Anchoring in Heavy Grass & Weed

[UFO]

So I tried to Anchor where the grass is around 2 feet long and the bottom is densely covered with Grass and Weed - No Sand patches at all.


I have a 40KG Rocna and 12mm Chain on a Lagoon 440 - After the 3rd attempt, the conditions were benign, so I decided to snorkel down as the boat was being held on the chain and the depth was only 3.5m.


The Anchor was just sitting on its side, so I got the better half to back down - Under idle it did not move at all, but with a bit of power it just skidded across the weed.


Fortunately a mooring came free and I took that, but then proceeded to watch a couple of other boats (Mono and Powerboat) try to anchor multiple times with no success.


If I had Scuba gear, I could have cleared a patch and guided it into the sand underneath as it was backed down, but that seems a bit excessive to anchor



So my question is, is there a technique or any tips for anchoring in such conditions?

[slug]

Originally Posted by UFO

So I tried to Anchor where the grass is around 2 feet long and the bottom is densely covered with Grass and Weed - No Sand patches at all.


I have a 40KG Rocna and 12mm Chain on a Lagoon 440 - After the 3rd attempt, the conditions were benign, so I decided to snorkel down as the boat was being held on the chain and the depth was only 3.5m.


The Anchor was just sitting on its side, so I got the better half to back down - Under idle it did not move at all, but with a bit of power it just skidded across the weed.


Fortunately a mooring came free and I took that, but then proceeded to watch a couple of other boats (Mono and Powerboat) try to anchor multiple times with no success.


If I had Scuba gear, I could have cleared a patch and guided it into the sand underneath as it was backed down, but that seems a bit excessive to anchor



So my question is, is there a technique or any tips for anchoring in such conditions?

Grass is photosynthetic , it needs sunlight

As a generalization ...The grass zone in “ clear water ,”. Is in the depth range of 2 meters to 15 meter

In less than 2 meter the sun is so strong it kills the grass

In depths greater than 15 meters the grass doesn’t thrive due to low light penetration

As s result you best bet is to anchor in deep water

15 meters plus

If the water is turbid you can go shallower

Gin clear and you might need to go out to 20 meters

[HankOnthewater]

Hi Ufo, there was a little while ago another thread on anchoring in seaweed. looking, looking.... here is a link:
https://www.cruisersforum.com/forums...ia-230139.html

I think as a generalisation, pointy and heavy anchors do better in weed than others not so pointy.

I don't know a special technique with a Rocna. I have the same Rocna as you have, but do not use that on weed.

[foggysail]

I had similar experience with my 80# Manson Supreme. I also had that thing pull out when we had a 180 wind shift. Of course, it also full of mud at ''pull out'' time and would not reset until I cleared the mud from it.

I have a good size Fortress FX55 new in the box stored onboard. Not sure if I want to try that as my main anchor, maybe later this new season if the government decides to allow boating again. Everything is closed around here.

[Uncle Bob]

Originally Posted by UFO

So I tried to Anchor where the grass is around 2 feet long and the bottom is densely covered with Grass and Weed - No Sand patches at all.


I have a 40KG Rocna and 12mm Chain on a Lagoon 440 - After the 3rd attempt, the conditions were benign, so I decided to snorkel down as the boat was being held on the chain and the depth was only 3.5m.


The Anchor was just sitting on its side, so I got the better half to back down - Under idle it did not move at all, but with a bit of power it just skidded across the weed.


Fortunately a mooring came free and I took that, but then proceeded to watch a couple of other boats (Mono and Powerboat) try to anchor multiple times with no success.


If I had Scuba gear, I could have cleared a patch and guided it into the sand underneath as it was backed down, but that seems a bit excessive to anchor



So my question is, is there a technique or any tips for anchoring in such conditions?

Others have suggested the marsh stockless anchor is the one for heavy weed. South Australian so reasonably local.

[iliohale]

I have an 85lb Mantus for my Lagoon 450S. My experience in anchoring in heavy weed in the San Francisco delta is to bring the boat to a dead stop. Drop about 2x depth chain and let the anchor reach bottom before backing down slowly and letting out more scope. If the anchor is moving while being lowered it just gets fouled with weed and has no chance of setting.

[boat driver]

an old-style # 75lb plow type II (hinged) dropped on line seems to dig in and work well on a 60' boat. only past suggestions with heavy grass and bottom debris is a trip line. otherwise, it may come up with an additional 100lb of sod if grass long enough.

[BlackHeron]

Originally Posted by iliohale

I have an 85lb Mantus for my Lagoon 450S. My experience in anchoring in heavy weed in the San Francisco delta is to bring the boat to a dead stop. Drop about 2x depth chain and let the anchor reach bottom before backing down slowly and letting out more scope. If the anchor is moving while being lowered it just gets fouled with weed and has no chance of setting.

We've yet to have an issue with grass with our 45lb Mantus But we cruise the East Coast and spend most of our time in turbid waters where grass isn't typically so thick. But we are full time anchoring cruisers, spending every night on the hook. Our Mantus has only once failed to set in the past two years, and when we pulled it up it was fouled with a beaver dam's worth of small sticks the size of reeds from what must have been a large waterlogged brush pile on the bottom. Digging it all out of the anchor and moving a couple hundred feet fixed that on our second try.

Any anchor can foul and fail to set if the conditions are bad enough at the bottom so that the tip of the fluke can't reach through to the bottom.

I agree that having the anchor drop cleanly and not fall backwards or, worse yet, foul itself by piling chain on top of it is a key technique here as the bottom becomes more difficult. The new-generation rollbar anchors do an excellent job of turning over quickly but nothing can help bad technique of fouling with extra chain dumped on the anchor or around it.

Even though rollbar anchors turn over and present their fluke tip to bite in, any amount of added dragging would contribute to loading up of the anchor with material, and fouling with a wad of grass if it is extremely thick and can wedge into the notch of the fluke.

We always back down at half throttle. With 46hp and a good fixed 3-blade prop if hasn't dug in and set it is going to be obvious at that point. We have a turbodiesel so I don't really like backing down with much more than half throttle as turbo temps get pretty high and that means another few minutes of idling to get them back down before being able to shut down the engine safely.

[Paul Howard]

The only anchor I have had any luck with in weed and (sometimes including) coral rubble is a fisherman type, Luke style anchor that the pointy end really digs in and holds.

[Captain Scott]

Sailing the eastern Caribbean, I have found that the shallow water has less weed. But one time on Anagada the bottom was like a sponge. I think old weed with sand over the top. In about 7 feet of water I had crew backing (and dragging anchor) at about 1/2 a knot. I got behind the plow anchor a did like an old school farmer behind his horse plowing a field. It too about 10 seconds until is bit. Then we did an extra hard back down while I watched to be sure it was doing it's thing

[SV__Grace]

FWIW I have one experience to share- I normally avoid areas thick with grass, but one time I had the time, desire, and lots of space so I gave it a try. This was a Bruce anchor so I knew that however it fell a fluke would be pointed down, so knowing that simply backing down as normal wouldn't work, I let out scope and tried jerking it quickly to break through the grass. Worked on the 4th try.

Anchoring technique can vary with anchor type and bottom. In that situation the Bruce came through, combined with changing up setting technique.

[copaco]

Not easy to store aboard, but fisherman up here(Antcosti Island),will not use anything but graplins.Pleasure craft make DIY S/S ones.

[Ken Z]

I use a forged grapnel and 25’ of chain, works good, sometimes it rips a chunk of grass out when picking it up making it heavier, a little harder to clean at times

[hamburking]

As others have said...you need a pointy anchor for those conditions...the plow type.

I'm a fan of Bruce style anchors, and they are useless in weed/grass. Same with Danforth style.

[Mike Banks]

You need to modify an anchor if this is your usual anchoring situation. I have seen several such mods--usually involving an Admiralty type anchor fitted with sharp stainless points welded on. the resting bar extended, and weighted with a link or two of heavy chain or cast on or bolted on lead where the shaft joins the curved fluke bar. An absolute BASTARD of a thing to have aboard, but will work OK in grass and weed most times.

Whatever you use needs to be sharp and heavy and unable to roll on to its side.

I have even seen an old lead-filled CQR with a couple of inches of extra length of stainless sharpened to a point. It seems once that initial penetration occurs, the anchor will set.

It is not just a matter of getting a good initial set by using the engine--it should also re-set without such engine assistance, such as when the tide or wind changes and this happens while the crew is ashore. If the anchor will not self-set with minimum effort--the anchor is not a good risk.
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