Telford consulted widely with shipowners, who favoured a canal instead of the hazardous journey around the north of Scotland via Cape Wrath and the Pentland Firth. He obtained advice from Captain Gwynn of the Royal Navy, who stated that Loch Ness and Loch Lochy were sufficiently deep for any size of boat, and had safe anchorages if winds proved to be a problem, but that Loch Oich would need to be made deeper, as it was shallow in places. He established that Loch Garry, to the west of Invergarry, and Loch Quoich, beyond that, would provide an adequate water supply. He estimated that a canal suitable for ships with a draught of could be built in seven years, and would cost around £350,000. An additional benefit would be the protection that the canal offered to shipping from attacks by French privateers. Telford also looked at the possibility of a canal to link Loch Eil to Loch Shiel, both to the west of Fort William, but ruled out the scheme because of the depth of cuttings that would have been required.