tl;dr - custom made ships, just for hauling masts, were built to transport masts from New England to original England.

Long Answer:

This is an excellent question and one I had never thought of until reading Tall Trees, Tough Men by Robert Pike, which is about New England logging prior to mechanization.

First, you needed to find a suitable tree. In 1602, that might have been close to shore. By the 1650s, that might be a few miles inland. By 1750, that might be many miles inland. Assuming we're working in the 1700s, the next step is building a road. The road had to be straight, because you are going to tow a 100-120 foot straight log down it. So swampers cut down underbrush, filled in ditches, etc. to make a straight road to the nearest river.

Then a massive tree would be felled by ax. While they had saws even as early as the 1600s, the saws were used above pits (pit saws) for creating boards. These masts were sometimes 120 feet long, and would be hauled/towed from the forests to the rivers by massive teams of oxen. The first log drive in America was on the Piscataqua, and the logs were brought down by "pig-tailed, pantalooned Pilgrims."

The tree had to be felled in the opposite direction as it was going; i.e., you wanted the wide butt end to point towards the road and the river. Green saplings and brush piles were created and laid up where the log would land to cushion the fall. If the log shattered, cracked, broke, or was otherwise damaged when it fell, it could not be used as a mast. Or, if a void or hollowness was found. Then it was worth about 50% less than a mast tree.

When watching a mast being hauled from the woods of New Hampshire that was 28 inches across at the base, Judge Samuel Sewall of Boston observed that it took 32 oxen pulled it, with "four yoke" of oxen on the side (not sure if that's four or eight additional on the side).

The best time to do this was the deepest part of the harsh New England winter. The ground would be frozen, the logs could be sledded or sledged, and then you could roll them right out into a frozen river. Then you would wait until the spring thaw. Also, when you felled the tree, it would land in snow which was less likely to break and shatter a tree that was destined to be a mast. Finally, the spring thaw would raise the river water level and you could float the masts down to the ocean.

During the summer, a pair of 18 foot high wheels were placed under the front end of the log, and another pair at the rear end. This allowed big logs, drawn up by chains, to clear forest obstructions. This process was used at least until 1792. By the late 1700s, the same mechanism was used (huge tall wheels) but the process of loading the log changed slightly.

Great teams of oxen were used. It was reported that as many as 200 were sometimes used; with a large team (60+) towing, with helper teams along the sides, and then fresh oxen stationed along the road to the river to substitute in. There are reports of 30" to 39"" wide masts being felled and moved down New England's rivers.

This was serious business because masts to the Royal Navy were like . . . nuclear reactors to the U.S. Navy today. The Royal Government of Massachusetts in 1691 made it illegal to cut any trees wider than 24" at the base except on private land, and this was eventually spread to all of New England and New York.

Special mast-ships were built to haul these masts They were 400-600 tons (one may have been 1000 tons), with oversized ports in the stern for loading and could hold 40 to 100 masts. The remainder of the hold would have other naval stores like boards, spar, etc. in it. 25 man crew, and would have armed escorts during war time.

In 1770, a large mast was worth 110 GBP. That's about 21,300 GBP today or nearly $29,000. I do not know if that's the price in Maine or the price landed in England. A large mast would have been 36" across the bottom and 36 yards long. One crew was able to get across the Atlantic with a mast shipment in 26 days, captained by a man from Newburyport.