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Old 30-01-2008, 13:41   #16
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Nylon stretches, big big advantage in an anchor road, and dont forget that you absolutely need to rig a bridle on a multihull, it avoids much of the swinging at anchor that other suffer.
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Old 30-01-2008, 15:36   #17
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I would think that buoying your rode would increase the chance of it being cut by some passing boat. Surely if you had 300' (or even 200') of chain on the bottom, then it would be sufficient in most cases to put out just enough nylon to cover the depth of water. Perhaps adding a plumb near the chain/nylon joint would offset the loss of holding power resulting from the catenary in the chain.
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Old 30-01-2008, 16:20   #18
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I agree with the points Joli and Lodesman make. In Atols with coral bommies surrounding the boat you sometimes weave the boat up into them. Not a place for rope!
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Old 30-01-2008, 16:26   #19
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When you put floats on nylon road, you simply tie some small line (about 5' long) through the twists in the rode. You can attach a small milk bottle or a proper buoy. The float should just barely support the anchor line about 3-5' below the surface while there is no wind. When the wind is blowing, the floats sink with the tension and the tension keeps the road off the bottom.

It you are anchored in 50' of water, one buoy will be required for every 75-100' of line to keep the line off the bottom. If there are coral heads, the depth of the coral needs to be considered. Coral will cut through 3/4" nylon in short order.
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Old 06-02-2008, 02:26   #20
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Chain for coral waters

Here's another vote for all chain rodes. You attach a long length of nylon with a chain hook to give it some spring. I cruised all across the Pacific, and while I have no problem with nylon rodes in temperate climates, they don't mix with coral. Coral is very, very sharp. Yes, I know, chain is heavy, and big windlasses are heavy. On the other hand, finding your boat unexpectedly hitting bommies in the in the middle of a dark and stormy night would be way worse than carrying the weight. ********* This notion of protecting you line by buoying it up just sounds too dangerous to me. All nylon rodes use a lot of scope, and if the wind comes up, it will have to straighten out to do its job. This puts in the reach of coral, buoy or no buoy. The latest issue of Multihull magazine has a story about somebody in a multihull that found its bay to be a lee shore in a storm. The boat was lost, and the skipper felt very lucky that no one was killed.
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Old 06-02-2008, 07:56   #21
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Bigcat, can you specify why the boat in Multihull magazine was lost?
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Old 06-02-2008, 17:05   #22
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Loss of a tri in the S. Pacific

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Bigcat, can you specify why the boat in Multihull magazine was lost?
Hi, Schoonerdog-It was a series of misadventures. I am recounting this from memory, so there may be minor inaccuracies. Prop shaft repairs in Fiji were made, but the prop shaft came undone from its coupling soon after, at sea, jamming the rudder. After repairs at sea, the plywood tri sailed into a harbor with no motor. I forget which Island, but it was a rarely visited high island, not an atoll. It anchored in a bay open to the sea on one side. A large storm came up, making the bay a lee shore. Despite having several anchors out, the huge rollers coming into the anchorage led to the chafing through of the main rode, the destruction of the roller, and the pulling out of cleats. The tri then ended up on a rocky shelf where the shore was still a ways away. The skipper and crew abandoned ship, climbing onto a rock that was sometimes swept by waves. The skipper washed off the rock, and made it ashore. He sought help, and the islanders came and rescued the passengers in the dark of night. The boat broke up. The part of the story of relevance to the rode thread is that the line chafed through. Chains don't chafe through. ********************************************** IMHO, the whole boat was too lightly built, as well, and the skipper didn't know enough about the mechanical workings of his boat to inspect the work the boatyard did. At least, he should have had a hose clamp on his prop shaft next to the packing gland to keep the shaft from moving very much if it came free of its coupling. I think prop shafts should not only have key ways and keys, but a cotter pin or bolt right through the shaft and coupling, and not just set screws-I don't know what his arrangement was on the tri.
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Old 06-02-2008, 17:21   #23
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While in a perfect world all chain is best for areas with coral, it can not always be had. There are some multihulls that should not under any circumstances carry all chain. These are performance oriented cruisers that would not be able to carry the extra weight of all chain. Extra care and caution must be taken if you anchor in an area with lots of coral heads.
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Old 06-02-2008, 19:46   #24
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Any idea if Aramid (Kevlar) rode would stand up to coral?
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Old 06-02-2008, 20:16   #25
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Better than nylon, as it is famous for dulling the tools used to cut it. However, nobody seems to use an oil can and hack saw to cut it, so it won't equal chain. Chain's weight creates a catenary, and you can use much less of it than rope for that reason. Kevlar certainly isn't stretchy, so it isn't an ideal rode. Chain isn't stretchy, but its weight gives you a similar effect by falling to the bottom and taking a lot of force to lift and straighten it. High tensile chain is certainly lighter than the BBB chain that was all that was used many years ago. And of course, Kevlar costs a lot.
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Old 06-02-2008, 23:11   #26
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As someone who's been to the Pac Islands many times and supplies many who do - all chain baby or at least 200ft min. Not many would leave here with less than 200, most would have 300-350 ft.

With a multi maybe a bit less as they can sneak up into the shallow water and see exactly what they are anchoring over. You can do this in many places but with monos it's not always that easy.

If coral can strip the galvanising off chain in a couple of months who long will a rope last? Might be the entire trip but equally it might be 15 minutes.

We have made a Kevlar jacketed Nylon for a couple of weight restricted boats but they weren't full on cruisers more racers having a few weeks up there after finishing a race. Works well but not at the cheaper end of things.

Who said use a floating rope? Don't want to be rude but that's goes into the same basket as playing silly buggers with a loaded gun i.e. bloody stupid.
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Old 08-02-2008, 07:14   #27
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To translate that back then to topic, for those who do and have travelled to the south pacific on cats where they can scout out the shallower anchorages, it sounds like the vast majority of places are less than 30 ft...anyone else want to chime in with their experience? It's also difficult for many monos to understand really the flexibility of catamarans for some anchorages. In Georgetown I was able to tuck into 5 ft of water with our boat in a storm and be completely protected right by the entrance to the town and I repaired my props when others couldn't leave their boats.

I can say for the Caribbean and east coast of the US that really you don't need much chain at all. I sailed for 10 years on a boat that had 40 ft of chain, no worries.

I know a LOT of catamarans that have completed circumnavigations with 120ft of chain. It's a serious mistake to look at a catamaran like a monohull and simply slug in batteries, generators, extra water tanks and hundreds of feet of chain into a boat that was not designed for that weight (and I've seen it done by new owners again and again). It's not simply speed, who cares really about that, it's things like suddenly a boat which was designed to be able to releave the stress of wind gusts or storm wave action by slipping lightly over the water is now being dragged through the water and is absorbing the full impact, rigging fittings, deck joints, rudder posts all then contend with an exponentially increase force. It's kind of like a boxer who needs to bob and roll with the punches now has to stand completely still. So catamaran owners really have to look at things that carry a lot of weight in a similar way, you know someone is going to punch you, how motionless do you want to be? And yes 300 ft of chain would be bulletproof for the chain, and were I sailing a monohull I'd pick a big steel boat with a ton of large chain and be done with it. But since on a catamaran chain length and weight beyond a certain point you now are talking about reduced safety, you obviously need to find a compromise.
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Old 08-02-2008, 07:46   #28
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I can't imagine any normal boat withstanding full on ocean cresting storm waves while lying completely unprotected at anchor. Even a large steel boat with full chain would be looking at 40,000 lbs of force moving quickly back on the waves and being quickly halted with the bow trying to be pulled under the waves. It would make short work of any anchor. I wouldn't want to be in anything short of a cruiseliner in those conditions.

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Hi, Schoonerdog-It was a series of misadventures. I am recounting this from memory, so there may be minor inaccuracies. Prop shaft repairs in Fiji were made, but the prop shaft came undone from its coupling soon after, at sea, jamming the rudder. After repairs at sea, the plywood tri sailed into a harbor with no motor. I forget which Island, but it was a rarely visited high island, not an atoll. It anchored in a bay open to the sea on one side. A large storm came up, making the bay a lee shore. Despite having several anchors out, the huge rollers coming into the anchorage led to the chafing through of the main rode, the destruction of the roller, and the pulling out of cleats. The tri then ended up on a rocky shelf where the shore was still a ways away. The skipper and crew abandoned ship, climbing onto a rock that was sometimes swept by waves. The skipper washed off the rock, and made it ashore. He sought help, and the islanders came and rescued the passengers in the dark of night. The boat broke up. The part of the story of relevance to the rode thread is that the line chafed through. Chains don't chafe through. ********************************************** IMHO, the whole boat was too lightly built, as well, and the skipper didn't know enough about the mechanical workings of his boat to inspect the work the boatyard did. At least, he should have had a hose clamp on his prop shaft next to the packing gland to keep the shaft from moving very much if it came free of its coupling. I think prop shafts should not only have key ways and keys, but a cotter pin or bolt right through the shaft and coupling, and not just set screws-I don't know what his arrangement was on the tri.
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Old 08-02-2008, 09:54   #29
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From what I have learned reading the Cat owner’s comments is that you will need to compromise and carry as much chain as you are comfortable with. I see no problem with that as long as you are a bit more inventive in “poor anchorage scenarios” which are much more common in the spread out Pacific Atolls.

Beach lines or bow and stern using a lightweight stern anchor to hold your gear away from the coral heads will work, provided you keep a close watch for squall lines.

The problem I have seen with Cats that regularly anchor close in to the beach on one hook is that when weather comes up quickly, things happen really fast and they need to scramble. Most cruisers I know would prefer to have ample sea room to drag and stay away from a shoaling bottom that can quickly become a surf line in a 180 degree switch.

My simple litmus test for deciding how close I would get to a beach is to look at the beach line and see how steep an angle the sand has been pushed up. If it is quite steep, I know that beach gets a pounding at times and I give it a bit more space.
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Old 08-02-2008, 11:10   #30
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Quote:
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To translate that back then to topic, for those who do and have travelled to the south pacific on cats where they can scout out the shallower anchorages, it sounds like the vast majority of places are less than 30 ft...anyone else want to chime in with their experience? It's also difficult for many monos to understand really the flexibility of catamarans for some anchorages. In Georgetown I was able to tuck into 5 ft of water with our boat in a storm and be completely protected right by the entrance to the town and I repaired my props when others couldn't leave their boats.

I can say for the Caribbean and east coast of the US that really you don't need much chain at all. I sailed for 10 years on a boat that had 40 ft of chain, no worries.

I know a LOT of catamarans that have completed circumnavigations with 120ft of chain. It's a serious mistake to look at a catamaran like a monohull and simply slug in batteries, generators, extra water tanks and hundreds of feet of chain into a boat that was not designed for that weight (and I've seen it done by new owners again and again). It's not simply speed, who cares really about that, it's things like suddenly a boat which was designed to be able to releave the stress of wind gusts or storm wave action by slipping lightly over the water is now being dragged through the water and is absorbing the full impact, rigging fittings, deck joints, rudder posts all then contend with an exponentially increase force. It's kind of like a boxer who needs to bob and roll with the punches now has to stand completely still. So catamaran owners really have to look at things that carry a lot of weight in a similar way, you know someone is going to punch you, how motionless do you want to be? And yes 300 ft of chain would be bulletproof for the chain, and were I sailing a monohull I'd pick a big steel boat with a ton of large chain and be done with it. But since on a catamaran chain length and weight beyond a certain point you now are talking about reduced safety, you obviously need to find a compromise.
schoonerdog hit the nail right on the head. The sea performance characteristics of each type of vessel demand varying techniques in weight control.

If you have ever been at sea in heavy weather and see the way that a large ship handles seas compared to the way that your small sailboat reacts to the seas, you will have a better understanding of this concept.

I'll never forget one passage North of New Zealand. We were in 30kts of wind and 20-25' seas (which is common in that area). We were quite comfortable sailing on a beam reach and really weren't taking much water on deck. Off in the distance, I see a large ship and we are on converging courses. We passed at about 100 yards apart (the ship altered course to pass close on).

As it drew closer, I recognized it as a French Naval Frigate. The ship was about 400' long and the pilot house was about 60' off of the water. The seas were breaking completely over the top of the pilot house on that ship while we were merely getting some spray on our deck.

In that same scenario, I could see a well balanced cat staying right on top of the seas and enjoying the same dry conditions that we were. If that same cat were heavily laden, she would be slowed and lower in the water. This would expose more hull to resistance and the amount of water coming onboard would have been increased substantially.

It is important to have any vessel balanced well but it is particularly important on a cat because the forces on the hulls and rigging are in direct proportion to the amount of weight that is carried. A mono-hull is better able to compensate for over-weight conditions by the movement of the boat and the stress on the rigging is not in direct proportion to the weight. Not so with a multi-hull. More of the weight is absorbed by the very nature of the resistant capacity of the multi-hull as it resists the heeling force, which, in turn drive the vessel harder and faster. When a multi is over loaded, it then must contend with the additional forces of added drag from the water and inability to stay "on-top" of the water.
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