[C38] tide reversals in SFB

Mon Aug 10 13:11:19 EDT 2015

I was on a friend's boat once in the Bahamas and we entered an anchorage 
during a summer squall.  We motored to weather to drop the hook and we 
let out considerable nylon rope rode.  We went about getting supper 
ready, etc., but the surge on the rode kept everyone falling all over 
the place as waves came into the cove where we were anchored.

The owner of the boat finally had enough of this mayhem and decided to 
motor forward toward the anchor and replace that anchor with one with a 
total chain rode.

We swapped anchors and rodes and the boat settled down like it was 
beached on high ground.  The chain held us in place so the wave action 
didn't push the boat rearward which allowed a much more comfortable 
situation.  Because the anchor rode was total chain, we didn't have to 
worry about getting fouled in a tide reversal as we had on previous 
occasions.

After that experience, we always either used a total chain rode or a 
very long chain rode to rope rode where it transitioned via a swivel.  
On my boat I used an over sized swivel between the chain and rope to 
help act as a kellet weight.

Another friend who claimed to have a lot of sailing experience said he 
would never use a total chain rode because it would be too jerky when 
the boat pitched against the waves, just the exact opposite of our 
experiences.  I doubt he had ever experience a chain rode.

If you tie to a dock with short chains, jerky shocks would be true but 
with a long rode of chain to an anchor, the catenary, or gravity sag, in 
the rode path to the anchor,  gives enough shock absorption to keep the 
boat safely in place without jerking.  A nylon rode will stretch when 
waves hit causing an elastic surge forward during troughs between the 
waves.

The weight of a chain anchor rode also keeps the anchor pulling 
horizontal so holding is greatly improved even with a relatively light 
anchor and any kellet along the rode helps even more.

I know I am "preaching to the choir" with most if not all of you but I 
am amazed at how many people have the wrong ideas about chain anchor 
rodes and kellets.

Tom Troncalli

On 8/3/2015 4:50 PM, Michelle wrote:
> After some net surfing and post-event debriefing, we've learned (a) we need more chain rode and (b) we need a 15-20lb kellet to weigh down the rope rode and theoretically keep it plumb and away from the keel at turning tide.
>
> After the first mishap, I downloaded a free anchor dragging app to my iPhone (Drag Queen) and set it so we could get some sleep. It woke us for the second wrap and drag.
>
> We've anchored Dulcinea at Clipper Cove, Treasure Island and didn't have this happen. Perhaps we've been lucky the lee of the island is more protected from tidal flux than San Pablo Bay. We've anchored our Ranger 23 in many places and have never had this happen to Rigel.  Lessons learned! The only fouls were, well, the anchors, and we snapped one of our winch handles trying to grind in the hooks on our manual windlass that has no mechanical advantage, straight 1:1. Woof.
>
> We've now downloaded a book on anchoring to learn more and will definitely go back to China Camp, with more knowledge and more tackle tools better prepared next time!
>
> :)
> MD
>
> Michelle Diaz, BSN, RN
> C38 Dulcinea #110
> Sent from my iPhone...
>
>> On Aug 3, 2015, at 13:33, Don Strong <drstrong at ucdavis.edu> wrote:
>>
>> Michelle: Great story, and sorry about your tangle. We had 4 reversals during a night anchored at China Cove of Angel Island. The GPS alarm awoke me for the first two, and I happened to awake during the third, about 4 am. The final reversal came during morning coffee. No anchor drags, we were lucky.
>> SFB tidal currents are wicked.
>> Don, C38 Discreet Charm, Emery Cove
>>
>> On 8/2/15 11:53 AM, Michelle wrote:
>>>> We anchored out last night in the San Pablo Bay muck in the lovely general anchorage outside McNear's Beach, China Camp State Park, Marin County, CA with a 33lb claw anchor with 25' chain and 110' of rope rode. Twice in the night (once around 00:30 ~3 hours after setting anchor and 2hrs to high tide, the other this morning around 8:30a) Dulcinea had spun herself and wrapped her ground tackle around her keel and dragged anchor. It was no fun trying to undo the mess, twice. Thankfully we have a backup danforth that we dropped to slow the drag and give us time and slack on the primary tackle to untangle the keel.
>>>>
>>>> Anyone have this happen to them? Any thoughts? We've never had this happen to us on our other boat.
>>>>
>>>> :)
>>>> MD
>>>>
>>>> Michelle Diaz, BSN, RN
>>>> C38 Dulcinea #110
>>>> Alameda, CA
>>>> Sent from my iPhone...
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>>
>> -- 
>> Donald R. Strong
>> Professor,
>> Department of Evolution and Ecology
>> and
>> The Bodega Marine Laboratory,
>> University of California, Davis,
>> Davis CA
>> 95616
>> 530 752 7886
>>
>>
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