Once you have saved your verified Boat US information to your Dockwa account - any discount on dockage will be automatically applied to your reservation request.
You can see the discount applied on the last step of the reservation process - before you click the "request reservation" button. You will also see your Boat US membership number displaying under the "Boat US Discount" section.
Please Note: Not all BoatUS affiliated marinas discount dockage. Some do fuel and other discounts, that might not automatically apply to your reservation. If you believe you have not received a BoatUS discount that you should have, you can "Message the Marina" and ask them to manually add it to your reservation. You can find the exact breakdown of the marinas BoatUS discounts on their profile page, further information HERE