Ballast Computation

[redboat219]

Interesting video about a 1/200 Japanese I-400 class being converted to RC using an FRP inner hull. Being a dry hull the model is very bouyant. Here he is using metal weights to bring the boat down. It takes 114 (gms?) of weight to do that. He weighs the internal components and it's 69.

I'm curious where he got the value of 13 which he subtracted from the weight of the weights. He labels it bouyancy of weight. If he's pertaining to specific gravity the metal he is using has a sg higher that lead (11.3). Can anyone please explain the computation.

So he needs 15 gms of water to dive the boat. 17gms for trimming.

[redboat219]

According to Wat, 13 is the volume of the weights...

[Subculture]

13g would be the weight of water displaced (13ml) by the weights that are hanging external to the dry hull.All boils down to Archimedes principle-

"A body totally or partially immersed in a fluid is subject to an upward force equal in magnitude to the weight of fluid it displaces."

[trout]

13g would be the weight of water displaced (13ml) by the weights that are hanging external to the dry hull.All boils down to Archimedes principle-

"A body totally or partially immersed in a fluid is subject to an upward force equal in magnitude to the weight of fluid it displaces."

That makes sense! Thank you, I did not even think of that.