Manic Moore Posted February 4, 2005 Report Share Posted February 4, 2005 I have heard a couple of different lengths, Depth x 6 and depth x 3? Also where's the cheapest place to get. I will probably have to go for poly for the price. Thanks Gordon Quote Link to comment Share on other sites More sharing options...
duncan Posted February 4, 2005 Report Share Posted February 4, 2005 a great subject for a winters day........... firstly 3x and 6x are both good anchoring numbers - but for different things! 3x is the generally accepted optimum working scope for the correct anchor (for the boat and sea bed conditions), in average depths (30/80ft) - once it is set correctly! In practice this means that in a tide or current you will have to carefully get the gear down and set if you are limited to 3x as it may never set. In shallower water you ay need more scope and in deeper you may get away with less. 6x is the scope beyond which there is no (realistic) mechanical advantage in increasing the scope further (there may be an advantage in shallow water with a large swell but that's a completely different issue). Finally you should have approx 1.5 times your boat's length in chain. If you are concerned about the above scopes then increasing the size (not length) of the chain will help - but will not add to the ultimate holding power of your anchor tackle one bit! Quote Link to comment Share on other sites More sharing options...
Jack the Lad Posted February 4, 2005 Report Share Posted February 4, 2005 If you are concerned about the above scopes then increasing the size (not length) of the chain will help - but will not add to the ultimate holding power of your anchor tackle one bit! I always understood that the 'catenery'; the angle of the rode, affected the holding power of the anchor. Therefore more weight - chain( increased size or length) or adding weight on the rode does increase the holding power. Hence chain= 3:1 and rope 5:1 of max depth is the normal guide scopes. The more the pull is along the sea bed the better the anchor holds. That is why some boats carry 'pigs' - a heavy weight to slide down the anchor rode to increase the holding power of the anchor. That's why the longer the rode the better the holding power; reducing again the angle of the rode to the sea bed. Increasing the rode beyond 1:6 will also have a beneficial effect in a good blow/squall line. How ultimate are we talking about? I've anchored in storm 10. When, I believe it's best to tandem anchor, but that's a seperate anchoring discussion! I understood these principles applied to any size vessel anchoring - except perhaps a 'rib'; which I reckon would be flying in a 10 or even less, if anchored. But, by that time, I highly recommend that you are not anchored but well tucked up ashore enjoying a pint! I would appreciate your response as these are important facts concerning people's safety. As a qualified professioal skipper have I been doing it wrong for last 40 years OR have I misunderstood your statements Duncan and therefore some clarification is needed? Jack Quote Link to comment Share on other sites More sharing options...
Newboy Posted February 4, 2005 Report Share Posted February 4, 2005 I think most of the consenses are that rope is 3 x the depth you intent to anchor/fish. Reason we can get away with this length is that small boat angler tend not to go out in anything F5 or more, unless you are James or Adam . Quote Link to comment Share on other sites More sharing options...
duncan Posted February 4, 2005 Report Share Posted February 4, 2005 tandeming the anchors will increase the holding power ultimately - and it doesn't need to get up to a force 10 to have the anchor warp/chain in a straight line! - it is the holding power of the anchor (well apart from the warp or a connector actually failing!) that is the critical factor. angle of pull relative to the holding surface - lets assume flat sea bed, therefore relative to the horizontal - will have an effect on the holding power of all anchors but differently. Other factors include the seabed and, in some cases, there are differences in the way particular anchor patterns react to jerk and/or contant pulls. Will go and get some detailed numbers in a minute to illustrate these for the common anchors. increasing your scope beyond 6:1 gives you only a minute improvement in this angle. It is this angle that the various steps we are discussing attempt to improve and therefore improve holding I believe. Pigs (chums, anchorbuddy etc) are all in common use but they are a poor compromise on an increased anchor size - often they are used because they can be handled seperately from the weight of the anchor and chain (and that is basically the only valid reason to use them). This is similar to the 'all chain gives a better hold' argument. Catenerary effects are the primary reason that you can 'get away with' a lower scope in deeper water however anyone who has anchored on an all chain rode in shallower water will quickly become aware of the fact that it becomes almost straight and solid from time to time, in even quite easy conditions. I don't think we are disagreeing about anything - (possibly the effect of adding weight (a pig) on the warp - but even here I don't think we disagree that once the pull is straight from stem to stock it is only the holding power of the anchor and the angle of that pull relative to the stock that counts. Will pull in some material from sources ............. Quote Link to comment Share on other sites More sharing options...
Jack the Lad Posted February 4, 2005 Report Share Posted February 4, 2005 I think most of the consenses are that rope is 3 x the depth you intent to anchor/fish. Reason we can get away with this length is that small boat angler tend not to go out in anything F5 or more, unless you are James or Adam . I totally understand and concur for normal circumstances when doing a bit of dangling - but if Sod or Murphy came aboard, or perhaps people are out there when they should have run for home ( because the fish were biting) or are awaiting the RNLI, due to mechanical failure; I would like to be sure they have the correct knowledge and facts in anchoring techniques. My experience and therefore lack of understanding and is with the following statements: increasing the size (not length) of the chain will help - but will not add to the ultimate holding power of your anchor tackle one bit! 6x is the scope beyond which there is no (realistic) mechanical advantage in increasing the scope further (there may be an advantage in shallow water with a large swell but that's a completely different issue). In shallower water you ay need more scope and in deeper you may get away with less. Jack Quote Link to comment Share on other sites More sharing options...
duncan Posted February 4, 2005 Report Share Posted February 4, 2005 oh well - got bounced out of edit mode by you post....... covering the 3 specifics you raise - 1. the first is actully your pig argument - increasing to heavier chain at the lower end of the rode would be just the same as adding a small pig. Once sufficient force is applied to the anchored boat it doesn't add to anchoring force which is governed by the anchors holding power and the angle of the pull to the stock. 2. yes increasing scope beyond 6:1 will give marginal improvement to holding but not significantly (still looking for the maths............ may have to do them myself!) 3. primary reason is the relationship between water depth and swell/waves, secondary is the height of the stem head and thirdly the lower overall elasticity in the gear as rodes shorten in shallower water and forthly (in tide) the lower effect of the tide on the catenerary improving the angle of pull. As an extreme example if I anchor in 10 feet with a 1 ft swell and a stem head 4ft above water level I already need 45ft to achieve an effective 3:1 scope............ Havew a good read here Quote Link to comment Share on other sites More sharing options...
Jack the Lad Posted February 4, 2005 Report Share Posted February 4, 2005 ultimately - and it doesn't need to get up to a force 10 to have the anchor warp/chain in a straight line! - it is the holding power of the anchor (well apart from the warp or a connector actually failing!) that is the critical factor. ........... I agree it doesn't need to get to force 10 to straighten anchor rode - but obviously increasing the weight and length of the rode needs a greater wind and swell to straighten it. Which is exactly what I am saying. There must be a point when insufficient pull can be generated on the boat to straighten the rode weight. But here I'm not trying to discuss drawing board theory I'm trying to be clear what people should do when anchoring in difficult circumstances. Whilst you say increasing above 6:1 only gives you a minute improvement - when the chips are down please take any improvement. Nylon is also better than polyprop as an anchor rope; lessens the jerk. A tested galvanised shackle is better than the modern connectors which have had 'break off' ears; s/s connectors/shackles can suffer galvanic action. We could discuss the attributes of various anchors and how to use etc. etc etc But I thought you were trying to give a general overview. Which I still believe is:- More weight and longer rode increases an anchors holding power. Jack Quote Link to comment Share on other sites More sharing options...
Jack the Lad Posted February 4, 2005 Report Share Posted February 4, 2005 Hi Duncan, The read 'here' is a bit technical and like I said I'm being practical. I'm glad to see that you normally add in your deck height above the water line - you should. That's if you're giving an exam result answer. If you normally do a rough calc for max depth then add a few feet more it'll work - if the anchor is dragging either pull it up and check the anchor or let out some more rode! The poorer the holding - the longer the rode needed! I only mentioned a 'pig' as it's demonstrates the invalidity of your statement "increasing the size (not length) of the chain will help - but will not add to the ultimate holding power of your anchor tackle one bit! " You state also "Catenerary effects are the primary reason that you can 'get away with' a lower scope in deeper water ".Actually the deeper the water the greater the length of rode needed to reduce the pull on the anchor. 1M extra rode in 10M of water increases the catenery far more than that 1M in 20M of water. It seems to me you are trying to discuss theory rather than practical anchoring guidance. I reiterate - More weight and longer rode increases an anchors holding power. Lets hope peeps are learning something from this Duncan Cheers - Jack Quote Link to comment Share on other sites More sharing options...
duncan Posted February 4, 2005 Report Share Posted February 4, 2005 working towards the end agreement only...... ..........and totally agreeing that longer rode is better..........can we agree that a 10kg anchor is better than a 10kg ball of lead? If we can then it is but a short step to 'by what proportion' and thence to 'the right anchor - but for any given style the bigger the better (for holding)'. re practical v theory I am confident that a 20kg anchor will outperform a 10kg one plus a 10kg pig any day - happy to conceed a 20kg pig and still put money on it! Ah just re read the bit about chain length........and see where I mislead you! Silly me I think - I meant that if, for example, you had 20m of anchor warp attached to 5m of 6mm chain then anchor you should increase the chain to 8mm rather than increasing the chain component to, say, 7m (and 18m warp). I can see how you could have read this as shorter but heavier overall which is definitely not what I meant! Sorry. Quote Link to comment Share on other sites More sharing options...
Jack the Lad Posted February 4, 2005 Report Share Posted February 4, 2005 Great we agree now Thought I was suffering a 'senior moment' But it's just a bit of a communication problem. I couldn't agree more about a ball v an anchor. Have you seen the new light weight plastic anchors - they are light to handle then, you fill them with water to make them heavy; that should give good holding - think they're available April 1st Here's my personal views on anchor types for you to knock about - what do you all use (should that be a different thread?) Plough - genuine CQR ( balanced with weight at tip) best overall. Stock can move slightly if swinging a bit and re-sets ok when tide swings. Will set and hold well in most bottoms. Danforth - extremely good in mud but obstruction across flukes can stop the anchor resetting on tidal swing. Bruce - when set holds well. Initially designed for North sea oil rigs and the Bruce was placed and buried by divers. Can be a problem getting it to set. Real advantage, no moving parts to trap fingers. Fisherman - good as a rock pick. Rig with a trip! Needs to be heavy for sand/mud. Lots more - mostly designed on and improved or cheaper? versions of the above - so the sellers say. Get the correct weight anchor for your boat as recommended by the anchor manufacturer. Please don't hang your boat and perhaps your life on a cheap anchor and ancilliary connections! Jack Quote Link to comment Share on other sites More sharing options...
duncan Posted February 4, 2005 Report Share Posted February 4, 2005 I like the delta which, I think, gives the best of the CQR/Plough dynamics and the bruce's simplicity. Unfortunaetly expensive for wht it is. Spade is excellent for power to weight holding power, and setting. However I have used Bruces exclusively for the last 7 years. For the last 4 because they sit nicely on the bow roller and self stow! I carry a main 10kg and backup 7.5 fully rigged with 15m /8mm chain then 14mm octoplait - all a bit over the top for a 25ft boat but I have never regretted it - and often had cause to really appreciate it. Quote Link to comment Share on other sites More sharing options...
Jack the Lad Posted February 4, 2005 Report Share Posted February 4, 2005 I like the delta which, I think, gives the best of the CQR/Plough dynamics and the bruce's simplicity. Unfortunaetly expensive for wht it is. Spade is excellent for power to weight holding power, and setting. However I have used Bruces exclusively for the last 7 years. For the last 4 because they sit nicely on the bow roller and self stow! I carry a main 10kg and backup 7.5 fully rigged with 15m /8mm chain then 14mm octoplait - all a bit over the top for a 25ft boat but I have never regretted it - and often had cause to really appreciate it. Although I've always preferred a CQR I'm starting to think I should get a Bruce for self stowing simplicity and when set they do hold well. Perhaps these points is why I see a lot of Bruces on power boats etc.. Just be careful of clay! I saw a yacht in Fortelaza that was anchored on a Bruce and after a few days of holding no prob - the boat went walk about. The Bruce had scooped out a ball of clay ( acting like an ice cream scoop, when swinging) and when the wind increased pulled out the ball and just rolled around - proving your point that 'balls' don't make good anchors. Fortunately not too many sea beds are clay. We recovered the boat for the guy ( he was not on board) and re-anchored it; so no probs. Jack Quote Link to comment Share on other sites More sharing options...
great white Posted February 4, 2005 Report Share Posted February 4, 2005 Blimey I was going to join in, but the depths that these post have gone into meant I don't have time to read them at work. I will try and get the kids off my PC at home and have a look. Charlie Quote Link to comment Share on other sites More sharing options...
Jack the Lad Posted February 4, 2005 Report Share Posted February 4, 2005 Duncan - I hope you appreciate this comment I made in one of previous postings on this thread was not directed at you but meant as a general comment for anybody following the thread. "Please don't hang your boat and perhaps your life on a cheap anchor and ancilliary connections! " Cheers - Jack Quote Link to comment Share on other sites More sharing options...
Newboy Posted February 4, 2005 Report Share Posted February 4, 2005 Back to the main question, cheapest place to get some anchoring rope. I'll avoid the poly stuff, will work out a lot more expensive over the long run. Nylon is best and last forever (almost), unless you're like me and keep losing them over the gunnel. 59p per metre is the standard price for 10mm 3 strand at ebay, sold by Barry something, do a search on nylon rope. Also there's ropeseller who is in Dorset and has some 10mm 3 strand at about 45p but probably you can pick up to save on postage. 300 ft for Quote Link to comment Share on other sites More sharing options...
Maverick Martin Posted February 4, 2005 Report Share Posted February 4, 2005 Corr a little technical for us fishermen types in it . I just chuck my 7.5kilo Bruce look alike with 8 metres of chain and 210 metres of 12mm potting line over the side at a scope of around 3:1 or more depending how far up tide of the mark I have travelled and it usually works for me . Gundry Marine of Bridport are one of the cheapest suppliers and deliver to Poole on a Friday. I haven't got their details to hand will try and sort it out. Martin Quote Link to comment Share on other sites More sharing options...
duncan Posted February 4, 2005 Report Share Posted February 4, 2005 Ah - but we are trying to get something to work twice for Kam..... and Dan... I think your rig illustrates the issue quite well Martin - technically many would say a 5kg would be fine for your boat but my view, and I think Jack's, is that a 7.5 makes it all work so much more easily. maybe 10 quid more and a little more weight to handle /recover; might even cost you an extra 0.1p per mile in fuel to - but worth it. Quote Link to comment Share on other sites More sharing options...
Manic Moore Posted February 4, 2005 Author Report Share Posted February 4, 2005 WOW Thank you, I think!! I would certainly take that rope and splice the extra length as I obtain it. Or have I just committed the deadly sin? Thanks for all your help Gordon Quote Link to comment Share on other sites More sharing options...
duncan Posted February 4, 2005 Report Share Posted February 4, 2005 take 2 lengths from Kam and splice them together - I can give you chain that will suit from a few odd lengths I have lying around; and will splice it to your line if you wish - all for the price of a pint (well not the price the actual pint really) Quote Link to comment Share on other sites More sharing options...
Maverick Martin Posted February 4, 2005 Report Share Posted February 4, 2005 Ah - but we are trying to get something to work twice for Kam..... Not possible, he will only throw it all away Martin Quote Link to comment Share on other sites More sharing options...
Manic Moore Posted February 4, 2005 Author Report Share Posted February 4, 2005 I should have explained, I have a bruce anchor and chain, although I need to measure it to see if it matches the reccomendation. At the moment it only has about 6mm poly short rope so I was looking at my options to get the boat sea worthy. The man in dorset looks though it might be a rap. Thank you again for your advice and offers Regards Gordon Quote Link to comment Share on other sites More sharing options...
Coddy Posted February 4, 2005 Report Share Posted February 4, 2005 One thought I have found 10mm rope just a bit too small to comfortably hold, 12mm gives you that little more grip. Off my box now Coddy Quote Link to comment Share on other sites More sharing options...
Newboy Posted February 4, 2005 Report Share Posted February 4, 2005 First of all, what type of boat have you got? Length and weigh? According to chandlery chart, 10mm is good for boat up to 6m (some will claim up to 6.5m). I have the 10mm and my boat is smack on 6m, however, I can't but think it look awfully 'thin' Quote Link to comment Share on other sites More sharing options...
domino Posted February 4, 2005 Report Share Posted February 4, 2005 I'll just add my two-penneth.... ( and be prepared to be contradicted ) I don't think it'll make much difference how long you make the warp if you do use polypropelene.... it floats! As such all it does is connect you to the anchor... it won't do anything to increase it's holding power. Good luck, Alan Quote Link to comment Share on other sites More sharing options...
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