IRC Bulb weight

[Rattler]

For a new 2018 IRC cert a question is asked about the weight of the Bulb on the keel. I have a keel which has a lead bulb at the bottom of a cast iron fin, how is it possible to measure the Bulb with removing it from the fin? What is the best way to deal with this question?

Any suggestions would be great!

 

[anoccasionalyachtsman]

Simplest to ask the designer or builder for the theoretical answer- but if you can find them, the people who cast it will tell you what it actually weighs. There is history if that sounds slightly cryptic, but I can't tell you about it...

 

[Rattler]

The boat is from 1995 and the builder is no longer around but I will try the designer and see what happens, not sure he will be interested looking up an old small boat 23 years later.

 

[Lucky Duck]

Should be simple enough to work out the weight of the iron fin and therefore how heavy the bulb is, assuming the published ballast weight is correct and doesn't include any non-keel items

 

[wotayottie]

next time you have it out of the water, take a large plastic bowl / drum whatever that the bulb will fit into and lower the boat into it until the bulb is just level with the tiop. Fill the container with water to the brim. remove the boat and then carefully fill up th container using a measured container of water. the amount of water added in litres will give you the colume of the lead bulb. use the density of lead to work out the weight of the bulb. Eureka!

 

[awol]

next time you have it out of the water, take a large plastic bowl / drum whatever that the bulb will fit into and lower the boat into it until the bulb is just level with the tiop. Fill the container with water to the brim. remove the boat and then carefully fill up th container using a measured container of water. the amount of water added in litres will give you the colume of the lead bulb. use the density of lead to work out the weight of the bulb. Eureka!

But what if it is gold (or enriched uranium)?

 

[Puggy]

But what if it is gold (or enriched uranium)?

I think you mean depleted uranium? unless you have a cheap supply of enriched uranium suddenly available from N Korea

 

[bbg]

But what if it is gold (or enriched uranium)?

If it was either of those two elements you would use the density for that element.

If it was gold you could call me and I would recycle it for you and provide you with a denser keel, built of lead (for a small fee).

If it was uranium I am pretty sure it would be illegal under the racing rules. If it was U235 you would have bigger problems than measuring its mass ...

 

[wotayottie]

But what if it is gold (or enriched uranium)?

Gold - well obviously its a Swan so you can get the weight from them. Enriched uranium - obviouslt Putins boat and you are a Russian spy.. But you would have noticed the giant 14 legged octopus trying to get on board.

 

[flaming]

If it was uranium I am pretty sure it would be illegal under the racing rules. If it was U235 you would have bigger problems than measuring its mass ...

Unless it was in use before they banned "exotic" materials in bulbs. I think there is still a maxi sailing with a Tungsten bulb that was grandfathered in when they changed the rules to ban anything other than steel, iron or Lead (IIRC).

 

[michael_w]

IRRC Pen Duik VI (Eric Tabarly) and Allied Bank (Bertie Reed) had depleted uranium keels

 

[wotayottie]

Unless it was in use before they banned "exotic" materials in bulbs. I think there is still a maxi sailing with a Tungsten bulb that was grandfathered in when they changed the rules to ban anything other than steel, iron or Lead (IIRC).

he was referring to U235 isotope Flaming - thats the highly radioactive one they use for atomic bombs. Use that and you wouldnt need nav lights, but a lead lined salopette might be handy.

I'd be surprised if there was a boat sailing with a tungsten keel - its likely to be worth way more than the boat

 

[lpdsn]

he was referring to U235 isotope Flaming - thats the highly radioactive one they use for atomic bombs. Use that and you wouldnt need nav lights, but a lead lined salopette might be handy.

I'm sure the critical mass of U235 is low enough that you'd have difficulty even before you launched. Water is good at bouncing neutrons back so the critical mass in water would be lower.

 

[bbg]

I'm sure the critical mass of U235 is low enough that you'd have difficulty even before you launched. Water is good at bouncing neutrons back so the critical mass in water would be lower.

That was my point too - but I guess I was a bit too subtle.

 

[lpdsn]

That was my point too - but I guess I was a bit too subtle.

I'm not sure subtle works.

 

[bbg]

I'm not sure subtle works.

There wouldn't be anything subtle about a keel bulb made of U235!

 

[flaming]

he was referring to U235 isotope Flaming - thats the highly radioactive one they use for atomic bombs. Use that and you wouldnt need nav lights, but a lead lined salopette might be handy.

I know what U235 is... I think you missed the humour, in retrospect it wasn't that funny, so never mind!

I'd be surprised if there was a boat sailing with a tungsten keel - its likely to be worth way more than the boat

Former Alpha Romeo, now known as Black Jack.

https://www.theaustralian.com.au/sp...y/news-story/9059ab35d23a502aa80c3f0cdad939b6

 

[Daydream believer]

To find the volume of the bulb without the use of a crane. Construct a box around the bulb with some ply or boards complete with a base. The base will be the hard bit as it will have to be cut around the blocks with as little gaps as possible, so a polythene lining may be needed. Calculate the volume of the box, which if made correctly should be easy enough.
Using a small box of known dimension fill the main box with sand, or earth, counting how many small boxfulls used. This will tell you the volume of the box not occupied by the bulb so now you know the bulb volume.
Then whether it is an atomic bomb, or just plain old lead you can apply the weight per ft3 prior to detonation & there you go