It was a rushed job to meet the launch date, so the builders had filled in the massive gaps between the planks with bath sealant or some damn stuff. Happily, the boat now floats after being taken apart and reassembled properly using entirely Bronze Age gap-filling gloop made mainly of beeswax.
The tale was told in a recently-broadcast Time Team Special that featured a two-second clip of Bembridge's bow, all that aired of a three-hour session in which we rowed Sir Tony Robinson round the harbour explaining why a boat has to have a bow if it is to slip through the water efficiently.
The replica has a bow but the design is rather speculative as the original had lost its entire front end. They don't even know how long it was.
The crew struggled manfully but progress was painfully slow. Was it an inefficient bow design or the fact that it was being paddled by a bunch of sedentary archeologists that dragged it back to finish 327th in a time of four and a half hours?
The first shall be last, as the good book hath it.