Stow Anchors

[daletournier]

I swapped out all my chain for new chain yesterday while on a mooring buoy, I can assure you I will never be moving my 30kg anchor and 80m's of chain around my boat while at sea , I respect my boat and myself to much.

[charliehows]

In general I'd say hulls constructed in the modern (ie post fibreglass) era are designed to carry a substantially weighty engine amidships, a number of substantially heavy fluid tanks distributed around the hull and a substantially heavy anchor and chain in the foredeck area. Ive got 3 up forward and quite a weight of chain, for example. I've never considered it necessary to the boats performance to start shuffling big chunks of weight around at random, nor would I expect to. Of course, my argument lacks the faux-old-salty grammatical flourish of previous contributors so I wouldnt expect to be taken seriously...

[Mike OReilly]

Originally Posted by charliehows

In general I'd say hulls constructed in the modern (ie post fibreglass) era are designed to carry a substantially weighty engine amidships, a number of substantially heavy fluid tanks distributed around the hull and a substantially heavy anchor and chain in the foredeck area. Ive got 3 up forward and quite a weight of chain, for example. I've never considered it necessary to the boats performance to start shuffling big chunks of weight around at random, nor would I expect to. Of course, my argument lacks the faux-old-salty grammatical flourish of previous contributors so I wouldnt expect to be taken seriously...

Your boat, like mine, isn’t easily affected by relative weights on the outer ends. My boat does not even notice "a few people's mass sitting on the pointy end”. I’ve even checked by unloading and loading all anchor gear and measuring what it does to the water line. Nada.

But some boats are clearly more sensitive to weight distribution, so I can see that if you’re in one of these kinds of boats, it could make sense to do as Alan does. But it’s not a common practice in my experience.

[a64pilot]

Originally Posted by Mike OReilly

Never have removed them for passage. Don’t know anyone who does.



I suppose it depends on your boat. Unless we’re talking a pretty high performance boat, I really doubt most cruisers would notice much difference. If yours is one of these, where bow/stern weight really makes a measurable difference, then I suppose it’s a good idea. But that’s not the kind of boats I’ve owned.

I used to worry about all the weight causing hobby horsing or have her down by the bow, but I put all four of us on the bow one day to see, I could tell no drop in the bow looking at the waterline at all. A very narrow fine bow hull may be different of course.
She has never hobby horsed either, but I did learn the hard way to be double sure the anchor is well secured as we were almost knocked down once and the anchor came loose and came around and slammed pointy end first into the hull, made such a loud noise I was sure a chainplate had broken.
Having to run to the bow and pull that 25 kg Rocna up by hand and redefine it in those winds and waves wasn’t easy either.
Now I tie the anchor roll bar to the pulpit rails.

[CassidyNZ]

Originally Posted by a64pilot

I could tell no drop in the bow looking at the waterline at all. A very narrow fine bow hull may be different of course.

See, right there is my argument. If my boat is sitting stationary fully loaded and is floating to the waterline, my apparently limited knowledge says that this is the condition that the naval architect intended.

If one loads the bow until it dips of course that’s different. But dragging 160kgs of chain from the anchor locker and stowing it under the saloon dining table just ain’t going to happen I would rather pump out the 650kgs of water from the tank under the V-berth

[Alan Mighty]

Ah! Sheep.

Wonderful beasts that should be celebrated. Very stable barge-type platform supported by 4 legs.

So sheep are very aware of transverse stability, both static trim and dynamic stability. No sheep wants to roll transversely. So sheep are quite aware of GM and GZ.

Sheep are natural at dynamic roll stability. Put them on a ship that heels and, as long as they are not in pens and so are mobile, they're perfect rail meat. They'll always head to the high side.

Sheep seem to be less aware of the longitudinal aspect. When they are young, they enjoy pitching, even to the extent of deliberate hobby-horsing. Happens at spring time. Older sheep are quite focused on longitudinal trim, especially when stationary. You'll see them orient themselves stern-to-windward. That keeps them in stable posture, with scent of anything coming from astern borne on the wind and their eyes tracking anything coming from ahead.

One big problem is that sheep confuse trim with dynamic longitudinal stability. They do have strong hindquarters. After all, when a ram tups a ewe, the mass of a goodly proportion of the ram is suddenly imposed on the ewe's hindquarters.

(side note: take care pronouncing that word "tup". You can frighten people from Long White Cloud land, some of whom get accused of tupping sheep when all they did is tip them).

Tipping sheep is a common practice, by which I mean a particular move in which you grab a sheep - these days many of which are just as massive as a healthy adult male human - and simultaneously lift its forequarters and turn the sheep on its back. Then you hold the sheep, stern down and bow up, and that's the perfect position for what Kevin Sarre called the Tally Hi method - Mr Sarre, a top-gun was much revered in Big Brown Land for his skill and the Tally-Hi method. It was THE method for many years. Here's a quick reminder for you: https://www.wikihow.com/Shear-a-Sheep Look for the position in Part 2 Step 1.

Tally Hi is out of favour now, because blokes (Long Pigs) from Long White Cloud Land introduced wide combs to the Big Brown Land. The wide combs reduced the number of strokes and sped up shearing. Mr Sarre had sped up shearing by about 30 seconds with his Tally Hi method. Used to be that a good team of Tally Hi shearers could do synchronised shearing - a sight to behold. The Long Pigs (the ones whom some say get tempted to tup a ewe instead of tipping it) cut off another 30 seconds, putting narrow comb shears in the dustbin of history.

Back to longitudinal stability ...

In a seaway, the meadow is not flat. It's dynamic and much of the time it has a rhythm. If you're sailing in a seaway, pitching is almost unavoidable. Doesn't matter how nicely trimmed your vessel is when it sits in flat water such as in a marina berth.

You do best if your vessel is not pitching at a frequency which is the same at the frequency of the waves and swell you meet.

If the "natural" frequency of pitching of your vessel is the same as (or resonates with) the frequency of meeting waves, then your vessel will "hobby horse".

What's a hobby horse? The key word "hobby" comes from the name for a breed of horse that was much used by the natives of the land we now call Britain. Those native apparently had small robust horses that at least some of them called hobyn. And they used those hobyn equines as their steeds in light cavalry, mounted infantry, and as pack carries when confronting the Romans, the Anglo-Saxons, and their descendants. Small short horses - probably arrived in the British Isles before Doggerland got wet - pitched more than the bigger steeds used by the later invaders.

Why is hobby horsing important?

Here's a quote for you. You'll find its source on books.google.com if you but search for it (I've enclosed it in quotation marks so you can cut and paste it into the search window of books.google.com):

"Going to windward at a particular speed in a certain wave length, pitching, or hobby horsing can become quite severe. Much driving force is lost from the sails when hobby-horsing, which combined with the added hull resistance, kills performance".

If trim doesn't matter, what does?

A metric called the pitching mass of inertia is the key. Also the metric of the natural frequency of pitching of your boat.

Let's consider the second of those metrics first. Your boat exists in several different states. It can be fully loaded, what's called the departure state, with provisions, gear, fuel, crew, and the crew's possessions. At the other end of the spectrum is the arrival state, when fuel and provisions are close to exhausted and you're in your target port. In between departure and arrival state, you've that spectrum of load conditions. But if you know what the natural pitch frequency of departure state is, and arrival state, then you know the range of pitch frequencies. And all you need do is (1) have the boat in still water at a load state; (2) start the boat pitching by someone pulling/pushing on one end; and (3) time the pitches.

Now here's the BIG THING: you can control (within limits) your vessel's natural pitch frequency by your stowing practice.

And to do that, you need a handle on the Pitching Mass of Inertia. In an ideal world, you might calculate the PMI of each item of gear, provisions, and the persons on board. One easy way is to find the Centre of Gravity of your vessel. Then measure the distance from the CG to the centre of mass of, say, your best bower. For that item, it's PMI = mass x (distance from the CG)^2

- where ^2 means "square of". So PMI varies with the square of distance from the CG.

Side note: if you watch your boat pitching in a still water harbour, you will likely see it pitch about its CG or v close to that. But when your under sail (dynamic, i.e. moving and with sail hoisted and providing driving force), the pivot about which your vessel pitches will usually be aft of the CG. On my Led Myne, I reckon the pitch point when sailing at 6 - 7 knots is about 0.25 x LWL forward from the transom. Which is a bit aft of the CG. But let's not complicat things muchly.

I'm not advocating that you calculate the PMI of every item on board your vessel. That's silly and impractical. But you can consider the mobile items (which vary from boat to boat because of design and set-up limitations; on my Led Myne, I can easily move my best and small bowers from the bow to positions on deck and amidships; I can haul the anchor chain - or a big proportion of it - aft as the designer intended so it sits just forward of the mast; and of course I can choose to load heavy provisions - anything that would fail a float test - low and near the CG while loading anything that would pass a float test higher and closer to the ends of the hull).

Then you can consider where to stow those heavy mobile items (which, I'll say again, for my Led Myne include two bow anchors, a stern anchor, most of the chain rode for the best bower, and of course provisions and gear).

Calculate the PMI.

See which ones make a significant difference. Try it in still water in your marina. See what happens to the "natural" pitch frequency if you stow the mobile heavy things away from the ends of the boat.

Then consider what the frequency of meeting the waves might be in different sea states.

Your aim is to avoid resonance, avoid a situation in which your vessel would naturally pitch at the same frequency as the waves.

Your other aim is to keep the ends of the boat light, so she rises to waves and does not bury either the bow (playing submarine temporarily) and lifts to a passing sea.

Then you can graduate to being a goat.

You don't want to be a grumpy old Billy Goat. In a goat herd, the Billy Goat might be the alpha male.

But the real boss is the Queen Goat. She's the one that leads the herd to pasture, the one that teaches the young'uns which plants not to eat, which ones are good kai kai.

And she leads them up hill and mountains. Just like a good racer leads the fleet in ocean swells and coastal chop (two sea state conditions with very different wave frequencies and so call for different stowing).

Or how a good cruising skipper manages the stowing of the boat (and doesn't bleat bleat like a sheep sheep about how much respect he or she has for his body and the perfection of the static trim of his boat so s/he is not going to consider a sophisticated stowage plan).

Grumpy old Billy Goat is just as likely to want to smash his head into a mountainous wave than to climb over it fast and smoothly.

[Jim Cate]

wow! What a lot of words, and some clever allegories to boot. I'm kinda overwhelmed, Alan!

So, I'll but say that there are other factors in the development of the dread hobbyhorse maneuver beyond longitudinal weight distribution. Things like hull shape, as in rocker, and waterline plane symmetry. I'm not a NA by any means, but have noted the difference in tendency to HH between various boats that I have sailed. Our current ride has almost zero rocker and somewhat asymmetrical waterlines. The dynamic damping this provides means that she does not exhibit HH to a noticeable degree, even with the anchor and chain in their active position forward. Would it be even better if I moved all that stuff aft? Probably. Would it be to a degree that I'd notice or be able to measure? Not so sure about that.

On the other hand, when we have arrived somewhere after a passage, there is no required exercise of moving all that stuff back to where it becomes useful. I undo any lashings, step on the down button and off she goes. And if that maneuver should be required in a hurry... and we can invent any number of scenarios where that is desirable, I'd be damn glad everything was ready to go.

Really, Alan, all this discussion was stimulated by your insinuation that folks who didn't stow their anchor aft didn't care about sailing performance. Can't speak for others, but I do care about sailing performance, but I have to temper that care with thoughts of safety and practicality which are also aspects of seamanship. And if I REALLY cared about sailing performance I'd have to remove all our worldly possessions from the boat, sail with only a few liters of water and diesel, reduce to near nothing the spares that I carry and then choose 8 or maybe 6 mm G70 chain and an aluminium anchor. Now THAT would improve sailing performance! But I ain't gonna...

And I heard that in Wales the sheep had shorter legs on one side so they could stand straight in the pastures. Meant that they could only walk in one direction, for if they gybed and reversed course they exceeded their AVS and rolled down the hill to the bottom where they were in danger of tupping.

Jim

[steve77]

Like some others have said, our boat does not notice if our 85 lb anchor is on the bow or not. With a 56,000 pound boat, it is not a weight distribution issue.

However, the Mantus has a very large (wide) fluke area. When burying the bow there are huge forces applied which I wanted to avoid. The same properties that make it great for keeping us secure when on the hook are a disadvantage in heavy seas. I would think that other modern anchors would be the same.

When we crossed the Atlantic we removed the Mantus, disassembled it and stowed it at the bottom of the cockpit locker. For those unfamiliar, our anchor disassembles by removing six bolts, which separate the anchor into three pieces. We also have a 65 lb CQR but I left it on the bow with extra lashings. I really don't have another place to stow it that I think is secure.

When we cross back to the Caribbean, I will do the same thing.

Cheers!

Steve

[El Pinguino]

If I truly cared about sailing performance I would have a very long and skinny boat with an in mast furling laminated mainsail and I would sleep in a pipe cot. I would also use the pages of the novel I was reading as bog paper... to cut down on weight.

I obviously don't care that much .... my boat is short and fat and I carry paper charts for half the planet.....

My anchor stays up the front... it is well secured ... a bolt over the top or through the shank is the best way to do that... and the spurling pipe should be plugged with a bit hessian and mortar..

To any one who thinks sending their bower anchor below is a good idea I suggest that they remember the 'Teddy'... thats how she was lost.

[GordMay]

Originally Posted by El Pinguino

... To any one who thinks sending their bower anchor below is a good idea I suggest that they remember the 'Teddy'... thats how she was lost.

Tell us a little more. "Teddy" isn't lighting my lamp.

[El Pinguino]

Originally Posted by GordMay

Tell us a little more. "Teddy" isn't lighting my lamp.

Ah , you young pups.....

'Teddy' was belongum Erling Tambs... he later owned 'Sandefjord'...

Missed stays in light airs after having left Auckland/Kawau for Brisbane... drifted ashore and was lost... had sent the bower below...

https://waitematawoodys.com/2015/04/...ailing-sunday/

Hope my memory serves..... 40 years or more since I read the book.

Saw 'Sandefjord' in Cape Town in the late 60's after she completed a circumnavigation under the ZA flag and again in Tonsberg 20 years ago when she was back under the Norwegian flag and owned by a nice Norwegian lady.

[GordMay]

"Teddy": Ah, a local story, from before I was born. Thanks for the link.

[Fore and Aft]

Gord May you surprise me I had you pegged as an old salt. I got the Teddy reference straight away. I must admit I have read a lot of sailing books including Skenes.
Alan Mighty I understand what you are saying but I am no fancy sailor and every time my boy and I (150kg) are on the bow relaxing while sailing the boat does not suddenly start hobby horsing or going wild she just keeps plodding along. Is this “keep the weight out of the ends” another thing that has gone along with the sextant?
I just wonder, as a lot of modern boats I now survey have generators in the bow, water tanks well forward, the same with the aft end. All those extras people do not want in their living space so surely modern designers have allowed for it in the aft ends?
Maybe I have missed the point Alan, I love Sailing I am just not that into it.
Cheers

[El Pinguino]

Originally Posted by GordMay

"Teddy": Ah, a local story, from before I was born. Thanks for the link.

Erling Tambs, Teddy, and Sandefjord were hardly 'local ' in anybody's water... they are part of sailing history... unless one restricts oneself to the anglophone world...

[Leo Ticheli]

The bilge in our Sun Odyssey 40 is slightly smaller than a shoe box; I don't believe it's possible to stuff my 55lb Mantus anchor into it.

I suppose I'll have to carry on bumbling along with it firmly lashed to the bow roller, but thanks anyway.

Fair winds,
Leo