Do you trip you anchor? If not then you need to - 3 or 4 cable ties (others will correct me if that is not enough as I use 2 but my boat and engine only weigh 400kgs!)
If it is not tripped then you can not pull it out backwards if stuck.
you should not need to tie the rope on to the boat - if you do it correctly it will not foul the prop.
Ensure you only head off at 30\45 degrees for a few meters (10 -20) then drive parallel to the line you held when at anchor (almost over the top of your anchor).
The tide on the line and the buoy will stop it getting near the prop.
There is certainly a knack to doing it and you need to be confident too, as you can't to it at 50% or you will have problems! Next time you are out you might well find a club boat who will demo this for you - or hitch a ride!
I certainly learn't this by being shown from being out with Alun J and Paul D.
Rob
Found on Web:
1) This is the boat at anchor
2) Steam off at approx. 30 degrees from anchor position.
3) When the buoy is just past your transom, steam parallel to the anchor position.
4) Keep steaming forwards until the anchor is on the surface and the buoy is against the anchor.
5) Turn the boat across the tide, take it out of gear and drift back to your anchor pulling the rope in.