In response to the OP's original qustion, a very long response in two posts:
Part 1:
Although I love the Adirondack classic (the 90 miler) and have raced that 25 times so far, plus more than a dozen 'cannonball 90s" (the unofficial entire original 3 day 90 mile race route completed in a single calendar day). I have to go with the Yukon as my favorite race of all. There are two well know Yukon Race venues, the 440 mile Yukon River Quest (YRQ), and separately the Yukon 1000 mile (Y1K). I've done the YRQ three times, and the Y1K twice. I by far prefer the Y1K. I was in the Y1K for its first ever event in 2009. I spent months studying the river, the main channel route, its many hundreds of islands and gravel bars, whatever I could glean from Google Earth maps and historic routes.
The first Y1K race organizer, Peter Coates, was a joy to work with. With his experience as an official with the YRQ, the original stated rules were strict - For the newly organized rules on the Y1K, no outside support was allowed after race start, meaning no pit crew resupply or other direct assistance is allowed that was not available to every racer. However, anything that would be available to all equally was fair game. If any team wanted to stop to rest or to resupply themselves (without pit crew assistance) at Carmacks or at Dawson, that option is available to all equally. As with the YRQ, required onboard equipment was checked to be present in each boat and with each paddler. As with the YRQ, an active SPOT tracking device was required, and before coming to the Yukon, a local home route trial with SPOT data had to be sent to Peter, demonstrating the team knew how to use it. During the race, the device had to be mounted horizontal, antenna toward the sky (not randomly oriented in a paddler's pocket where it would likely not communicate with satellites) and set to transmit geolocation every10 minutes so race officials could monitor every paddler and provide an active open online map for anyone with interest to see every paddler's progress in near-real time. I had written a fairly complex spreadsheet calculation app so my pit crew (wife) could map our location and predict what time we would be at any given future point, especially the finish line, with updates based on calculated speed from predicted, accumulated and the most recently received SPOT location points and times on the river.
The YRQ has two mandatory stops that each team must rest for a minimum number of hours (seven hours at the first, three at the second). The first is at the 190 mile point for seven hours at a public campground, where your pit crew can care for you, clean and disinfect your canoe from food debris and other nasty stuff, and you can sleep for a few hours, either in a tent, or in your pit crew's rented RV, or the lucky few may get a comfortable rented campground cabin and shower. The second mandatory common place YRQ rest is on an indistinct random riverside grassy slope a couple of hundred miles after the first, for only a three-hour minimum. The race committee provides a sandwich and a drink there, and a large awing tent to sleep sweating within in your too warm 30F bag to escape from hoards of hungry mosquitoes.
There are no such common rest stop during the Y1K, you are completely on your own for the entire 1000 miles with no personal pit crew support allowed at any point. Unlike on the YRQ, there are no critical point safety boats or other emergency stations based along the river anywhere on the Y1K. First nation villages and fish camps are sometimes encountered, but given the state of “dry” laws (no alcohol being legally allowed) in most, we are cautioned to only stop at those in case of a true emergency. SPOT devices of the day had several functions: Auto tracking at ten minute intervals, “I am Ok” optional instant signal sending, “need non emergency help” and “SOS – need emergency help now, a formal immediate request for professional SAR”. The response to the second option of non-emergency help signal was up to between us and any pit crew we might have on standby who received that signal from us. In our case, it meant we were terminating the race for some non-critical reason, but as long as you see us continuing to move, meet us at the next possible take-out location, which could possibly be as much as a couple of hundred miles further down river.
We were only allowed to paddle for 18 hours per day on the Y1K. We must stop to rest for a minimum of six hours each "night" (although it never really gets dark at "night") at some likely looking random riverside landing of our own choosing when and where ever we wish before the mandatory turn into a pumpkin (penalty) time of 23:15. Many places that we stopped at had bear tracks in the muddy shore. In fact, we often saw many bears (both black and griz), moose, hundreds of eagles, and even wolves along the shore while paddling. The rules required that we must stop paddling at our own timing choice and be off the river for a total of six hours to include between the “darkest” hours of 23:15 to 02:00 local. Press the SPOT "I am ok" button when stopping for the mandatory night and again when starting to paddle from the same location in the morning as proof.
Violating these rules would result in a 30-minute time penalty added to our finish time for each such failure. My team suffered no such penalty at any time, which was not true of all teams. Race organizer Peter is on a pre-race video stating to all teams that "there is no greater sin than to not have a properly positioned constantly transmitting SPOT or to fail to mark night rest stops and starts". Our strategy was to press on paddling to as close to the mandatory quit time as possible each night past 22:30. That way, any near following competitors would be less likely to see our camp location and know how hard they had to work the next day or to take short cut risks (which we did ourselves with success). By the time we landed, cleared and cleaned the canoe well up on shore so that no bear would want to walk through it, set up tents and went to bed, and then before reversing the process in the morning, only about 4 real hours of actual rest was possible out of the mandatory six available stopped hours. I am very happy we did not have to prepare meals as well during that time. As navigator and official time keeper, I kept us to the precise mandatory six hour rest stop period, right to the minute.
Other than the SPOT, required gear included various safety items carried on the person of each paddler, $20US and #20 CDN cash and a credit card, plus a sleeping bag rated at 30F or lower for each, and tent(s) sufficient for the team packed on board, floatation or a full spray cover for the boat, and a ridiculous 20kg of food for each paddler (that's 44 pounds each, mandated the first year, 2009 only). Every mandatory item was inspected and checked off by race organization team volunteers prior to starting. Since I home prepared and dehydrated 90% of all main meals (breakfast & dinner) for the team, that is a lot of weight and fuss for a crew of 7 paddlers (do the math), especially since the weight of water to rehydrate could not be counted in the total 20kg weight. Oh, and since we would be traveling through a segment of the Yukon-Charlie National Preserve, where by regulation all food had to be carried in bear resistant containers when camped. I chose a large 120L certified bear resistant Yeti, which did fit nicely in our large voyageur canoe with all food packed in it by its sorted by menu and day. One paddler (seat #5) was chosen as galley cook, with a removable table cooking station where he could boil water and rehydrate food while we remained underway, rehydrated food to be distributed in individual mugs to each paddler in turn, while still paddling as we each took a short break to eat, one at a time. No need for the entire voyageur canoe team to stop paddling to prepare food or to eat. In the end, we only consumed about 1/3 of the required food we carried during our six-day race to the finish and no one went hungry or lost any weight.
A racing team of seven paddlers needs to consume a lot of drinking water each day. The Yukon River, below the joining with the Teslin, and especially the further lower sections, is so full of gray glacial silt that you cannot see even a millimeter into it. The heavy silt sounds like the canoe is getting the hull constantly sanded as we paddle along. Or the constant sound of a mistuned AM radio static. Can't drink that water directly. So, each night we prepared two 5-gallon buckets by first passing through simple fabric and coffee filter filtering, then adding a chemical product by PUR (meant for 3rd world country water purification), which both de-silted and disinfected, and made enough of the river water safely clear and potable to drink the next paddling day.
I have had female crew members on board with males for each of my five Yukon River races. How to take care of bio needs among mixed friends without stopping our progress down river? No problem for the guys, of course, with an empty Gatorade bottle. The ladies had various commercial and creative devices made for their purposes, but most, I gather, had limited success, one reason for attempts at washing out the boat at each night rest stop.
Any more demanding bio shore stops were kept to a maximum of no more than seven minutes each, usually only one time per day. At one such stop that happened to be next to a beautiful clear running stream cascading down over rocks from a mountain elevation, we all decided to fill our water bottles with the fresh clean water. Just after we started paddling again, one paddler turned her Nalgene bottle over to find a flake of gold drifting through. I immediately GPS marked that location and later research discovered that stream had not been previously claimed or mined for gold. Hmmmm…
The Yukon River is mainly flat water, with only two significant areas of very fast standing waves, Five Finger Rapids, and a short distance later, the relatively minor Rink Rapids. However, the current in most areas is fast moving at 6mph or more with tricky currents and eddies. Five Fingers is a big deal, with large standing waves during most of the early season, and often several boats may capsize there during the YRQ. But there is a safety boat stationed there during that race to assist recovery. Not so during the Y1K race, you are on your own to self-rescue if you swamp or capsize. There is a wood platform observation deck constructed at the end of a 300+ step stairway and half mile hike above FFR for spectators to see the huge standing waves directly below and the excitement as boats work their way through. I have photos of me taken from the safety observation boat during a YRQ passage. In one photo I am elevated in the bow paddling air, in the next I am taking a wash of wave directly on me over the sunken bow. That is why we are required to have flotation or a full spray cover (which is what we had). A successful passage only lasts about 15 exciting seconds, and at the end you wish you could paddle back upstream and do it all again.
Current advice… Flowing in a main channel at 6mph in most places, or even more in some places, seemingly dead in few others. Add our voyageur no current paddling speed of 6+mph and we finish the 1000 mile in only six days. But it is not that easy. Subsurface currents collide and make upwells with side currents going nowhere. Often you may think you are in a main current moving along nicely, but you discover that if you shift parallel only a boat length or so away, then you may gain as much as 2mph more in a faster current. Paddling along steep sided shore cliffs usually puts you into a faster main current rather than close and parallel to less steep shores. Extensive areas of widened river shallows, especially near where the Stewart River joins, will slow you to a crawl if you can get though at all without dragging over shallow gravel shoals and bars. You must look for faster alternate current paths.
Many areas of shortcuts that bypass the main current channel are tempting to jump into. A lot of water may seem to be flowing into narrow passages and you think it would be a lot faster to travel that way and join the main channel later. But this is the devil deceiving you. If that channel widens at all significantly after you pass through, then you may be in dead water with no significant current to propel you along for a much longer distance than you care to be in. Paddling extra hard gains you little. You might have better stayed in the longer course main channel current. This is where previous years’ experience and map study pays off. Take care to note that the river nicely flowing side channels and gravel bars may change greatly from year to year. Be careful of dated maps as well. As Island banks disappear and gravel bars appear where you don’t expect from year to year. We paddled in sections where maps showed solid land or where white permafrost iced blocks of earth were actively falling into the river, some making large waves as they splashed nearby. We had to be careful of not getting caught under eroded undercuts, where the current happened to be the fastest. We actually crossed the Arctic Circle on a day when the air temperature was near 90 degrees F