Active Anchoring

[nolagal]

Originally Posted by belizesailor

Wahoo! Hand setting the anchor DURING a blow certainly qualifies as "active" ! =-O

Whenever feasible, I dive mine after initially setting, but have not dove it during....handy time to have a local fisherman nearby....especially since the only thing that can out free dive a Belizean fisherman is a FISH.

Still in BZ I assume?

No we left end of February. We're in the DR now and that fun event happened during our 6 wks in the the great unmentionable.
We'll definitely be back however as we're low on New Zealand canned butter, Dutch Cheese and Running W italian sausage. Not to even mention dis da wo wee chicken! Thankfully my mother in law taught me to make johnny cakes.

S/V Wahoo

[Andrew Troup]

Originally Posted by cwyckham

I'm curious about this. In a very linear world, the thrust will offset the wind load. However, in my experience at lower winds, the boat is sailing around the anchor and fetching up on the chain, even with all chain rode.

Does this stop happening at high wind speeds? I also find that you're often in pretty "dirty" air from surrounding hills, etc. so gusts are hitting you from different directions.

So if you're veering back and forth, even a bit, then the thrust will be at a different angle than the wind loading and you'll accentuate the swing from side to side by having the engine in gear, no?

In my experience (admittedly limited to monohulls), once the chain is hauled straight by a particularly strong and prolonged gust, the head only falls off to the side if the anchor starts to drag, even on tall-masted fin keel sloops with big rudders and small foretriangles. I'm not sure if this is universal, but I think the only thing which would make it worse would be major windage forrard, like a high bow with bulwarks on a motor sailor, perhaps.

- - -

If I had to apply engine thrust routinely, rather than only at this top end (due to shockingly poor holding, perhaps) I would make sure to apply lots of urge only when the boat was lined up with the chain.

If necessary, one person can position themselves where they can see the chain, and signal whenever it goes out of line.
This is inconvenient and uncomfortable, but so is swimming in the dark!

I haven't experimented with riding sails, as I used to use a two anchor V in bad 'sailing across the anchor' situations, but I can certainly see the appeal of a riding sail provided there's holding power to spare.

Very occasionally, (once or twice) when lying to a 'V' set, I've instead used engine power in the LULLS, to provide propwash ahead and astern across the rudder, when random puffs from unusual directions might otherwise cause the boat to circle, and the rodes to cross. An ounce of prevention beats a pound of cure in this scenario.

In one instance, the motor was an outboard, which made it easier to control the boat's attitude.

A mate of mine omitted to do this when lying to a single anchor in 40-50 knots with occasional williwaws from random quarters, and got his rode hooked around the tail of his ballast bulb (torpedo at the bottom of a fin keel).

Not a good way to be anchored.

I forget the exact story but he had to start the motor (v scary with a mixed rode passing beneath the prop - a sail drive, which makes it worse) and do a sort of 'three point turn', timed with the yawing and the gusts: at one point the rope rode was stretching like knicker elastic, and I seem to recall the boat being fired like a bolt from a crossbow at some point in the crazy evolution ...

A vectoring drive or thruster(s) would achieve a similar result, on a bigger boat.

[boatman61]

Speaking as someone who never use's his engine to bed the anchor.. if the wind pipes up I'll increase my chain by one boat length.. normal setting is depth plus 3.5 times boat length..
I'd rather natural elements like weight of anchor, boat and windage do the work for me..
Beats the hell outa ploughing up the bottom for 20 metres or so

[belizesailor]

Originally Posted by cwyckham

I'm curious about this. In a very linear world, the thrust will offset the wind load. However, in my experience at lower winds, the boat is sailing around the anchor and fetching up on the chain, even with all chain rode.

Does this stop happening at high wind speeds? I also find that you're often in pretty "dirty" air from surrounding hills, etc. so gusts are hitting you from different directions.

So if you're veering back and forth, even a bit, then the thrust will be at a different angle than the wind loading and you'll accentuate the swing from side to side by having the engine in gear, no?

Sailing at anchor is heavily dependent upon the specific boat. Its more likely with monohulls, particularly narrow fin keels (less w full keels), because you have one relatively skinny bow into the wind and the air will naturally get on one side or the other and one central point of rode attachment. A riding sail, or even a reefed and trimmed flat mizzen, helps reduce sailing at anchor. Most typical cruising cats don't sail at anchor (unless there is counter current involved and then they can do wild things).

I recently sat and watched a big honkin' mega yacht (mono, power vessel) sail at anchor....you'd think they would have some fancy thruster system to counter act that. Mutli story, acres of windage, the loads in big winds must be huge.

Nearby terrain could have a big effect and of course that's going to effect any boat. Cayos Cochinos, Honduras comes to mind...

For example, my Hobie 33 (go fast mono, 33' LOA, 7' beam, 6' fin keel, ULDB ) was not designed to sit still. She sails at anchor like she's chompping at the bit. My WildCat 35 (Cat, 35' LOA, 23' beam, 3.5' draft) sits into the wind like she's in park (except in counter current, then she does crazy stuff). So in that case (W35) its a very linear effect. True of most crusing cats I've run.

Higher winds should offset counter current effect, but may increase sailing at anchor for boats prone to it.

I've seen a number of monos get much worse in heavy conditions, slamming from one tack the other like they were trying to escape. Case in point, first time I ever anchored this W35. Actual winds were higher and from a different direction than forecast (this shift happened late at night of course). We found ourselves anchored on a newly lee shore with about 40 knots coming across open water. It got ugly, but we were set in deep sand on a trusty oversized Fortress and did not budge one inch (nope, I never even put the engines in gear beacause I knew the bottom and knew unless the rode parted we were not moving, but I did have them running just in case, and was up on anchor watch). We had a rough night, but in the dawn a nearby mono was painful to watch (not knocking monos, I own one too). We had about 3-4' short steep breaking waves by then and he was crashing from tack to tack with heavy spray coming over the deck. Amazing to me he held and did not break/chafe something. But again, it was ideal holding bottom. We bailed shortly after dawn for a protected anchorage (retrieving the Fortress from half way to China was fun in those conditions). Not sure what the mono did...going forward a handling ground tackle in his case would have been risking serious injury I think.

As I said earlier, I think this tactic is just one tool in the toolbox. I chose not to use it in the case above because I did not think it was necessaery. If the holding had been poor, I would have used it to hold position till dawn and then bailed. Come to think of it, did exactly that on a charter to Glovers Atoll a number of years ago.

On a boat that tends to sail at anchor, especially if a single screw mono, I don't think I would use this tactic (engines) beacause not exacerbating the shock loads would be very hard to do. I think I would start the engine, monitor position, and haul up and move if necessay.

[Terra Nova]

On TN I was fortunate to have been given the Maxwell windlass off a 50' sailboat when we replaced it with dual counter-rotating vertical capstan windlasses to provide ready, redundant systems. It came setup for 3/8 chain. So I have loaded 270' of 3/8" High Test chain as the primary rode. This would be appropriate for a yacht much larger than TN's 24,000 lbs. But this and a selection of reasonably heavy anchors (66Bruce, 60 Danforth, 45CQR) give me peace of mind.

I see that this approach could not work for the OP because of the very lightweight nature of the boats he operates and the corresponding weight limit of permissible ground tackle. So I have sent him a PM to apologize for my comments. And do so, here, as well.

[belizesailor]

Originally Posted by boatman61

... normal setting is depth plus 3.5 times boat length...
...

Unusual metric, what's the original/rationale?

[Andrew Troup]

Good to see a misunderstanding cleared up, and kudos for the goodwill and humility involved.

- - -

I wish strong tackle, heavy anchors and good technique were sufficient to anchor safely, but I don't believe that's always true.

It would be a shame to refrain from going to certain wonderful places, which offer no 'good' anchorages, just for lack of the soundly based confidence and painfully acquired techniques to actively make up for the difference between ideal and real.

And even in 'good' anchorages, bad things can happen, perhaps compromising holding unexpectedly, and it's not always desirable to re-anchor or go walkabout: you might have multiple lines ashore, for one thing.

[colemj]

Originally Posted by Terra Nova

I have loaded 270' of 3/8" High Test chain as the primary rode. This would be appropriate for a yacht much larger than TN's 24,000 lbs. But this and a selection of reasonably heavy anchors (66Bruce, 60 Danforth, 45CQR) give me peace of mind.

I see that this approach could not work for the OP because of the very lightweight nature of the boats he operates and the corresponding weight limit of permissible ground tackle. So I have sent him a PM to apologize for my comments. And do so, here, as well.

I don't see this as being way oversized for your boat, and is certainly within standard anchor gear size for 35-45' catamarans.

Mark

[Terra Nova]

The windage loads on a 45' cruising catamaran must be many times greater than my submarine.

[belizesailor]

Originally Posted by Terra Nova

On TN I was fortunate to have been given the Maxwell windlass off a 50' sailboat when we replaced it with dual counter-rotating vertical capstan windlasses to provide ready, redundant systems. It came setup for 3/8 chain. So I have loaded 270' of 3/8" High Test chain as the primary rode. This would be appropriate for a yacht much larger than TN's 24,000 lbs. But this and a selection of reasonably heavy anchors (66Bruce, 60 Danforth, 45CQR) give me peace of mind.

I see that this approach could not work for the OP because of the very lightweight nature of the boats he operates and the corresponding weight limit of permissible ground tackle. So I have sent him a PM to apologize for my comments. And do so, here, as well.

Appreciate the apology.

On my W35, the primary is 250' 5/16" G4 and a 20KG Bruce. Not exactly undersized for a boat that loaded only weighs a bit more than 1/2 TNs 24K. Hanging on 200' of chain + bridle in 30' of water with a clear sand bottom as I write this. (Surely someone will chime in to tell me this is all horribly wrong!)

I sleep well that way (as I have every night at anchor for the last few months...except a couple). Keep in mind that the discussion is not about average everyday anchoring conditions (or ground tackle, or technique for that matter), but strong gusty conditions and/or less than ideal anchorages.

As stated, I over simplified my original statement about 30 knots. Thirty knots doesn't worry me much in good holding ground, but that's usually where I start paying attention. In the regions where I've mostly sailed, its not the 30 knots, but what may be coming shorlty behind it that's a concern. I may be a bit more vigilant than some, but that's my call.

[belizesailor]

Originally Posted by nolagal

No we left end of February. We're in the DR now and that fun event happened during our 6 wks in the the great unmentionable.
We'll definitely be back however as we're low on New Zealand canned butter, Dutch Cheese and Running W italian sausage. Not to even mention dis da wo wee chicken! Thankfully my mother in law taught me to make johnny cakes.

S/V Wahoo

Cool.

Yes, there are just a few peculiar things that you can get in Belize that you don't find in the rest of the W Carib. Add to that list Lime Squash and Marie Sharps!

[belizesailor]

Originally Posted by belizesailor

Unusual metric, what's the original/rationale?

Meant "origin / rationale".

[Polux]

Originally Posted by belizesailor

..

"Active" anchoring I'm defining as taking action to avoid dragging. Specifically what I do is that if I suspect a strong squall is eminent I get up and start the engines. If winds increase to about 30 knots I engage the engines and use them to hold the bow into the wind and take some load off the rode.

I've also used this technique to allow the boat to drag slowly, but check the drag rate so it does not build momentum, and allow the hook to reset successfully.
....

Last summer I stayed on the protection of a small Greek Island (with more two sailboats) waiting the Meltemi to blow away. It blew for two days between 25/37K. I cannot complain: sometimes it blew for a week. Do you mean you intend to run your engines for all that time?

[Bash]

My first impulse is to insist that I don't do "active anchoring" because I get it right the first time. However, if it's gusty enough that I'm not sleeping well, I would certainly set up an anchor watch. (Might as well be wearing the foulies anyway if there's a chance you'll have to cut and run?)

Apart from putting out a bit more scope, whenever that's a good idea, my main active activity would be to check the snubber from time to time as a precaution against chaffing. But if the anchor starts to drag I'm outta there. Better to battle the gale in deep water than in the skinny stuff.

(Let me add, parenthetically, that the last time I had to do this was in the summer of 1999. One learns to avoid situations where you can't get a good night's sleep out of a single set of the hook.)

[belizesailor]

Originally Posted by Polux

Last summer I stayed on the protection of a small Greek Island (with more two sailboats) waiting the Meltemi to blow away. It blew for two days between 25/37K. I cannot complain: sometimes it blew for a week. Do you mean you intend to run your engines for all that time?

Of course not.

The intended context was local intense squalls. Sustained conditions, often more predictable, would require different tactics such as being in an appropriate anchorage, setting heavier tackle to start with, letting out more scope, secondary anchor etc.