First time my 26M left unattended on the hook

paj637 · Post by **paj637** » Wed Dec 26, 2007 6:09 pm

I have had my 26M on the hook near my local marina and I drug anchor the second night in light (5-7 KNOT) winds with the outgoing tide. I'm anchored in about 5 feet of water at low tide with about a 4-5 foot rise at high tide. Got out almost 100 feet of rode with 20 feet of 3/8" chain and I believe a 30# anchor (the biggest danforth that fits in the M anchor locker). I just put out a second anchor on the stern tonight. It's the 13# danforth off my 18' center console. Hopefully now the M won't dance around so much. Almost zero wave action at the anchorage and it's in a cove so to speak with less tidal currents. Read the posts about mast failures at the moor. My rig is tuned right with a LOOS gauge and I thinking I'm good to go since the water conditions are so subdued. Although I think I'm going to be reluctant to anchor it out again. Hoped to get onboard several times this week but it didn't work out. I'll just bite the rig/derig time bullet from now on.

Divecoz · Post by **Divecoz** » Wed Dec 26, 2007 11:11 pm

Seems to me, like you have a lot of rode and chain out for being in only 5 feet of water 10 feet at the most. Maybe that's actually your problem. Too much rode ?
Can a girl be too pretty? A car be too fast? Beer be too cheap ? and a boat have too much rode out ?
I guess we will have to just wait and hear from someone with the answer.

jasper · Post by **jasper** » Thu Dec 27, 2007 12:04 am

Scope should be at least 5:1 and preferably 7:1 + length of boat at high tide.
At 10ft tidal depth, rode at a minimum would be perpendicular distance to bottom from deck cleat =10 + 3.5 x 5 + 26 ft = 113.5ft scope minimum. So at 100ft you may be a bit short. Chain length sounds ok, if you anchored at low tide. Could be the type of bottom that is the problem. If it is relatively flat and rocky there would be not much for the anchor to bite.
I would deploy a second auxillary anchor at the bow to form an approximately 30 - 40 degree angle with the prime anchor. Maybe a kedge type anchor for rocky bottoms would be good as the auxillary, as a stern anchor won't prevent the bow from drifting.
I remember back I the 1970's being anchored in Tobermoray harbour on the Isle of Mull, Scotland. It ws my second overnight experience of overnighting at anchor. We deployed about 100ft of rode in 7 foot of water. We forgot to include the distance from the bow cleat and add the boat length (30)ft or to allow for tidal lift. I woke at 4am hearing a bumping and clanging. and got on deck to find we were drifing slowly out of the harbour. I let out an additional 50ft of rode and it bit. Then we started the motor, up anchored and returned to out original mooring, This time, we let out 180ft of rode and it held. Just to be sure, we deployed an auxillary kedge in about 120ft of rode at about a 30 degree angle. We slept safely but not soundly from that point, as I lay awake the rest of the night wondering if we would drift again.

Divecoz · Post by **Divecoz** » Thu Dec 27, 2007 12:23 am

So to anchor in 7 feet of water you need to find room to carry 2 anchors and 300 feet of rode and no doubt somewhere between 30 and 60 feet of chain?
So by that if I was to say . . need to anchor in 21 feet of water your saying I should have aboard 2 anchors and somewhere close to 1000 feet of rode / chain combo?
Its late at night and want to make sure I read that right.
With my mast and boom up and sail cover on my boat and ALL macs can heel pretty good in a bit of wind. So on a hook, with bare poles we could swing a bit as well. I would have thought having so much line laying in the water would have added to the problem. Hummm?

pokerrick1 · Post by **pokerrick1** » Thu Dec 27, 2007 1:59 am

Admiral Dive, Sir, methinks you have exposed an obvious flaw (1,000 feet of rode?). However, this is all making me dizzy (dizzier?), and is ANOTHER reason why I rarely anchor

My Mac is 2 years old now and I haven't anchored yet, though I carry full equipment (I love to be weighed down by stuff I don't use)

Rick

jasper · Post by **jasper** » Thu Dec 27, 2007 3:49 am

The figures I gave are directly from the Canadian Power and Sail Seamanship Certification Manual.
Chapman's Piloting and seamanship states "under favorable conditions using nylon line, 5:1 might be considered a minimum under average conditions, 7 or8:1 is regarded as satisfactory. Tests show that proper scope ratios range between 5:1 and 10:1, the latter for heavy weather."
Sorry guys, the figures are from the experts not from me.
The only thing that would lessen the scope ratio is when using an all chain rode. But, who wants to carry 150ft of chain in a Macgregor chain locker?
The puropse of scope is to decrease the angle of pull. With a low angle of pull, and sufficient chain to weight the rode down, the rode pulls close to horizontally allowing the anchot to bite. With insufficient chain or a high angle of pull, the anchor will pull at a steep angle and off the bottom.
I would recommend doing a test run or two during the daytime. Anchor on a rising tide and allow for the maximum depth at high tide and let out the recommended scope. Then turn on Jimmy Buffett on the stereo, break out the fishing rods and the barbeque and sit it out until high tide and see how the boat reacts. If it drags at all, then either there is not enough scope, or the bottom ain't suitable.

Divecoz said........ "So to anchor in 7 feet of water you need to find more to carry 2 anchors and 300 feet of rode and no doubt somewhere between 30 and 60 feet of chain? So by that if I was to say . . need to anchor in 21 feet of water your saying I should have aboard 2 anchors and somewhere close to 1000 feet of rode / chain combo?"

No, I don't think that there is a need to carry a second anchor in all situations, especially if you already know the bottom condtions. I carry a 5/8 100ft tow rope in one of the storage areas and I have a small navy type anchor to use as a backup with only 10ft of chain. I can quickly rig this using a shackle.
To answer the second part, I would never anchor in 21 feet of water unless tied onto a mooring. But, you are right, you would need about 1,000 ft of rode, again per the experts, not me.
As a suggestion, for those of you who have not done so, it may be in your best intereset to take one of the seamanship courses offered either in US or Canada. Perhaps the UK offers these too. Coming from a seafaring family and having spent a lot of time in boats, I thought I had a good grounding, but after taking the course I realized in fact how little I knew about the proper techniques, rules etc. Of course, a good manual such as Chapman's or the Annapolis is a must read also.

Catigale · Post by **Catigale** » Thu Dec 27, 2007 4:07 am

You almost certainly didnt get a good anchor set (you should back down on the anchor for 5-10 seconds at 3000 rpm with the motor to dig it in well) or what happened is when the tide changed, the boat was pulled in another direction and pulled the anchor out.

Do you have information on the bottom condition (mud, grass, rocks, or sand)??

That 100 feet of rode and chain were fine in your conditions if you anchor set well btw. A 7:1 scope in 10kts of wind will hold fine.

If you are staying on board, a GPS with an 'anchor drag' feature is a must imho.

Chip Hindes · Post by **Chip Hindes** » Thu Dec 27, 2007 6:22 am

As well set Danforth in the "correct" bottom for a Danforth should hold fine in the conditions described.

However, the Danforth is not a particularly good anchor for many bottom conditions, and Danforths are famous for pulling out and not resetting if the angle of pull changes substantially. It doesn't matter so much the amount of tidal currents or wind speeds, if the direction of pull changes the anchor will almost certainly pop loose, and if it doesn't reset...

I would never trust any long term unattended boat to a single Danforth. BTW, does the M locker actually hold a 30 lb Danforth? Hard to believe. The X locker holds a 13 max.

What math was used to get the 1000 feet figure? (21' of water plus say 3' from the water to the cleat) X 7 +26 = 194.

Divecoz · Post by **Divecoz** » Thu Dec 27, 2007 6:37 am

I am more like Rick as I have only anchored once in 3 years.
That was in a lake in Wisc. Most or at least many lakes up there are pretty shallow. We were brand new at sailing and had no depth sounder. I walked to the front opened the locker grabbed the anchor and dropped it over the side . ( thank goodness I had tide it off to the forward cleat!) I was in close to 100 feet of water

. I got a rope burn as I watch ever bit of that line Zooooom to the bottom with a 13 lb. Danforh wanna-be on the end.
Again like Rick , I seem to love to have a bunch of stuff on board to see just how slow I can make my boat go in Hurricane condition's under full sail. But I have taken out the CLAW, and its accompanying rode and chain.
The Claw for now lives in the garage on the floor with 8 feet of chain and 150 ft. 1/2inch rode. It is btw holding the garage perfectly in place.

Catigale · Post by **Catigale** » Thu Dec 27, 2007 6:39 am

Couple things to add

1 Why is the boat length added to the rode calculation - it would seem to me that the length doesnt change the angle of the rode to the bottom, so it isnt relevant???

2 Technically, rode calculations assume a flat bottom, which is likely not he case. If the depth at the anchor is less than at the boat, you need more rode, and vice versa...On edit - I actually got that backwards....less depth at anchor means better angle on the anchor and ergo less rode needed for same holding power....

If the bottom is described by coth(x)sinc^2(e^y) where x is the number of knots in your hair and y is the price of tea in China you dont need an anchor at all......check with your attorney first...

3 You can lower the scope needed by cleating or attaching your anchor to the boweye, instead of a bow cleat.

Divecoz · Post by **Divecoz** » Thu Dec 27, 2007 7:08 am

Chip Hindes wrote:As well set Danforth in the "correct" bottom for a Danforth should hold fine in the conditions described.

However, the Danforth is not a particularly good anchor for many bottom conditions, and Danforths are famous for pulling out and not resetting if the angle of pull changes substantially. It doesn't matter so much the amount of tidal currents or wind speeds, if the direction of pull changes the anchor will almost certainly pop loose, and if it doesn't reset...

I would never trust any long term unattended boat to a single Danforth. BTW, does the M locker actually hold a 30 lb Danforth? Hard to believe. The X locker holds a 13 max.

What math was used to get the 1000 feet figure? (21' of water plus say 3' from the water to the cleat) X 7 +26 = 194.

My figures were just multiples Chip.
I basically X 3 that which Jasper found necessary to feel confident in 7 ft of water. I am dieing to sail in an area where we can over night on the hook! ( have a slip on lake Michigan

SO I am just asking questions not finding fault. My brother lives in Florida and does this all the time on a power boat. He insist on 50 ft of chain 300 ft. of rode X 2 with anchors you need a wheel barrow to move on dry land... BUT. . . .I don't have like he has, 2 - 150 amp alternators and a gen-set and enough batteries to power an Electric Peterbuilt. By hook or crook I too am going to experience what many of you do, even if have to go it alone, and I want to be somewhat prepared.
I have two anchors both 13 lbs. Both with 150 ft. of rode and 8 or 10 ft of 3/8 chain. 1 is a danforth wanna-be the other is a claw wanna-be.
I have a Lowrance with anchor drag alarm, so with little to no wind or tide, as I read it , I am only prepared for a 20 ft anchorage ??? OK so I cruise around looking for a bay with 20 feet or less depth. I should drop the aft anchor and continue forward and drop another anchor, then back up till that 2nd anchor is set and then tighten the 1st anchor to set it and then release some scope, till the rode is slack to the bottom?
In My case some way some how I need to end up with just about all my rode in the water ??
On Edit:
One of my Genus buddies ( birds of a feather BTW)who doesnt sail but is familiar with the Apostle Islands, said.
Screw all that anchor crap! Go to Home Depot. Go to the rope section and buy 500 ft. of decent 3/8 rope! Then walk over to where they sell compressors and buy a hose reel. Then walk over to hardware and buy 4 - 3/8 " lag bolts and lag the reel to the deck. Find an island where you want to stay. Swim to shore and tie off to a tree. Swim back BEFORE a bear See's you and call it quits for the night. If bear doesnt leave the area by morning cut the rope and leave and never admit you were there.
If needed go back to Home Depot for more ROPE!

Craig LaForce · Post by **Craig LaForce** » Thu Dec 27, 2007 7:52 am

Just to add my 2 cents.

Tide reversal situations require 2 anchors set in 180 degree opposition, up and down stream of the tide. Or better still, 3 set at 120 degrees apart (might be worth it if you are trying for a makeshift semi permanent homemade mooring. Maybe a real mooring is what you need for long term hookage. And each anchor should be set by backing down hard for a few seconds. You are trying to bury it to the shank in whatever bottom is down there.

Danforths will pull out easily as Chip says, when pulled in direction opposite to th way it was set. And they are very prone to not resetting, due to mud packed up on the flukes. Almost any other anchor is better for long term anchoring. A 30# Danforth?? I had an 18# superhooker Danforth knockoff and it was big time overkill. I changed to a 13# which seems about right. All anchors can come loose though, seems that the bottom is what nature provided, not West Marine.

100 feet not a 1000 ft looks like a slipped decimal.

Too much rode might be a problem if it slams the boat into an obstruction somewhere in the swing radius.

You anchored to your steering console?? Cleats with good backing blocks or plates should be used. Also, the rode as it passes out the back of the boat will likely do all sorts of damage (abrasion cutting of fiberglass surfaces, or getting looped around the prop or rudders.

Don't forget to add cleat height above water to the water depth when calculating rode length required

Bears can swim.
Sleep tight.

jasper · Post by **jasper** » Thu Dec 27, 2007 7:53 am

"Why is the boat length added to the rode calculation - it would seem to me that the length doesnt change the angle of the rode to the bottom, so it isnt relevant??? "

I haven't seen an explanation, but I am sure there is. However, adding the boat length is in most formulas I have seen.

"If the bottom is described by coth(x)sinc^2(e^y) where x is the number of knots in your hair and y is the price of tea in China you dont need an anchor at all......check with your attorney first... "

This equation is only applicable in relation to amount of whisky consumed then another equation would apply......
a x m x t / d = HC
a= aclohol proof, m = capacity of shot glass, t =time taken to consume, d= distance to toilet and HC of course would be the holding capacity

Andy26M · Post by **Andy26M** » Thu Dec 27, 2007 8:00 am

Catigale -

The calculation which includes the length of your boat is for finding your "Swing Circle". The swing circle is the area which could potentially be covered by any part of your boat as it floats around the anchor with changing tides, winds, etc. Once you've anchored and fixed the position of your anchor, the swing circle is what you draw on the chart to ensure that there are no obstructions (rocks, buoys, etc.) which you might run into during your stay.

The swing circle is generally simply defined as length of rode + length of boat, without doing any trigonometry. The extra radius just gives a little margin for error.

In the original example posted on this thread, the swing circle would be 146 feet in radius (100' of rode plus 20' of chain plus 26' boat). This would be considered massively excessive in any popular anchorage I've ever been in - putting out that much rode would be a sure way to make every other boater in the vicinity angry.

As far as the rode length goes, it is usually just stated as 5 to 7 times the water's depth, with that length veered out to the water's edge (i.e. if using 7x scope in 10 feet of water, the 70' mark on the rode is at the water's surface, not on the deck of your boat somewhere). If you are using a danforth with less than the recommended length/weight of chain then some extra rode might help make up for the difference.

Regarding rode, more is NOT always better. If, in the process of swinging about the anchor overnight all that extra rode winds up tangled around the anchor, then the anchor is not going to remain set nor will it properly re-set if pulled loose.

Likewise, when initially dropping anchor, it is important to have slight sternway on so that the chain/rode does not just all fall in a clump on top of the anchor. Properly setting the anchor by backing down on it gently to ensure it is holding stretches your chain and rode out nice and straight and helps avoid tangling the anchor.

Most important, is to have some idea of the bottom type where you are anchoring and have the right type of anchor for the job. This is more likely the reason for having two anchors on board most boats - they are two different types to allow for use in a wider range of conditions.

- Andy

Post by **Russ** » Thu Dec 27, 2007 8:47 am

jasper wrote:Scope should be at least 5:1 and preferably 7:1 + length of boat at high tide.
At 10ft tidal depth, rode at a minimum would be perpendicular distance to bottom from deck cleat =10 + 3.5 x 5 + 26 ft = 113.5ft scope minimum.

Interesting, I've never heard of adding the boats length to the calculation. You are correct that many people fail to add the freeboard between the bow cleat and the surface of the water. On a Mac, this can be quite a bit.
The 7:1 or 8:1 ratio is optimal and recommended for severe conditions (gale force winds).
So, if he's anchoring in 10 feet of water at high tide, that's would be say 13.5 feet from bottom to cleat. Therefore 13.5 x 7 = 94.5' of rode. Plus he's got 20' of heavy chain, so I think thats' pretty good.

The failure experienced is mostly likely caused by the wrong anchor for the bottom or a 180 degree shift in angle. I doubt that's a 30# anchor. That would be one huge anchor suitable for a 50 footer and a devil to pull out.

Danforths hold like crazy in mud. Sand and grass, no so much. Also, how do you lift out a stubborn danforth that is deep in mud? You drive over it and change the angle and pull it backwards. Well, if the tide/current flip you 180 degrees, that's exactly what happens. If the Danforth is full of mud (from setting so well in the first place) it won't reset when flipped over. Also, if it's clogged with grass, it won't reset. This is why I don't sleep well in places where currents swing me 180 degrees.

Two anchors will lessen the probability of dragging too far. A forward and stern anchor will prevent the 180 degree change, but also might cause the boat to fight wind if it changes to the beam.

Anchor alarms will help you sleep. Modern GPS units are wonderful, however you can make do with simple methods. Years ago, I created a very simple mechanical anchor alarm. I bought a pull chain like they use for ceiling fans and installed it in a small plastic box with batteries attached to a buzzer. Then I tied a small piece of heavy chain for weight to a string and tossed it over the side and attaching the other end it to my pull chain on the buzzer box (allowing for some slack for swing). If the anchor pulled loose, the string would tighten and pull the switch sounding the buzzer alarm. It was remarkably simple but helped me sleep on those places where anchor dragging is a concern.

MacGregorSailors.com

MacGregorSailors.com

First time my 26M left unattended on the hook

First time my 26M left unattended on the hook

Anchoring

swing circle