Rode Courtesy
- Thread starter MikeHoncho
- Start date
The 5-7 rule goes out the window in crowded anchorages. Blakely Harbor is well protected and with calm weather conditions 200 feet is excessive. I would get by with 60-90 with 20 ft below me.
The 5-7 rule is also based on a range of depths. In deeper water you may have 100 feet out at 4:1 scope, while in shallower water that would be 7:1 or 10:1, but the effect of catenary in lighter conditions is the similar. It is haveing 100-200 pounds of chain in the water that makes it work and keeps the chain on the bottom. Crowding is not the only difference. Using 3:1 scope in 7 feet (say, 21 feet of chain--wouldn't that feel silly?) is quite useless and will drag in anything stronger than mosquito farts. The chain will lift in 5-10 knots and the hobby horsing in any kind of chop will pop it right out. I often anchor in 3 feet, so 3:1 rode would be about 15 feet of rode. Heck, that would mean just shackling the anchor to the bridle... which I have done just for fun. But I won't leave the boat unless I add another 25 feet.
IMO, people tend to set too much scope generally, evidently attempting to prepare for conditions that will not arrive. In sheltered waters with moderate to zero sea state, even in relatively high wind such as 25-30 kt, on chain, in 20 to 30 ft of depth, 3 to 4 is enough, if not more than enough, with the right anchor. Less if deeper.
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San Juan Sailing, a charter company at Bellingham, WA, tells its bareboat charter customers to use 4:1 scope. “Excessive” scope could be needed to dampen hard (shock) pulls on the anchor that might break it out, but that occurs with incoming seas, not in fully sheltered coves, etc. Watching someone trying to lay out 7:1 in a crowded, sheltered cove and in calm, settled weather is a little bit nauseating (forgive), especially if too close to begin with.
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This time of year, in this part of the country, 3-6 knots during the day, followed by 50 knots and hail at 5-6 PM, is not unusual (last night, for example). In the summer, Chesapeake sailors often don't know what is coming. Add to that poor holding (a 45-pound NG will hold about 500 pounds at long scope--this has been tested numerous times), and it is hard anchor short with confidence. We also very seldom anchor in 20 feet. Most harbors and coves are 6-9 feet.
Just sayin' that different places have different rules.
Yeah. I understand the point you are making. But I see the same anchoring here in southern California where we do not have afternoon or evening thunderstorms daily. The weather is very predictable, light and variable most mornings followed by windy conditions in the afternoons, all along the coast from British Columbia to Baja California. Wind dies off during the night. Typically warnings of gale force winds are given when in the making, etc.
I recall my trip to the Dry Tortugas one May, anchored at Garden Key, with nightly thunderstorms. When one hit with high wind and torrential rain I was very thankful we were securely anchored
. There was a BIG power boat a couple of hundred meters up-wind that started dragging one NIGHT and got underway, search light a blazing, in the heavy downpour trying to pick his way past us out of the anchorage.
But when folks attempt to follow a “general rule” wherever they are no matter the conditions, etc., then I object. Such scope is not needed in most places, most of the time boats are there, in my observation (which does not include Chesapeake). It’s like advising “don’t try to resolve all the variables; just throw out 7x your depth and relax.” Or similar.
I recall my trip to the Dry Tortugas one May, anchored at Garden Key, with nightly thunderstorms. When one hit with high wind and torrential rain I was very thankful we were securely anchored
. There was a BIG power boat a couple of hundred meters up-wind that started dragging one NIGHT and got underway, search light a blazing, in the heavy downpour trying to pick his way past us out of the anchorage.But when folks attempt to follow a “general rule” wherever they are no matter the conditions, etc., then I object. Such scope is not needed in most places, most of the time boats are there, in my observation (which does not include Chesapeake). It’s like advising “don’t try to resolve all the variables; just throw out 7x your depth and relax.” Or similar.
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Agreed.Yeah. I understand the point you are making. But I see the same anchoring here in southern California where we do not have afternoon or evening thunderstorms daily. The weather is very predictable, light and variable most mornings followed by windy conditions in the afternoons, all along the coast from British Columbia to Baja California. Wind dies off during the night. Typically warnings of gale force winds are given when in the making, etc.
I recall my trip to the Dry Tortugas one May, anchored at Garden Key, with nightly thunderstorms. When one hit with high wind and torrential rain I was very thankful we were securely anchored
But when folks attempt to follow a “general rule” wherever they are no matter the conditions, etc., then I object. Such scope is not needed in most places, most of the time boats are there, in my observation (which does not include Chesapeake). It’s like advising “don’t try to resolve all the variables; just throw out 7x your depth and relax.” Or similar.
As you can imagine, if there is a >20% chance of severe thunderstoms you anchor for the duration, as you would for a strong gale, because getting underway, in the middle of a crowd, at night, with lightning flashing, is a bad recipe. Relaxing summer cruising is about knowing that when black clouds suddenly gather, you can go below, button up, and enjoy dinner. In the spring, fall, and winter, I have a very different mindset; the weather is predictable many days in advance.
You’re entitled to your opinion, but IMHO 3:1 scope is typically not ideal for you or anyone else. The bell curve is 3:1 to 7:1. You’re out on the edge of the bell curve, and it seems you’re expecting others to march to your drum. That might not be a reasonable expectation, and another skipper might feel more prudent about scope.
An analogy is when someone sets 2 anchors Bahamian-style. Might be fine for them, but it upsets the order of things when it doesn’t play well with others.
If I was into a Tanqueray and Tonic, and had to move anyway, I think I would leap-frogged in front of the douch bag and blocked his view!
…but my wife says I have road rage issues, so maybe you shouldn’t listen to me
Greg
Your wish is possible.
Tie a trip line to your anchor. Let enough line out to deal with the depth and tie on a big bright marker buoy. It will ride above your anchor and give all who care the length of your scope.
Good idea but one that does not always work. On chain in light conditions you cannot tell the scope of the boat at anchor as seen between a marker and the boat itself. The weight of the chain brings the boat much closer to the anchor marker than it would be if all of the scope was needed to hold the boat, etc.
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That is a great idea! I frequently use a trip line but I run out as much trip line as scope (plus a little slack), and tie it off on the boat. Never thought of using a buoy to mark the anchor like that.
I did this for one week. Then one night during the tide change I heard something scraping the bottom of the boat while lying in bed. Luckily I used an old 3mm line to hold the float because I heard it stretch and snap. The next morning as we raised the anchor, I put the boat in reverse and it flushed out the buoy and short piece of line. So glad it worked.
Bummer! I generally anchor with keel, rudder, and outboard up, so it's not a risk for me, fortunately.
Except when a boat runs over your marker and sucks the line into their prop. The result as you can imagine is a # 10 mess. Trip line is ok if the anchorage isn't crowded. But then, it isn't needed.
Add to that, when you are in a place with tidal swings, for much of the time as the tide shifts you may move right over the anchor or very near to it as you swing to the other of the anchor set. When I look at my anchor alarm "plot" of where I was lying at anchor for the night I find much of the time the plot shows me very near the actual anchor location although it doesn't show how much time was spent in any given location. Just saying - while an trip line and buoy is a good idea it takes a lot of knowledge of local conditons, including on what tide you anchored for someone not on your boat to interpret the actual scope out, at least where we have 8+ foot tides.