Ignoring the 10 knot
requirements ad concentrating on the depth
limits, there are a number of UK boats with twin keels from Westerley and Moody that would meet your requirements. Alternatively the French have made a series of lifting keel
yachts over the years, indeed we nearly bought a Jeanneau
Sunrise with a lifting keel
but sadly the owner had made a mess of her. She had crossed the Atlantic twice according to the previous owner.
For a yacht of 30 feet I am not sure that self raising and lowering the mast
is a good idea. I think our Moody 31 has a 43 foot mast
which is also quite heavy. One mistake and it could cause a lot of damage either to the mast or the deck
. Better to use boat yards to raise and lower the mast as required at each end of the canals and many yards are set up to do this.
What sort of budget
are you working to? which would give us a better idea for recommending particular makes.