Charts and Nautical Publications Regulations, 1995
Now just like the US for boats required to carry them, then...
(3) The chart may be in electronic form only if
(a) it is displayed on an ECDIS or, in the case of failure of the ECDIS, on a back-up arrangement; and
(b) the ECDIS
(i) in waters for which an ENC is available, is operated using the ENC,
(ii) in waters for which an ENC is not available, is operated using an RNC,
(iii) when the ECDIS is operating in the RCDS mode, is used in conjunction with paper charts that meet the requirements of subsections (1) and (2), and
(iv) is accompanied by a back-up arrangement.
However...
(2) The master and owner of a ship of less than 100 tons are not required to have on board the charts, documents and publications referred to in subsection (1) if the person in charge of navigation has sufficient knowledge of the following information, such that safe and efficient navigation in the area where the ship is to be navigated is not compromised:
(a) the location and character of charted
(i) shipping routes,
(ii) lights, buoys and marks, and
(iii) navigational hazards; and
(b) the prevailing navigational conditions, taking into account such factors as tides, currents, ice and weather patterns.