This looks like an interesting book -- relevant to some of our earlier discussions about Doggerland and about Neolithic seafaring. I have glanced at a few pages (on the Amazon web site!) and I get the impression that around 5,000 years ago (when lots of bluestones were supposedly being moved about by our heroic ancestors) there was no real capacity for heavy-duty long-distance stone transport by sea.
It appears that the early voyagers used very simple log boats rather like those found at Carpow and Must Farm. Some had rounded bows and sterns but more seem to have had transoms or "end-plates" slotted into a groove at the stern end, making steering easier and making it easier to protect boats from theft. (The idea is then when you leave your boat on the shore for hours, days or weeks, you take the transom with you, making it impossible for anybody to use the boat in your absence......)
Although boats like these were sometimes over 9m long, and could accommodate maybe eight paddlers, they must have been seriously unstable in rough water or out in the open sea -- and were clearly best suited for use on lakes or within sheltered estuaries. Robert van der Noort speculates on whether they were utilitarian items, used for fishing and rough duties along the coast -- or whether they were high-status items. Probably they did have a lot of status attached to them, since they must have required many hundreds of hours of hard work to make them in the first place -- even in the Bronze Age, with metal tools available. In the Neolithic, with only stone tools available, the status or value of such a boat must have been even higher. On that basis the author of the book suggests that they were used primarily for carrying high-value trade goods -- necklaces, maces, ornamental axes, amber and other precious stones, and maybe high-value pottery or fabrics or skins.
Even with outriggers in place, and with the use of sail, I cannot see that boats such as these can have carried 4-tonne bluestones across the Bristol Channel in pre-Bronze age times. This leaves us with rafts and skin boats or curraghs as the only contenders -- and there is likewise no evidence at all that the required technology was available to Neolithic seafarers at the time we are talking about.
The only slight consolation for those who want to believe in the sea transport of the bluestones is that domestic animals must have been transported between Great Britain and the continent, and between Britain and Ireland. How would a sheep, or a cow, or a goat, be carried in a dugout canoe? Animals are notoriously difficult to move about in boats. Maybe they were trussed up and forced to lie on the floor of the dugout for the duration of the voyage? Seriously uncomfortable, for both the paddlers and the animals concerned........ But to transport a bluestone is to move up another notch on the difficulty scale.
By the way, there is more on the dugout canoes here: