Chain length Caribbean & tropical waters on a 35ft cat??

[donradcliffe]

Originally Posted by Franziska

Hi,



Do we need to go all chain by your experience? If yes, how much?
I am aware of the issue with sharp coral, but would think that normally you have say 20m (65ft) of chain out to get enough catenary and than have a rode which is floating above the coral heads.

This is specifically a question to folks with tropical experience on non luxury budgets.

As always, thanks to let me use your know-how.

Franziska

Rode doesn't float, and if it can catch on a rock or coral it will. Think of what happens when there is no wind or current. After almost losing the boat at Pitcairn with 20 meters of chain, I went to all chain.

[Stu Jackson]

I've posted this tons of times before:


Steve’s Anchoring 101

The Rocna. All 20kg of it with 100ft of chain. The rest of the world can debate all they like. When I pull into a place like Bodega Bay at midnight and the fog is so thick I can't see the jetty 50 feet away to make an entrance, I drop my hook in the rolling ocean swells with the surf crashing (Foster says it's like staying in a cheap Best Western beside the highway), and I sleep. And in the morning I have a windlass to pull the beast up and I wouldn't trade it for anything. (I also wouldn't add more chain - this works perfectly in 25 to 30 feet of water - you let all the chain out and you tie off nylon at the preferred scope and don't bother with snubbers and chain hooks and all that stuff...)

[Cheechako]

To minimise I would want 100-120 ft of chain with nylon spliced behind that. My preference is 150-200 ft, all chain. But the 120 ft or so will get you done for probably 90% of anchoring in the E. Caribe. If you anchor in 15-20 feet of water that gives you 5:1 scope or more.

Here's the issue with short chain and rope behind it: If you are retrieving the anchor, you first have to hand the rope in and fish it like a wet noodle though the hawse pipe. then you can start using the windlass and chain.
If the wind is blowing and there is sea chop, this can be quite difficult and hard on the back and hands. If you have adequate chain, you simply keep cranking the windlass.

[zstine]

being weight conscious, we carried 125ft of chain and then 150ft nylon for 275ft rode. We were once anchored in 50ft and had a 40knt blow go through. I had basically everything out and luckily we didn't drag, but I wish we had had 200-250ft of nylon.

[belizesailor]

Since you said you were weight concious also keep in mind that different grades or chain have different weights. What does your windlass gypsy accept?

[boatman61]

Originally Posted by belizesailor

Since you said you were weight concious also keep in mind that different grades or chain have different weights. What does your windlass gypsy accept?

She changed it to 8mm from 10mm.

[garychurch]

I spent 18 months cruising the Caribbean as well as time off and on over a number of years in the Bahamas.

The Bahamas are shallow and sandy with good holding (except for cuts when the current can scour a channel to leave very little sand bottom if at all) with an average anchoring depth of 6-10 feet. Minimalist rope anchor rode with some anchor snd anchor chain would do well. A rode of 100 feet would probably do you well in almost all locations and conditions.

Many locations in both the Bahamas and the Caribbean have mooring balls although you don’t know how well they are maintained. Some are well maintained by government offices (Martinique) and some by volunteer organizations (St Lucia at y to he Pton’s) and some privately (Bequia).

The Caribbean has volcanic islands and I would recommend 250’ minimum of chain anchor rode and a very robust anchor (oversized modern design). While some locations are shallow (less the 25’) with sandy or shell bottoms, many more can be 40 to 75 feet with other than sandy bottoms. Also, the sea floor can fall away quite rapidly away from the beach to a thousand feet or more a few hundreds of feet from shore.

Anchoring in the Caribbean is not hard but there is a lot more to consider than the Bahamas. Winds, waves, currents, tides, anchor depth, bottom type and bottom profile.

Good luck.

[rslifkin]

Originally Posted by Cheechako

Here's the issue with short chain and rope behind it: If you are retrieving the anchor, you first have to hand the rope in and fish it like a wet noodle though the hawse pipe. then you can start using the windlass and chain.
If the wind is blowing and there is sea chop, this can be quite difficult and hard on the back and hands. If you have adequate chain, you simply keep cranking the windlass.

If you're going to regularly use a mixed rode, you choose a windlass that can handle the combo on the gypsy. As an example, my Maxwell HRC10-8 pulls rope just fine on the gypsy. When you get to the splice, let off the button for a second and let the splice coast over the gypsy. At that point it grabs the chain and you continue. It'll handle the splice at full speed going out, but if you bring it over at full speed coming in, sometimes it'll have trouble grabbing the chain (due to the splice being a little bulky and stiff compared to the rest of the rode).


In general, if you've got 150 of chain and then rope, you're fine to 5:1 scope on all chain in 25 feet (assuming 5 feet from roller to water). Realistically, you could put out 5:1 in 30 feet, as you'd only have 25 feet of rope out, so it would never get within 10 feet of the bottom even hanging straight down. But that would be about the limit in waters where coral is a concern.



The time the combo becomes an issue is if you're going somewhere that you have to deal with coral and deep water at the same time. If it's only 1 or the other, it's easy. But both together requires a lot of chain.

[Franziska]

@All

Thanks, once more. Good input.

@Chickachoo

Our new windlass handles both rope and chain.

We tend to pile it on the tramp and than store it away once underway.

For 30 years I did pull the anchor up on all my boats without windlass, but we are not getting younger, so a windlass is nice to have, even though I reckon I will use it only until the bulk of the chain is onboard and than pull the rest up by hand, much quicker, it's a manual windlass (by expressive choice!).

Originally Posted by Cheechako

To minimise I would want 100-120 ft of chain with nylon spliced behind that. My preference is 150-200 ft, all chain. But the 120 ft or so will get you done for probably 90% of anchoring in the E. Caribe. If you anchor in 15-20 feet of water that gives you 5:1 scope or more.

Here's the issue with short chain and rope behind it: If you are retrieving the anchor, you first have to hand the rope in and fish it like a wet noodle though the hawse pipe. then you can start using the windlass and chain.
If the wind is blowing and there is sea chop, this can be quite difficult and hard on the back and hands. If you have adequate chain, you simply keep cranking the windlass.

[Pete7]

Franziska, can you locate a 6mm gypsy for that windlass?

Now at this point you are probably think I am barking mad, but it is an idea I picked up recently from someone with a sister yacht to ours.

Your cat weighs 4.2T loaded according to this website: Mira 35' ocean cruiser by Woods Designs

Now the minimum breaking load (MBL) of 6mm G40 or G43 is about 2000 kgs. That's over the safe working load which tends to be 1/4 of the MBL. The maximum holding for a 15kg anchor could be 2000 kgs in ideal conditions. However, watching Steve's anchoring YT channel I would suggest an average 600-800 kgs is more likely. The load on my mono hull in 50 knots of wind is likely also in the 600 800 kg range. Your cat might be a bit more. Finally do a calculation of 6mm chain at 0.8kg per m against 8mm at 1.4kg and the weight quickly mounts up making 60m of 6mm very tempting, if you can find a 6mm gypsy.

That should give you something to ponder over

Pete

[singlespeed]

Eleven years in the EC and a couple of trips through the Bahamas, Turks & Caicos, the Dominican Republic and Puerto Rico and I never found need for more than 180' of chain on a 42' cat. The entire EC and semi-Tropical Atlantic islands are increasingly regulating where you can anchor to prevent further damage to the grass and coral on the sea floor. Legal anchorages are seldom more than 40' deep, most in the 10' to 30' range. While there are exceptions, the variety of anchorages available usually means just a short sail to another anchorage with a more suitable depth. Except for the Bahamas and the Turks & Caicos, coral heads in the legal anchorages never seemed to be an issue, most likely due to years of anchors being dropped on them.

[rgleason]

@Pete7
Note that the Safety Factor that is normally used is 3 (or 1/3) instead of 1/4! Don't know if it changes anything though.
6mm= just short of 1/4"
8mm= 5/16"
From Anchoring 32' Sloop

1/4" HT Peerless ACCO G43 Chain has a WLL=2600 lb x 3 MBS=7,800 lb
5/8" HT Peerless ACC) G43 Chain has a WLL= 3900 lb x 3 MBS=11,700 lb

High Tensile Strength Carbon G43 is also known as "Towing Chain" has very heavy hot dipped galvanizing. Working load limit (WLL) is generally 1/3 the Minimum Breaking Strength (MBS) for G43 chain, instead of 1/4 or 1/5 for other classes of chain. Beyond the WLL the chain may deform.

Modifying your:

"maximum holding for a 15kg (33lbs) anchor could be 2000 kgs (4400 lbs) in ideal conditions. However, watching Steve's anchoring YT channel I would suggest an average 600-800 kgs (1322-1763 lbs) is more likely. The load on my mono hull in 50 knots of wind is likely also in the 600 800 kg (1322-1763 lbs) range."

"Finally do a calculation of 6mm chain at 0.8kg per m (.73 lbs/ft) against 8mm at 1.4kg (1.03lbs/ft) and the weight quickly mounts up making 60m of 6mm very tempting, if you can find a 6mm gypsy."
-- That is about 25% lighter. I am very interested if the loads work.


-- Pete You are making a good point here, with regard to what Steve s/v Panope actually measures for break out loads. Where are you getting the figures for the 50 knot loads on your boat and Franziska's boat? I am very interested!!

Originally Posted by Pete7

Franziska, can you locate a 6mm gypsy for that windlass?

Now at this point you are probably think I am barking mad, but it is an idea I picked up recently from someone with a sister yacht to ours.

Your cat weighs 4.2T loaded according to this website: Mira 35' ocean cruiser by Woods Designs

Now the minimum breaking load (MBL) of 6mm G40 or G43 is about 2000 kgs. That's over the safe working load which tends to be 1/4 of the MBL. The maximum holding for a 15kg anchor could be 2000 kgs in ideal conditions. However, watching Steve's anchoring YT channel I would suggest an average 600-800 kgs is more likely. The load on my mono hull in 50 knots of wind is likely also in the 600 800 kg range. Your cat might be a bit more. Finally do a calculation of 6mm chain at 0.8kg per m against 8mm at 1.4kg and the weight quickly mounts up making 60m of 6mm very tempting, if you can find a 6mm gypsy.

That should give you something to ponder over

Pete

[rgleason]

It looks to me like Pete7 is interpolating or taking these loads from something like the

ABYC Horizontal Working Load Guidelines

Am I correct in thinking that these Guidlines do not include the forces from Wave and Current, and surge action?

[Pete7]

Originally Posted by rgleason

It looks to me like Pete7 is interpolating or taking these loads from something like the

ABYC Horizontal Working Load Guidelines

Am I correct in thinking that these Guidlines do not include the forces from Wave and Current, and surge action?

The 500-600kg wind loading was a comment Steve Godwin (Panope) made in one of his videos. I think he was testing anchors in the 10-15 kg range (that's us) and said something along the lines that these anchors would likely be used for 30ft yachts and which would have a wind load of 1000 lbs in winds approaching a tropical storm.

I thought that was interesting and confirmed in another couple of posts on CF, possibly this one:

https://www.cruisersforum.com/forums...ce-249475.html

Also some superb work by someone called Mathias on deep anchoring, I need to find that again.

Edit, try this, but make yourself comfortable it needs careful studying: https://www.cruisersforum.com/forums...ml#post3525942

Pete

[Franziska]

Hi,

as we have some 8mm chain already and I do have a kind offer to swap the 10mm Gypsy which came with our brand new windlass for a brand new 8mm Gypsy we will go for 8mm.
I rather err on the high side than on the low side.