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Feb 14, 2019, 02:08 PM
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Atlantis Ballast

Looking to source some pictures/details of an atlantis ballast. so I can build a mold and cast a new one...

short story. ballast was removed from boat during a move. got lost in the shuffle. trying to help a friend get theirs back on the water.
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Feb 14, 2019, 03:35 PM
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Use lead shot to fill the keel.
Feb 14, 2019, 03:45 PM
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ClaudioD's Avatar
Hi Marc, you may find some solution here :

You can fix a bloc of balsa and shape it directly on the hull and after that make mold for curing. Pictures can be found on the web with "Atlantis by Robbe"

BTW, lead shots are an alloy that weight 7gr/cm3 instead of 11.3g

Feb 14, 2019, 03:49 PM
Modeler/ Historian
Stephen Vick's Avatar
It might be easier to use lead shot, although it will not be removeable. The ballast in mine is fixed permanently, and I don't find it too hard to transport. I usually pop off the center cabin and carry by the front lip of the access hatch. Without exact specs, making a removable ballast will be difficult, but not impossible. It is doubly tricky, since Robbe shifted to a cast iron keel in later production. I am 90% certain the stock ballast weight on mine was about 22 pounds. You could make a molded ballast to that weight , then add a couple pounds of cheaters if needed. However, Krick Modellbau, should have all the specs, since they own the Robbe line now. How's your German?
Feb 16, 2019, 04:53 PM
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Hi Marc - I just weighed a couple of Atlantis ballasts - they must be the later generation - they are not lead. One weight about 22.9 pounds. The other weighed about 23.5 pounds.
Feb 16, 2019, 05:21 PM
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mine seemed to be cast iron...was around the same weight..23 pounds give or take a bit.
Feb 16, 2019, 05:44 PM
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A few pictures. Note that I've cut off about an inch at the front - makes getting it in and out of the boat easier.
Feb 16, 2019, 11:52 PM
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Thanks guys. I have a 4lb smelter. So it would take a few pours. I washing thinking of using plaster of Paris to make a plug. Line the inside of the hull with a plastic bag. Let dry. Remove, And then use the plug to make a sand cast. And then pour the lead

The biggest issue was figuring out the weight. Thanks for those above. And some basic dimensions. Such that I knew kind of where to cut and trim to make it close.
Feb 17, 2019, 02:35 AM
a.k.a. Bob Parks
bbbp's Avatar
Plaster of paris expands a bit when drying!
Feb 17, 2019, 07:32 AM
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Originally Posted by bbbp
Plaster of paris expands a bit when drying!
Usually about .5%

But since it has a way out. In this case up I would nOt be too worried about it blowing out the hull.
I could always line the sides with a sheet of 1/8 in foam to abs or any expansion..
Feb 22, 2019, 11:57 PM
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arthur0903's Avatar
I use 8x laundry mesh bags with small fishing lead in it.
Easy to remove them from the hull for transportation and adjusting the ballast total weight.

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Last edited by arthur0903; Feb 23, 2019 at 12:23 AM.
Feb 25, 2019, 02:34 PM
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Thread OP

I could one step further and use dive weight bags...


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