OK it's time to get your slide rules out. I have a 35 pound CQR on my Hunter 335 with 40 feet of 5/16" HT chain and 300 feet of rope rode. Swing room is frequently a concern in our waters which has me considering changing to an all chain rode. Problem is that all chain rodes are heavy which has me thinking about a windlass. Well windlasses are expensive and the foredeck of the 335 is not really designed to handle those stresses. I'm sure money can overcome all, but it all has me thinking about another option which creates my engineering puzzle. Let say I'm anchored in 30 feet of water. With an all chain 5/16" HT rode, the weight of 90 feet or a three to one scope would be 98.1 pounds. Thus my forty feet of chain would be fifty feet and 54.5 pounds light. However, the weight of that chain would be spread out along the catenary. Let's say I lowered an anchor sentinel or kellet down my rope rode to the top end of the chain. Since it would be a concentrated weight lower down the rode, how heavy would that kellet have to be to provide equivalent stability for the anchor? How do you calculate that? Thanks for your help. Gary Wyngarden S/V Shibumi H335
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This is a Test! Right?
Let's see now, the angle of the dangle is directly proportional to the weight of the kellet..... Ahhh, let me get back to you on this! Jim S/V Java
Let's see now, the angle of the dangle is directly proportional to the weight of the kellet..... Ahhh, let me get back to you on this! Jim S/V Java
No, it's not a test.
I really want to know, and don't remember how to figure it out if I ever did. GW
I really want to know, and don't remember how to figure it out if I ever did. GW
Gary, don't know answer but look at this link
Appear to have lots of information, whether it has the answer or not is for detailed reading. Jim http://www.anchorbuddy.co.nz/index2.html
Appear to have lots of information, whether it has the answer or not is for detailed reading. Jim http://www.anchorbuddy.co.nz/index2.html
Way to go Jim!
I was starting to get a headache(I really do have a sliderule). But I think your link answers it for me. Probably not for Gary though, he still wants a formula.
I was starting to get a headache(I really do have a sliderule). But I think your link answers it for me. Probably not for Gary though, he still wants a formula.
Puzzle answer
Move to the East Coast, I've never anchored in water over 10 feet deep. And as an added bonus we get some great sunrises. I couldn't begin to come up with a calculation that will answer this but.... assuming 1 ft of chain = 1lb, then a 30lb kellet should (along with your 40ft of existing chain), give you "most" of the benefits of an all chain rode in the situation you describe. One trick we use here in hurricane alley is to attach one kellet to the chain about 2 feet from the chain to rope rode connection and then use another sliding kellet with a check line about 1/3 of the way down the rope rode. That might help save your back.
Move to the East Coast, I've never anchored in water over 10 feet deep. And as an added bonus we get some great sunrises. I couldn't begin to come up with a calculation that will answer this but.... assuming 1 ft of chain = 1lb, then a 30lb kellet should (along with your 40ft of existing chain), give you "most" of the benefits of an all chain rode in the situation you describe. One trick we use here in hurricane alley is to attach one kellet to the chain about 2 feet from the chain to rope rode connection and then use another sliding kellet with a check line about 1/3 of the way down the rope rode. That might help save your back.
Thanks, Jim
That link is encouraging. I know Ed was being facetious, but I would like to know how to calculate this. In essence I want to cheat on scope. I would like to turn my chain/rope rode into the equivalent of an all chain rode using a kellet/sentinel/anchor buddy and be able to reduce my scope from seven to one down to three to one or close to it. But not at the risk of dragging. Maybe Ed will get back to work with his slide rule now ;-) Gary Wyngarden
That link is encouraging. I know Ed was being facetious, but I would like to know how to calculate this. In essence I want to cheat on scope. I would like to turn my chain/rope rode into the equivalent of an all chain rode using a kellet/sentinel/anchor buddy and be able to reduce my scope from seven to one down to three to one or close to it. But not at the risk of dragging. Maybe Ed will get back to work with his slide rule now ;-) Gary Wyngarden
Kellet weight is up to you.
The Kellet is a compromise to use less chain. Too heavy a Kellet defeats the purpose of a Kellet. Pulling up a chain rode, the weight of the chain is distributed evenly, whereas the weight of the Kellet is deadweight until you pull it on board. There is Excel spreadsheet that calculates the anchor catenary and the upward tension on the anchor rode using Kellet and different lengths of chain. I haven’t used it, so I don’t know how well it works. Fair Winds. Clyde
The Kellet is a compromise to use less chain. Too heavy a Kellet defeats the purpose of a Kellet. Pulling up a chain rode, the weight of the chain is distributed evenly, whereas the weight of the Kellet is deadweight until you pull it on board. There is Excel spreadsheet that calculates the anchor catenary and the upward tension on the anchor rode using Kellet and different lengths of chain. I haven’t used it, so I don’t know how well it works. Fair Winds. Clyde
Mushroom Anchor
An option is an eight pound mushroom anchor. With a snap shackle or other shackle on a separate line, it's easy to run down your rode. We've used it successfully where wind and tide oppose.
An option is an eight pound mushroom anchor. With a snap shackle or other shackle on a separate line, it's easy to run down your rode. We've used it successfully where wind and tide oppose.
Instead of geting a 30 lb weight for $200...
you could just get another 30 ft. section of chain and put hook it up in your rode. Then when you're down with 3-1 scope in 30 feet you'll have a short (20 ft.) length of nylon to act as a snubber plus it will be less stuff to mess around with. Same amount of weight at a third the price. That's a pretty impressive spreadsheet by the way!
you could just get another 30 ft. section of chain and put hook it up in your rode. Then when you're down with 3-1 scope in 30 feet you'll have a short (20 ft.) length of nylon to act as a snubber plus it will be less stuff to mess around with. Same amount of weight at a third the price. That's a pretty impressive spreadsheet by the way!
Answers?
Well I found a site which is listed below that has a formula. It may be the same one Clyde suggested though I couldn't get that one to open. The spreadhseet allows you to vary water depth, amount of chain and nylon rode, and weight and placement of a kellet. It calculates the horizontal pull of your rode as a measure of how much force is required to pull the rode off the bottom and start stressing your anchor. In my example of 30 foot water depth, and forty feet of chain, it calculated a horizontal pull of 184.4 at a scope of 5 and 237.9 at a scope of 7. A scope of 4 with an all chain rode produced 214.2. A scope of four with my chain/rope rode and a 30 pound kellet 5 feet off the upper end of the chain produced a horizontal pull of 200.5. Assuming the formula is correct it could be an inexpensive way to either reduce your scope and thus swing room or increase the security of your anchor's holding power. It would also get a lot of weight of extra chain and a windlass off the bow. Any more thoughts? Gary Wyngarden S/V Shibumi H335
Well I found a site which is listed below that has a formula. It may be the same one Clyde suggested though I couldn't get that one to open. The spreadhseet allows you to vary water depth, amount of chain and nylon rode, and weight and placement of a kellet. It calculates the horizontal pull of your rode as a measure of how much force is required to pull the rode off the bottom and start stressing your anchor. In my example of 30 foot water depth, and forty feet of chain, it calculated a horizontal pull of 184.4 at a scope of 5 and 237.9 at a scope of 7. A scope of 4 with an all chain rode produced 214.2. A scope of four with my chain/rope rode and a 30 pound kellet 5 feet off the upper end of the chain produced a horizontal pull of 200.5. Assuming the formula is correct it could be an inexpensive way to either reduce your scope and thus swing room or increase the security of your anchor's holding power. It would also get a lot of weight of extra chain and a windlass off the bow. Any more thoughts? Gary Wyngarden S/V Shibumi H335
Now you know
Why Jim Seamans endorses having a laptop computer onboard instead of a flat panel tv... Markdb PS. Of course you could program the formula into your GPS/PDA...
Why Jim Seamans endorses having a laptop computer onboard instead of a flat panel tv... Markdb PS. Of course you could program the formula into your GPS/PDA...
Sentinel in use
Gary, I've used a kellet as part of my ground tackle in the waters in which you also cruise. One aspect of using a sentinel that never occurred to me before actually using one is that the sentinel on a rope rode tends to confuse others who attempt to anchor around you. Many boaters rely on trying to determine the location of your anchor based on the angle of the rode above the water; yes, I know, it would also depend on the length of chain attached to the rope rode, but this is what people around me in the San Juans have claimed to do. The kellet will fool a lot of people. I’ve had boaters drop their anchor right over my anchor (at Skagit Bay's Hope Island, & Fossil Bay and Shallow Bay, Sucia), thinking that I did not have very much scope (“Your rode is hanging almost straight down!”). Well, the easy way to prevent this is to have courteous neighboring boaters ask where my anchor is located or how much scope or rode I have out, but nobody has. Or else stay up at night and monitor the situation while boats enter the anchorage and circle around you. Also, it’s interesting when people get pretty upset (irate?) when I try to explain where my anchor is actually located and that they should move. Many people here do not understand terms like sentinel and kellet. So, this is may be one more peculiarity that you may experience in anchoring with a sentinel. Possibly better to use one when conditions warrant their use rather than to use it regularly.
Gary, I've used a kellet as part of my ground tackle in the waters in which you also cruise. One aspect of using a sentinel that never occurred to me before actually using one is that the sentinel on a rope rode tends to confuse others who attempt to anchor around you. Many boaters rely on trying to determine the location of your anchor based on the angle of the rode above the water; yes, I know, it would also depend on the length of chain attached to the rope rode, but this is what people around me in the San Juans have claimed to do. The kellet will fool a lot of people. I’ve had boaters drop their anchor right over my anchor (at Skagit Bay's Hope Island, & Fossil Bay and Shallow Bay, Sucia), thinking that I did not have very much scope (“Your rode is hanging almost straight down!”). Well, the easy way to prevent this is to have courteous neighboring boaters ask where my anchor is located or how much scope or rode I have out, but nobody has. Or else stay up at night and monitor the situation while boats enter the anchorage and circle around you. Also, it’s interesting when people get pretty upset (irate?) when I try to explain where my anchor is actually located and that they should move. Many people here do not understand terms like sentinel and kellet. So, this is may be one more peculiarity that you may experience in anchoring with a sentinel. Possibly better to use one when conditions warrant their use rather than to use it regularly.
Use an anchor float.
In a crowded anchorage, tie a small float to your anchor to mark your anchor location. The length of the line should be the depth plus high tide. If you use a fluorescent float, you can shine a light at night to mark your anchor position to late night boaters looking for a spot. A 30 pound Kellet is at the upper limit for Hunter 335. The rule of thumb for the weight of a Kellet is 0.7 lbs. to 1 lbs. per LWL with the lighter weight being preferred. Always assume that the weakest crew member is the one who will have to haul in the Kellet during a storm. I think a Kellet Bag is more versatile than the lead weight Anchor Buddy. You can make or buy a Kellet Bag and use chain or other weights. If you add a small float and some weights to adjust the buoyancy, I think it could be used as a drag drone in an emergency. You can always find use for a Kellet Bag, but a lead weight is always a lead weight. Fair Winds. Clyde
In a crowded anchorage, tie a small float to your anchor to mark your anchor location. The length of the line should be the depth plus high tide. If you use a fluorescent float, you can shine a light at night to mark your anchor position to late night boaters looking for a spot. A 30 pound Kellet is at the upper limit for Hunter 335. The rule of thumb for the weight of a Kellet is 0.7 lbs. to 1 lbs. per LWL with the lighter weight being preferred. Always assume that the weakest crew member is the one who will have to haul in the Kellet during a storm. I think a Kellet Bag is more versatile than the lead weight Anchor Buddy. You can make or buy a Kellet Bag and use chain or other weights. If you add a small float and some weights to adjust the buoyancy, I think it could be used as a drag drone in an emergency. You can always find use for a Kellet Bag, but a lead weight is always a lead weight. Fair Winds. Clyde
That Excell program works well.
basically a 18 lb sentinel all the way down the rode is worth more to keeping your anchor shank down that 2 times that weight in anchor chain all the way up to your boat. Think about it. Those last 5 pounds of anchor chain a few feet off your bow really aren't doing anything to keep your anchor on the bottom.
basically a 18 lb sentinel all the way down the rode is worth more to keeping your anchor shank down that 2 times that weight in anchor chain all the way up to your boat. Think about it. Those last 5 pounds of anchor chain a few feet off your bow really aren't doing anything to keep your anchor on the bottom.
Calculations aside.....
Gary, I have a h40.5 with 160 feet of 5/16 HT chain with a 45# CQR all hauled by a windlass. My experience is that when I have anchored with a scope of 3-4:1, I have dragged on a couple of occasions, or have not been able to get the anchor to set to my satisfaction. I always use 7:1 (under 22' depth) for peace of mind and a good night's sleep. On the times that I have anchored in 30-50 feet of water, I put out all 160' of chain and have had no problems. I also have another 130' of rode in addition to the chain, but have not felt the need to set it out. Bottom line, I don't believe there is a good substitute for scope. I'm not sure that I could feel confident with a sentinel on a 3:1 scope, but maybe that's just my problem. I realize that this doesn't answer or solve your swing room problem, but is just a thought. Rich
Gary, I have a h40.5 with 160 feet of 5/16 HT chain with a 45# CQR all hauled by a windlass. My experience is that when I have anchored with a scope of 3-4:1, I have dragged on a couple of occasions, or have not been able to get the anchor to set to my satisfaction. I always use 7:1 (under 22' depth) for peace of mind and a good night's sleep. On the times that I have anchored in 30-50 feet of water, I put out all 160' of chain and have had no problems. I also have another 130' of rode in addition to the chain, but have not felt the need to set it out. Bottom line, I don't believe there is a good substitute for scope. I'm not sure that I could feel confident with a sentinel on a 3:1 scope, but maybe that's just my problem. I realize that this doesn't answer or solve your swing room problem, but is just a thought. Rich
Gary,
While I understand your question and your need to shorten scope, I agree w/ Rich.... I have a 420 w/ 250' of 5-16 BBB. Ditto everything Rich said.... 5-7/1 scope w/ all chain rode (and a snubber) makes for a very good night's sleep.
While I understand your question and your need to shorten scope, I agree w/ Rich.... I have a 420 w/ 250' of 5-16 BBB. Ditto everything Rich said.... 5-7/1 scope w/ all chain rode (and a snubber) makes for a very good night's sleep.
Tiss true, but that much weight in the bow
(or stern) does not always mean desirable sailing characteristics. But then again most have davits with dingies and engines and all sorts of things so I guess that doesn't matter as much.
(or stern) does not always mean desirable sailing characteristics. But then again most have davits with dingies and engines and all sorts of things so I guess that doesn't matter as much.
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