Anchor setting question

[Catigale]

Ive read in many places that you set an anchor at 5:1 scope, then set your final scope according to conditions of weather and neighbors etc.

Why would you set an anchor at reduced scope, then lengthen? Seems to me you would get more settting force at longer scope, then shorten per conditions or even set at final scope??

Anyone??

[James V]

It depends on your anchor and if you have rode(rope) or chain (or both and how much of each) and how much and what type of bottom and waves and wind and direction of each. It would be best to contact the maker and ask them. Most makers do not know Mac's so a good discription would be needed - Draws 11" has high freeboard with 6 foot standing head room and fully loaded less than 5000 pounds with a mast ect....

On most anchors 5 to 1 or 7 to 1 is normal. The Super Max is 3 to 1 with all chain or less is loose sand conditions.

[delevi]

7:1 should be ample. My 13 lb Danforth w/ 15'chain has been very reliable with about a 5:1 to 7:1. Honestly, I never really measured the amount of rode.... just a guestimate, but depth permitting, I would alwasy err on the side of caution and just let out a bunch of line. It's worked for me.

[Frank C]

Just one opinion, but while 7-scope is widely suggested as the safest approach, I think most rec-boaters use only 5-scope. During class last month they were teaching us at 5-scope, said to let out more if conditions warrant.

Until recently I had only 120' max rode, 20' in chain balance 3/8" nylon. In lake settings that's enough for a 7-scope but off Santa Cruz Is. depth was a bit over 20' at high tide ... so I used two anchors at 4+scope. Based on Moe's research last summer, I bought 260 feet of Yale Brait (also swapped the 20 feet of 1/4" chain for 6 feet at 3/8".)

During Fleet Week last fall, there simply wasn't room for any more than 4-scope due to hundreds of boats in a small area. Even though the late afternoon wind and waves built-up to about 20kn & 3 ft. most held their ground just fine - including my BUL!!

[Night Sailor]

I mark my rode with numbered, colored ties available from WM so the admiral and I won't have to guess once we drop the hook and confirm it agrees with the depthfinder. Do they sometimes disagree? Yes, by as much as 20 0r thirty feet. Underwater clif ledges, boulders, tree trunks, wrecks, etc can have your observations disagreeing.

For us, 5 to 1 with a 12 lb Danforth HiTensile II and 10 ft. of 1/4 in. chain on a nylon rode has been adequate at 25 knots in open water with sand bottom. When we expect winds 30 or higher we set the whole rode out, regardless of depth, if there is room available.

So far, the worst at anchor has been 50 knots, in twenty ft. of water over a mud/clay bottom for a 12.5 to 1 ratio. It did not budge, and the extra elasticity of the added length cushioned the swells on the bow.

If it's going to be a big blow and you are short on rode for the depth you must anchor in, I suggest that you rig a bridle or shackle to allow the rode to pull from the bow retrieval loop, instead of the deck cleats . It allows you have an effectively bigger ratio with the same length of line, and the bow is dead into the wind or waves, which ever is having the greatest influence over the boat.

[mike uk]

These are interesting comments but on behalf of Catigale I don't think they answer his question. I don't know the answer to his question but I would be interested to know!

The question wasn't "what is the correct scope"; the question was "why set short and then pay out line, is it not better to set long (better setting angle) and then take line in?

Mike

[Catigale]

Thanks Mike, that is what I was after....although thanks for the other posts too, always informative...

[Night Sailor]

Yes, I forgot to answer the real question. Sorry. I"ve heard some say that setting on a short scope is better because there is so little line to stretch that any over the ground movement will be anchor movement and readily obvious. I don't buy that because I don't count it set until it will hold at WOT in reverse for at least 30 seconds whether at 3:1 or 12:1.

Proponents also argue that if it sets properly at short scope you can then sleep soundly knowing it will hold at a longer scope.
I don't buy that either, because I've had the experience where an anchor dropped in the blackwater of a sheltered bayou, hooked on a log, not the bottom, on a 3:1 scope and the motor did not back it out. Of course I assumed the anchor was properly set, as it had always been before. Rode was let out during the night for freshening winds to about 7:1, the maximum swinging room. Next morning I discovered we had drifted 50 feet. With sheet winches and much grunting we hauled anchor up upon leaving and found the flukes firmly embedded in the mud covered log . The short scope couldn't pull it up out of the mud, but a sideways pull overnight accomplished it. That was the only time in 50 years I had an anchor drag, but I know it can happen with any scope, or anchor. So, my theory is except for a lunch hook in gently conditions, set it like you mean it for the worst case reasonably expected, given swing room, and check at least twice during the night for drift.

[Paul S]

Ive read in many places that you set an anchor at 5:1 scope, then set your final scope according to conditions of weather and neighbors etc.

Why would you set an anchor at reduced scope, then lengthen? Seems to me you would get more settting force at longer scope, then shorten per conditions or even set at final scope??

Anyone??

I generally pay out a lot more and pull in the extra. Also rarely even go 5:1 (usually a lot shorter 3-4:1), hate to admit it.. but never had an issue either. The fortress seems to hold its own in every condition I have thrown at it. If you have the line..and the swing area..pay it out.

[KayakDan]

Catigale,I think issues like type of anchor,rode vs. chain,length of scope,all have lot's of answers,most of them good,all different. I think you just find what works for your boat and situation and run with it. On Champlain last week I set about 3.5 scope in mud using an FX-11. Held great until the wind picked up,and we started passing our neighbors. I reset to 6:1 and we were fine. My mistake? I should have set for the wind expected the next morning,and been a bit more cautious. Probably should have run out some rode that evening,just to be sure.
Sometimes surroundings don't allow a lot of scope either.6:1 or 7:1 will have you visiting your neighbors in some tight anchorages in ME!
Mostly,go with what works for ya,and take the opinions with a grain of salt.

[craigsmith]

Ive read in many places that you set an anchor at 5:1 scope, then set your final scope according to conditions of weather and neighbors etc.

Why would you set an anchor at reduced scope, then lengthen? Seems to me you would get more settting force at longer scope, then shorten per conditions or even set at final scope??

Anyone??

It's just that most people would frequently use less than 5:1 scope - 3:1 or less is unfortunately not uncommon, especially in crowded anchorages, and amongst newbies - so anyone writing "instructions" of any kind will be explicit about what scope to use when setting. In other words, even if you intend to pull the scope back in to 3:1, you should set the anchor at 5:1, since you can't properly set most anchors at anything less.

Consider our User's Guide if you like.

In deep water, you can get away with less. In really shallow water, you should use more.

Of course if you're going to use more than 5:1, then you might as well set the anchor with all the rode out.

Claims regarding anchors that set well at short scope are a little misguided. SuperMax are guilty of this - they also claim the anchor requires no chain. Bruce was also heavily advertised as setting and performing well at short scope. It's just a case of "if you can't beat 'em join 'em", with regard to the kind of boaters that are going to use 2:1 scope with a piece of string, no matter what you try to tell them.

[Catigale]

Of course if you're going to use more than 5:1, then you might as well set the anchor with all the rode out.

...a couple of weeks ago, on Martha Vineyard, I was the only boat on 16 sq miles of bay... ....I dropped the Bullwaga into about 6 feet of water at low tide, and realised my 150 feet of rode in the locker wasnt doing me any good in the locker....

I let most of it out, with 15 feet of heavy chain.

That night it blew to 35....and we didnt move of course. Admiral impressed.

(I had my 18# mud anchor of the back, stopping the Mac dance.)

[James V]

craigsmith - have you used or seen a Super Max anchor?

I have one, only used it a few times so far and have found that a shorter scope is best. It makes it dig deeper. It id not really a scooper but more like a shovel.

Very few on this board have a Super Max. The only thing that I can say is to check with the maker of the anchor and see what they say and read the test reviews of the anchors.

I did find with a Fluke type anchor the more scope the better.

[Frank C]

craigsmith - have you used or seen a Super Max anchor?

I'm pretty sure that craigsmith has both seen, used and comparison-tested a Super Max.
He is the manufacturer of the Rocna anchors.

Consider our User's Guide if you like.

[James V]

Frank C - Thanks, I thought I remebered his name in SSCA's forum on anchors.

There is a lot of discussion about anchors and what is best. Which ever type you choose - it is best to see what the manufacturer says on scope and try that first.