Crazed Portlights and Hatches

[Salty]

Acrylic Deck Hatches and Portlight replacements on a Bavaria 36 from 2002.

THE PROBLEM.
The Lewmar acrylic deck hatches and portlights on my 2002 Bavaria 36 were so badly crazed, that by the winter of 2017/2018, I had decided that something needed to be done. As they were, the crazing had reached the stage where although the acrylics would allow light to enter the boat, they were pretty much hopeless for being able to see through.

Photo 1 shows how bad the portlights were, while photo 2 shows where adhesive strips applied to the outside of the main cabin hatch had prevented the areas under those strips from crazing.

HISTORY
I bought the boat from its original owner in January 2010. During its previous ownership, strips of non slip self adhesive tape had been applied to all of the deck hatches, and in those areas, the acrylic under the tape had not crazed at all. Conversely, those areas exposed to sunlight had suffered badly.

See photo 2

Something was causing the acrylic to craze, but only in those areas where light could pass through. The boat had two large and two small deck hatches, and of those smaller hatches, one appeared to have been changed at some time in the past. It is not clear which of the two was the original small hatch or which was the one that had been replaced. Obvious differences between one and the other was the type of latching handles provided where both of the handles on the starboard hatch penetrated through the acrylic while on the port side hatch one handle penetrated through while the second handle appeared to be glued to the acrylic.

A further difference was that the starboard small hatch had been covered with a plastic film as well as with non slip tapes, and that hatch had not suffered from any crazing. Unfortunately the plastic film had broken down,  and had not proved to be very long lasting. Fortunately, what was left of the film was relatively easy to remove without damaging the underlying acrylic. At this point the conclusion I’d come to was that sunlight was somehow causing the acrylic to craze. Elsewhere I’d read that stress can cause crazing, so it was possible that heat from the sun where the sunlight could pass through, was causing the acrylic to expand, thereby creating the stress that resulted in crazing. Maybe it was that, maybe it was something to do with UV light, perhaps it was something else, but the evidence was clear that where the sun was prevented or restricted from shining through the acrylic, no crazing took place.

RESEARCH
Enquiries were made from a vehicle window tinting firm to find out whether they knew of a plastic film that could be applied to the outside areas of the acrylics that would stop the sunlight from passing through, and which might last better than whatever had been applied to that starboard hatch.

Initially the window tinting firm advised against the idea on the basis that acrylic apparently tended to give off tiny amounts of gas when warmed by sunlight, and it was likely this that had caused the original film to bubble and break down. However, they checked with their supplier and were advised that a new plastic film was available which would allow those minute amounts of gas to permeate through the film without causing bubbles that might eventually lead to breakdown. So it was decided for my boat that any new acrylics would be covered with this specialised reflective plastic film.

Photo 3 shows the main cabin hatch where a new Lewmar Acrylic lens has been fitted. That lens had been covered with reflective film just prior to installation.

Photo 4 shows the same hatch from inside after the changes had been made.

A major area of concern however was the cost of replacement acrylics, and where in a comment seen elsewhere it had been suggested that when a boats hatch and portlight acrylics needed changing, that it was best to sell the boat to someone else and let them deal with the problem. I have no plans to sell my boat, at least not for several years to come, and so costings for replacement acrylics were looked at. What I found caused a rapid intake of breath followed by a pained exclamation of “ow much??!”
Because of the costs involved, I had no plans on changing any of the aluminium framework.

COSTS USING MANUFACTURERS REPLACEMENT PARTS
From a UK supplier, the costs were as follows:-
Lewmar large hatch acrylic lens, overall size 556 x 556mm complete with new rubber gasket, £197 each of which two were needed.

Small hatch acrylic size 556 x 276mm with rubber gasket at £174 of which one was needed, the other being ok.

Portlight acrylic size 633 x 159mm with Lewmar part number A081620H2 at £177 each of which six were needed.

The two small portlights facing into the cockpit from the two aft cabins were in fair condition so it was decided not to change these for the time being.

Estimated costs so far were
Two large hatches £197 x 2 = £394
One small hatch =. £174
Six portlights £177 each x 6 =£1062
Total £1630

Looking more recently at the SVB website in Germany suggests that acrylics sold there are significantly less expensive to buy than in UK, but then one has to add on the postage charges. Additionally their website, from what I’ve seen of it in regard to hatch and portlight replacement acrylics, is significantly lacking in detail. I’d need considerable reassurance from SVB before ordering to be certain that what I wanted was what I’d actually get.

FIRST ORDERS
My first order for acrylics was to replace a single large deck hatch and was followed up with an order for two sets of portlight acrylics. These were purchased from a UK supplier.

Initially I replaced the main cabin deck hatch, and my window tinting firm applied the acrylic friendly plastic film to both that new hatch and to the smaller starboard side hatch which was not being replaced. Their charge for this was £30 (Mates rate because it turned out I was a friend of a friend)!!

THE FIRST DIY BIT
Taking the deck hatch off and apart to remove the old and replace it with new acrylic was fairly straightforward although it was worthwhile taking a look at one of the “You Tube” videos to gain an insight into the removal of the hinge pins. Once those pins had been removed, this allowed the hinged part of the hatch to be taken off and removed to the cockpit where I could work on it. I also removed the two plastic locking handles as well as the small plastic thing that the friction stay attaches to. Looking now at separating the two aluminium side pieces that hold the acrylic lens in place, there are four small screws on each side which lock the two parts of the framework in place. Those screws were a little unwilling to undo, but nothing that very gentle use of an impact driver was not able to address. (One person I spoke to suggested that it was worth trying to tighten the screws first before undoing them, but I was lucky and they began to unscrew with just a couple of light hammer taps on the impact driver). It was only actually necessary to undo two adjacent screws on one or other side of the join on each side to allow the two sides to slide apart. To assist in the separation, I’d brought a couple of pieces of wood with me that day. One fairly substantial piece of wood was laid on the cockpit deck while the other which was about 800mm long with a cross section somewhere around 50mm x 20 mm was propped under the inner edge of the hatch against one side of the aluminium surround (not the sides with the joins in them) and the whole assembly with 800mm wood hand held in place was gently bumped down onto the other piece of wood I’d laid on the deck. The weight of the frame plus the acrylic lens it held within it did the trick and this was enough to start the process of separating the two halves of the frames on each of the deck hatches as they were worked on. A couple more bumps and the two sides of the frame were separated.

[Salty]

 Acrylic Deck Hatches and Portlight replacements on a Bavaria 36 from 2002. The second part continuing from the previous post.

PROBLEMS !
The portlights however were another matter. Lewmar have modified the port light hinges and catches such that those fitted to new replacement acrylics will not fit the old aluminium hinge supports. Because of this change, new aluminium supports for both the hinges and catches have to be fitted. Removing the old supports is not an easy task, and is made even more difficult by the fact that these supports are held in place with stainless (I think!) screws secured into the external aluminium frame. Over the years there had been some corrosion of the aluminium around those stainless screws making them impossible to undo. Checking around all of the frames where portlights were to be replaced confirmed that many of those screws were not going to be undone easily if at all! If they could not be undone, this would mean having to buy new frames to fit the replacement acrylics, and an already expensive job looked like it was just about to double in price !!

Initially I was unaware of the changes that Lewmar had made, and my supplier had not advised of any differences in regard to those hinge and catch fittings. So when trying to fit the new portlights I found that those differences would not allow the new portlights to shut. Checking with an electronic digital calliper revealed that the measurement from the outside of the portlight to the innermost point of the new hinges was 2mm greater than that of the old hinge system, 29 mm instead of 27 mm and at the time my UK supplier had not provided me with a full kit of replacement parts. The full replacement kit was remedied within the price I’ve quoted above and, with considerable difficulty, I was able to remove the old aluminium hinge and catch brackets and fit the newly supplied ones. I now had two new portlights in place plus one new hatch acrylic, and a smaller existing hatch acrylic which had been smartened up with a covering of reflective film.

See photos 1 and 2 below of the hinge and catch supports

So now being confronted with a possibility that I might not be able to replace my remaining portlights, I began looking at what alternatives there might be.

ALTERNATIVES
Firstly in regard to the second large deck hatch that I wanted to change, having removed one I now had a template which I could take to a local plastics firm to ask them to make me a new replacement. This was done for considerably less than the £197 charged for the first deck hatch, saving me well over £100 off the cost, but with a down side that I had to re-use the original seal rubber. The original seal rubber fortunately was in reasonable order, and so it was re-used. Over the last month rain showers have been very few, but liberal use of several buckets of sea water over the replaced hatch has shown no signs so far of any water leakage.

See photo 4 below.

Secondly in regard to the portlights, even if the acrylic part could be supplied, a major difficulty was immediately evident in that none of the boat window manufacturers that I approached were able to offer a replacement for the Lewmar portlights, let alone one that might be more cost effective than what I’d paid so far. I’m guessing that the main stumbling block was the fact that the plastic hinges and catches used are actually stuck to the existing acrylic windows, and I didn’t know if they could be successfully removed or not. If they were to be re-used, they would have to be very carefully removed, and up to the time of writing this I have not seen these plastic hinges or catches available to buy anywhere. Furthermore, at the time I had no idea what kind of plastic they were made of, or what type of adhesive could be used to stick them back on to a new acrylic portlight.

INVESTIGATION AND EXPERIMENTS
Having already purchased and fitted two Lewmar replacement portlights I now had two old portlights left that I could experiment with. Initially I cut around each hinge with a hack saw, but that was not an ideal solution. So I tried a different approach. With the portlights clamped down onto a flat surface to support the acrylic, and with the hinge and catch fittings uppermost, that with a 6mm carpenters chisel pointed into the “U” shaped area between the acrylic prongs that plastic hinges are attached to and initially at the seam between one of the acrylic prongs and the plastic hinge or catch, that gentle tapping of the chisel with a light hammer resulted in the plastic fittings separating from the acrylic. Gentle tapping here is the watch word, and the chisel needs to be reasonably sharp. The one I used was not razor sharp, but I wouldn’t want to argue with someone wielding it in an unfriendly way either !! First one end of the fitting being worked on began to lift and at that point I turned my attention to the other end. Gentle tapping worked better than impatience, and most of the fittings came away without taking any of the acrylic with them, but often leaving some traces of the adhesive attached either to the acrylic or to the fittings. It was really important at the time that the acrylic was very securely clamped at either end of the hinge or catch fitting that I was about to try to remove in order to ensure that the old portlight acrylic was left intact for use as a template for its replacement.

MORE DIY
Having determined the most efficient method for removing the hinges and catches, most of the removed fittings came away with some of the old adhesive still attached, but careful use of the same chisel and a few light hammer taps enabled removal of the remaining adhesive. I was now left with an intact acrylic template plus six fittings made of ‘er “some kind of plastic !!” Someone more versed in plastics might be able to tell me exactly what kind of plastic those hinges and catches are made of, but please no guesses.

See photos 1 & 2 below.

A BIT MORE RESEARCH
Having removed all of the hinges and catches from one of the old portlights I now spent some time trying to figure out what type of adhesive to use to stick those fittings to the new portlight acrylics that a local manufacturer was about to make up for me. In the meantime I had discussed the matter with several users and suppliers of plastic adhesives and had come across a Structural Acrylic Adhesive called “Partite 7300 (MA300) consisting of a product called Methacrylate. This costs a little under £10 on eBay from a seller called “e-Teck”for a 50ml twin pack of the adhesive and hardener. This I used in a test securing of one hinge to the leftover old acrylic portlight. To say that I was impressed, is a gross understatement, indeed it is so strongly attached that I believe it has more permanency than the proverbial brick built outside toilet !!

Partite 7300 is a two part adhesive mixed at a ratio of one to one. The seller, whom I phoned and spoke to, advised that it had a working time of about ten seconds from start of mixing to getting the fitting held in place before it began to cure. So if you intend to stick six fittings into place on an acrylic portlight blank, you need to be pretty quick. Having used the adhesive it was my opinion from my first mix that there was probably a little more leeway than ten seconds, and so some twenty or so seconds after my first test gluing of a hinge in place, I gave the remnants of the mix another stir and placed the metal mixing tool that I’d used onto those remnants. An hour or two later when I went to have a look at my handiwork, that tool could not be separated from the mixing palette, though I didn’t try too hard at that stage as the mix may not have have cured. I did try very very much harder next day, and couldn’t remove either the hinge or the mixing tool from where each had been stuck.
I’d found a satisfactory adhesive, but it’s application considering its limited working life was still an area for concern.
In discussions with E-Teck, they were extremely helpful by the way, they suggested I buy from them a £16 glue dispenser and some mixing tubes. These tubes fit to the outlet from the twin tube adhesive container, and as the adhesive passes through the mixing tube it arrives at the nozzle ready for use. On the basis that each fitting would take probably a tubefull of adhesive, I figured that so long as I didn’t waste any time I’d be able to apply adhesive to the first fitting and press it correctly into place while the adhesive on its way down the mixing tube remained within its working life ready for the next fitting. So don’t hang around once you start !! My theory worked and after all of the fittings were attached to a port light the used mixing tube was then discarded and the cover replaced onto the twin nozzle of the adhesive container. I marked both the nozzle and the cover on one side so that the cover was always put back on the same way round in order not to contaminate the adhesive outlets.

IN FOR A PENNY!!
Four portlight acrylic blanks were ordered from the plastics firm. The old portlight from which I’d carefully removed the hinges and catches was used to make a CAD drawing, presumably for controlling their machinery in order to cut out the replacement acrylics. A few days later I collected the blanks and set about preparing each of the fittings in readiness for gluing into place. While waiting for the blanks to be made I spent time working on the removed hinges and catches in order to clear away as much of the old adhesive that remained. The carpenters chisel and hammer were ideal for this, and finally checking that the measurements of 27mm referred to earlier were retained. They weren’t, but I managed to get between 27 and 27.5 mm which I thought the seal rubber would likely accommodate. It did, just !! But I’m going to get another 0.5mm taken out of where those fittings attach to the acrylic in any future blanks that the plastic firm makes.

ASSEMBLING THE PARTS
Where the hinge and catch fittings were to be placed, the acrylic had been machined to provide a recess, and you will see from the photos that each of the plastic fittings was shaped so that they would fit to the ends of the horns projecting from the top and bottom edges of each portlight. It was important that the distance between the outside face of the portlight and the innermost point on each hinge or catch was 27mm as measured earlier in this description. Mine in fact were just slightly more at around 27.5mm making the portlights a bit of a tight fit when they are shut, but they didn’t leak when given the three buckets of sea water test !!

See photo 5 below
The photo here shows one of the new replacement acrylic portlights with plastic fittings securely glued in place and fitted into one of the portlight openings on my boat. The original protective plastic film was left in place for the time being, but it will of course be removed at final fitting.
In addition to the discrepancy referred to above, the hinge and catch positions at each end also need to be moved closer to the centre hinge and catch positions by about 1mm. Minor adjustments were made with the use of a file, and all four portlights were fitted into place and secured, albeit temporarily as they were then removed to go to the auto tinting firm for reflective film to be attached. The size adjustments will be advised to the plastics firm so that they can modify their CAD drawing. In addition I will also ask them make me one more new portlight blank that I can then make up and check that it fits without further need for adjustment, and will then hold it onboard as an “in case of emergency” spare.

CLEAR OR TINTED ACRYLICS ?
The hatch and portlight blanks that I have had made up have been in clear rather than tinted acrylic as this was what the plastics firm either had in stock or was readily able to obtain. I don’t know whether a tinted acrylic would involve different costs, but clearly if only one or two small parts were needed, the plastics firm would need to recover the cost of a sheet of tinted plastic if there was little likelihood of being able to use the rest of the sheet of material.

As mentioned earlier, I’ve had a car window tinting firm fit a reflective film to my acrylics in order to reflect sunlight, and this also serves to provide a form of tinting visible from inside. From outside the hatches and portlights appear reflective. This increases internal privacy while on a marina berth, as well as reducing the transmitted heat from the sun, thereby keeping the cabin cooler. That reduction in sunlight will I suspect also reduce fading of internal fabrics and of the mahogany finish to the internal woodwork. Hopefully it will also stop the acrylics from crazing, but the longevity of the coating remains to be seen.

SUMMARY,
on the plus side:-
1. What I’ve done so far, has got around the need to remove and replace those aluminium hinge and catch fittings which Lewmars modified replacement acrylics have demanded, but which are so difficult to take out from the older boats where corrosion has resulted in the stainless screws becoming seized in place.
2. It has very significantly reduced the cost of fitting replacement acrylics on those boats that have been fitted with Lewmar hatches and Portlights, such that when the time comes to replace those acrylics, that “Selling the Boat” should no longer be a consideration !!
3. It has removed the awful crazed acrylics and has allowed me the pleasure of being able once again to see out from within.
4. At the completion of this exercise I will have one spare ready to fit portlight carried onboard for that emergency occasion.
5. The new portlights are made from slightly thicker material, so arguably they may be stronger and more resilient than the originals, but no guarantees!
6. My plastics firm have CAD drawings for controlling their machines and machining such that should readers want to try doing things themselves, that replacement blanks for the two sizes of acrylics I have ordered from them so far will be readily available.
7. The plastic film provides for greater privacy while on a marina berth, as well as reflecting the sun and thereby helping to keep the cabin interior cooler, and hopefully prevent or reduce the rate at which the acrylics start to craze.

On the negative side :-
1. I have no assurance that the acrylics made up partly by my plastics firm and partly by me are strong enough to survive seriously bad weather, but I’m very very impressed with the strength I’ve seen in them so far.
2. Should one want to remove the hinges and catches from one of the newly made up portlights, they will come apart as I’ve already checked that, but I can assure the reader that it will be nowhere near as easy a job to take them apart as they did from the original portlights.
3. For those of you who may wish to go down this route you will note that I’ve not been specific yet about my actual costs for the acrylics, but after I have spoken again to the plastics firm I will hopefully have a figure for individual hatches or portlights to be able to report back, likewise also for film covering if it should be required.
4. For those of you that want to go down the same route, you have the somewhat daunting task of removing those plastic fittings from your old portlights, cleaning them up to remove most of the old adhesive, and then sticking them to your new portlight blanks. Not a job for the faint hearted, but very much lighter on the pocket.
5. Can’t think of anything else, but I’m sure you the readers can.

The large deck hatch acrylic held on CAD refers to one made by Lewmar where the hatch size is given as 556 x 556mm with two openings for securing handles on one side and with a separate oval opening opposite to enable a plastic fitting to go through to which a friction clamp controls and holds the hatch open to where you have set it. The actual acrylic size for this hatch is 520 x 520mm overall, or 500 x 500mm from inside frame edge to inside frame edge when viewed from outside.
The portlight acrylic held on CAD is similar in size to a Lewmar portlight bearing the part number A081620H2, and measures 633mm x 159mm to the ends of the horns or prongs that hold the hinges or catches in place. The nominal depth of the portlight opening is 131mm.

If anyone should be interested in ordering replacements for the above sizes of hatch or portlight, send me a private message and I’ll discuss your requirements with the plastics firm and get back to you. Should you have different sizes of hatch or portlights that you want to replace, the first person ordering would need to send an acrylic sample so that it can be accurately measured up for its replacement, costed, and of course carriage charges would be involved for all orders.

July 3 2019 update regarding the adhesive.
Browsing the adhesive sellers website a few minutes ago, I saw they had an almost identical adhesive namely Partite 7310(MA310) which has a longer curing time of 15 - 18 minutes. This would take the pressure of getting all of the hinges and catches in place before the adhesive became unworkable. See the last photo below for details. The adhesive is available through eBay.

[Yngmar]

Thanks Salty, excellent write-up.

I feel very glad my boat came with Rutgerson portlights and Gebo hatches 

[Odysseus]

Well done Salty, good article, another crap product with a work around.

Odysseus.

[MarkTheBike]

Fantastic article, Salty, very well done. Tons of info and clearly explained. How's the writer's cramp?

[Salty]

Thanks Yngmar, Odysseus and Mark, your comments are greatly appreciated. I wish I could have done a YouTube video of the DIY bits, as the DIY stuff is really not difficult to do if one is reasonably handy with a small hammer and a narrow bladed chisel. The difficult bit was to take the plunge and have go, knowing that if it all went pear shaped that I was about to wreck a usable (even if badly crazed) portlight. As it happened the hinges and catches came off easily, and I got really lucky in finding a suitable adhesive.
I have yet to go back to the plastics firm to get them to modify their CAD drawing of the portlight lense, and that modification will change the portlights from needing some minor trimming to a straightforward fit. The deck hatch fitted perfectly first time, so they can be turned out whenever needed. The one remaining small deck hatch will be done over the next winter.
Thanks again guys.

[Ricd]

Thanks Salty, excellent write-up.

I feel very glad my boat came with Rutgerson portlights and Gebo hatches 

Interesting like you my hatches are Gebo and ports are Rutgerson (2000 B34).  Just last week we were rafted against an identical B34 (2002 build) that had Lewmar hatches and i assume likewise ports as the external frame was a dull brushed aluminium rather than SS. The owner asked how we maintained ours which are very slightly crazed only while the Lewmars were like frosted glass.  Answer was we don't really It must be down to the different manufacturer choice of acrylic?

[Salty]

Yes, that is interesting as to why some acrylics craze like mad while others don’t. One of my  Sailing friends has a Dufour 41 of the same age or slightly older than my B36, and his portlights and Hatches are all perfect while mine were like frosted glass, until I changed them !!

[MarkTheBike]

...The deck hatch fitted perfectly first time, so they can be turned out whenever needed...

Hi Salty

I've had a look at my deck hatches and they are a different style, with hinges either side of the centreline rather than a hinge in the middle. Having worked with the acrylic now, would you think a 'blank' (i.e. without the hinge cutout) is modifiable using hand tools - drills, chisel, file, rasp, sandpaper, etc? If so, what information would the plastics company need to make them, and in what form? Drawing? Spreadsheet? CAD file? Back-of-an-envelope? Also, at some point, I have to replace my companionway hatch as it's damaged. Again, do you think they could supply? These can be jobs for the winter but it would be good to find out.

Interestingly, both my hatches (Lewmar, like Ricd's) are crazed but none are of the portlights (Rutgerson) or companionway (?) acrylics.

Cheers 

[Yngmar]

All of ours are tinted acrylic. Maybe that protects the acrylic itself from UV damage? It certainly protected the interior varnish, which is still fine except for a few areas that are worn from use.

[MarkTheBike]

All of ours are tinted acrylic. Maybe that protects the acrylic itself from UV damage? It certainly protected the interior varnish, which is still fine except for a few areas that are worn from use.

Interesting, Yngmar. Mine are also dark tinted but, as mentioned earlier, look like a smashed windscreen so it didn't help in my case . My failed acrylics are Lewmar, is that the same for anyone else or are there different manufacturers whose acrylics go crazy?

[Salty]

Hi Mark,
I’m a little confused. You say your hatches are Lewmar, and that suggests to me that they must be similar to mine, but then you say they are different. Any chance you could take some photos please both inside and out.

Like Yngmar’s hatches, my hatches and portlights were all dark tinted, smoky rather than green, but the tinting had not prevented the acrylic from crazing. I don’t know if Lewmar produce hatches or portlights where there is a choice in regard to how dark the tinting may be. I’d assumed the choices were simply smoky, green or clear, full stop. What did stop the crazing was the non-slip tape that had been stuck to the outside of the hatches and in one case some plastic film stuck to one of the hatches.

[Ricd]

...The deck hatch fitted perfectly first time, so they can be turned out whenever needed...

Interestingly, both my hatches (Lewmar, like Ricd's) are crazed but none are of the portlights (Rutgerson) or companionway (?) acrylics.

Cheers 

Correction, my hatches are Gebo (not crazed).  The ones that were crazed on the identical boat we rafter to were lewmar.

Also both my hatches and portlights are tinted (blown) and likewise intenal woodwork has not been bleached by the sun.

[MarkTheBike]

Hi Salty
Only pic I have at the moment but am going down later so will do some better ones. I think both hatches are identical but will confirm dimensions, etc. asap...
Cheers

[MarkTheBike]

Correction, my hatches are Gebo (not crazed).  The ones that were crazed on the identical boat we rafter to were lewmar.

Oops, serves me right for skim-reading. Silly me...

[Salty]

Hi Mark,
From your photos you have Lewmar hatches. They are hinged in the same way as mine, but on your larger hatches you have a different stay arrangement for propping the hatch open. Subject to overall measurements being the same, the plastics firm would be able to make new blanks for you that did not have a cut out area for the friction stay that I have. Also if you were to make a paper template of the entire upper surface of the hatch acrylic within the boundary of the aluminium frame, and showing the exact size, location and shape of the cut out for your hatch stay and the precise location and shape of the cutouts for your securing handles, then I’m sure they could produce new acrylics to suit your large hatches. In regard to the smaller oblong hatches, I notice that yours are not fitted with securing handles that go right through the acrylic. Assuming they are the same size as my oblong hatches then they should be easy enough to produce without the holes for the handles, but while your handles would need to be glued back on, what I’m not sure about is whether the acrylic has a machined out recess for those handles to fit into. One of my smaller oblong hatches has a combination of one through fitted securing handle and one glued on handle, while the other identically sized hatch has two handles that both penetrate through the acrylic. Don’t ask why, the boat was purchased second hand, and there was no history provided with it. As it was an ex charter boat I do suspect there may have been some movement of portable parts between boats and between agreement to buy and handover dates 🤢

Going on to Yngmars comment about the tinted acrylics having prevented fading of the interior surfaces, my companionway hatch has a smoky brown tint, but the wooden companionway bulkheads either side of the steps are both noticeably faded. The problem here however is that because the hatch would have been open for part of the time its not possible to be entirely sure whether the hatch tint provided protection or not. Strangely neither the companionway hatch or door on my boat are crazed !!!!

[MarkTheBike]

Hi Salty
Yes, as you say, the stay is a bar fixed to the acrylic that runs through a friction handle attached to the coachroof frame. I'll take more photos of the inside to post up, and check how the small hatch handles are attached. Not got long down there today but will do drawings/dimensions asap.

All my acrylics are tinted brown and there is no discernable fading inside anywhere (after 12 yrs in Guernsey and 5 yrs in Plymouth) so I suspect it's the tint that stops fading and the manufacturer's choice of acrylic that determines whether they craze or not. My companionway hatch and 'door' are tinted, have always faced south and are not crazed. Also, the interior wood nearby doesn't appear faded at all but the hatch is left closed for long periods. From what I remember of our past charter boats, those are always left open unless it's tipping down or nighttime.

I'm curious about one of your earlier comments that some film on the acrylic had prevented crazing. Was it a clear film? If so, I'm intrigued.

[Jeff Jones]

Hi Mark, just seen your photo above... we have the same boat only a year apart (yours newer) My hatches have Gebo labels  and the outside handles are different to mine.. and no crazing at all..

it defiantly seems that Bavaria just fit what ever hardware they got the best supply deal on at the time

Jeff

[Salty]

Hi Salty
Yes, as you say, the stay is a bar fixed to the acrylic that runs through a friction handle attached to the coachroof frame. I'll take more photos of the inside to post up, and check how the small hatch handles are attached. Not got long down there today but will do drawings/dimensions asap.
.
.
I'm curious about one of your earlier comments that some film on the acrylic had prevented crazing. Was it a clear film? If so, I'm intrigued.

Hi Mark,
If you measure the dimension of the upper visible surface of the hatch between the aluminium framework surrounding the acrylic, I can compare it with the measurement of my old acrylics which I’ve not yet thrown away (I’m going to try polishing to see if I can remove the crazing that way, but I’m not hopeful).
As for the film covering that had been placed over one of my hatches before I bought the boat, I’m really not sure whether it was clear or tinted, the remaining pieces were small where it had almost completely broken down, and in removing the stuff I didn’t keep or examine what came off. It may have been tinted, but that’s only a guess.

[MarkTheBike]

A quick note -
  Jeff, that adds to my thoughts about manufacturers and acrylic choice. I hadn't thought about it before but as you say, our boats are almost identical so Bav were fitting hardware to hand rather than to plan.
  Salty, I'll upload details/photos later but whilst there yesterday, I had a really close look at the crazing and now I'm not so sure that the cracks are caused by UV. When I put my finger behind the acrylic, I could clearly see the crazing is shallow (< 1mm) and so wonder if it's possibly caused by heat-induced stress of the outer surface rather than UV. Assuming acrylic is an insulator, the sun side would heat more than the interior side, generating internal stresses and so the integral strength of the acrylic is more important than its UV resistance. Possible??? Does anyone out there have a boat 10+ yrs old, in a cooler environment with Lewmar hatches that are crazed?
  In the interim, the visible acrylic dimension from the outside L & W is 514mm. Outside of that is a 4mm rubber bead and then the aluminium frame. Hope this all helps...

[Symphony]

Thanks Salty, excellent write-up.

I feel very glad my boat came with Rutgerson portlights and Gebo hatches 

Interesting like you my hatches are Gebo and ports are Rutgerson (2000 B34).  Just last week we were rafted against an identical B34 (2002 build) that had Lewmar hatches and i assume likewise ports as the external frame was a dull brushed aluminium rather than SS. The owner asked how we maintained ours which are very slightly crazed only while the Lewmars were like frosted glass.  Answer was we don't really It must be down to the different manufacturer choice of acrylic?

I suspect like my 2001 37 your original hatches were Rutgerson like the ports but were a disaster as they leaked around the seal the acrylic was set in. They were all replaced under warranty with Gebo and then new boats used Lewmar. It took a year for mine to be replaced and the table still has a crack in the veneer caused by the puddles of water!

[Salty]

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  In the interim, the visible acrylic dimension from the outside L & W is 514mm. Outside of that is a 4mm rubber bead and then the aluminium frame. Hope this all helps...

Hi Mark,
Your hatches are of different dimensions from mine where the external visible acrylic dimension is 500 x 500mm with an overall dimension measured once removed from the aluminium frame of 519 x 519mm. In this case the only safe thing to do would be to remove the acrylic in order to provide an accurate template for the supplier to match. I did this with my hatch and covered the opening with a sheet of plywood bolted through to a temporary timber strong back placed under the cabin top. The plywood was then covered over with a sheet of heavy duty plastic from a garden or builders waste bag in order to keep the rain and hopefully any light fingered visitors out.

[MarkTheBike]

Hi Salty
I had a feeling that might be the case as soon as I measured it. OK, well this will have to be a back-burner for a few weeks as life, once again, is interrupting me!
Cheers all, ufn

[Salty]

For those of you that read through my original postings on this subject, you may remember that I mentioned in regard to covering the acrylics with plastic film to prevent possible UV damage from sunlight, and that the window tinting firm had initially advised that acrylic gave off tiny quantities of gas which until then the ordinary films could not cope with. Well today I read an article posted on the BBC News App about some research carried out by Dr Sarah Jeanne Royer. In her research it seems that most, if not all plastics give off methane and other ozone depleting gasses.

In her article the following statement was found
“What's causing these emissions?
In short it's the Sun. Solar radiation acts on the surface of plastic waste. As it breaks down, it becomes cracked and pitted, these defects increase the surface area of plastic available.”

At the time she was only looking into what was happening with waste plastics, but my contention is that it must be happening to all plastics, and starting from the moment of manufacture.

Perhaps we should start to insist on Portlights and Hatches being made from suitably toughened glass which won’t craze and won’t give off ozone depleting gasses, but then isn’t the whole boat hull made from plastic?  🤢

[Ricd]

For those of you that read through my original postings on this subject, you may remember that I mentioned in regard to covering the acrylics with plastic film to prevent possible UV damage from sunlight, and that the window tinting firm had initially advised that acrylic gave off tiny quantities of gas which until then the ordinary films could not cope with. Well today I read an article posted on the BBC News App about some research carried out by Dr Sarah Jeanne Royer. In her research it seems that most, if not all plastics give off methane and other ozone depleting gasses.

In her article the following statement was found
“What's causing these emissions?
In short it's the Sun. Solar radiation acts on the surface of plastic waste. As it breaks down, it becomes cracked and pitted, these defects increase the surface area of plastic available.”

At the time she was only looking into what was happening with waste plastics, but my contention is that it must be happening to all plastics, and starting from the moment of manufacture.

Perhaps we should start to insist on Portlights and Hatches being made from suitably toughened glass which won’t craze and won’t give off ozone depleting gasses, but then isn’t the whole boat hull made from plastic?  🤢

Having said all that Salty, from the posts here the Gebo hatches are not crazing to any significant degree while the Lewmar ones appear to be frosted after only a few years.  That points to a variable in the materials used by the two companies.  No need for glass, just Gebo acrylic.  My hatches ar 18 years old and have little crazing.