On Sat, 17 Feb 2007 09:07:01 -0500, "Roger Long"
wrote:
"Wayne.B" wrote
Hopefully you back down on it with the engine at some point. That is
the acid test for me and I highly recommend it. Take a shore sight on
something to verify that you are not moving even an inch, then go to
sleep.
Nope. Interesting how people's environment effects their perspective. What
is it you have Wayne, 6-71's? People have been anchoring under sail for a
lot longer than there have been engines. I'm not going to start the engine,
warm it up barely, and the run it up to near full power just to set an
anchor. 15 hp in reverse isn't going to put a lot more strain on it than my
heaving.
Well Roger, you are entitled to your opinion of course, but I beg to
differ. Yes, I do have 6-71s driving big 30 inch props, and yes, they
can generate a *lot* of thrust even at idle speed. I estimate they
put out about 20 hp each at idle, but I usually only back down on one
engine unless really concerned for some reason. 20 hp is capable of
generating 300 to 600 pounds of reverse thrust thanks to the big
props, enough to stretch a 3/8 chain bar taught or nearly so.
Now for a little story, a very recent one in fact. We went cruising
this weekend up Pine Island Sound in SWFL, to a nice little cove
called Pellican Bay on the north end of Cayo costa Island. It is a
well protected harbor and we had it almost to ourselves because of the
chilly weather. On our way in however we noticed a very unusual
trawler that had clearly been modeled after a George Buehler "Diesel
Duck" design.
http://www.dieselducks.com/
We motored over in the dinghy on Saturday afternoon to get a better
look, ended up meeting the owner, and were invited aboard for a tour
of the boat. He had hand built it over 4 years and something like
$100K in cost even though doing virtually all of the work himself. It
was beautifully done to professional quality in almost every respect,
and he and his family were out for their first cruise since launching.
To make a long story short, we got hit with a 35 to 40 kt squall about
2:00AM on Sunday morning, and awoke to see his boat heeled over on a
sand bar about 1/2 a mile away from us. Sure enough his anchor had
broken loose during the squall, and they had dragged aground at nearly
high tide, on their very first night out. We are not entirely sure of
all the subsequent details but believe he was required to sign a
salvage contract with SeaTow to get pulled off. I'm sure it was an
expensive lesson in how not to anchor, and it would not be a good
thing to have on your insurance record.
We of course had done our usual due diligence anchoring on 5:1 scope
with 3/8ths chain, and a heavy anchor well dug in under power. As far
as I could tell from the GPS plot, we never dragged an inch even
though the anchor load probably exceeded 2,000 lbs during the squall.
This morning when we pulled up, the windlass would not even budge the
anchor off the bottom. I ended up locking off the chain and pulled it
out with the 6-71s. The anchor was so well set it must have had at
least 200 pounds of mud and clay on it.
Moral of the story? You really can't be too careful. The force of
the wind at 40 kts is 16 times greater than at 10 kts, and 40 kts is
just a routine squall in my experience. I've seen them as high as 60+
on an otherwise nice day.
PS: Thank you Glenn Ashmore. That 120 lb Spade is some awesome
anchor, and it is darned cheap insurance, especially these days when
your first claim is likely to be your last.