Lead Ballast

[Davo1Participant @davo1]

Hi All,

 

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.

 

Cheers

David.

[Davo1Participant @davo1]

[Colin BishopModerator @colinbishop34627]

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.

 

Colin

[Davo1Participant @davo1]

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?

 

Cheers

david

[Colin BishopModerator @colinbishop34627]

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!

 

Colin

[Davo1Participant @davo1]

Oop’s I will really have to re -think this. Advice about lead and water taken on board. Thank you.

 

David.

[hammerParticipant @hammer]

My method is to cut scrap lead cut into small pieces and  mix with cement.  Hammer

[David MeierParticipant @davidmeier28154]

Hi David.

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.

 

Cheers.

David.

[Ian GardnerParticipant @iangardner62867]

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.

Go steady!

Ian

[Tony HadleyParticipant @tonyhadley]

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.

 

Tony.

 

 

[John W EParticipant @johnwe]

Hi there

 

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.

 

aye

john

[Ian GardnerParticipant @iangardner62867]

I think this is what we were saying!

Ian

[Colin BishopModerator @colinbishop34627]

Not Quite, Bluebird was drawing attention to the presence of voids in the laminate so molten lead wouldn’t simply burn its way through it would create minor explosions which could blow back or out through the gelcoat – and if there was water on the other side….

 

These days there should rarely be a need to melt lead unless you are casting an external appendage such as a bulb for the keel of a yacht in which case you would cast it properly in a separate mould. Whenever it comes to filling a cavity or simply laying ballast in the bottom of a boat then shot or small pieces either encapsulated in resin or in polybags is the way to go. Lead is still the preferred material due to its density and the fact that it will not significantly corrode.

 

Colin

[TankermanParticipant @tankerman]

To introduce lead ballast in to awkward or remote spaces this is the easiest product to use:

 

http://www.eileensemporium.com/index.php?option=com_virtuemart&page=shop.browse&category_id=224&Itemid=1

 

Maybe it is expensive but is still cheaper than blowing bits of your anatomy off with molten lead.

 

Chris

 

 

 

 

Edited By Colin Bishop, Website Editor on 13/06/2010 11:23:49

[Davo1Participant @davo1]

Thanks everyone for your input ,appreciate advice concerning safety.

 

The problem I have is the limited  size of the keel cavity. 2kilos of lead is a lot of lead. If I use shot  and resin combined it could need twice the space of that  of solid lead ..I am finding it difficult to track down a local supplier of lead shot anyway and I will be making more than 1 boat.

 

I like the fluid lead product but 2 kilos freighted to Australia would be too costly.

 

I think that properly dried  out a plaster mould could be the best answer allowing me to cast the lead in one piece.

 

David

 

 

Edited By David Walters 1 on 13/06/2010 13:44:06

[Colin BishopModerator @colinbishop34627]

Hi David,

 

If you were to use shot then you wouldn’t need necessarily to mix it with the resin. The resin just goes on top to seal it in. If you are using sheet lead then, as suggested in an earlier post, cut it into manageable pieces and wedge it in and then again use resin to hold it in place. Also, with sheet lead, if you cut slices out to approximate the shape you need you can use a hammer to bash them together into a homogenous mass which should fit the cavity pretty closely.

 

Moulding it off the boat as you suggest would certainly be an alternative but would entail making a male plug from the cavity and then using this to make the female mould for casting which seems a lot of work for something that will never be seen.

 

If you do go down the moulding route then Google ‘melting lead’ and you will see lots of advice on methods and safety precautions on various angling sites.

 

Colin

Edited By Colin Bishop, Website Editor on 13/06/2010 14:15:17

[Tony HadleyParticipant @tonyhadley]

Quite an old thread this, but one question which would help re: lead ballast.

With lead sheet/block ballast, what is the best adhesive to hold the lead sheet down and prevent the ballast from moving, when it can't be wedged in place? Would silicon sealant from the DIY be ok?

[Malcolm FraryParticipant @malcolmfrary95515]

Silicone sealant would stick it OK, but has the side effect of giving off acetic acid fumes (the vinegar smell). This hangs around like a…bad smell, and acts like acid with anything metal over time when in an enclosed space. Wet grab acrylic adhesives from a bit further along the shelf in the DIY shop work well.

[Dave MilbournParticipant @davemilbourn48782]

I have recently encountered a product made by Evode, which is called (and I kid you not) "Sticks like sh*t". I've used it to stick polypropylene anti-intruder strips to roofing felt, and more recently some injection-moulded plastic guttering end-stops into aluminium guttering on a greenhouse. In both cases silicon sealant wouldn't touch the job.

It's claimed to be solvent-free and it really does do what it says on the tube. **LINK**

DM

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Great stuff Dave, I've used it several times. It sticks under water and to damp wood and brick etc. Takes time to go off (over night). I've used it to mount motor supports direct to hulls and to give support to exposed sections of prop tubes. It dries semi rigid. I've used it in plastic hulls and vac form hulls and it hasn't 'melted' through. It is expensive compared to silicone sealant – but well worth it. I've had a tube in use for near 2 years, just keep squeezing some through the tube every month or so to expel hardened material.

It'll stick anything to anything that's not oil covered. I've even used it to form a bow bumper for a yacht by squeezing it into an appropriately shaped chocolate box plastic insert, letting it go off and then carving and cutting to shape. Use a dab to then stick it to the yacht's bow.

Kim

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