Well, this is just a random guess, but as you can see here [0], the navigation channel where a linked article roughly located the wreck [1] seems to vary in depth between 50-120'. Looking at a similar style ship from the same timeframe [2], we see a main mast height taller than the water depth in that location. I would imagine if you scuttled the ships in a precise pattern, it would make it incredibly difficult for a ship under wind power to enter the port and avoid hitting the mast of a scuttled ship. I just happened to be in Newport this summer and learned about the area's history. The people who lived there were very accomplished seamen and I would not doubt their knowledge was put to good use in setting up that blockade.

[0] http://www.charts.noaa.gov/OnLineViewer/13223.shtml

[1] https://www.smh.com.au/world/north-america/hms-endeavour-fou...

[2] https://en.wikipedia.org/wiki/USS_Constitution

It's a little odd that the article says this:

> The site is located just off Goat Island, a small island in the Narragansett Bay.

...but the map in the article doesn't actually reflect this. The little red circle is southwest of Brenton Point, and it's a couple miles away from the vicinity of Goat Island. I guess whomever put the map together phoned it in...or decided there wasn't enough room on the map to place the circle more accurately.