You can use a SCUBA drysuit for kayaking but it doesn't work so well.
The SCUBA drysuits are much heavier, are much bulkier, are much bigger, and they don't breathe. They also have the air inlet value positioned such that it is covered by your PFD, which means the PFD pushes a hard piece of plastic/metal into your chest (not very comfortable).
The big problem with using a kayak drysuit for SCUBA is that you can't control the air volume in it. The other problem is that the kayak drysuits are not designed for the level of stress that is required for SCUBA (the kayak drysuit would leak and fall apart).
===>> "(And what do divers do without a pee zip?)"
Keep in mind that the dives are only about an hour long and you don't wear the drysuit "all day".
The standard technique is to just hold it. Clearly, it is prudent to go before you suit up. I've never had a problem (in about 170 dives with a drysuit). It appears the urge is somewhat suppressed when diving.
For divers doing very long dives (let's say 4+ hours), they sometimes wear diapers or they (males) use what is called a "p-value", which entails using a prophylatic with a hose at the end connected to a valve on the drysuit. To use this setup, you open the valve and pee into the ocean.
One correction Everything you said is true except this:
“Keep in mind that water leaks into a wetsuit. This leakage avoids the squeeze you get with a drysuit.”
Not only do SCUBA wetsuits not all leak - mine seeps only a tint bit of water at the neck, cuffs and ankles - but they are warmer when they don’t allow water in. Water in a wetsuit not only adds nothing to its insulating ability, it reduces it. It’s a common misconception that wetsuits need to be wet in order to work. Nothing could be further from the truth.
Seepage has nothing to do with squeeze, which is only a potential problem in areas that are full of air, such as your lungs, inner ear and mask. Your regulator compensates for the lung, equalizing your ears and exhaling into the mask takes care of those areas.
Another correction "Note that not only does the kayak suit not have easy ways to add and release air, it isn’t strong enough to hold up to the pressure changes. A SCUBA drysuit is constructed with much more strength (there is a lot more glue holding the suit together)."
When diving, the pressure on the inside and outside of the suit is equalized, so there is no stress on the fabric. When you ascend, the pressure in the suit will increase slightly, but the relief valve will bleed off any excess pressure. Barring that, the seals at the neck and wrists will leak out excess pressure.
The reason that diving dry suits are made of tough materials is that they’re often used in rocks, reefs and wrecks where abrasion and tearing are distinct possibilities. A dry suit failure at depth would be catastrophic, so the suit need to be extra rugged. Kayaking doesn’t have the same risks and freedom of movement is critical, so kayaking dry suits are made with lighter, typically breathable, materials. There is no way for a suit to breathe underwater, so there’s no point in making diving suits from breathable material. For diving water tightness is more important.
I think the pressure issues for SCUBA drysuits are more significant than people realize.
==>> "When diving, the pressure on the inside and outside of the suit is equalized, so there is no stress on the fabric. When you ascend, the pressure in the suit will increase slightly, but the relief valve will bleed off any excess pressure. Barring that, the seals at the neck and wrists will leak out excess pressure."
The suit would be "equalized" if it and you were perfectly flat and you were swimming horizontally. Because the diver takes up volume, there is a pressure differential between the highest and lowest point. This differential (as small as it is) is enough to squeeze the air in the suit to the highest point. This stress isn't great but it's constant (this kind of stress is only seen in a kayak drysuit when you are swimming).
I certainly would not trust the seams in my expensive kayak drysuit to hold up for very long to this stress.
The stress is even greater if you invert yourself (feet up) in a drysuit (not a good thing to do), the all the air goes to the top (to the booties) and, in this case, there is no way to automatically release the air.
The suit has to be sturdy enough to deal with the air constantly moving around (all due to pressure changes). Note that there is only one relief valve (typically) and that has to be open (yes, they can be closed) and in the correct position to work.
Personally, I would not trust the wrist and neck seals to release air too readily or quickly enough.
==>> "The reason that diving dry suits are made of tough materials is that they're often used in rocks, reefs and wrecks where abrasion and tearing are distinct possibilities. A dry suit failure at depth would be catastrophic, so the suit need to be extra rugged. Kayaking doesn't have the same risks and freedom of movement is critical, so kayaking dry suits are made with lighter, typically breathable, materials. There is no way for a suit to breathe underwater, so there's no point in making diving suits from breathable material. For diving water tightness is more important."
Yes, being able to hold up to these kinds of abuses is a major reason SCUBA drysuits are sturdy.
Still, even ignoring these abuses, a SCUBA drysuit is, in normal use, under a lot more stress than a kayak drysuit is. That is, even without these potential abuses, a SCUBA drysuit would be build much more ruggedly than a kayak drysuit.
==>> "A dry suit failure at depth would be catastrophic"
Maybe not catastophic, at least not always. It's pretty common to get leaks and people generally survive.
squeeze unbearable at 3 meters Hi, I know this is an old thread but have experienced diving in a surface dry-suit and thought I would add my experience.
I am a scuba diver and have taken up kayak sailing/fishing/diving. I have always used a wetsuit when diving, when I got my Adventure Island (AI) and started sailing in 10 degree C water, I purchased a Northern Diver surface dry-suit. Curious as to its dive ability I loaded up the weight belt and had a go off a local pier. Maximum depth you can get is about 6m but I only got to about 3m when the amount of squeeze began get really uncomfortable. At this point I will also tell you that I work at a scuba diving shop and had a fair idea what would happen. You can actually feel the suit squeeze by just walking waist deep in the water, even if you open the neck seal as you descend to let all the air out, not all the air will come out. Small pockets of air will stay in the suit, you will also have tiny air bubbles in the paws of your skin, these in return will act the same as air in your ears, if you do not equalize the two pressures then you will get squeeze, also you then have no internal pressure in the suit to keep the water out so you might as well wear a wet-suit, water leaks in.
As for thermal protection, the warm air trapped inside the dry-suit is the same as the warm water trapped inside a wet-suit, the amount of clothing you wear under the dry-suit helps control the body temp which in tern heats the air inside the suit. Meaning both the air and the clothes you are wearing under the dry-suit are what gives you thermal protection.
I am now looking at buying a dive specific dry-suit hence my browsing and finding this site. The thing I am trying to find out, is: are their any kayak dry-suit users, using pee valves in their dry-suits and if so how do they find them?
I am mainly interested in Hobie owners that pedal more than paddle as this is what I mostly do, and I am wondering how the external catheters stand up to the pedal motion of the legs, also where there outlet valve is situated?
Anyway that’s my two bobs worth, thanks for having me on board.