Dart Harbour Authority will explore temp mooring on V buoys for short periods. There is also winter river mooring pontoon with/out elec. Perm. mooring have heard 10 yr wait.
I looked into this last year. I was told 3 - 10 years waiting list ... with £150 to join the list. I decided not to bother .... which is probably the outcome they want?
Noss-on-Dart Marina have some trots or piles or something. You get all the marina facilities ... but they are nearly as much as a marina berth. I think the waiting list is about 2 years.
There are a couple of other private mooring suggestions in the back of the Dart habour info pack too
Is there a particular reason you specify the Dart? I have a mooring on the River Exe and the Dart is a regular destination for me. I own my mooring which you can buy similar for under a grand. (deep water) I am able to cruise Lyme bay, Torbay and as far Salcombe and Plymouth at weekends and less than 70 miles to Alderney. The access in and out is easier than others make out it to be and there are number of good local clubs in the area. access from the M5 is really easy unlike the road journey to the Dart.