4 forum posts
Looking for advice on how to pour molten lead into the keel/bilge of a fibreglass yacht under construction. First not to destroy the fibreglass from the heat and and to make sure the waterline is correct. Any help would be appreciated.
|Colin Bishop||11/06/2010 09:09:07|
5152 forum posts
Probably not a good idea David, Molten lead will melt the GRP for sure. You would have to make a mould in sand or something first.
I think the usual thing in these circumstancess is to use lead shot or small scraps of lead. Pour them into the cavities until you get the waterline you want (allowing for the weight of any deck structure,equipment etc). and then encapsulate the lead using GRP resin.
Don't pour too much resin in at a time as this will also get hot and could distort the hull structure.
There is rarely a need to melt lead these days and you should only do so if you are fully aware of the risks. There are plenty of safer alternatives.
4 forum posts
Thank you Colin, I have to place about 2.5 kilos of lead as far low as possible in the yacht. I think melting is the only way to achieve this. Hopefully adding small amounts of lead at a time .
Would it be best by floating the boat in water while adding the molten lead or is it best done in the original mould?
|Colin Bishop||11/06/2010 10:25:06|
5152 forum posts
I have not tried it, but given that you can soften and manipulate a GRP hull with a hair dryer I should think that molten lead lead will go straight through the GRP like a dose of salts and if there is water on the other side you will have a very nasty explosion wit5h lead droplets everywhere!
I have never, ever heard of the practice of pouring molten lead directly into a hull and I think it would be very dangerous indeed to do so. Above all, water (even dampness) and lead is an explosive combination and there have been many injuries over the years caused by people not taking the necessary precautions such as drying out plaster moulds properly etc.. Lead shot will mould itself to almost any shape and can be fixed in situ - a much safer method. Unless you swallow some of course!
4 forum posts
Oop's I will really have to re -think this. Advice about lead and water taken on board. Thank you.
|geoffrey yarham||12/06/2010 05:45:49|
|42 forum posts|
My method is to cut scrap lead cut into small pieces and mix with cement. Hammer
|David Meier||12/06/2010 10:33:14|
205 forum posts
I agree with Colins suggestion of using lead shot.
My RTR Monsoon yacht had a hollow GRP keel bulb with about a 6mm dia hole in it. I was able to get more than the minimum suggested weight in the bulb this way and I sealed it with a bit of Silaflex RTV so that I could adjust the weight at a later stage if I should need to.
|Ian Gardner||12/06/2010 16:50:04|
|566 forum posts|
I have heard of folk pouring molten lead into a floating grp hull to avoid distortion. My blood runs cold at the thought of what could happen!!! I saw the results of a youngster messing about with molten lead when I was a schoolboy - it has stayed with me for the rest of my life.
I have, in the past, made plaster moulds from hulls. You need to make a male mould, then a corresponding female mould using vaseline to part them and then dry the mould very thoroughly in the oven. Then the lead can be poured -but it would be much easier to use shot I think.
Vic Smeed described the moulding and pouring process in 'Simple Model Yachts' published in 1970.
|Tony Hadley||12/06/2010 20:19:12|
914 forum posts
Lead shot mixed with primer paint does the job easily and safely.
Watch which lead shot you get, the shot sold at fishing shops is no longer lead. It is a safe metal mix to prevent poisoning wildlife (swans etc), it is not as heavy. If you need real lead shot look elswhere, I bought mine from a divers supply shop.
|John W E||12/06/2010 21:46:44|
298 forum posts
SAFETY NOTE do not DO NOT attempt or even try to pour moulten lead into a fibre glass mould or hull of any description.
Even if the hull is resting in a cold bath of water.
The reason for this is NO MATTER HOW GOOD THE LAMINATOR IS WHO PRODUCED THE HULL - HE WILL NOT HAVE REMOVED ALL OF THE AIR OUT OF THE RESIN.
EVEN THOUGH you cannot see with a naked eye the air bubbles trapped in resin THEY ARE THERE!!!!!! The only way you can be sure there is no air in the resin is if it has been constructed using the vacuum method, which is a little too expensive for our model hulls.
What happens as you can imagine THE MOULTEN LEAD WOULD HEAT UP THE AIR POCKETS WHEN IT COMES INTO CONTACT WITH THE LAMINATE - THE AIR HAVING NOWHERE TO ESCAPE WOULD RUPTURE THROUGH THE LAMINATES AND YOU HAVE A POTENTIAL bomb I HAVE SEEN IT AND IT IS pretty hair raising.
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