The boat will need four scoops for two ballast tanks or some sort of interconnect that balances the tanks.
Some people use Andersen Super Mini Special dinghy bailers These look heavy and expensive although durable. They may be a bit small.
Here is a good looking carbon design. This is the only picture I found and it does not show any of the internal mechanism
Jan Gougeon's boat Strings as well as his earlier designs used this type of system. Again, I am lacking details. Here is a picture of a control center for Strings' ballast system.
Perhaps YOU have some experience you could share with me.
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Why do you need 4 scoops? I think you can make it work with 2 scoops, one pipe betwee the tanks and one valve. At least, it works in my head!!!
ReplyDeleteLaurent
I had the same idea, but it turns out the tanks are meant to be separate. Downwind, you can put water in the aft tank and keep the bow up a bit.
ReplyDeleteMy "idea" (it is a big word...) is that you have one pipe between the 2 tanks - running below the lowest point on the tanks - with one valve in the middle, and one scoop at the bottom of each tank, facing each other (meaning with the opening towards midship).
ReplyDeleteI understand that you want to fill in the aft tank and empty the forward tank.
So let's assume you start with empty tanks.
You want to fill the aft tank:
- close the valve
- open the aft scoop until tank is full
- close the scoop
Now, you want to shunt:
- open the valve between the tanks (it could be remotely operated with lines as well) and let the water equalize between the tanks during the shunt
- close the valve once the boat starts moving on the new tack
- open both scoops; the front one allows the forward tank to dump half of the water that was left inside after the equalization; the rear one allow the aft tank to fill up from half full to full
- close the forward scoop once the front tank is empty
- close the aft scoop once the rear tank is full
"Et voila!!!" (as they say back home ;-) )
Laurent
One step I forgot; how do you empty BOTH tanks under way, when the wind gets lighter?
ReplyDeleteLet's assume that you had the aft tank full and front tank empty (but which one is full does not really matters...)
- open the valve, the tanks levels equalize
- open the front scoop, you empty the front tank, and because both tanks are connected, you will eventually empty both
This operation is really the one that requires the connection between the tanks and the valve; if you do not have this connection, you cannot empty the aft tank, you will have to wait to shunt to have the sole scoop under that tank in emptying orientation (facing aft)...
Cheers,
Laurent
for scoops look for "Sofo" it's what the mini Transats and other water ballasted boats use
ReplyDelete