Filling voids

[BarryH]

If I wanted to fill the void between the inner and outer mouldings of my hull. What would I use?
Don't want anything that will hold water if it got wet. Don't want anything that wieghs a ton when its gone off. But I do want something that can be pumped or poured into the cavity. What do you think?

Oh nearly forgot. It must retain the bouancy aspect that the air between the 2 mouldings gave!

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<P ID="edit"><FONT SIZE=-1>Edited by BarryH on 20/09/2004 15:57 (server time).</FONT></P>

 

[Althorne]

Would it be possible to spray the aerosol foam stuff thats also fire retarded Barry.
I used to use it for filling gaps to fireproof areas in properties. Was recommended by several insurance companies, was like a hard sponge, light and the aerosol had extentions to get into deep places. Used to by it at a builders merchants in London called Travis Perkins. Might be useful.

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[stevebrassett]

According to PBO, you need to be careful with the expanding foams, as they can generate a lot of pressure between two mouldings and can force them apart.

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[Phoenix of Hamble]

Yep....

A recent Kids TV programme filled a car with this stuff, and blew the roof off!

It also gets VERY hot if not mixed in exactly the right ratios.... hot enough to start fires......

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[Captain Coochie]

Id say foam , just leave a gap for it to expand and escape so no worries of your roof blowing off . Hilti do a great application gun for the foam for around 40 quid . So you can take your time doing the job without wasting a can of foam everytime . I might get one myself soon so if your going foam give me a shout and you can use mine )

<hr width=100% size=1>No thankyou , i don't drink .

 

[BarryH]

Ok so all read and duely noted. Bascically I want to stop the hollow echoy sound while under way. As well as a bit of insulation. So how do the builders boat builders do it. Seen a fair few boats that have the cavity filled with foam. Just thought there'd be a way to "retro fit" the stuff. Surely the builders must inject the stuff?

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[aitchw]

The biggest problem with expanded foam is that it will take up water if immersed for long enough and when it does it's very hard to dry out especially in the confines of a between skins void. If you do do it buy the bulk components for expanded polyurethane foam and read the guide to how much it expands. You can inject it through a hole and as long as you provide breather holes for the displaced air or excess foam to escape from and you won't get the pressure build up. The builders know from experience how much to inject and will get fairly consistent results in their humidity conditions. Even they will leave unfilled pockets. Bigger voids are often not filled completely anyway. They use blocks of expanded polystyrene which are placed on a bed of PU foam as they place the two mouldings together. This provides both fixed buoyancy and dampening to stop the booming and stiffen the structure.

Have fun.

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[oldsaltoz]

G'day Barry,

Stay away from the expanding foam, it's not water resistant at all and will be a major problem if it gets wet.

You can inject a mixture of resin and micro balloons or for a bit less money use "Q-Cells", both are closed cell spheres that will not take up water and can be used underwater.

I would use an epoxy resin to ensure a better bond and less weight. Mixed to a consistency of runny toothpaste it can be injected using a number of methods, for larger areas I use a 600 ml caulking gun, clean up with white vintager and water.

No high pressure or temperature problems and no water entry later on, good stuff, have been using it to fill rudders for years.

Avagoodweekend and give my regards to the two ladies.



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[squidge]

Fill it with tinnies! The extra weight deminishes with time leaving an alloy can. Very light weight and radar reflective giving you a much better image ,unlike foam.By there nature they are fire resistant(depending on contents as SHMBO tried some g&T in a tin and by the smell it would have started the barbi nicely) and if you needed extra heat proofing you can open them out and stick them down flat to reflect or keep in heat a bit like a solid emergency blanket.You can buy them any where in the known world so if you run out you can always buy some more although they are cheeper in some places than others ( coke can £1.00 boat show)buy beer its cheeper and wont rot your teeth.
You will need quite a few to fill a void but after you have emptied some it will seem less of a problem, a few more and its no problem at all, one or two more and you will wonder why you made such a fuss in the first place retire to bed to await the onset of the side effects.
If you dont know what these are i will let you find out yourself as i hate it when someone tells you the ending before you have read the book.
good luck.

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