Suddenly Washington is a big-time port-of-call.

It started when the Norwegian tall ship Christian Radich came to town for a week this spring, the first major sailing vessel to call on Washington in memory. Not to be outdone, the Danes followed with their seagoing square-rigger Danmark.

Now come Smoky and Sheila Knowlton all the way from La Habra, California, in an 18-foot outboard skiff and on the wings of a dream.

"This is Smoky's dream book," said Sheila, leafing through a tattered edition of the Rand-McNally highway guide to the United States.

"We originally planned to use nautical charts, but we go through them too fast and they cost $5 apiece," said her suntanned husband. "People think we're nuts, trying to navigate around the country on a road map. So far we've been lucky."

Smoky Knowlton's dream is to circumnavigate the nation in his little Glastron with the 115-horsepower Mercury. This is not easy to do, since on two sides the United States is bordered by land. "We're trying to do it with as little overland travel as possible," he said.

So far it has meant only one land voyage. The Knowltons left Long Beach a little over a year ago and traveled 2,000 miles south into Mexico by sea before the Mexican peninsula narrowed sufficiently to meet their standards.

Then they hired a flatcar on a trans-Mexico freight train for $200. The boat was hoisted onto the car and Smoky climbed aboard to live on the boat on the train for the three-day adventure across the mountains. It was, he says, the highlight of the trip. So far.

Plenty more thrills are in store.

The Knowltons putted up the Potomac last week for two days of sightseeing in The Nation's Capital. They had just completed their run up the East Coast through the intracoastal waterway, which will probably be the leg of their 12,000-mile odyssey they remember as easiest.

From here they were heading back to the Chesapeake, north to the Chesapeake-Delaware Canal, across Delaware Bay and up the Delaware River.They plan to link up with the Delaware-Raritan canal, which will eventually deposit them in the Atlantic again at the stinkpot city called Perth Amboy.

From there they intend to go up the Hudson River and across New York State on the Erie Canal to Lake Erie. They will follow the Great Lakes to Chicago, then take the Illinois-Mississippi canal to the Mississippi River.

They will go south on the Mississippi to St. Louis and pick up the Missouri, then follow it west and north across the midwestern states of Missouri, Nebraska, South and North Dakota and on to Helena, Montana, where the Missouri finally peters out.

That's their second land bridge. Smoky says he'll find someone to trailer the boat across the continental divide, and he'll put in at the earliest navigable point on the Salmon River in Idaho.

From that point it's a downhill, hair-raising sleigh ride to the Snake River, the Columbia River in Washington State and on out to the Pacific. He figures to be back at Long Beach at 3 p.m. October 25, but won't be surprised to miss by an hour or two.

Just one question: Why?

"We got married when I was 17," said Smoky Knowlton. "We had our three kids. All my life it's been work, work, work.

I'd always thoght that when I got to be 40 and the kids were grown I'd be able to get away, to travel around and see the country. I forgot to figure on one thing: I just assumed I'd be rich, but when I got there I wasn't."

What he did have was a boat business, and the then-new Glastron sat on the lot saying, "Take me, take me."

So he did. In the summer of 1977 he and Shiela took off in the boat and went to Alaska, where they stayed 2 1/2 months. That grueling adventure only whetted Smoky's appetite for more, and thus the grand plan to circumnavigate the nation was hatched.

For her part, Sheila can largely take it or leave it. "I can only stand about two months at a time. Then I have to go home."

Smoky takes occasional breaks and goes home to round up money by selling boats at boat shows.

But he always looks forward to getting.

"In a small boat like this you don't have the shell you get when you're a tourist. The people we meet accept us because of the simplicity of the way we do things. People will loan you their car after they've known you three hours.

"But to do it you have to be 100 per cent willing to adapt to where you are. We adapt to the situation. We don't try to bring us into where we're going. We just relax and meet people."

To conserve money they almost always sleep and stay aboard the boat, even if it means anchoring off in rough seas. The Glastron is tiny but well planned, with a place for everything and everything in its place.

Only two things really bug Smoky Knowlton: People who tell him what he's doing can't be done, and people who ask him "Where are you going?" or "Where'd you come from?"

"Sometimes you have, to lie," he said. "The story just takes too long."