DIY shop Silicon

[dave_gibsea]

Being miles form a chandler but close to B&Q I was wondering if the silicon sealant they sell is OK for windows and such on boats. There seems to be a big choice of types too. Has anyone got any knowlege on the subject?

 

[andyball]

I have tried some cheap & "quality" building silicones....and found them wanting, although there may be good ones out there. "Aquarium" silicone seems v.good ,(just as well, it's restraining 1/2 tonne of water in my house), although expensive.

cheap/cheerful but good (imo) stuff available from www.beal.org.uk, 0113 253 8888 in black/clear/white, sold for making silicone gaskets....£2.50 + vat for std 310ml tube. Beals also cheap for other "workshop" supplies,recommend a catalogue

Often read that silicone sealants no good in seawater, but thousands of marine aquariums held together purely by the stuff would seem to show otherwise.

 

[30boat]

I think that silicon is perfectly suitable for seawater use but it should always be in compression.

 

[Jacket]

this summer, when my boat started leaking around the keel bolts in a rather alarming manner (non-stop bailing for 12 hould till we reached land- and yes, a bucket is much better than a bilge pump when you're scared) I lifted her out and sealed the hull to keel joint with building silicon - we were in the middle of nowhere and it was all that was available.

The stuff isn't designed for use below the waterline, and the boat got chucked back in the water before it had properly set, and yet I had no further trouble for the remaining 3 months of the cruise.

So my reply would be yes, ordinary silicone is probably OK for use with non-critical elements such as sealing windows.

 

[BarryH]

If your near a good car spares out let. Try a polyurethane sealent called PU-Flex from a company called Granville. Its the same as sikaflex. It comes in white, grey and black. Normally used for car windscreens and sticking the frames of bonnets to the skins. I've used it on my boat. It hasn't leaked for the last 5 years. It only costs around 9 quid a tube. Don't get it on your skin tho! Its a bugger to get off.

 

[rich]

Sikaflex is great stuff, but very expensive from chandleries - you can get Sikaflex from builders merchants for a third of the price.

rich )

 

[LadyInBed]

I've found black roof gutter joint sealant is very good for windows.

 

[pete]

I have just replaced the windows on my boat myself and on enquiring to two marine window company.s they said not to use silicone or sikoflex and to only use a non setting mastic as the windows expand at a different rate to the hull. they could supply same for about £6-50 a tube which I thought was fair but in the end I used double sided vhb tape instead.
PS the windows are bolted in as well.

 

[Guest]

Sikaflex ....

One of the best suppliers that I found was Strand Glass .... they sold it for moulds, sticking together hulls and decks etc. etc. ........ so maybe a trip to your GRP resin supplier will bring forth what you want at a good price ??

Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[wishbone]

You local glass shop sells glazing silicone only a couple of quid a tube

Keeps the burglars out !!

Wishbone

 

[neil_s]

I used it and it seems to be OK. B and Q sealant emits acetic acid while it sets, but I don't think this is much of a problem for GRP and plastic windows.

Neil

 

[Guest]

there definitely are different grades of silicone sealant - our local bearing supplier has 4 grades on his shelf, though i must admit that i cant remember what they were.

my own boat was built in 1987, and the builder use silicone for all underwater fitments. no problems whatsoever, except that when it came to try and get a blakes seacock out of the hull, it took me 2 days

so i would use silicone, but i would remember the bit about the ha'porth of tar. that was a sealant in those days.

buy the right stuff!