Learning curve

I thought long and hard about this post, as the events which occured make us look like total prats, but then, it may serve others who read it as a timely reminder....
We had two sails today - one this morning which was delightful, then again this evening, with Hanna and Nathan aboard.
We decided for a change to go North from the marina, dropped the anchor and the kids went for a swim off the back.
We laid a ratio of 5:1 in 3.4m of water.
The kids were swimming, all was good.
I noticed that the depth changed to 2.3, so I told Mike and he said it's ok, just swinging around a bit.
Then I heard a little voice from off the starboard side saying "Jan, you're dragging the anchor and we can't swim fast enough against the tide to get back on" *GULP* Then, the depth alarm started going off, we're in 1.7........1.5........1.2.....and the beach is getting closer and closer....
Mike threw our safety line to the kids, I started the motor, then......the motor stopped working, and we're drifting towards the beach still. Not happy Jan....
Cut a long story short - we'd picked up a length of hose from the sea floor which had fouled the anchor, and the folding prop had folded and wouldn't open out. Nathan and Mike cut the hose away, the motor started, and we were then out of danger, but boy, were our hearts pounding.
Bottom line is: we anchored way too close to the beach to begin with and didn't take in to account the prevailing current in that area, plus we anchored in sea grass. In retrospect, it's easy to see what we did wrong. I'm not too proud to admit we stuffed up, but, no harm was done and we learned from it.
One little gem that I have to end this tale with is a classic Hanna quote: "Did you know theres a big triangle thing on a stick hanging off the back of your boat under the water?"
Gotta love her, don't you :)