problems with windows

[ChasB]

(You can skip the first para)

This seems like it's gone on forever. I have a 1982 Carver with leaky windows at the rear. After a lot of research I found that Bomar do replacements. They're in the US and don't respond at all to customer queries. Seller's market. Dealer's here are C-Quip who (after some tedious explaining that Bomar haven't responded) asked the technical questions on my behalf. Several months into all this (and with continuing leakage into the boat) I order the windows. 4 months and £400 later they finally arrive.

You can see the windows in this pic:

The problem windows are the two at the rear.

They are made of some black plastic. The outer ring on each (which is a bit like a picture frame) was severely cracked. I thought this may be due to age sunlight and the elements. The lenses were looking somewhat aged so I thought it wise to replace the whole window.

Upon removal it was apparent that only the ring was defective, and indeed the lenses are now refurbished to a nice standard (thanks to another thread here). Still, that's boating for you - wasting money needlessly.

I was very careful to mount the new windows exactly like the old ones, even down to the number of turns on the retaining bolts, which turn out to be little more than finger tight. it took two days of careful work. I was very happy with result and drenched it thoroughly with a hose. No leaks.

A few weeks later and there are multiple cracks in the external 'frames', and the boat interior is sopping wet. /forums/images/graemlins/frown.gif

Where did I go wrong? The bolts are little more than finger tight.

The (minimal) instructions state that the surface to be mounted on must be perfectly flat, but it isn't. It bows out very slightly, more so on the foreword one, by about a quarter of an inch!

My theory is that the weight of the flybridge directly above has, over 25 years, forced the GRP to bend slightly, and the window frame is highly intolerant to any bending - the cracks are at the corners where there is most bend.

So how do I fix this? (Apart from giving up and selling the boat!)

I could order some more frames from the US, but that will take another 4 months (of water ingress /forums/images/graemlins/frown.gif ) and the problem will recur. A waste of time.

Or I could make some myself. The shape is simple enough. But what do I make them from? What would be a suitable plastic? Where do I get it from?

Or, and this a radical idea, could I make them out of some high quality marine plywood polished and then painted black? Same questions: what should I use? Where from? What is a suitable varnish and paint that won't crack when bent slightly?

Many many thanks for your patience in reading this, and I would be so grateful for some help. This is so thoroughly exasperating. /forums/images/graemlins/frown.gif


/forums/images/graemlins/ooo.gif

 

[colinroybarrett]

A few thoughts and or remedies:-

Did you use any mastic to seal the windows in? ¼ inch bend doesn’t sound excessive to me, so even with slight cracking, it shouldn’t have been enough to soak the boat?

If the plastic frame is soluble with something like nail varnish remover (ask the Wife) you could try to mix up some filler, using the thick glue used for sticking together plastic plumbing pipe? Grind in some more bits of plastic let it dissolve in the stuff push it into the cracks and if needed paint over the result after letting it all dry and sanded down etc. Or you could simply use black Sikaflex or TEK-7 if you can dry it all out beforehand.

If all else fails and you fancy the ‘handyman bit’ I would go the marine ply route. Make up and fit the frames then bring ‘em back home and using well thinned varnish as a primer give them as many coats as you can before re-fitting to the boat but do use some sealant between the outer frame and hull.

Best of luck, I guess I could have double-glazed a whole house for the amount I’ve spent sealing windows over the years!

 

[santeana]

Have had similar woes. Is there sufficient grp thickness to 'fair-out' and flatten the curve? I take it the windows themselves are not cracking - just the frame. So the windows are flexing as the frame bears down? This was my problem and at least using the above fairing approach have made them watertight, though not happy with the mechanical strength of the fitting.

 

[catmandoo]

What clearance is there on the bolt holes .. . Black Plastic will absorb heat from the sun and presumably will then expand . If there is no room for expansion say in clearance around the bolts then the plastic will become stressed and crack probably on the outside radius of the corners .

What is the actual direction and source of crack propagation . Ie is it from the inside radius outward or the outside radius inward .

If it is due to expansion then perhaps you need a flexible sealant and larger diameter bolt holes

 

[ChasB]

interesting point. The cracks all go outwards from the holes. Kind of implies that the frames have shrunk (?) I countersunk the holes (as the originals were) which I think may have created extra stresses by making the heads act as wedges into the plastic forcing the holes apart.

As to "fair-out' and flatten the curve" That would mean padding out by a quarter inch top and bottom. Ron I would also not be happy with the mechanical strength of the fitting.

The original frames were fitted when the surface was flat, so I think that using the same plastic frames (which may take months to arrive) is lees than ideal.

Anyone got any thoughts on my making these out of marine ply and painting them? The originals are 1" wide. I could easily make that 1.5" for added strength and even a bit thicker. At the same time I could make several more ready for when the other frames crack - as they no doubt one day will.

 

[vyv_cox]

What sealant did you use? A solvent based sealant such as Sikaflex 291 will cause stress-corrosion cracking with certain plastics, particularly poly carbonates. Very small amounts of solvent will cause this problem, ref. motorcycle crash helmets that failed on impact because users had put stickers on them.

I made and fitted polycarbonate windows to a previous boat, using Sikaflex 291. Within a week every screw hole had begun to crack and within a month they had nearly fallen apart.

Check the Sikaflex website. They make a special sealant for this application.

 

[ChasB]

Colin. Missed reading your post the first time around.

The window is directly below where rain water drains off the flybridge. In a heavy storm the flow is such that it is virtually under water. Over a couple of hours this can let a lot of water in. The previous windows were leaky and caused much damage to the interior.

I used Sikaflex 295UV. This is made for the job but doesn't appear to be nearly as 'sticky' as regular sikaflex 291 glue - the black plastic frame is peeling away in a way I've never seen with 291 (which sticks like that woman in Fatal Attraction).

So, no-one sees any probs with using marine ply?

Anyone know where I can source small bits? I don't really need a the regular 2m x 1m sheet!

Thanks for the input. /forums/images/graemlins/wink.gif

 

[santeana]

I think painted marine ply would work and as you say be straightforward to replace if you make a spare or two. You could even sand it to the exact contour. Just a couple of other thoughts that no doubt you've cogicated on; are the cracks in the frames themselves the cause of leaks or is the consequential loss of window integrity? What was going thro' my mind(!?) was fitting a gasket under the frame and then painting the frame with a sealant/paint of some sort. Seems a shame to waste your squids invested. The other thought demands further investment. Would it be feasible to get some aluminium frames made. There are specialists in this line of business that googling or others here could reference if needs be. BTW my "fairing" suggestion was more about shaving material off rather than packing out but guess you've considered that as well.

 

[ChasB]

Cheers.

What would you make the gasket from? Rubber would eventually perish wouldn't it? I would have thought that the frame itself plus sealant should be enough. It was when the surface was flat...

I'm going to start a separate thread on marine ply.

 

[colinroybarrett]

Chas,

Do look at the Vetus Catalogue they supply fittings for almost all boats built in the EU and have a vast range of ‘windows’ ready-made which builders use for fitting in boats, such as ours.

If you call them they will send a catalogue and you will almost certainly find a replacement or they can manufacture to size. Since you appear to have a large amount of water ingress perhaps making the holes in the hull fit the windows may not be such a bad option?

 

[ChasB]

The large water ingress is due to the unfortunate positioning of the window under a drainage hole from the flybridge.

Carvers are made in the US (gawdknows how it got here), but one of the Vetus windows looks like it could be a fit so I might be able to use the associated frame. I'll get the tape measure out. But I'm reluctant to use a plastic frame again if it might break, and I don't want to go aluminium because the rest are plastic. Black painted ply seems to be the only route... /forums/images/graemlins/frown.gif