Summary of information on
Practical Boat Owner forum for those wishing to show respect during this period of national mourning. It would appear from the guidance we are to wear the ensign as normal and if possible, adorn with black ribbons. Not many ribs with masts these days.
Half Mast means the flag is briskly raised as normal to full-hoist and then lowered to either a flag's width below the peak and no more than one third of the way down the mast.
If your staff (as is the case on almost all yachts/boats) is not long enough to achieve this then it implies the flag should remain at full hoist on the staff and ideally be adorned with black ribbon(s) -( to be as long as the flag and attached near it's upper clew) . A black border sewn on would also be perfectly acceptable.
Think of it this way...any proper flagpole/mast will be tall enough to achieve the one width/one third protocol. If the pole is too short it is likely not actually to be a flagpole or mast at all, more a staff as carried for instance by troops or the British Legion etc which is by necessity fixed on the pole. Lowering the flag on the staff in this case would clearly be inappropriate and look daft. Thus it should be decorated by black ribbons of mourning instead, or just flown as normal.
According to
www.college-of-arms.gov.uk "Flags of foreign nations should not be flown unless their country is also observing mourning."
Navy protocol is for ensigns to be flown (or should that be “worn”) at half mast from the announcement of the death up until the end of the day of the funeral, with the exception of the Proclamation Day when they are hoisted to the top of the flag pole.
The BBC are now reporting flags to be raised at 13:00 on Saturday, returning to half mast the next day.