When I first got interesting in sailing I read all the old guys, Hal Roth, Lynn and Larry Pardy, and others. They were using the CQR and heavy chain. Hal Roth said he never anchored overnight with less than 5 to 1, and if it was breezy he went out to 7 to 1. When I anchored anywhere up in Georgia Straight the tides were at least ten feet of change so I often anchored in no less than 25 feet. In the tropics the tide changed only a couple of feet so you could anchor with a lot less chain, but I still hardly had less than 120 feet of chain out in 15 feet. I believe you sleep better knowing you have a good anchor, lots of heavy chain, and plenty of scope.
Real world data means using youre anchor every day while sailing around the world. Do you trust it or not to sleep in 50 knots. I use a 20kg rocna. It's the best anchor I have ever had. It only drags if fouled by something on the bottom. That's real life data for the past 10 years. Before rocna I would drag any plow anchor quite often. Never trusted my gear till rocna.
I have heard that the US Navy actually uses chain to hold its ships in place and that the anchor (which is heavy) is just used to pull the chain out. Of curse there chain is very large +2”ish. I tend to anchor in shallow water ( 8’-12’) and always add the distance from the bow roller to the water to the depth. Just my way of doing things.
Super interesting! A great extension of this test would be to show how deeper depths require less scope. But maybe you don’t want to climb 50 feet up into a tree :)
My approach is very simple: chain you have in your boat doesn‘t help but chain on the bottom of the sea does. So if space allows I always put out generous 5:1 till 17m depth, that’s what my total 85m chain length supports, from then on I shackle in a 18kg anchor weight after about 40m which keeps the angle on the anchor shank lower and I feel safe till 1:3 till around 27m of depth. The anchor weight in the middle of the chain also provides additional damping due to enlarging the catany of the chain. Have a cat and my bridle contains rubber dampers to further enlarge damping and also less stress on the attachment points of the bridle. The gypsy of my lofrans windlass doesn‘t support rope and there is none available for 10mm DIN chain that would support rope so that’s the best I can do.
On my 35 ft sailboat I have all chain (3/8") with a 45 lb CQR. I use 3:1 scope if in a protected anchorage. Have drug a little once in a mud bottom covered with "newspaper seaweed". I always set an anchor alarm. If I get blasted with very strong winds I would let additional scope out. (SE Alaska).
Someone could show me scientific numbers on a chart from MIT and it would not mean as much to me as some guy on a ladder in a tree with a come-a-long and a level Thank you so much ! I would like to spend some of the most valuable thing on earth with you Time Hope that doesn't sound creepy
Great stuff. One god reason for using using rope rode is that it simulates what happens in a strong blow when the chain straightens out. A while ago i sent a email to Spade and asked: "How does holding power and anchor weight/(size) scale ?" they answered "Actually holding power is between 1.5 and 1.7" . Slightly off topic, but maybe an ide to future investigations. Fair winds! ;)
I am not sure how to interpret that number given by Spade, but naively, I would argue that for any given anchor type, if I double its linear dimension (like length of anchor shaft) and keep all proportions the same, then the holding power will go up by a factor of 4, since it relates to the surface area 'wetted' by the sand. On the other hand, the weight of the anchor will go up by a factor of 8. So, if I now put all this into perspective in a formula, I would write 2^(2/3) = 1.59... Perhaps this is what Spade had been referring to?
We have a 25' Albin trawler. I know all chain is superior to rope, but we can't carry chain. I guess if we plan to anchor in 15' of water, we could carry 50' of chain and the rest rope might be a good compromise. We also don't have a windlass so maybe that's not a good idea. LOL
Hi Steve, your various tests and experiments are so interesting and valuable. Big thanks from Sweden and keep going if you have the time, means and motivation. Your video's are so appreciated. I know that this video was at a fixed scope 3.5 but I wanted to ask if this experiment gave you any insights to the general rule of thumb regarding scope: 15 m plus 2 times the depth? Also please test 15 kg anchors. A popular size here.
Please test chain, three strand and chain for chaif. A length of chain to the anchor, three strand for shock in the water and attached to the boat with chain to avoid chaif.
I personally like the “short rode” tests cause for lake anchorage 5:1, 7:1, or 10:1 is unrealistic for my type of boating and my boat size. Keeping say 500 to 1000 feet of rode on a 22 ft powerboat isn’t going to happen. typically on lakes (around me at least) allowing for that much sway with other boats around is practically impossible too. For the record I’m in the SW of the US and lake depths range from 20-100+ feet.
I’m curious about the angle at anchor comparing kellet to chain because the math gets complex. In another comment you responded that your chain weights much more than the anchor even but the load is spread and so would a kellet point load in the middle be as effective to achieve the same rode angle with much less weight than the chain total weight. A kellet yes is generally impractical but it would be an overall less expensive and less heavy rode on the boat and I have only 3/4” rode with a 45lb mantus on an 11,000lb Tartan 34c. I like the stretch I have too and usually anchor in 5-7ft depths (4ft draft w low tidal range in Barnegat Bay, NJ) but let’s say I travel somewhere and I want to have my rode handle a tight anchorage or deeper water with heavy wind a kellet is something I would consider. If you anchor between a buch of chain rode boats in a tight anchorage like you see happen in the Mediterranean and you have rode you need a way to get catenary effect to make the system work. I would really want to know if you need that much weight or because of point load effect in the middle of the line if that leverage requires less weight. Plus you can maybe cheat some boyancy weight to your favor in a kellet by using one made of lead and letting it out more than half the rode length say 2/3rds would also help a kellet cheat since in the chain that weight has a bigger vertical component which hangs on the vessel and closer to the anchor it would Maybe help the angle a little more.
Yes, tricky math. My guess is that a Kellet vs. equal weight chain will result in a more favorable angle at the anchor for the reasons you gave. It would be tempting to conduct a simulation/test in the shop, but, to be accurate, the "boat end" of the rode would need to be free to move horizontally in the same way a boat moves closer to the anchor with catenary. I'll put that test on my list of potential future projects. Thanks for the idea.
I wonder how much the tree gave way in this test as it wasn't anchored on the other side at the attachment point, so I'm sure it moved in relation to the force applied and has an effect on the readings. Maybe next time a building or a tree on a hill, and attach to the base of the tree where it won't move, instead of near the top of the tree to do the test...very interesting.
I searched high and low for a suitable "tree on hill" test location and could not find a one with a clear flat approach (for driving the truck, filming). That said, I detected zero deflection of the treetop during the the test. Strong tree.
@@flygoodwin I understand it'll be a hell of alot of work for you, but all chain, all chain of a smaller size, all rope and mixed. over your normal 3.5:1 and 5:1 rodes would be very interesting to see. But I would suspect that'll be a ridiculous amount of work
Hi, a very interesting and spectacular test! I'm a physicist and sailor/cruiser. I was also very interested in the theory (and practice) of anchors/anchoring. I wrote a little catenary program that calculates the exact shape (plus angles, forces and displacements) of the scope (either all chain, or mixed chain/rope, even a kellet can be added) for a given ancoring situation (wind speed, depth, scope etc.). I can send you the program if you wish, or I can run some calculations for the situation of your test and we can compare the results. Let me know if this would be interesting for you. Best, Denes
Greetings Denes. By all means, do run a calculation for my test. I would be very interested to compare. Height = 30 ft. Chain length = 105 ft. Chain weight = 1.6 lbs. per foot (in air) Thanks, Steve
Hi Steve, I did the calculations. You can download the plots with the results from here: drive.google.com/file/d/1-18PWntTHk5MsWgpVBvbC3ltwVMM05Wf/view?usp=sharing There is a surprisingly good agreement between your measured values and the calculations! I was surprised... Cheers, Denes
Great statistics. Thank you. I am a Great Lakes sailor anchoring in anywhere between 10 and 30 feet with mud or sand with a mostly rope rode and on low wind events. I have considered, if needed, to put an heavy mushroom anchor on a snatch block and a control line back to boat and letting the block/anchor go down the anchor rode to act like the weight of an all chair rode, 0r to increase the catenary, to allow less scope with the effect of a chain rode. Your thoughts?
I believe a weight that you describe (a kellet) can be of some benefit during setting at short scope when using a mostly rope rode. However, in order for a kellet to have much effect at reducing the angle of pull at the anchor during higher winds, it will have to be very very heavy. Keep in mind that the 105 feet of chain (that I normally use for testing) weighs almost 4 times as much as the anchor.
A waste of time, in high winds. The best use of a kellet is in low winds (near calm) to keep the boat from meandering around the anchor. Such meandering in calm conditions can cause a rode to snag on the anchor stock or collide with nearby boats. A kellet also complicates anchoring and retrieval.
Wow, this is a serious way to establishing what you already have told before. May I ask why assuming a rode of rope (nylon) and not chain is preferable in your tests? Wouldn’t most serious sailors use chain for the first 100 meters? Or is it because I’m living at 63°N that chain is the only way to go?
“most serious sailors” implies a strong pre-judgment and bias. In objective calculations and real world experience, elasticity is helpful in reducing shock loads such as those caused by waves and a boat’s “hunting” back and forth. This video illustrates quite clearly that the benefits of chain catenary are dramatically reduced as load increases. Therefore most “serious” sailors wouldn’t be without rope rode (or long rope snubber) for at least a segment of the rode.
Quite! The snubber is of course an important part of the set-up and probably almost impossible to find a good way to measure in these tests, as well as for nylon rodes, since there are no standards. By doing the measurements with only chain I guess you are getting as close as possible to a scientific standpoint. Then every one can get an idea of what loads can be expected and apply it to their own way of handling it.
Steve - is there any way you can correlate wind speed to the pulling force you have listed for each 100 lb data point? That would be great info Thanks, Ron
I can't use all chain so I use 6' of 1/2" chain on the end of my rode. It works well for me. But it's totally different than your test. Any plans on combining a length of chain to rode? I sleep very well swinging on my 17lb Mantus with my set up. MacGregor 26D (around 3000 lb)
Marty, that is an interesting combination you have: Short, but extremely oversized chain (for the size of anchor/boat). I can see how that would work very well when setting and perhaps provide some catenary at lower wind speeds. Thanks for the idea.
@@flygoodwin I'm in Ontario Canada and sail mostly in the Great Lakes. Most boats around here are trailered. I think because of that all chain anchor rode isn't used. Too heavy. The bigger cruising boats that are in the marina and need to be crained in and out don't care so much about weight. The chain I have came with my boat when I got it used. I think it's over kill but why change it when it works. Yes I think that extra chain on the end helps with setting the anchor. It's never fouled or failed to set.
I'm seeing discrepancies between your real world test at only 3.5-1 compared to this article with a 6-1 ratio and their model is showing WAY more angle to the catenary. I've also been researching kellet or sentinel weights for adding during tropical storms or hurricanes. From your data does it appear true that a kellet, say, 20-30' from the anchor would aid in keeping the anchor buried? www.petersmith.net.nz/boat-anchors/kellets.php
Robert, I did not find the discrepancies that you mentioned. Note that the graph in the article is depicted with the vertical axis in a far different scale as the horizontal. Re: Kellets, I agree with the article. A kellet's effectiveness at reducing angle of pull at the anchor will be reduced to having almost no effect as wind increases to "storm" or especially "hurricane" strength. The exception would be a case where the rode is very long (many hundreds of feet) and the kellet is very large (many times heavier than the anchor).
@@flygoodwin it seemed to me that your angles for the cantenary were not as steep as what they showed in the graphs even at your 1,000 lb pool it did not look as steep of an angle as their lower Force test, 650 lb if my memory serves me?
@@wakeboardbob In the Peter Smith article, the graph that is shown cannot be used to determine "angles" because the two axis are not drawn to scale (with one another).
@@flygoodwin not sure if you understood my direction with the question but just to clarify my concern was their angle was very steep with only 650 lb whereas your angle was nowhere near there's... My concern being the shank of the anchor being pulled from the seabed with such high angles on the road. Your test gave me some reassurance due to the very shallow angles of the cantinary even at 1,000 lb pull. Thank you again
