in the '80's that I put polycarbonate windows in and in about 6 or 7 years they were really cloudy.
It's still to be seen if the modern polycarbonate formulations perform as promised on the UV resistance front. But I figure if they are good for at least 10 years, that's OK with me.
For me the reason to use the the polycarbonate over cast acrylic is that cast acrylic can shatter while with the same forces, Polycarbonate will just laugh...
Of course, recall, I'm looking at a boat that will be in the ocean getting hit with whatever mother nature throws at you. I want that added security of added mechanical properties... I'm hoping for excellent longevity.... I can say that my current hatches are still perfectly clear same as the hatches on the last boat I did this on. So that last boat is now close to 15 years with those lenses, but, it's in northern climes and not in the tropics. That could make a big difference. I have spent close to a year in the tropics with my current boat so I've got my fingers crossed...
dj
The skylights are crazed. I should also add that they are not perfecly flat. There is about 1/2 curvature in the surface from side to side. Because of the curvature, I'm not sure that fabricating replacements out of flat stock will fit the opening properly.
Both acrylic and polycarbonate can be quite easily shaped by applying heat. (Be sure to read up on a few minor safety caveats.) You would not want to heat it in-place because you will likely get a sag in the middle, though there are ways to prevent that. The absolute easiest way to do it is build a little jig that the negative of the curve you are trying to follow. Then, heat an oversized piece evenly with a heat gun so it settles into jig. Then, cut to size. It is actually super easy as long you don't get impatient.