By bbalme - 18 Apr 2012
So, we 're relatively new in the sailing game - so I 'm sure I can learn from the old salts that frequent the OCC 's forum...
My boat is a 28,000lb, 44ft cruiser (Outbound 44) with pretty high freeboard and therefore demands (I believe) some reasonable care during anchoring. We have an 80lb Manson Supreme on 5/16" Chain. Last year we were anchored out in winds up to 40kt and in depth of about 20ft.
What would be the recommendation on length of rode to deploy? (We dragged!)
Thanks,
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By rptrsn - 19 Apr 2012
Bill,
With all chain in normal conditions we use 5:1. If we expect higher winds, say in the 25kt+ range, we will go to 6 or 7:1, if we have enough swing room. Don 't forget to add in the height from your bow to the water when figuring the amount of chain.
You certainly have a good heavy set of ground tackle and it should serve you well. 40kts of wind is a challenge for all of us and no one sleeps well when it blows that hard. If we 're expecting a gale we put out extra rode as above. If we know the direction the wind will be coming from, we seriously consider putting out a second anchor and have done this on numerous occasions.
Hope that answers your question.
Cheers,
Pete
s/y "Brilliant"
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By bbalme - 19 Apr 2012
I agree with what you say Pete - unfortunately at the time I had 100ft out - which with about 5ft of freeboard means I was only at 4:1. When we re-anchored we went to 150ft and held fast.
My old boat, 37ft 10,000lbs had a 60lb Supreme and 3/8" chain and I was able to hold well with as short as a 3:1 and would lengthen to 5:1 in a blow. I think the size of chain plays quite a role...
I guess I have to re-learn to anchor the bigger boat!
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By alshaheen - 22 Apr 2012
Hi Bill
You are right, chain size, and consequently weight, plays a major role in secure anchoring. Our boat is about the same displacement as yours and, I suspect has less freeboard and less windage, but we use 10 mm chain whereas yours is only 8mm so we have 25% more weight down there. We use a lighter 25 kg (55 lb) Rocna and almost never drag using 4 or 5:1 scope. The secret is to keep the chain on the bottom close to the anchor so that the pull on the stock is in line with the stock. With insufficient scope the chain lifts in the gusts and once it pulls at an angle to the stock you WILL drag. A large catenary also serves to stop the chain snatching.
We rode out hurricane force winds anchored with a borrowed 60 lb spade with 60 m chain veered and a scope of about 9:1. We did drag a little but later found that the anchor had snagged a large tree branch which I think stopped it burrowing properly.
I like to anchor with plenty of swinging room, then I can use lots of scope. My maxim is that you may as well veer the chain as it is not doing you any good in the chain locker!
Happy hooking!
John
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By DariaBlackwell - 29 Apr 2012
Bill,
I agree with everything said. We routinely deploy a minimum of 5:1 unless we 're really in a tight spot. In a crowded anchorage, we set the anchor at high scope to maintain the correct angle relative to the bottom to make certain it really sets well, after which we shorten scope if we have to. In a blow, we 'll put out everything we have. We tend to anchor a bit further out than many people just to be sure we have enough room to swing.
In a real blow (40+ knots), we always have a second anchor ready to go on a long rope road. It doesn 't actually do anything until needed and cannot foul with the primary. But, I must say that since we switched to the Rocna and then the Ultra, we have not dragged.
Can I ask what kind of bottom you were anchored in? If you had sand over a hard bottom, that could contribute to failure. Also, if you use the slot in the Manson Supreme and the wind or current reverses, your rode could simply pull the anchor right out like a trip line.
Bear in mind that "more is better" when it comes to scope. A 10:1 ratio will double the holding power of your anchor and a 3:1 ratio delivers only half. Also, it 's usually not the strength of the wind but the action of the waves pulling up and down on the anchor that causes it to pull out. You need the caternary and a stretchy snubber to cushion against the constant motion.
Happy Hooking!
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By bbalme - 30 Apr 2012
Daria,
I 'm sure that my problems that night were due to inadequate scope. We were in a difficult spot, on the outside of Hadley Harbor (entrance to Woods Hole) in Massachusetts. We 'd arrived too late to comfortably navigate the narrow entrance into the harbor, the north east wind meant we had no protection, there was miles of fetch therefore and currents swirl around Woods Hole (albeit we were not in the main flow!) - so it was a bit of a disaster waiting to happen. I had no need to use a short scope - since I was the only idiot parked out there! I deserved what I go - a lousy night 's sleep! Fortunately, I was awake and immediately aware when we started to drag. My only solace was watching a boat inside the harbor dragging and re-setting repeatedly.
You ask what the bottom was. No idea! I don 't remember what came up with the anchor. Short of diving on the anchor or being in crystal clear water, is this the only way to tell whats below you - or do real sailors probe the bottom first to see what lies beneath?
I don 't use the Manson 's slot - don 't understand the purpose. (Self tripping anchors don 't appear very sensible to me!) I tend to buoy the anchor - so that if I get it snagged, I can use that to reverse the anchor out. (Touch wood, has not happened yet.)
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By DariaBlackwell - 30 Apr 2012
Hi Bill,
I know Hadley Harbor well. http://www.coastalboating.net/Cruising/Destinations/NE-US/Buzzards%20Bay/HadleyHarbor.html Pretty exposed outside the harbor. Isn 't it interesting how attuned we get to the motion of the our boats? Any variation and we tend to wake up. Our cat even wakes up before we do and gets us up right away. Lucky!
I do know people who probe the bottom to see what its composition is. They drop their anchor and bring up a bit of bottom to see what it is made of. It 's much easier, however, to look at a chart. The bottom type is clearly labeled as sand, mud, rocky, grass, etc. in most harbors. But you do have to know how to interpret the symbols which are listed in NOAA chart 1 for US waters.You can download it free here http://www.nauticalcharts.noaa.gov/mcd/chartno1.htm. For example, hS is hard sand. It 's not always accurate but it 's a useful place to start. Cruising guides usually mention bottom composition as well. You probably know this all, but sometimes we forget the simple things. Friends of ours who are very experienced cruisers anchored in a mine field once because they were too tired and in a hurry to check the charts first! They 'll never do that again. A fisherman alerted them to their dilemma in the morning.
The Manson 's slot is intended to be used as a trip line. It was developed for use in rocky Australian cruising grounds where anchor eating monsters are known to roam. It is also used by dive charter boats where they need to re-anchor many times a day and quickly. I would never use it under 'normal ' cruising circumstances.
Happy Hooking!
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By bbalme - 8 Apr 2013
So, heading off to unfamiliar shores this year - with the prospect of anchoring in some relatively deep locations.
What 's the general consensus about the amount of scope to use if one is anchored in say 100ft?
Additional question: My rode is 275ft of 5/16 chain plus 100ft of 3/4 rope. If I were to anchor in 100ft depth, I 'd probably let the whole lot out... What 's the best way to secure the rope - since the gypsy isn 't really very good at holding rope - and my chain hook won 't do much good on rope!? I don 't have a sampson post and the closest cleat is very close - but does not have a fair lead to the anchor roller. I 'm thinking I 'd set up a bridle to both forward cleats using a rolling hitch?
Final question: Is 375ft enough?
Thanks!
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By DariaBlackwell - 9 Apr 2013
Hi Bill,
To address the bottom properly, an anchor has to be at the correct angle relative to the bottom. So you need at the least 3:1 to hook it and more to set and hold properly. If you are going to be short on scope, then I 'd suggest an oversized anchor, one that works reasonably well with short scope like the Rocna (not a Spade - which needs more scope).
You should never secure the rode to the gypsy or the windlass. Always secure it to the cleat or cleats, with adequate chafe protection. Additional security in a blow can be derived from securing the rode to the base of the mast.
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