Is my chain undersized?

Marine Trader 44. I live on the hook, so first thing I did was buy a big anchor (85lb Mantus). Boat came with 5/16 chain. Half the chain was rusted junk. I have about 75-100ft that is good, which has been enough because I'm in South Florida and most anchorages are 10ft or less. However I would feel better having at least 150ft (if not 200).

If I buy new chain, the debate is 5/16 bbb vs. spend $400 on new gypsy and upgrade to 3/8 bbb.

If I was a weekend warrior or marina guy, sticking with 5/16 would be a no brainer. But what are your opinions considering my situation?

Does your gypsy accept 5/16" g43? If it does, that's what I'd use. It's plenty strong for the boat and won't add weight over what you have now.

An 85 lb Mantus is a beast of an anchor and a good choice. But extrapolating from various anchor tests that anchor should hold 5.000 lbs or more in good bottom conditions with 6:1 scope. Your current chain- 5/16 BBB has a maximum working load (MWL) of 1,900 lbs and a breaking strength of 7.600 lbd which is way too low IMO.

5/16 G43 chain has a MWL of 3,900 lbs still too low and 3/8 BBB has a MWL of 2,650 lbs also too low.

Since this is a heavy duty anchor that presumably could carry you through near hurricane strength winds or above I would go with 3/8 G43 chain which has a MWL of 5,400 lbs.

You spent a bunch on a quaility heavy anchor, now complete the system by matching it with heavy chain. Also look at your snubber and chafe protection. I would use a pair of 3/4" nylon three strand rope for snubbers.

David

In my book, the working load of 5/16 g43 is plenty when you consider the boat. The anchor may be able to hold more, but it would be very hard to get that boat to put 3900 lbs of load on the chain, especially with a good snubber.

The question should probably be stated as what tensional rating should I use.
So I agree w rslifkin.

Interesting that everybody here seems to be recommending HT chain. When I inquired to someone at Miami Cordage about HT chain, he said he "wouldn't touch that stuff with a 10 ft pole". And didnt want to give a reason.

I also notice that most commenters are recommending HT to save weight. And nobody thinks I would want to step up to 3/8 chain FOR the weight. Wouldn't heavier chain be beneficial for holding? Seems unnecessary to worry about carrying an extra 75-100bs on a boat this size.

Heavier chain is definitely better for holding and I agree that the extra weight should not be a problem for you. I can’t imagine and have never heard a reason not to use HT chain. 3/8 BBB has too low a working load limit, so either 3/8 HT or something larger in BBB. The biggest deal though is going to be finding what works in your windlass. To set everything up right you may need to change the Gypsy to work with a properly sized chain.

Ken

5/16 would be fine. You’re not going to break the chain. If your windlass would accept HT I would go with that just for peace of mind.
Worry about anchor chain breaking is for folks sitting on their couches, not for folks using their boats.

ERTF said:

I have about 75-100ft that is good,

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How much is bad? What is your total length? better to have the correct amount of GOOD chain than 50% of crap rusted stuff.

I would sleep better with 3/8" chain. That said, the important thing to understand is shock absorption. While I never heard of anchor chain in good condition parting, I have seen some too small chain stretch and deform. Had to do with anchor in shipwreck and only chain between it and the boat, no shock absorption.

With your stout anchor that will likely not budge, you will want probably several options on snubber based on conditions. The idea is to eliminate shock load so than the chain only sees pulling force. For what you plan to do, I would consider maybe 2 snubbers. One that is smaller with more stretch to slow the boat down and a second one of larger size with limited stretch to to make the final stop. Maybe in that configuration 5/16" chain might be ok.

But, there's no kill like overkill!

Ted

One thing to bear in mind with hi test chain is once it gets regalvanised, its no longer hi test.

I bought 5/16 BBB chain for my windlass and 40 ft boat.

I figured that I'll never get up near the working load except maybe in very very high winds.

If I have to ride through a hurricane and I get beyond the working load, and it deforms ...okay but what's the chances of my anchor even holding up to the breaking load of 7600 lb?

If I do survive all that, I'll just replace the chain.

To be clear, I've lived on the boat 18 months already. I run 1/2" dual snubber for cushion, but have a thicker one should I feel I need it. Also, If there's a hurricane I'm going to the mangroves. The only reason I am debating this is because I feel my chain is short and figure I should buy new chain regardless. And I enjoy the ease of mind of being able to drop anchor confidently in a large waterway and not worry about what happens when the wind shifts 180.

I have a Lofrans Tigres windlass. They appear to make different size gypsy's for bbb and ht. I'm very hesitant to buy 5/16 HT chain, because I assume my windlass is bbb and they certainly make 2 different 5/16 gypsy's for a reason. Regardless, if I'm buying a new gypsy, then it's a no brainer to move up to 3/8. And defender appears to sell HT for less than bbb, so i guess the debate is 5/16 bbb vs 3/8 ht. There's really no logical middle ground.

I'd get a foot of 5/16" HT and see if it fits your current gypsy. Some windlasses use the same gypsy for both types of 5/16", some have different ones.

rslifkin said:

I'd get a foot of 5/16" HT and see if it fits your current gypsy. Some windlasses use the same gypsy for both types of 5/16", some have different ones.

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My windlass already jams constantly without somebody tapping the chain with a bar just right on retrieval (especially under any type of tension), so I'm particularly hesitant to buy an out of spec chain for it. I just doubt I can get a real confident confirmation with 18". But maybe I will contact manufacturer to see if they are the same gypsy with different names.

Regarding load: a 44' trawler let's say has a beam and air draft of 15' so 225' frontal area. 1900 lbs constant load will be reached at a bit under 50 knots wind. Surge loads maybe double. That's a squall not a hurricane.

Regarding the gypsy: sounds to me like you already have the wrong one. Or the chain or gypsy are badly stretched/worn. It shouldn't act as you describe. Could it be that your gypsy is actually intended for HT and someone fitted BBB unknowingly?

That's if your boat is 15 feet square in the front, mine is pointed at the bow and rounded topsides....that changes things significantly.

I have found most internet guesses wildly inaccurate for calculating load forces on a boat.

DDW said:

Regarding load: a 44' trawler let's say has a beam and air draft of 15' so 225' frontal area. 1900 lbs constant load will be reached at a bit under 50 knots wind. Surge loads maybe double. That's a squall not a hurricane.

Regarding the gypsy: sounds to me like you already have the wrong one. Or the chain or gypsy are badly stretched/worn. It shouldn't act as you describe. Could it be that your gypsy is actually intended for HT and someone fitted BBB unknowingly?

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I'm thinking the same about the current chain / gypsy match. It's already not right, so getting new of the same and keeping the gypsy is definitely the wrong answer.

As far as load, 1900 lbs seems high in 50 kts of wind from some of the measurements I've seen done. Don't forget to account for wind speed being lower closer to water level. So 50 kts at flybridge height might only be 40 kts 3 feet off the water, meaning the force on the hull is significantly lower.

But in general, I agree that 5/16" BBB is a bit light for this application.

I have been using 5/16 BBB chain for the last 20,000 miles of East coast ICW cruising and have been through numerous gusty thunderstorms and the chain is not deformed .

I'm try and NOT anchor out if the weather is predicted to be e severe....but as they say, I have been caught occasionally.

If you are the type to even dare hurricanes at anchor... sure go heavy. If you are like me and are well prepared for 95% of the time.....5/16 BBB chain is probably more than adequate..

I would rather have some extra chain to feed out as snubbers fail/chafe, rather than get to the end of a heavier chain with no extra and have shock loading because I no longer have a few more feet of lighter chain to feed out.

The trouble with these discussions as we all in our minds eye see different scenarios, thus different needs and threats.

rslifkin said:

I'd get a foot of 5/16" HT and see if it fits your current gypsy. Some windlasses use the same gypsy for both types of 5/16", some have different ones.

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Better yet, take the wildcat off and take it with you when you shop.

At Seattle Chain, they used to insist that the wildcat needs to be brought in to purchase chain. They made sure 10' of chain would feed through the wildcat without jamming. There are no returns of cut chain.

I have 400' of 5/16" HT chain with a 66# Genuine Bruce and a Tigress 1200.

Ok new info!

Found 5/16HT stamped on my gypsy. Always just assumed chain was BBB...looked on side of link "G3". So the previous owner put proof chain on the windlass

Ventana said:

5/16 would be fine. You’re not going to break the chain. If your windlass would accept HT I would go with that just for peace of mind.
Worry about anchor chain breaking is for folks sitting on their couches, not for folks using their boats.

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I agre. 5/16" HT is ideal.

psneeld said:

I have found most internet guesses wildly inaccurate for calculating load forces on a boat.

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I am living full-time on the hook on a 44 ft Sun deck cruiser that weighs 44000 lb. I have a 105 lb mantus that is connected with 5/16 HT chain. I have been in 50 mph sustained winds and have not really been concerned about the strength of the chain the anchor has held every time and the chain has held every time with no apparent ill effects

motion30 said:

I am living full-time on the hook on a 44 ft Sun deck cruiser that weighs 44000 lb. I have a 105 lb mantus

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Haha we have very similar rigs. I feel a tinge of jealousy that you have a 105lb Mantus because that's actually the size I would have gotten, except local dealer didnt have it in stock when I bought my boat.

Interesting your boat weighs so much more. Mine is supposed to be only about 25000lbs displacement weight. Although it is really just a 40 with a 4ft cockpit.

ERTF said:

Haha we have very similar rigs. I feel a tinge of jealousy that you have a 105lb Mantus because that's actually the size I would have gotten, except local dealer didnt have it in stock when I bought my boat.

Interesting your boat weighs so much more. Mine is supposed to be only about 25000lbs displacement weight. Although it is really just a 40 with a 4ft cockpit.

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44000 lb is the advertised weight, to be honest I've never had it on a scale so who knows. I do have an 85lb mantus as a second anchor and I have no doubt it would hold absolutely far. Still bigger than recommended

Yeah I really have no fear of my anchor dragging. It's other boats anchors that scare me, so I make my own anchorages...and avoid the community spots at all costs.

The other day I made the mistake of dropping hook in a community spot. Purposely anchored as far away from other boats as possible. Then a storm kicks up in evening and an older 50ft MY is fumbling around trying to reset and not sticking. So then he repositions to try and drop just directly upwind of my bow, even though there was wide open space behind me or to starboard. Had to go out and yell at him. Next day in the light I saw them pull up their tiny anchor arm over arm BY HAND.

I got out of there.

Anchor Chain

3/8"

For weight/catenary effect.

You will need a new gypsy.

Just this week I replaced my anchor rode. Admittedly a smaller boat than many here but I will throw in my 2 cents. I prefer a combination chain/nylon rode over all chain using 8 plait nylon. I'm sure I'm in the minority here but here is my reasoning.....

- If you have a properly sized well-designed anchor and properly set with sufficient scope, you don't need a lot of chain to increase holding strength.
- In very high winds, your chain is likely bar straight and not helping your holding power.
- The stretch of nylon rope improves your holding power by not jerking the anchor free. Additionally, you don't need to deal with snubbers and it's easy to add or subtract scope as needed.
- It's very dependent on where you are anchoring, but unless you are overly concerned about abrasion on the bottom (as in coral) a boat length or 2 of chain and the rest nylon should be fine. Also less weight to carry around.

My new rode is 316L HT stainless chain (to the avoid galvanic problems with galvanized chain and a stainless anchor) spliced to a few hundred feet of nylon. Yes the chain is very expensive but it is also very slippery so mud doesn't cling as much and it goes through the gypsy and into the locker smooth as butter.

There seems to be confusion about BBB vs HT. As far as I know BBB refers to the dimension of the links. You can get BBB chain in various strengths, proof, HT, etc. Might as well get the strongest rating unless you are purposely adding more weight by using a weaker grade but larger size.