T10 marker is off the Fraser middle arm by the airport. The "North Arm" is the northern exit of the 3 arms of the Fraser River off Point Grey.
Not to be rude, but you should really study up on a few things before venturing onto the ocean. The mouth of the Fraser River can get pretty nasty at times. If you can't even identify your location, if something were to go wrong then you would be SOL. You need to be able to summon help and let rescuers know your exact location. A VHF radio is a whole lot better than a cell for that. Cell coverage is unreliable, be prepared if your venturing out on the chuck with little experience.
Good luck, but be prepared, and be safe.