with a product like this, I believe you need to be in a location and position to show the product to consumers. Have you exhibited at The outdoor show, or Boat Show.
This would be ideal for yacht clubs that move boats on trails at start and end of season? Setting a booth or display at local yacht clubs could help get interest and word of mouth.

Physical products often have an Aha! Moment (moment when user get to know the real value of the product) when they first get to use it. Organize test shows, or free trials...anything to get the product working in front of potential customers.

You'd be surprised, there is actually some cost effective ways to reach consumers online. You just need to think outside the box a little bit :)

Let me know if you'd like to discuss.