Techniques to rebed dead lights (windows)

[hellosailor]

Wheels-
www.sikacorp.com (global hq) aka www.sika.com

Or http://www.sikaindustry.com/ the US branch, which also has links to global sites.

[GordMay]

Wheels:
I e-mailed Sika International, asking how to read a manufacturing date stamp code. I received a return phone call from Sika Canada within 2 hours (at their start of business day).
If you email the actual code numbers, citing Sikaflex 295, Mary will get back to you. (She wasn’t specifically familiar /w 295).
Write:
henry.mary@ca.sika.com

[Sunspot Baby]

I just received my Sikaflex 295. There is a date on the tube under the UPC that says Best before: 02/2007.

So at least on U.S. sold fairly new production, there is a date.

George

[Alan Wheeler]

Hmmmm, interesting. Thanks Guy's. We have been told that the serial No. on the tube is how the date works and not the funny symbol at the bottom. So at least we are one step ahead. However, there is no "best before" marking nor any other form of date on the tubes. And anyway, the serial No. still means the tubes are either beyond their use by date or close to it. Some are as old as 2005. The other isssue is, we would like to assume the serialNo. is the production date. But not sure. As we understand it, the serial No. will start with the first numeral determining year and the second the month. So if it was say 53***** then it is 2005, 3rd month. I am presuming the folowing No. are batches and product ID and so on. Is that correct Gord???

[GordMay]

Alan:
I don't know, for certain.
Ask Mary at:
henry.mary@ca.sika.com

Regards,
Gord

[svChezFreddy]

An answer to original question of thickness of bedding compound: Working on a rebedding project in Trinidad, a local shop suggested using wooden match sticks. Put the tip of the match stick slightly under the flange at each screw/bolt. Tighten until match stick starts to tip up from pressure. Stop and leave it for 24 hours. Pull out the match sticks and tighten down. You can caulk the dimples left by the match sticks if you want. I haven't tried it, but it sounds like a great technique.

[Sunspot Baby]

Sika wants spacers of "at least" 3/16". Their preference is to run a bead of 295 the proper thickness, then let it cure. That can be placed and left in the bead of sealant around the pane.

Getting a consistent bead of the right thickness sounds a little tricky to me. I have some O’rings 3/32 thick. I plan to put two on about every 2nd or 3rd screw. Sika’s concern about a thick bead is to allow enough flex for thermal expansion differences in substrate. I am still seeking better alternatives, but am very close to starting the project so if I don’t find something soon, I’m going with the O’rings.

Some people have used tile spacers, but those would seem to be pretty hard and not flex enough when the screws are snugged up on the finished product.

Does anyone know the coefficient of thermal expansion for acrylic, poly, and fiberglass?

George

[GordMay]

Typical Linear coefficient of expansion for common Plastics:
http://www.edl-inc.com/Plastic%20expansion%20rates.htm
http://www.engineershandbook.com/Tab...thermalexp.htm
http://www.machinist-materials.com/c...r_plastics.htm

[Sunspot Baby]

Gord:

I found most of that but didn't get good info on fiberglass. I found one site that said fiberglass was 1.1 * 10 -6 and other 3.8 * 10 -6 in/in/degF, which is about 1/10 poly. Anyway, it is an order of magnitude different. I guess the fiber really reduces expansion.

Looks like a good size bead thick bead is in order.

George

[alanperry]

I hate to puncture this highly technical bubble, especially since I made my living in a highly technical way for many years before my present life.

But it is clear that Sikaflex is =designed= to be used on these plastics and if my experience with industrial products similar to Sikaflex is any gauge there is generally quite a bit of leeway in it's application and acceptable performance. Meaning that there are many different ways you can use a product like Sikaflex 295, spacers, no spacers, differing thickness of bead depending on your application etc and it will still work just fine. Engineering specs are written to achieve the same kind of performance as the product displayed in laboratory testing. This seems to me a more legalese endeavor having read Sikas 295 spec sheet and application directions off the website.

I just finished my first hatch with it and did not use the primer as I did not want such a tight bond that if I screwed up and had to do it over I could get it apart without hurting my handcarved teak hatch. (and it was $40 for what for me was an experiment) Not knowing what to expect from the 295 I wasn't sure what I was going to end up with. But now after curing for a week in my garage the bond seems like it would take a tractor to separate and it is definitely waterproof. Thank goodness I was happy with the result!

This is just a long winded way of saying I think you can relax and use good common sense for your application without worrying too much about thermal expansion rates and such and exact bead thickness. I think the product is more versatile than the specs would lead you to beleive and it is used for this all the time. My friend here in construction says that one of our major hospitals windows are all bedded with 295 and expected to last 30 years. Asked if they take all these elaborate precautions in applying it and he said "no we pretty much just pump it into the groove and set the window"

Having only met up with Sikaflex recently myself I cant claim any first hand long term knowledge of it's performance. But all my friends that know of it and use it in industry say it's the best stuff out there for lots of things. My son uses it at his work to repair trailers! I was surrounded by it and didn't know it. Sometimes all you have to do is ask!

[exposure]

I used sikaflex to rebed my front winodws on our Prout 37. They are recesses with screws avery 18" or so. For spacers I used some self adhesive felt pads that are designed to protect wood floors from furniture leg scratches. I stuck them on the fiberglass side in four places so that I could peel them off when done. I used four screws to hold the windows lightly in place while things cured. Finally, I installed all of the screws and finished the project with another application of the 295 around the perimeter to fill the remining void and create a nice finish.

I did use both the primer and the cleaner as reccomended. One error I made was that I masked the area to prime on the side the primer was applied. The primer was very thin and ran over the edge to the unmasked side. I should have placed some tape around the edges on the unprimed side. I now have some primer on the outside of one window (I did better the second time around). The excess primer is a little unsightly. Even with this I am very happy with the results. No more leaks! And it should far outlast the old silicon seal.

BTW, I found jamestown distributors had good prices and great service when I purchased my supplies.

http://www.jamestowndistributors.com...FEE73365A5F006

Woody

[Latitude9.5]

I bought the whole kit from http://www.catalinadirect.com have not installed it yet as the c30 seems to have more windows then the c36 and I've been busy with other projects. I did remove the plastic in the front hatch and rebed it, to my suprise it fixed the leak, i didnt do a very neat job, i put a whole tube of window flashing, but it was leaking on our bed, so I wanted to make sure i got it sealed up.

[Alan Wheeler]

When I was in Chandlery, I had a sample of two pieces of metal glued together witha 10mm bead of the sika(can't remember No) and a competition. If the customer could pull apart the two metals, they could win a free Tube of Sika. I even watched one guy put one piece in a bench vice and hold the other end with vicegrips and pull for all he was worth. I never ever gave away one tube of the stuff over several years.

[ssullivan]

A little late, but after rebedding most of the ports and many other oddities like my deck mounted genset on my boat, I would strongly suggest using plain old silicone, such as you find as the cheapest thing in a tube at West Marine.

It's not fancy at all, but I had to try it with my Beckson ports, since they would not honor a "no leak guarantee" if you didn't use it. Boy, was I surprised! I did exactly what wheels mentions. I cleaned the *heck* out of the surfaces. You can't have *any* old gunk on any of the surfaces you want to seal. Take your time and clean them so they look like new. Use a very fine grit sandpaper if you need to (super fine).

Once the surfaces are clean, put your trim ring in place and tighten the screws just enough to hold it in place. Or, if there isn't enough room to stick the nozzle of the silicone tube in with that configuration, just slap it on the trim ring as you are getting read to put it in place. Either, way... LOAD it on. You can always clean up the drips and slop with a paper towel later on. And you MUST do so, or the silicone will make a mess of your deck and ports.

Now, as Wheels says, tighten the screws. But tighten them until you see some silicone getting squeezed out everywhere... inside, outside, a bead squeezing out just a hare everywhere. Then STOP!

Don't tighten all the way. Clean up the "ugly stuff" haning out around where you don't want it all beaded up (leaving a seal though!).

Wait for your product to dry (again.. silicone is the best... stays very flexible). When dry, tighten down the screws so that it forms a nice, tight, and most importantly, watertight seal.

I did this even with 1/2" bolts that go right through my deck holding a genset frame in place. Not a drip all summer, and these bolts vibrate to the tune of a diesel engine! Same with the old "problem" leaky ports the previous owner complained about.

Silicone, silicone, silicone. It's not just for chests anymore.

[CSY Man]

Well, I finally shot a picture of the porthole I removed and re-bedded a few days ago..

Perhaps not relevant to the topic of this thread, but here it is:

http://www.cruisersforum.com/gallery...&imageuser=308

Used Life-Seal caulking and it seemed to bed and seal good.

Only time will tell if it holds up without leaks or cracks....After 5 years everything is a bonus:

One of my buddies bought a brand new 38' production sailboat in 2000, and it had deck-leaks after 3 years or so.
Guys came out and fixed it under warranty, but still...Same problems as we have with the "Good Old Boats"

Sika may be the way to go, and I have used it in the past, but a bit expensive and cumbersome with their primer and all.