With the proven presence of the Romans at Cefn Caer, close to the river at Pennal, there must surely have been activity on the river at that time, but the earliest written evidence I've read about dates to 1109, in the "Chronicle of the Princes", which says "Cadwgan and Owen fled into a ship that was lying in the River Dyfi which had come from Ireland a little while before with 'exchange' in her".

In 1569, there's mention of seasonal fishing taking place from Aberdyfi: 30 years later, there's a record of a ship "Le Seadog de Emdin" arriving on the river with a cargo of 15 tons of salt and 5 tons of wine, and leaving 18 days later with a cargo of 15 tons of lead ore.

Trade really built up from the mid 1700s, and - despite the inevitable booms and busts caused by politics and foreign wars - continued through to the time that the railways came, in the latter stages of the 1800s, after which it dwindled very rapidly.

Dyfi Shipbuilding

It was inevitable that a shipbuilding industry should be established on the river, and (probably incomplete) records show the following types vessels being built on the Dyfi:
 

There were shipbuilders operating at a number of locations on the river:

Cei Coch

This is a bit of a mystery, and I've not been able to find out much about Cei Coch, except that it was at Garreg, below Glandyfi Castle, and there was a plan in 1858 to extend the Corris Tramroad to this location. The Tramroad was extended to Morben, West of Derwenlas, where it saw heavy use 1859-1863.

Rowland & John Evans, Shipbuilders, Morben Isaf

Rowland Evans was a farmer from Dinas Mawddwy who moved his family down to Morben Isaf, near Derwenlas, in 1845. He maintained his thriving bark and timber business but in about 1852 sponsored the building of a small ship at Derwenlas, which he operated as majority shareholder. He established his own modest shipyard at Morben the following year in order to build his second vessel. Other ships followed, but Rowland met with a fatal accident in 1856. His son John took over the business and gradually increased the rate at which their ships were built. Despite the coming of the railways, his business prospered, with the building of quite sizeable ships, the largest being the barque "Mary Evans", launched in 1867. She was 258 tons gross weight, and subsequently made voyages around the world, including a Cape Horn passage to Chile in 1868. Tragedy struck the Evans family again that same year, when John died as a result of a riding accident. He was buried at Graig Chapel, Machynlleth, where there's a memorial to him. His ships continued trading successfully for a few more years, until inevitably they were either wrecked (as seemed to be all too common in those days) or de-commissioned. A detailed report on can be found in Volume 88 of the Montgomeryshire Collections, available through The Powysland Club.

Derwenlas

Derwenlas needs a special mention, because for a time it had a very important role in shipping on the river. Before the railways came and destroyed the little ports of Cei Ward and Cei Ellis, up to 80 vessels at a time were reported as having been seen riding the tides up to Derwenlas. All manner of supplies were brought in and out from Derwenlas, and one document lists the following average annual imports and exports:

However, in Aug 1861 goods related to the building of the railway start to appear in cargo manifests and by Dec 1863 the last export of lead ore (35 tons) was made from Cei Ward - carried by the "Seven Brothers". Pitwood (pit props?) featured in exports until the early 1870s, but river trade must henceforth have declined significantly, and the last recorded opening of the railway bridge at Dyfi Junction was in 1890. The opening section of the bridge was replaced by a fixed section in 1910, and that was the end of shipping from any stretch of the river above this point.

End of an era?

Well, actually, no! It seems that it just went into hibernation for a hundred years or so until the technology and demand co-incided again. I've recently been in contact with the people at Aberleri yard, a few miles downriver (see http://www.steelkit.com - but this site is currently down) and they've informed me that the Dyfi shipbuilding business is alive and kickin'. They've supplied over 50 vessels from 20 to 200 tonnes in the past 3 years, with roughly 15 of those being sailed away from the yard, and the others being shipped in various forms to be completed by other yards throughout the UK.

And there's another company, on the other side of the river at Abertafol, where they produce leisure craft and dinghies - although they tell me that most of the actual building is done elsewhere.

I find this continuity of river activity rather re-assuring.