Weights and Measurements Specifications for
Ultralight Control Systems Arms
Ultralight buoyancy arm specifications to help achieve neutral buoyancy for your camera rig. Making your camera setup neutrally buoyant is very important and a major part of setting up the right system for a specific need. It not only helps in getting that perfect picture but it will also reduce stress and fatigue on your body. The charts below along with this excellent informative video and this excellent article can be very helpful in setting up your camera rig.
Standard Arms
| Regular arms | Length* | Weight on Land* | Weight in Water* |
| 5 & 5 | 16″ | +13 oz. | +8.5 oz. |
| 5 & 8 | 19″ | +14 oz. | +9.5 oz. |
| 8 & 8 | 22″ | +15 oz. | +10.5 oz. |
| 8 & 12 | 26″ | +15.75 oz. | +11 oz. |
| 12 & 12 | 30″ | +16.5 oz. | +11.5 oz. |
| 12 & 16 | 34″ | +17 oz. | +12 oz. |
| 16 & 16 | 38″ | +18 oz. | +12.25 oz. |
| *All above measurements and weights include the two arms lengths mentioned plus 3 clamps, a base adapter, and a strobe adapter | |||
Small 1 1/4″ Diameter Buoyancy Arms
| 1 1/4″ Buoyancy arms | Length* | Weight on Land* | Weight in Water* |
| 8 & 8 | 22″ | +16 oz. | +4 oz. |
| 8 & 12 | 26″ | +17 oz. | +2.5 oz. |
| 12 & 12 | 30″ | +18 oz. | +0.5 oz. |
| 12 & 16 | 34″ | +19 oz. | -2 oz. |
| 16 & 16 | 38″ | +20 oz. | -5 oz. |
| *All above measurements and weights include the two arms lengths mentioned plus 3 clamps, a base adapter, and a strobe adapter | |||
Large 2″ Diameter Buoyancy Arms
| Table I | A | B | C | D | E | F |
|
Part number |
Length in inches |
Weight in pounds and ounces, out of water |
Buoyancy in water ounces |
Length in millimeters |
Weight in grams, out of water |
Buoyancy in water in grams |
| DB-BL08 | 8” | 6.8 oz. | 4.5 oz. | 203 | 195 | 128 |
| DB-BL10 | 10” | 7.7 oz | 8 oz. | 254 | 218 | 227 |
| DB-BL12 | 12” | 8.4 oz. | 11 oz | 305 | 238 | 312 |
| DB-BL14 | 14” | 9.1 oz. | 14.8 | 356 | 259 | 420 |
| DB-BL16 | 16” | 9.8 oz | 18 oz. | 406 | 280 | 510 |
Use this table, if you are replacing arm segments you already own. Weigh your complete system in water with housing, arms, and strobes to determine its weight in water, then look in the table, column C or F, to decide on which arm length(s) you need for the buoyancy you want.
| Table II | A | B | C | D | E | F |
| Arm section lengths | Length in inches | Weight in pounds and ounces, out of water | Buoyancy in water in pounds and ounces | Length in millimeters | Weight in grams, out of water | Buoyancy in water in grams |
| 8 & 8 | 22.75 | 1 # 7.9 oz | Neutral | 577 | 676 | Neutral |
| 8 & 10 | 24.75 | 1 # 8.7 oz. | 2 oz. | 628 | 698 | 50 |
| 10 & 10 | 26.75 | 1 # 9.5 oz. | 7 oz. | 680 | 723 | 198 |
| 10 & 12 | 28.75 | 1 # 10.2 oz. | 8.3 oz | 731 | 742 | 235 |
| 12 & 12 | 30.75 | 1 # 11 oz | 11.2 oz | 780 | 762 | 318 |
| 12 & 14 | 32.75 | 1 # 11.7 oz. | 15 oz. | 832 | 783 | 425 |
| 14 & 14 | 34.75 | 1 # 12.4 oz. | 1 # 3 oz. | 884 | 804 | 539 |
| 14 & 16 | 36.75 | 1 # 13.3 oz. | 1 # 6 oz. | 935 | 827 | 624 |
| 16 & 16 | 38.75 | 1 # 13.9 oz | 1 # 9 oz. | 980 | 846 | 709 |
Use this table if you are replacing your complete arms or do not have any arms for your system. Weigh in the water your housing and strobes and any other equipment you plan to use, then look in the table, column C or F, to decide on which arm set you would like, for the buoyancy you want.
All weights for large buoyancy arms are +/- 2 oz
Ultralight’s 2″ Buoyancy Arms
2.5 times more buoyant than the smaller buoyancy arms
Large Buoyancy double ball arm segments were designed for the heavy Digital SLR housings and video housing. They are 2″ in diameter and constructed the same as the regular buoyancy arms. They range in size from 8″ to 16″ in 2″ increments to be able to add just the amount of buoyancy you need to offset the weight of the housing and strobes or lights.
| Arm Length | Amount of buoyancy per arm length |
| 8″ (DB-BL08) | 4.5 oz |
| 10″ (DB-BL10) | 8 oz |
| 12″ (DB-BL12) | 11 oz |
| 14″ (DB-BL14 | 14.8 oz |
| 16″ (DB-BL16) | 1 pound 2 oz. |
It is important to weigh your whole system underwater. This can be done in a pool or a large laundry tub. Use a rope to gather the whole setup together and then hang a scale from the rope, keeping the entire unit under the water. A luggage scale is perfect for this, just be careful not to get the scale itself wet. Once you know what it weighs then you can decide how much of that weight you would like to take off the system with the sections of the buoyancy arms listed above. Please call us to discuss the results of the above tables and how they correlate to your weighed system. You might want to weigh your system with different lenses and ports for more accurate diving conditions.
With two arm lengths, 1x AC-CSB, 2x AC-CSF, 1x strobe adapter, and 1x base adapter these are the calculations: You will need to add in the weight of your strobes underwater to these calculations to get you to the buoyancy you need.
| Arm lengths | Amount of Buoyancy with parts listed above |
| Two 8″ | neutral |
| 8″ & 10″ | 1.75 oz |
| Two 10″ | 7 oz |
| 10″ & 12″ | 8.3 oz |
| Two 12″ | 11.2 oz |
| 12″ & 14″ | 15 oz. |
| Two 14″ | 1 pound 3 oz |
| 14″ & 16″ | 1 pound 6 oz |
| Two 16″ | 1 pound 9 oz. |
*Salt water is approximately 1.026 times denser than fresh water. All these tests were done in fresh water.
It is important to weigh your whole system underwater. This can be done in a pool, or large laundry tub, using rope to gather the whole set up together and then hang a scale from the rope, keeping the entire unit under the water. A luggage scale can work well for this. Just be careful not to get the scale itself wet. Once you know what it weighs then you can decide how much of that weight you would like to take off the system with the sections of the buoyancy arms listed above. You might want to weigh your system with different lenses and ports for more accurate results.
