Shallow Water Computer?

[Hypersaline]

Does anyone know of a computer that measures depths of 3 feet or less?

I'm on a scientific dive team and we are collecting aquatic vegetation for biological analysis at depths between 3-30 feet. The computers we have been using default to "surface" if we're in depths less than 5 feet. I'm looking for something that an accurately give a depth reading at 3 feet without thinking I'm heading in for the day. As part of our studies, we need to log the depth of a sampling location as accurately and precisely as possible. Ideally, I would like to find one that can measure depth beyond the whole number (e.g. 5.7 ft or 21.3 ft). Another consideration is that we are conducting these studies in a lake 2500 feet above sea level, so our computers need to compensate for altitude.

Is this too much to ask?

Thanks!

[T-Dog]

You could mark 1 ft or 0.5 ft intervals on the line to your dive flag or carry a 5ft stick mark in 1ft increments. Low tech solution but it would work. In groundwater studies we use transducers that have accuracy to tenths of a foot, some to the hundredths, but the data recorders and most of the electronics are always high & dry.

[Doc Harry]

Almost all scuba and free dive computers do not turn "on" until depth exceeds 1 meter.

[diver 85]

some say the human brain is a pretty good computer.....

[Hypersaline]

We are currently using a somewhat low-tech method of deploying small anchors tethered to buoys at specified locations. We're using our on-board depth finder to identify the appropriate depths, but this system is unreliable in areas of dense vegetation. We usually have to move the sampling locations once we're in the water, so we are hoping to be able to stream-line this procedure as precisely as possible. Because we're working in dense vegetation, entanglement is a major concern. We're also dealing with 18"x18" quadrats, sample bags, and cameras in addition to the usual equipment. That's why we're looking for something small to measure depth.

I'm not opposed to using an analog depth gauge, but it would need to have precision down to a foot and be able to be adjusted for altitude.

[divinglog]

On the OSTC the depth can be configured where the computer switches between dive mode and surface mode: HW (http://www.heinrichsweikamp.net/)

I don't know if this works in your case, but you can ask the manufacturer.

[Bob DBF]

My Oceanic Veo200 reads H2O at 5' but the download to the computer divelog graph will read depths less than 5'. You might want to check with Oceanic about it's limitations and whether it would meet your needs.

If you need the info during the dive try to find a capillary depth gage, they are the best for shallow water.

Bob

[sea_ledford]

How about a bourdon tube depth gauge? Like this:Suunto SM-16 Depth Gauge from DiveLife (http://www.azosensors.com/equipment-details.asp?EquipID=154)

Might have to look around for one that is more accurate for shallow water though.

[Walter]

A capillary gauge (http://www.divebooty.com/item/321/dacor-capillary_wrist_depth.html) might be even better.

[Mr Carcharodon]

I think this one will work for you. According the them:

Activation Activates at a depth of 3 ft. Deactivates after about 3 minutes above 3 ft. Threshold and end-timer are user-configurable.

See the link: ReefNet Inc. | Sensus Ultra (http://reefnet.ca/products/sensus/)

There is however no real time display. So you would have to log locations and times to relate after the fact downloads.