Window re-mastic

[BrayfordJon]

Hiya,

I need to take out, re mastic & replace the windows in my boat (Seamaster 27).

I am a little wary of this as I trashed a boat taking the windows out once (all the screws into the metal windows had corroded- so I ended up having to drill them out- queue much slipping of bit, case hardening of the metal- oh it was aufull...).

Anyway, I think this will be much easier- just wondering if any wonderfull soul out there knows of any picky based instructions on how to do this?

I have got some mastic roll from a caravan supplier, as this is supposed to be longer lasting as it gives a more solid run against moisture.

One on line thing I have seen suggests laying the mastic with the screw holes central to the mastic- I would have thought lay it so when compacted the edge is in line with the edge of the window exterior to stop the water at the edge...?

Any thoughts, resources, ideas, tales of woe appreciated.

Rgds, J.

(One day it will stop raining!)

 

[davidbfox]

I am in the middle of doing mine on a Snapdragon 747. I did the two small ones last year using butyl in a cartridge supplied by Eagle Boat Windows. They no longer leak! I have to refit the two large ones this weekend agfter having them reglazed. Again I am using butyl. Last time I put in far too much and had a lot of cleaning up to do. EBW recommend a 6mm bead of mastic along the run of the screw holes, which will compress and squidge to fill the whole flange.

If you are using a rubber strip, I guess where you put it will depend on how wide it will expand, if at all, when compressed.

 

[BrayfordJon]

Hiya-

Thanks for the reply- seems like this is an unpopular topic!

Mine are alloy with screws through into wood - maybe with a strip of alloy in front of the wood.
I have gone for the mastic strip option- hoping that is the right one!

 

[Martin_J]

Hi

What you might need to think about is 'what will stop water going into the screw holes?'...

A strip of sealant tape all around the window will stop the water getting past the frame edge... but water might follow the screw. It's the same when using a tube of sealant.. easy to squeeze around the frame but the screw will still need some sealant on it otherwise it will just push the new sealant through the hole.

If you have aluminium frame and the screws are holding the window in place.. then the sealant does not have to act like a glue. If this is the case then as David just suggested, check out a Butyl based sealant that will be much easier to remove whenever the time comes. Arbor Mast BR is the best example.. easy to work with.. sticks well.. but never sets solid. It's what was holding my windows in (I believe) and it was a really quick job to take out the old window, clean up and refit.

 

[Kyle2]

I fitted new windows last winter to my boat, also a Snapdragon 747. I used an adhesive closed cell foam strip to seal them. The foam strip was roughly the same width as the inner flange on the window frames, so I aligned the strip with the window edge, and the screw holes then also went through the foam. I made holes in the foam, smaller than the screws, so that the foam tends to seal around the screws. I also put a dab of clear silicone sealant on each screw before it went in. So far, no leaks!
If your sealing strip doesn't reach the edge of the frames, you could perhaps fill the gap with some clear silicone after the frames are fitted?

 

[BrayfordJon]

Thanks for that guys- more food for thought!

Putting a mini-hole in the strip for the screw is a good idea- I was wondering how to align properly (obviously once you have a couple of screws in you are fine, but untill then...!).

I have a mastic gun - again from the caravan boys- which is what they recommend- clear or white. So I am thinking mastic tape to edges, aligning holes, then a fill in on any extra space with the gun stuff, and a blob on the final bit of each screw. Then some razor blade action!

Apparently a corrosion inhibitor is advised in the American market for stainless to alloy contact- so I'll get some of that too.
I suppose some acitate (or is it acitone) to cleanup any gone off stuff as well prior to re-fitting; again in the US stuff they talk about amonia?
Oh no, that sounds like a trip to the overpriced chandelry....