I've been out the Straits many times in a lot of boats, but they were all sailboats so speed was not a luxury we enjoyed.
If you want a smooth quiet ride - leave Sooke at daybreak on a day after a relatively calm (less than 15 knots) night in the mid-straits. The winds seldom build before noon or 1 PM and the wind waves don't come for another couple hours after that. It will be about 70 NM to round Cape Beal and get into the protection of Trevor Channel.
If you are really concerned then leave a couple hours earlier and you will have at least eight hours of daylight and calm seas to make it into protected waters.
If you want to be even more cautious - wait for a calm forecast
with an incoming (flood tide) for the straits during the 7 AM - noon time frame. Then - even if the winds build unexpectedly the current
will not fight the wind and build bigger sharper waves.
We left Port Angles at 04:30 in early July in a 6.5 knot
sailboat in the company of another similar sailboat - headed for Neah Bay with a relatively calm forecast
. At 10 AM the 38' boat ahead of us was pitching so badly that her keel
was 50% exposed on many of the waves. We turned around an headed back to PA.
The waves were only about 6' but, being new wind waves and fighting the ebb current
, they were steep and breaking. Our 12 ton sailboat with a 50 HP diesel
was only able to make about 4.7 knots and even that was uncomfortable.
Same thing happened the next day.
On the third day we sailed over to Victoria in calm glassy seas and heavy fog
Based on a dozen or so trips - the key to easy passage
is early to mid-morning.
You mention oceanic swells - Well - one more story!
We (same two boats several years later) were anchored in Neah Bay where we had been for three days waiting for the NNW gales to subside. They did go down so on the day AFTER the winds dropped to NNW 5 - 10 I decided to head
up to Cape Beal and all the great stuff beyond there.
As we started to haul anchor
I noticed a long line of huge ships headed east in the straits and was puzzled. The skipper
of the other boat (ex-USCG XO of the buoy tender
Fir which had sailed these waters for years) suggested I take a closer look at the "ships" with my good 15x binoculars.
I did - they were not ships -they were enormous swells marching eastward at a 15 second period.
The next day the swells appeared to have gone down so I headed out to Cape Beale with a full main and full optimism. Two hours later we were motorsailing UP and OVER 15 to 20 foot high long period ocean swells coming from the WNW. They were huge, smooth, and about 20 seconds apart. Being on top of the swell was like standing on a small hilltop in the plains - you could see forever and there was nothing but other small hills.
The boat would slow to 3.5 knots going over the top and then accelerate to 8 knots going down the back. After 30 minutes of that fun, and seeing nothing but big swells to the NW we decided to turn back to Neah Bay.
That was a little tricky - trying to turn on a very large wave seemed to be a problem but it was actually quite easy because the face was so long and so smooth.
The next day we had a nice easy sail on WSW winds up to Cape Beal.
Here is a link to a video I made in September 2010 that is the dream, ideal day for heading out the straits:
The same thing happened to me in a 65' boat I was taking out the straits in September 2006.