Promote Your Brand, Not Someone Else's.
You send mailings. You pay for radio spots. You insist on a fantastic level of service from your crew. Then when some guy, who happens to need a new dock, goes paddling by the newest system on the lake (which you sold, delivered and expertly setup), who's logo does he see on the side of it? Not yours.
You see, someone who has a place on the lake doesn't grow up knowing where to buy docks the same way someone grows up knowing all the brands of phones or cars or TVs that are available. When they recognize they need a new dock, they start looking at the docks on the lake. If they see your brand you get the call. If they see another company's logo, it's a toss up.
The best way to multiply your marketing efforts is with free advertising to the people who matter. When that guy who needs a new dock paddles by one of yours, he not only sees your logo with your phone number, but he also sees proof. Proof it works for his lake and proof other's think the same way he does.