The DUCD is an Urine Collection Device for drysuit divers. Like P-Valve, diver's urine is discharged into a sheath worn over the penis, but the divice holds the liquid in a storage bag while pee-valve discharges it to outside water. The DUCD is worn over lower body and has a drain valve to empty its content. The large version can hold more than 1 liter and thus it can accommodate also very long dive.
Urination through a Pee-valve on ground or on board may be prohibited but you can use the DUCD anytime and anywhere you like, even in luxurious cabin of a dive boat! Unlike diapers, the DUCD is designed for multiple use. You can put on the DUCD at home before you depart for diving. What you must do is just empty it before it becomes full. The liquid kept in the DUCD never bleeds out, so that you don't have to clean inside crotch of your drysuit.
Although the DUCD consists of high pressure hose, it may be squeezed in depth. To avoid this, urination before dive to fill the hose is highly recommended. The best manner may be to put on the DUCD before departure to allow several urination before donning a drysuit. By doing so, you can endure not only long dive but also long d'r'ive.
You have to do nothing special when you don your drysuit, and it is invisible when you wear it in a drysuit undergarment.

Unlike diaper, the waste liquid can be discharged just by slightly opening the zipper. And like a diaper, you don't have to punch a hole to your drysuit. Why not widely used then? The reasons may be incompatibility with tight fit drysuit (basically, the DUCD is usable only with loose fit drysuit), uncomfortable urination, and necessity of complete cleaning and disinfection after use.

The DUCD is used with an external catheter as like Pee-valve. Urological storage bag, which is normally fixed on lower leg, is used. To avoid restricting fin kick movement, however, the bag is fixed over the lower body by a strap assembly designed for diving use. The double hose design allow maximum flow and proper positioning of the urinary organ.
This kind of device was originally developed by USNavy in early 80s based on the spacesuit Urine Collection Device(UCD) used by NASA atronauts. According to a document, this type of device was more comfortable than p-valve type device because of lower back-pressure while urinating.

UCD used in early Space Shuttle missions

UCD used in Apollo missions

Condom for NASA UCD ("Roll On Cuff")

Today, NASA astronauts use "Maximum Absorption Garment"(MAG) instead of UCD.
The DUCD was tried on ground.

This time, it is worn directly over the body.

Without the liquid, it is very hidden even by normal underwear.
It will be completely invisible if you wear it under drysuit undergarment.
A day was spent with the DUCD without any problem.
Skin is slightly irritated by abrasion with the waist strap.
If your skin is sensible, you are recommended to wear the device over your underwear.
The use of the DUCD may not be limited to drysuit dive. It is useful whenever you wish to avoid bathroom break.
The DUCD was tried underwater.
The result was very promising. Although there was too much space between the glans and the catheter, the catheter was kept in place without any sign for "peeling off".
With the DUCD, problems of the catheter like twisting, kinking, and detaching are less likely to happen since the tough hose assembly of the device keeps the "shaft" to the ideal position
Several "erection-relaxation test" do nothing to the reliability of catheter adhesion.
For more comfortable urination, fixing your penis "upward" by surgical tape to assure straight flow line may be good idea.
By "hold in place" effect of the device, it was very comfortable to wear and felt nothing strange.
Underwater urination was as smooth as that with pee-valve.
It is very well designed to provide comfort and reliability.

I was in drysuit from 10AM to 4PM.
Expanded bag is visible even from outside of the squeezed drysuit.

With loose fit undergarment, it is invisible, however.

1200ml urine for 6hours was held. Any diapers cannot hold that large amount under pressure underwater.
It was surprisingly well designed product. This is my real testimonial after my first actual use.
Minor issues of the DUCD are spilling urine when you detach the catheter and condensed sweat on the backside of the storage bag. To avoid these, brief type lightweight diaper is very useful. This diaper takes up just small amount of moisture, so that the lightest one is usually sufficient.
Components
1. Storage bag 2. External catheter (condom catheter) 3. Elastic waist strap 4. Velcro waist strap 5. Attachment tape 6. Crotch strap 7. Surgical tape (optional) Surgical tape is for fixing crotch strap. It is not used any longer, however, as it sometimes caused improper location issue. |
Assembly
Install valve clamp to the discharge valve on the bottom of the storage bag.
Close valve clamp after de-aerate the storage bag.
Insert a crotch strap in the slits on the bottom of the bag.
Turn the crotch strap and fix the position with backles.
The other crotch strap is assembled in the same way.
Insert the attachment tape in the slits on the top of the bag.
Attach one end of the elastic waist strap to Velcro waist strap.
Donning
Before this procedure, catheter must be put on.
Apply waist strap assembly on the waist. The navel covering position may be tried at the first time.
Attach hose assembly to the opening of the catheter.
Fix storage bag to the Velcro waist strap with the attachment tape.
If you prefer to fix the penis upward, do it here using surgical tape.
Turn the crotch straps over crotch from back to front, and fix it to the waist strap assembly.
Adjust height of the assembly to remove any kink of the catheter.
Donning completed.
To avoid hose squeeze, fill the hose assembly with urine before entering the water.