Stupid floatation question D500

After a year of forced shore leave due to covid, I should be able to get in the water again this summer.  Going through the gear in anticipation of getting to use it again I find that I have lost my notes and my memory about floatation, because I cannot recall what I was using.  I would rather not do the bathtub testing thing, if I don’t have to.  Since it is a pretty common setup, I am hoping someone can share how much buoyancy is needed  for a D500 in a Nauticam housing with 10-17 in a 100mm dome, two 8” and two 5” arms and a couple Z330s?

My last two dive trips before the Covid were both macro trips, so it has been almost two years since I used the mini dome.  I usually use Stix floats and add or subtract depending on lens/port.

Sorry; I feel stupid asking, but I am drawing a blank.  My guess is I was using a total four jumbo Stix floats and a couple small floats, but I am unsure.

Thank you.

Hey Draq

I used to use a very similar setup: D500 in a Subal housing with a Tokina 10-17, 100mm dome port, two Z240s and a 5" + 8" ULCS arm on each strobe.

I was using 4x Jumbo Stix on each arm set for that combination: 8" arm = 2.5 Jumbo Stix; 5" arm = 1.5 Jumbo Stix

That was slightly negatively buoyant.

Here's my calculations for the amount of buoyancy for Stix Jumbos:

8” arm = 2.5x = 181x2.5 = 452gms 

8” arm = 2.5x = 181x2.5 = 452gms

5” arm = 1.5x = 181x1.5 = 271gms 

5” arm = 1.5x = 181x1.5 = 271gms

And for the camera setup:

D500/Tokina 10-17/DP100/EXR13/2x Z240 strobes 

Out of water weight = 7.6kgs

In water weight = 0.7kgs

https://interceptor121.com/2014/03/15/floats-and-float-arms/

I have tables for all the arms and set ups combined. You Z330 with dome may be neutral so check them individually

Thanks, I will start there.