I have an interest in a schools IOM project and seek guidance as to environmental considerations.
Sand gives a rough finish to a lead casting and I do not relish the idea of sanding a rough lead bulb because of health and environmental issues.
Can a resin mold be used to cast the bulb or is there a better way that will produce a finished product without too much touching of the metal?
Should the lead be resin encapsulated in case the bulb falls off and poisons the pond?
Do club members put floatation blocks (such as polystyrene) into the hulls so that the loss of a boat does not allow poisonous metals from batteries to contaminate the water?
Contributions and guidance would be appreciated.
Environmental matters
Moderator: Pedro Egea
When I make a bulb, it is finished using automotive filler, sanded smoothe with very fine wet and dry sandpaper and then painted. The hulls are floated in a bath tub to check for water leaks so I do not (or anyone else in my club) fill the hull with polystyrene in case of sinkage. Make sure all hatches are on and sealed and it should be ok.
As far as keeping the bulb on the keel, when it is fitted, drill two holes through th bulb and keel and "pin" the keel to the bulb. Make sure the pins are shorter in length than the diameter of the bulb so they can also be faired into the bulb using automotive filler
As far as keeping the bulb on the keel, when it is fitted, drill two holes through th bulb and keel and "pin" the keel to the bulb. Make sure the pins are shorter in length than the diameter of the bulb so they can also be faired into the bulb using automotive filler
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Arvin S.
Environmental concerns
Good points James,
First of all I understand you are thinking of casting your own bulb, the obvious and tongue in cheek answer is that if you don't want to handle lead it is easier to purchase them from manufacturers, though often you still do have to do some finishing.
I have casted my first bulb several months ago using a wooden plug and plaster of paris. It turned out okay, but it is a bit dangerous, the plaster would crack under the heat and if you don't dry it properly you might have an explosion (lead vs. moisture). The casted bulb however was quite smooth.
On the other hand to make a long story short, most IOM sailors do what Steve does, use filler to make the surface smoother then sand the filler then paint.
This will not only improve the surface it will encapsulate the toxic lead, there are some keels that are encapsulated with fiberglass but to me I think it is overkill, but that is just me.
As for boats sinking. Trust me if you own an IOM, you really would like to salvage your boat no matter what, so it is unlikely that an IOM will remain underwater for too long if at all. As Steve said we all take precaution in making sure that the boat is water tight, no one wants to race an IOM that is taking in water.
As for the foam/floatation block. You will need to fill the whole hull in order to make it unsinkable. Which means you will make the boat really really heavy which is not good for racing. I have had a 36" boat's whole front end filled with foam, I test sank it and it still sank! So I ended up taking off the foam coz it's just making the boat heavy.
I had a 30 inch boat sink in a lake when I was just starting out, I went out on a rescue boat and actually dived in the lake to salvage it, luckily it was only in 15 feet of water and I could still see the white sails against the dark background. The boat is still in sailing condition though along with RC gear.
TTFN
Arvin
First of all I understand you are thinking of casting your own bulb, the obvious and tongue in cheek answer is that if you don't want to handle lead it is easier to purchase them from manufacturers, though often you still do have to do some finishing.
I have casted my first bulb several months ago using a wooden plug and plaster of paris. It turned out okay, but it is a bit dangerous, the plaster would crack under the heat and if you don't dry it properly you might have an explosion (lead vs. moisture). The casted bulb however was quite smooth.
On the other hand to make a long story short, most IOM sailors do what Steve does, use filler to make the surface smoother then sand the filler then paint.
This will not only improve the surface it will encapsulate the toxic lead, there are some keels that are encapsulated with fiberglass but to me I think it is overkill, but that is just me.
As for boats sinking. Trust me if you own an IOM, you really would like to salvage your boat no matter what, so it is unlikely that an IOM will remain underwater for too long if at all. As Steve said we all take precaution in making sure that the boat is water tight, no one wants to race an IOM that is taking in water.
As for the foam/floatation block. You will need to fill the whole hull in order to make it unsinkable. Which means you will make the boat really really heavy which is not good for racing. I have had a 36" boat's whole front end filled with foam, I test sank it and it still sank! So I ended up taking off the foam coz it's just making the boat heavy.
I had a 30 inch boat sink in a lake when I was just starting out, I went out on a rescue boat and actually dived in the lake to salvage it, luckily it was only in 15 feet of water and I could still see the white sails against the dark background. The boat is still in sailing condition though along with RC gear.
TTFN
Arvin
Re: Environmental matters
the finish on the bulbs from our CNC cut aluminium moulds is almost ready to use when the bulb comes out of the mold.Jamestj wrote:I have an interest in a schools IOM project and seek guidance as to environmental considerations.
Sand gives a rough finish to a lead casting and I do not relish the idea of sanding a rough lead bulb because of health and environmental issues.
Can a resin mold be used to cast the bulb or is there a better way that will produce a finished product without too much touching of the metal?
...
Usually you have to sand or file it anyway since the weight might not be exactly right...
If you want to make bulbs yourself and have access to a suitable CNC mill the plans for our bulb mould are at:
http://www.helsinki.fi/~awallin/iom/
use at your own risk...
AW
Hi Arvin
Thanks for your reply. I was really thinking of expanded polystyrene. It weighs only about 6kg for 1 metre cubed so a solid hull would only weigh a few tens of grammes. If I cut a block to the shape of a hull and sheathed it in balsa/epoxy, it would be far stronger than a hollow hull. It would also be unsinkable. Has anybody ever used this method of construction? It must be light since large model aircraft are sometimes made like this.
Thanks for your reply. I was really thinking of expanded polystyrene. It weighs only about 6kg for 1 metre cubed so a solid hull would only weigh a few tens of grammes. If I cut a block to the shape of a hull and sheathed it in balsa/epoxy, it would be far stronger than a hollow hull. It would also be unsinkable. Has anybody ever used this method of construction? It must be light since large model aircraft are sometimes made like this.