Wave riding (drafting) of dissimilar craft is not allowed in the Yukon River races (the 440 mile Yukon River Quest and the Yukon 1000 mile race) unless both parties are in the same class and agree to such. That rule may have had its origins with me and my team during the first ever Yukon1000 mile race starting in 2009. I was in a voyageur canoe, being closely drafted by a kayak. Drafting so close that it often impacted our stern and interfered with the stern paddler’s steering. When questioned why, and asked to back off, the kayak paddler stated he did not have or “lost” his river map, which was required by the rules for all boats to have onboard before beginning the race. That alone should have resulted in a DQ.
I officially objected because I had spent literally months of time in research and detailed inspection map study of the river, combined with our previous year’s YRQ experience on the river to create what I felt was the most efficient and fastest route possible. We finally shook the kayak off when a partner kayak showed up from behind. Afterward we lodged a formal protest against the kayak, for unfair practice. After long discussion with race officials, the no out-of-class drafting rule surfaced the next year. Turns out during our race, that kayak violated many other official rules of the race, resulting in a total of a 9-hour extra time penalty imposed on his finish time. We later found out that that particular international paddler has a history of inappropriate actions in races elsewhere.
In addition, during the Yukon races, such drafting could be interpreted as pacing, which is a disallowed activity.
Even with boats in the same class, courtesy demands that the drafter communicate intentions and ask permission. In other races I have been in elsewhere, with unlike species, long distance drafting may be allowed if both parties so agree.