Here is the link to submit a comment on the bill. Just click on the link, enter your address, click on "verify district", click the check boxes next to your legislators, enter your contact information, select "Oppose", and write a quick comment.
https://app.leg.wa.gov/pbc/bill/5597
Here is what I wrote to give you some inspiration:
This again? This bill was a terrible idea when it came up in previous legislative sessions, and it's still a terrible idea. Do you require a walker's education card to walk on the sidewalk? No, because it's a stupid idea, just like this bill. The only thing this does is line the pockets of whatever private contractor is going to be issuing the boater safety cards (I'm sure the same ones lobbying to get this bill passed). There's a big difference between a 2000-lb motor boat that can do 50 knots with spinning blades on the back, and a 50-lb human propelled kayak that can do 3 knots. No one has ever been killed by a kayak/canoe/SUP/inner-tube running them over. The same cannot be said of motor boats. Boater safety cards for operating a motor boat make sense, but they are completely unnecessary for human powered craft. You should not be erecting additional bureaucratic hurdles to people enjoying the outdoors, especially when they serve no meaningful purpose. Represent the citizens of Washington that elected you, not the corporations trying to extort them. Please try to convince your colleagues to oppose this bill, and hopefully send it to the committee compost bin where it belongs.