Saturday 18 June 2016

Ground Tackle & Anchoring Safely…Part 2

At anchor with borrowed ROCNA 33

If you read the first post on ground tackle and anchoring safely you won’t be surprised to know that since buying Maple we have significantly upgraded our anchoring system and our confidence in the system.

As we quickly learned upgrading ground tackle can be complicated and confusing.  There are many pieces of the system that must be considered and decisions to be made.  We’ll take a look at our new anchoring system moving from the boat to the actual anchor and outline the choices we made and why.

1)     The bitter end.  This is the point where the anchor rode (chain or rope) connects to the boat.  When we got Maple the chain was shackled to the attachment point (a well bedded u bolt) with a rusty and undersized shackle.  This was cut off.  Instead I opted to splice a 6-meter section of 16mm 8 braid line to the attachment point.  This was also spliced to our new chain.  The rope is the right size to run though our gypsy so in the unlikely event that we need to drop the anchor chain and flee an unsafe anchorage we can run the chain out and cut the line without having to climb deep into the anchor locker.

In hindsight I’m thinking I may have been better off using a much longer piece of line, which would give me additional anchor rode for those really deep anchorages, but it would probably end up being overkill so I’m not going to change it now.

2)     The windlass.  This is the hardest working part of the system.  Our windlass is a 5 year old Quick Aleph 1000.  It’s basically a 1000-watt electric motor and gearbox that is tasked with lowering and raising the anchor and chain.  It is expected to do this something in the range of 200 times a year in depths from 3-20 meters with minimal maintenance.  In order to do this properly, the windlass relies on a chain gypsy, which grips the chain and pulls it in/out of the chain locker.  Of course the gypsy is specific for the chain size being used.  We were increasing our chain size so we had to shell out for a new gypsy.  Fortunately, they are still being manufactured and one was available and easily installed.

I should probably try to sell the smaller size gypsy I took off.  If you know of someone with a Quick Antares or Aleph windlass that may need an 8mm chain gypsy feel free to put us in touch.  I’ll let it go way cheaper than new.

3)     The chain.  Ahhh – the simple part.  If that were what you were thinking you would be wrong.  As one of my good friends back in Canada can attest you can spend an entire career learning about chain.  It turns out that there are any number of variables to consider, wire size, link size, composition, strength, certifications and on and on.  Maple had 40 meters of 8mm (that’s the wire size) G3 (strength rating) chain.  I wanted heavier, stronger stuff to go around the world, not to mention a longer length.  We opted for 100 meters of 10mm G3 galvanized steel chain.  We could have gone stronger with G4 chain but it would probably have been overkill.  We could have opted for stainless chain but it is more brittle and when corrosion does set in it can be hard to see.  The chain we have is oversized for the boat and has a safe working load of 2500kg and a breaking strength of 5000kg.  With 100 meters of it we can anchor safely in depths up to 20 meters.  If we need more, we can add some rope to the bitter end of the chain (see above).

4)     Chain to anchor connection.  To swivel or not to swivel?  That is the question.  An anchor swivel allows the chain to swivel around the anchor when the boat turns in an anchorage.  Unfortunately, the swivel is often a weak link in this critical grouping of hardware.  There have been many instances of swivels catching on an anchor and breaking as the side loads exceed what they can handle.  The end result is a boat that drifts free with potentially catastrophic results.  While there is no decisive answer to the question of whether or not to use a swivel we decided not to – removing a potential weak link is good enough reason for me.  Instead we have attached our anchor to the chain using a 7/16” load tested Crosby galvanized steel shackle. 

Our new ROCNA 33

5)     The hook.  The last component of our ground tackle and probably the one you thought of first when you started reading this is the anchor.  You’ll recall we had a small (25kg) Delta anchor.  This was state of the art in the 70’s but it’s a plow style anchor and as you can imagine was prone to plowing the sea bottom rather than holding.  We knew we wanted a new generation anchor of the scoop or spade type. These anchors are known for digging their tip into the bottom and scooping the earth – the harder they are pulled the deeper they dig.  Testing done on land (granted its not the most scientific) proves that any of the top contenders outperform the Delta or CQRs that were popular in the past.  We chose ROCNA, partly because it’s owned by a Canadian Company but mostly because we have never heard a bad review.  We weren’t sure what size to get but were able to borrow a friend’s Rocna 33 (33kg) for a weekend and confirmed it fit our bow roller so that’s the size we got.  It is 1 size bigger than recommended by Rocna (and their sizing charts are conservative compared to others) and fits the boat well.  I don’t think we could have fit a 40 but it’s a moot point.  With what this cost it’s here to stay. 

ROCNA 33 fit in Leopard 384

We’ve now had this new ground tackle fit out for 500 NM of cruising and more than 60 nights where we’ve relied on it to keep us safe.  The anchor has set well every time and exceeded the performance we were used to from the Delta.  With the added weight of the larger chain and the added length we are confident and comfortable anchoring in deeper water when needed.  Over all, we sleep better in all conditions knowing we have a reliable anchoring system holding us in place. 

2 comments:

  1. There are a couple of things we did differently on our boat, Avant, a 44' monohull.

    1) To link the rode's bitter end to the hull, we used a thin line run through the hull eye and the bitter end of the rode, threaded through each several times over. Theoretically, this is easier (and faster) to cut. We used 1/4 inch threaded through four times over to give the same strength as a 1 inch line. Cutting thicker line is harder than you might think.

    2) we added a chain stopper between the windlass and the anchor (you can see a couple here http://www.westmarine.com/buy/lewmar--chain-stoppers--P005_155_002_501 ). This is a device that acts like a rachet and prevents the full strain of the anchor line from coming onto the windlass should the snubber fail (and we have had a snubber fail). The shock load of the anchor line on the windlass can cause the windlass to fail. They're not very expensive and they're pretty simpleton install and use. You need to release it or flip up the gate to lower the anchor, but you can raise the anchor through the stopper no problem. In the event the windlass takes a day off, the rachet-like operation of the stopper makes raising the anchor much easier since it takes the strain of the chain you have raised.

    What are you using to mark the length of the rode? We're zip tie people.

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    Replies
    1. Hi Rob - thanks for the comments.

      I agree that lashing would be easier to manage. I will probably go that route, though the 8 braid cuts fairly quickly, particularly under tension.

      Leopard Cats already have a chain stopper - thankfully we didn't have to add one to the mix. We use it religiously and it works a treat. The last thing we want is any kind of shock load on the windlass - the gears are not meant to take that kind of stress and I don't need to be buying a new one any time soon.

      We use dedicated chain markers (little rubber inserts in the chain) to mark our lengths. I'm not thrilled with them as they can be hard to see. We tried zip ties but the windlass ate them (probably because they were cheap ties). I think when I get the chance I'll paint the rode...I know it comes off but I figure I'll give it a shot.

      Thanks for reading!

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