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Winter Boating Safety

Winter Boating Safety

For those of us currently going into winter there is always an excitement that pervades this time of year. We can typically expect higher flows on our favorite runs and free flowing rivers to come up out of nowhere. If you are new to boating and you get invited on one of these winter trips the attitude surrounding the trip can seem a bit more serious than in warmer months. For those of us who are familiar with winter boating we realize that the more serious nature of the trip is by necessity. Chiefly among our concerns are hypothermia and additional hazards not often encountered in warmer months. Although these concerns are in the minds of boaters at all times, it becomes particularly salient to our lives in the dead of winter.

Cold Water

Water temperature is one of the most serious concerns for boaters in the winter. A swim in extremely cold water can cause the onset of hypothermia very quickly. Water is the most efficient medium for transporting heat away from your body. On our back yard run, the South Fork of the American River, near Coloma, CA the water temperature during the commercial rafting season often runs between 60-70 F during the commercial rafting months of June, July, and August. According to a US Coast Guard study at this temperature range you can survive between 2-7 hours of unprotected exposure. The winter is a very different story and the river often ranges between 40-50 F from the end of November and the beginning of March. At this temperature a person can reach unconsciousness within 30-60 minutes of exposure.

Hypothermia Chart

In a 2001 Dr. C J Brooks of the Canadian National Transportation Safety Board found that immersion into water colder than 59 F can cause cold shock, a loss of efficient breathing, and a dramatic decrease in swimming ability within 3-5 minutes. A swimmer spending 3 minutes in the river during a high flow, in Class IV, or Class V rapids before rescue arrives or they can self-rescue is a highly probable scenario. This scenario lays the groundwork for the rapid onset of hypothermia later on. 

Cold Weather Protection

Cold Air

Wind Chill

Part of the joy of rafting is splashing through big waves, but since water is such an efficient conductor of heat consistently soaking your gear can rapidly cause a decrease in temperature especially when coupled with wind chill. As temperatures decrease wind chill become increasingly more powerful. When you factor in the evaporation and chilling effect of water there is literally no way for the body to warm up on the water short of a powerful heat source. As such a wetsuit can rapidly drain your body of heat if left unprotected.


Rain and snow is also a powerful heat transfer mechanism. If you only look at the river temperature it does not paint a complete picture. If the temperature suddenly drops from 50 to 35 and it begins raining it doesn’t matter if the the water is 48 degrees you will begin to be rapidly soaked by 35 degree water. This is the same effect as if you were submerged in near freezing river water. This also cuts an unprotected parson’s survival time from 45 minutes to about 20. With the proper protection you can mitigate this, but if you planned for a 4 hour run swimming in 48 degree water and you spend 4 hours being constantly soaked by 35 degree water you may quickly realize that the full wetsuit you brought was not enough.

Middle Fork American River High Water

Short Days

In addition to significantly lower temperatures, winter comes with the added inconvenience of short days. In California the days can shorten to 9 hours and with that in mind if you are preparing for a 6 hour run and you are late you can easily find yourself paddling out in the dark. Even with an early start; long shuttles, slow prep time on account of the cold, and a 1 hour wrap could easily create the perfect storm of problems for your trip. This creates the twofold hazard of potentially boating an unfamiliar section of river completely blind and running said section with significantly lower air temperatures than you had initially planned on.

Abnormal Flows

Winter boating can be unpredictable. You can have a string of warm days that starts a freeze thaw cycle and the river starts running well just to have a freezing night and a cold day and the river virtually shuts off overnight. The more concerning scenario for boaters often is quite the opposite. The most epic river stories often abound with tales of the river running at ideal flow during a rain event and without warning the river rapidly spikes to an extremely high level that you are not prepared for.

The former scenario requires an acceptance of this being just what Mother Nature has to offer. Stubbornness can quite literally get you nowhere fast. Low water runs can be enticing, however if you normally plan for a 6 hour run during ideal flows, this can quickly add an extra hour to your run thus cutting out your margin for error on that stretch.


The latter scenario requires a little more understanding of your ego and bravado. The river brings out potentially dangerous cocktail consisting of fear and bravado. If you are at a put in with the water quickly rising you may find that the easy class IV run that you are used to becomes a big water Class IV+ run. The difficulty here in this scenario is that if you may be a Class IV+ technical boater, but you may be a Class III big water boater. This could spell disaster for your trip especially if you quickly realize that you are in over your head and fear begins to paralyze you when you should be paddling hard into the next wave. Remaining safe in this scenario will require a keen understanding of how good of a boater you are and the ability to set your ego aside to ultimately walk away from a run. Pushing limits is one thing, but keeping you and your boating group safe is another matter. 

Strainers and other hazards

South Fork American River High Flows

Rivers are dynamic environments and we tend to forget this especially if we are commercial guides running the same stretch of whitewater every day. The above mentioned abnormal flow windows will move debris around. High flows can flush logs downstream and the river flows freely through the defoliated vegetation on the riverbanks. This can pick up wood and deposit them into drops that you are not expecting. You can also end up swimming places that you never thought possible. Also if you are boating on higher flows the river can literally be running into the trees and on more than one occasion boaters can find themselves paddling through a forest. There is really no better place to wrap a boat or flip off of than a tree in the river. 

Safety Recommendations

Wet/Dry Gear - Clearly a wetsuit or drysuit with booties is the obvious answer here as the first line of defense, but how much do you need? Too much layering and you could end up overheating and sweating too much losing vital liquids and exposing yourself to rapid evaporation thus increasing your risk of hypothermia or heat exhaustion. The following chart offers a helpful guide on what type and thickness of suit is recommended. This is just a general guideline for suit thickness and additional layering my be required to insure maximum comfort and safety. We do not recommend a suit in excess of 5 mm at its maximum since it will severely hinder your ability to paddle and function effectively in a whitewater environment. 

Wetsuit Thickness

Just having a wetsuit or drysuit is generally not enough to be sure that you are comfortable and warm during the winter. Consider adding the following items to your list of gear:

A fleece and a spare bag of clothes can go a long way on a cold trip.

A fleece and a spare bag of clothes can go a long way on a cold trip.

  • Splash top or Drytop - This will help you on windy days when a drysuit is too much, but a wetsuit alone will cause too much heat-loss through windchill or evaporation.

  • Neoprene Socks - Helps add an additional layer to keep your feet warm in just wetsuit booties.

  • Fleece mid-weight layers - Micro Fleece is remarkable for its ability to keep you warm despite being wet. It works exceptionally under a drysuit, but it still is very good at keeping you warm under a splash top. it also tends to be inexpensive.

  • Neoprene or wool gloves - Having a pair of gloves is almost as important as booties and will keep you warmer and more comfortable as you paddle in increasingly cold conditions.

  • Beanie - If you wear a helmet this can be a problem as a beanie likely won't fit properly. A thin skull cap of fleece can go a long way to keeping you warm.

Carry Spare Clothes - Having an extra set of clothing and a towel is a critical part of your winter kit. We typically tuck a spare set of warm clothes and a couple Mylar blankets into our Watershed Bag just in case. When the weather is bad it can be impossible to get warm without extra supplies if someone is getting hypothermia after a swim.

Weather - Pay extra attention to what the weather is doing the day prior and the day of your trip. Plan your layers accordingly and select a section of river according to your skill and comfort level. When in doubt of the river coming up select an easier section that you know you will be comfortable with.

River and Flood Advisories - Check the national weather service bulletins for your area on river and flood advisories. It may not be raining in your area, but it can still flood if the weather changes upstream.

River Write up / Advisory Board - Some rivers have many write ups, advisory, and message boards both online and at put ins. These services provide invaluable information on what to expect from the river, recent warnings, and flow evaluations. Be sure to read up on them before you put in.

Swiftwater Rescue Classes - Much like backcountry skiers have avalanche classes so to do we have disaster preparedness classes. A swiftwater course can give you an incredible edge in terms of self rescue. You will also have a leg up on best practices when you do get into a sticky situation on the water.

Paddle in Groups - During winter stick together the risk to paddlers can be very high in this season and it is always best to avoid one boat trips.

Practice safe boating and we will see you on the river....

Basic Oar Selection

Basic Oar Selection

The Gear Shed - Hyside Mini-Max

The Gear Shed - Hyside Mini-Max