Question, is there a recommended way to get through something like this if it's an emergency. Let's say someone had a stroke on board you are dealing with the golden hour to get them to help down stream of this. Would the strategy be just enough power to keep the bow pointed towards the standing water and/or from being swept into the shore? I am assuming the standing waves are probably in the 6-8' range so too much speed may create hazardous issues for a boat?
Bowball, is there a link to the video you can share?
Your question prompts an interesting thought experiment. Some parts I’ve reasoned out before, and some now as I answer. My answers are based on considerable experience running such rapids in a heavy full displacement boat. And rivers in paddle boats. More medical training than most recreational boaters have. Including working with long distance medical support ashore.
The short answer is that in the event of a stroke, heart attack or other serious medical problem with a tight timeline there is not much you can do so it’s not worth the risk to yourself and everyone else aboard to run rapids like that.
I see you are in Bellevue. The Seattle metro area has one of the best if not the best response times and successes records in dealing with heart attack and stroke. Still so much depends upon timing, as you said the golden hour. Will you (or I), can you get the victim to care within 1 hr? Almost certainly not even on Puget Sound near major metro areas. At trawler speeds it’s possible even likely you will be an hour or several hours from a dock. And that dock may, likely, will not be immediately close to an emergency center equipped to handle stroke and heart attack. Then there’s the time to get the victim to highly skilled emergency care. The odds aren’t good. Now put your boat in a more remote area and how long to help, the how long to expert care? Because this thread is about Skookumhuck Narrows Skookumchuck and Sechelt a city of over 10K with a hospital are not really remote but you’re still about 16 nm from the docks at Sechelt when at the rapids. Your golden hour is more than gone before you get tied up.
But you asked, how to do it? Ok, here’s my input based mostly on 65ft, 78 tons, 8.5 cruise speed, 10.2 full speed. Obviously you can't make any progress swimming upstream when the current is anywhere near your boat’s full speed. Your question was about running downstream. So much of what you do will depend upon your boat’s characteristics, your experience and your skill. What I have learned is to go at just the right speed. Fast enough to have fast steering response but no faster. You need to be able to counter the upsets of the rapids NOW. As I said, depends upon your boat. Avoid if possible the standing waves if they’re big enough to stuff your bow. Obviously avoid whirlpools. In some rapids at some flow you will see areas of smooth water looking almost like a pillow slightly bulged up in the center. Stay away from those. They are often strong upwelling and will catch your keel or hard chines if you have them and try to upset your boat. Where do I go? Well my answer works for me only and what you do will again depend upon your boat and your skill. I look for the VEE fomed by the fast water and aim for the center of the VEE. Yes, it will be FAST. But you will have the best chance of missing standing waves, whrilpools and that smooth stuff I don’t have a name for.
Give some serious thought to speed of the current. Let’s say Skookumchuck is running 16 kts and you require 7 kts for fast steering you are now doing 23 kts over the bottom. Whatchagonnado if something goes wrong? Nothing except take your lumps.
You ask about the risk of hitting shore. Unless you lose directional control end up facing shore and fail to reduce speed the changes of hitting shore are actually pretty low. The faster water is in the deeper parts usually center or near center. Drop her into neutral, maybe even back down and that is most likely where she’ll go. This needs to be tempered by the bottom topography. If there is a large rock or shoal in the channel it can create back eddies and that changes everything.
There are good reasons to stay center channel as much as possible because the sides is where the back eddies will likely form. Get one end of the boat in the main current and the other in the back eddie and you will spin around. Not much you can do to counter it. You can with experience and skill learn to use back eddies to your benefit. This is where experience running rivers will help.
There is one thing you can try and I don’t recommend it until you really know your boat in these kinds of conditions and have considerable experience and skill. And have a compelling need. When the current is much faster than your boat run it backwards. That is bow pointed upstream with enough power on for good steerage and let the current sweep you downstream faster over the bottom than you are running upstream through the water. The reason is a boat is under better control going upstream than downstream. Let’s go back to Skookumchuck at 16 kts and your boat at 7 kts, you’ll be making 9 kts good. I’ve done it and as I said I can’t recommend it. You have to be doubly careful not to hit standing waves with your stern. Nothing good will come of that.
Don't trust your autopilot. Manual steering is the only way to handle fast rapids.
All of this is about running downstream. Running upstream is all together different. But this response is long enough already.
Back to your location being Bellevue. Deception Pass Narrows and Tacoma Narrows are great places to build your skill. They are relatively straight and easy to read. Deception pass will give you opportunities to learn about riding the VEE, staying clear of whirlpools and at times sizeable standing waves. Tacoma Narrows throws in learning about back eddies downstream of the bridge and south of Pt Defiance.
Start in about 3 to 4 kts current and work you way up as you learn your boat and skills. In Deception pass you see a significant difference between 3 and 4 kts current.
And once again so much is about the boat. The heavy boat most of this experience is based on is what I ran for much of my career. My personal boat I mess about in now is a Californian 42 LRC. It is a whole nother thing and I’m still learning it. It gets thrown around a lot more by the currents. But it will do 12 kts if I want to burn the fuel. I went back to running Deception Pass at 3 kts up and downstream and built up from there. Another boat I have considerable experience with is a KK 42. Handling that in the rapids is yet another thing all together.
A final note about going to Deception Pass school of rapids running. Don’t try it on a summer weekend when the fish are running. All the sport fishing boats will limit your options and complicate things.
And, most importantly, this is my opinion based on my experience. Take it easy, start easy, build the skill and experience a bit at a time.