It's not a bad idea at first glance. But the weight of the rope isn't the big deal; it's the weight of the chain that really adds up.
Compare 200' of 3/8" Spectra to 200' of 5/8" nylon (or whatever you are going to use). 200' Spectra = 11 lbs, 5/8" nylon 3 strand = 22 lbs. For a savings of 11 lbs you have a system that you can't handle with a windlass
. Save weight somewhere else. Get rid of a couple pairs of Cindy's shoes and a couple of Zach's books
when he's not looking!
I've been pondering the right length of chain for cruising in coral heads in Fr. Polynesia. 150' is sounding about right + whatever rope spliced on.
Picture this: it's blowing the dogs
off the chains, you're in a suddenly lee shore anchorage with 3 or 4' breakers rolling in. You don't like the anchorage much any more and you need to leave.
Now you're trying to motor
up to the anchor to weigh it by hand. As the boat sheers about, and you come up the anchor, it is alternately going slack and loosening enough to haul in a little more. I don't like handling loaded lines too much, and having a anchor rope of only 3/8" means it's hard to handle anyway. Add a slippery rope like Spectra and you're really having fun.
When I anchored in a river with a 5 knot current
, it was really exciting to haul up the rope part of the anchor by hand. The anchor was well set and I had to let go the rode several times when it came taught as we over ran it.