Bouyancy Calculator

[dbramley]

Just got a Gates and Z1U, with custom HID lights and battery backs came out to be 8 lbs neg. I found this helpful link from Mainland Robotics team which made it very easy to find the length PVC tube for my bouyancy adjustment. I have a fish scale I travel with so I can weigh my bags. I just put the camera in the water with batteries etc and got 8 lbs. Punch that into the excel spread sheet program, tell them what diameter tube you want to use and there you go.

Dan

www.geocities.com/mainlandrobotics/buoyancy_calc.xls

 

[ronscuba]

That's a cool program. Looks like you'll need a big PVC tube or move the battery packs to your BCD.

 

[Video rookie]

...I have a fish scale I travel with so I can weigh my bags...

Which fish scale are you using? I have one that is basically useless for buoyance calculations, since it measures in 2lb increments, and would like to get one that would measure more accurately. I saw one at Ace hardware, and I think it went up to 20lbs. Anyone find a reasonably priced "fish" type scale they would recommend?

Thanks,
Vic

 

[ronscuba]

I have this little Rapala scale.

It seems to work ok. But once you get to 1 pound or less, it's accuracy is probably off several ounces.

Rapala - Knife, Lure, Tools, Gear Accessories

 

[crpntr133]

I have this little Rapala scale.

It seems to work ok. But once you get to 1 pound or less, it's accuracy is probably off several ounces.

Rapala - Knife, Lure, Tools, Gear Accessories

Am I missing something with being that consumed by the buoyancy of my rig? Within 1lb is getting pretty close. The salinity of the water can change it close to that. I realize that you don't want it way off but within in 1lb should be good enough.

 

[ronscuba]

Guess it depends on what you are filming.

For normal shooting, 1lb doesn't matter, but when I shoot macro subjects and I zoom to fill the frame and I have to hover totally still for 15 seconds plus with my rig held out in front of me, 1 lb negative makes a difference.

It's a personal thing. Some people like slightly positive, some slightly negative, I try to get my rig as close to neutral as possible.

Just my 2 cents.

 

[HiDefPics]

Thanks for posting that spreadsheet. I'm shooting with the same rig + the SWP44 port, which adds more weight to the front. It's been trial and error to balance it out. This should help.

 

[dbramley]

For me one pound is a huge deal. At 185ft in local lake (interpret that black water) the less I have to wrestle the better. The large 3" tube worked great. I got some killer footage of an old hydroelectric generator house and large butterfly valves which was on the backside of an old dam which is now submerged. I am at work so I don't have the name of the scale but I will check and post when I get home. The scale measures in 1/10 of a pound. I have not tried to calibrate it with a known weight however.

 

[dbramley]

For me one pound is a huge deal. At 185ft in local lake (interpret that black water) the less I have to wrestle the better. The large 3" tubes worked great. I got some killer footage of an old hydroelectric generator house and large butterfly valves which was on the backside of an old dam which is now submerged. I am at work so I don't have the name of the scale but I will check and post when I get home. The scale measures in 1/10 of a pound. I have not tried to calibrate it with a known weight however.

 

[dbramley]

OOps, sorry for the double post