layering under & over a wetsuit

[dsigall]

Another newbie question...

I'm looking to stretch the paddling season as far as I can without having to spring for a dry suit (yet). Somewhere I read that a layer of fleece or polypropylene under a wetsuit (farmer-john in my case) would help converve warmth in cold air temps. Makes sense to me as long as I stay out of the water but I expect to get wet whenever I paddle and usually do. It seems that any insulation from a layer of polypro would dissappear when wet or damp. Fleece might hold some warmth when wet but out of the water. Could the extra cold water a layer of fleece would allow under a wetsuit defeat it's purpose?

I may have just talked myself into a drysuit but I'll hold out for your replies. Thanks!

Dana

[scamlin]

Properly fitted wetsuits are warm and comfortable, except in hot weather. The basic principle is to dress for immersion, not the air temps.

Most of us wear some kind of synthetic underlayer under the wetsuit for comfort as much as warmth. It can range from a non-thermal rash guard (thin, slippery nylon), through thin poly wicking layer, to thick fleece. Wetsuits with some kind of nylon lining can be worn without anything underneath.

The basic principle of wetsuits is that cold water does seep inside the neoprene, but the body warms it up and the insulating value of the neoprene helps keep it warm. To make this work, you need a tight fitting wetsuit: if it gapes around the edges, the cold water flushes the warmed-up layer of water out and it defeats the insulating value of the neoprene. Wetsuits are particularly hard to fit correctly around the armholes (most kayakers use Farmer John/Jane suits to give mobility in the arms) and around the neck (especially at the back of the neck between the shoulder blades).

You can argue the effects of fleece worn under the wetsuit either way: it slows down flushing by stopping up the gaps; or it doesn't allow the neoprene to seal properly and wicks cold water in under the neoprene. It is usually more comfortable. Personally, I have found that moderate layers of fleece have little negative effect, but I would not want to put on a really thick fluffy fleece under the wetsuit: maybe expedition/winter weight underwear or medium fleece. You want to keep the neoprene close to the body.

Fleece over the wetsuit would have a lot of insulative value when dry (especially under a shell layer), but not a lot once wet.

Note that a well-fitting paddle jacket or drytop over the wetsuit is an ideal complement to a wetsuit as it greatly limits cold water flushing. After a swim, wet neoprene does suffer from evaporative cooling: you may continue to cool off, perhaps dangerously, once you get back in the boat. The paddle jacket really helps limit this risk.

Note that 3mm is the standard thickness for cold water wetsuits: more is too stiff and less is a bit lightweight when trying to extend the season.

One rule of thumb is that you need a wetsuit for immersion under 60 degree water temps and a drysuit under 50 degrees. In the Boston area, that extends the wetsuit paddling season from May to November. See http://www.nodc.noaa.gov/dsdt/cwtg/natl.html for a water temp table for New England. This assumes that you are only in the water long enough for a rescue; if you have to bob around for hours waiting to be noticed by someone, you'll be hypothermic.

Of course, your actual comfort and survivability depends on a lot of factors, including motion in the water, wind above water, fatigue, hydration, food, etc. If you swim in 50 degree water with a 3mm wetsuit and paddle jacket, you'll certainly be cold, but will almost certainly survive to recover and get home--something you cannot count on without a wetsuit.

Once the water gets cold, you'll want a neoprene or rubber/fleece hood and neoprene gloves. The former will greatly help limit loss of body heat and the latter will allow your fingers to function enough to rescue yourself.

Best Regards,

Scott

[bob budd]

I don't believe Scott mentioned a thin neoprene or similar shirt on top. "Hydraskin" is one recognized name. One of these will likely extend your drysuit season a bit.