Anchoring Problem in the Bahamas

[Bear Essentials]

Hi,

We had an issue anchoring in the Bahamas that we were hoping some of the ‘sages’ familiar with both anchoring and the Bahamas can provide some insight on.

The Facts:
We have a 42’ CARVER Super Sport Convertible. It weighs in at 23 tons, gross weight.
We have a 45lb Manson Supreme anchor (the next size larger than recommended) which is attached to a 5/16” all chain rode.
When anchoring, I use a rope bridle that is 15’ long (on each arm) with about a foot long ‘tag end’ that has a thimble, shackle and chain hook.
This has the effect of driving the chain rode down so pull is almost horizontal (a good thing) and absorbs shocks much better than chain would.
I had between 75 and 100 feet of chain out in 15 feet of water – a pretty good scope, considering the conditions.
The bottom was mud (really clung to the anchor) with a lot of seagrass.
Wind was between 10 to 15 knots. Chop was light (less than a foot) and a light current was running at a 90 degree angle from the wind. We were on the leeward side of Gun Key (near Cat Cay, south of Bimini).

The Situation:
We drug! We dragged dramatically! Not once, not twice, but for times. Each time was over 200-300 yards, and fast! At one point, I was 435 yards from the nearest boat, directly behind us. Within 35 minutes, we were within 85 yards. This is known as I took readings with a laser distance measuring scope that golfers use (find it invaluable at night!).
One issue was that we swung, a lot! I would say that the swing was up to 90 degrees, but averaged around 45 degrees.
Something else consider is that there were a number of other boats around us and none of them had the swing issue or the dragging problem.

Plea for Help!
Okay, this is where you folks come in. What did we do wrong? Was it the bridle (no one else appeared to be using one) or what? This is the first time we used this anchor and to say we were disappointed would be a complete understatement. We’ve used Deltas (about the same size) before in similar situations without moving an inch.
To say we are frustrated would be an understatement. This isn’t a lunch hook – a light anchor just thrown over the side, but a major chunk of metal!

Any assistance or insight you folks could provide would be deeply appreciated.

Thanks a lot in advance

Lee and Terry
Bear Essentials II
Dinner Key Marina
Miami, FL

[GordMay]

By leeward* side, I presume you mean the Eastern (Bank) side of Gunn Cay. Although there is lots of grass in this area, I’ve always been able to find a good patch a clean sand in which to anchor (don’t recall any mud). The Western side is a little rocky, as I recall.

* The currents there run approximately North-South, and the prevailing winds are Westerly.

[Hud3]

Lee,

An initial question: did you dive on the anchor to make sure it was set? It's hard for the anchor to punch through grass.

[imagine2frolic]

I too use that area often. I look for a patch of sand with no grass. I would use more scope in a wide open area like that, and seek out the sand. I believe the grass was the problem.

[Bear Essentials]

Hey,

Thanks for responding! Will keep the 'sand' idea in mind next time I go there.

One question that comes to mind thouugh - does anyone know what the cause of the dramatic swinging was? The other boats were swinging, a little, but I was all over the place! Could that have contributed to the problem or was it part of the problem?

To answer a questions posed earlier, no, I didn't dive on the hook. I know I should have (in retrospect) but I didn't. Will do so in the future and, if necessary, manually set it.

I was on the Eastern side of the island (leeward). Wind was blowing from west to east. The Western side of Gunn had very dramatic surf conditions (over 4'). I'm familar with the sandy protected area, but that was totally full of boats (from Bimini) and they were all playing a different RAP tune - at 30,000 megawatts. Not my idea for R&R.

Again, thanks for all your replies - Both my wife and I do apprecaite it.

Regards,

Lee and Terry
Bear Essentials II
Dinner Key Marina
Miami, FL

[Gashmore]

I question the 23 tons displacement with a 45 lb Manson. I used to sell Spades which have slightly better hold than the Manson Supreme and I would have insisted on a 66 lb Spade for that displacement. If a customer had insisted on a 44 lb I would have suggested they look elsewhere.

[onestepcsy37]

i have a 10 ton 37 foot sailboat. we anchored at that spot with my 66lb (yes, sixty six pound) bruce on about 80 feet of 3/8" bbb. nearly lost the boat. it woudn't hold anywhere. we eventually bit the hundred dollar bullet and went into cat cay where i changed it out for my 45lb cqr. we had no further anchoring problems.

some anchors work some places and some work others. i used the 66lb bruce up and down the east coast of florida/georgia and never had a single problem with it. in the bahamas it was worse than useless - it was dangerous.

i'll probably be changing out to a 55lb delta, which is pretty popular among bahamas cruisers replacing their old worn out cqr's.

for what it's worth, bahamian fishermen use danforth anchors.

and i agree that 45lb is too small for your boat, as well as 5/16" chain. if i had your boat and your windage i'd have at least a 65lb anchor and 3/8" chain. but that's just my opinion.....

[Vasco]

Your hook was probably not set properly. That area can be scoured out and if you don't drop it in a real sandy patch you'll have problems. Sometimes there's an inch or two of sand and then it's hard, this'll account for sand on the hook when you haul it up. Your boat has a lot of windage and that might account for the skating about.

[forsailbyowner]

Did you back down on it? That should give you an indication if its going to dig or skate across the grass. I back down on mine till I see the bow dip then and only then do I feel comfortable with the set.

[imagine2frolic]

If you can find your anchor while in the dinghy. Just a simple turn in a tight circle will flatten the water, so it is like glass, and easy to see.

[Talbot]

Your chain is much too small. I know that the habit in USA is for a larger anchor and smaller chain than used in UK, but anchor sizing is normally based on appropriate sized chain, and even then the recommend is to go the next size up on the anchor.

I would have expected 3/8" chain at least, plus that size anchor. I even had 3/8" chain on a much smaller boat. the larger chain has a dramatic effect on the behaviour of the boat.

[Bear Essentials]

Thank you all for your comments! I really do appreciate them and have given me a lot of food for thought. I will admit that I'm not happy with the size of chain, but it is the largest that the Maxwell RC500 windlass can use, and both the chain and windlass came with the boat. As I've just had the boat since last February, I'm reluctant to change it all out now, but it is something that I'll put at the very top of my wishlist.
I am surprised at the comments regarding the size of the anchor though. I thought I was going the safer route, going with the next larger size than what's recommended. The next size available is the 66lb monster - isn't that the same size the Navy employs for it's aircraft carriers? Geez, that's a huge chunk of metal!
Anyway, thanks again for taking the time to comment and share your thoughts - I knew you folks would provide some excellent insight!

Regards!

[Talbot]

From your spec, that doesnt seem correct, a Freedom RC500 can only do 1/4" chain.

I suspect it is the RC800 which can manage 5/16" and or 5/8" rope.

The following is an extract from Choosing a Windlass


For example;

The weight of your anchor= 45lb The weight of your anchor rode comprises 100ft of chain (at 0.74lb/ft) = 74lb Total weight of ground tackle= 120lb

Second, take the total weight of the ground tackle and multiply by a factor of three to arrive at the required windlass pulling strength. The factor of three covers the effects of windage and the speed of tidal current and includes a safety margin for unknown circumstances.

In our example the required windlass pulling strength is 360lb(3 x 120lb).

Safety guidelines suggest that the required windlass pulling strength must not exceed 1/3 of the maximum pull capacity of the windlass. Therefore, the windlass selection of should be over 1000lbs which is way beyond the capacity of yours.


Your predeccessor has specced and fitted a lunch hook, and compounded his error by fitting too small a windlass for the task. I would strongly advise that you do not overnight on the hook until you have made changes.

[Ron_Fran]

Originally Posted by Bear Essentials

I had between 75 and 100 feet of chain out in 15 feet of water – a pretty good scope, considering the conditions.

The minimum recommended scope for all chain rode is 5:1. Since you must add the height of your bow roller to the water depth, you would have had less than 5:1 with 75 feet of rode in 15 feet.

[Auspicious]

I'm having a little trouble with the 23 ton weight. The gross weight on your documentation papers has little to do with what your boat actually weighs.

Check with Carver on what your boat actually weighs. They should have a good number for the boat, to which you can add tank contents and personal effects.

If the actual weight of your boat is 15000 to 20000 lbs as I suspect, the chain and anchor you have should be sufficient, assuming penetration of the sea bottom through grass (or finding a good sandy spot as discussed above), adequate scope, and reasonable technique.

good luck, dave