Anchor Management - part 1

Arriving at Rockhouse Creek (New Smyrna Beach, FL) late in the day we were not surprised to discover two other boats already anchored.  The creek narrows quickly as is flows towards Ponce Inlet, visible to our east.  The proximity to the inlet means the tidal current in the creek flows swiftly with changing tides.  Another intriguing aspect to add to the growing considerations in this nchorage are recent comments on Active Captain from vessels that claim to have hooked their anchors on a large diameter underwater cable left from dredging operations.   Time for some anchor management...

First step - motor around the anchorage and gather intell...  What is the topography of the bottom and depths around the anchorage?   What method of anchoring are the other vessels in the anchorage are using?  Vessels using a single anchor will swing very differently from vessels using two anchors.  Which direction will the wind and/or current push a vessel at anchor?  What is the state of the tide?

Here is what we found - We are arriving 1 hour before low tide. The catamaran to our east, in the narrow portion of the creek, resides on two anchors while the monohull sailing vessel to the west, near the ICW rides on a single anchor.  The wind will set us to the west while the current will drift us eastward.  By looking at the other vessels at anchor we see their are floating westward off their anchor - thus the wind is overpowering the current.  The shoal noted on the chart at the southern mouth of the creek gone providing more room than anticipated near the mouth of the creek.

Second Step - identify the spot to anchor and make a plan... Having successfully anchored here in the past on a single anchor, we choose to use a single anchor this evening.   Unsure of the two anchor method used by the catamaran, we select the wide area where the creek meets the ICW south of the other monohull.  Reaching the spot to drop the hook, we note the depth, 6.5 feet and use the Man Over Board (MOB) feature of the GPS mark the location.   Time to calculate the amount of anchor rode required.  This calculation is know as the "scope".   C'est la Vie typically uses a 7:1 scope ( 7 feet of anchor rode for each 1 foot of depth at high tide.)   The depth of tonight's anchorage is 6.5 feet at low tide + 3.5 feet to account for the tidal range = 10 feet deep at high tide X 7 feet of rode = 70 feet of rode at the water surface.  Once the anchor is set C'est la Vie will have the ability to swing 70 feet in any direction from the anchor.  Does this area have enough depth at the low tide to keep C'est la Vie safely afloat?  Due the the proximity of the previously charted shoal we are concerned about shallow water within our swing radius.  Using the MOB mark on the GPS as the center point we slowly motor circle 70 feet out.  The GPS gives us the distance to the MOB mark so there is little guess work making a accurate circle.  The depth at low tide within our swing radius in never less than 5'.  C'est la Vie draws 4" so we are satisfied with the depth.  These calculations are all made easier this evening because we are coming in at low tide.

Remember Active Captain reported the possibility of a large chain on the bottom.  When we are worried about the anchor fouling, then we add a trip line.  The trip line clips to an eye on the anchor and runs up to a float at the surface. This line can be used assist in freeing the anchor if it becomes stuck. We use a small fender as a float. C'est la Vie does not have a designated trip line.  We use various lines depending on the depth of the anchorage.

From left to right - snubber line with chain hook, trip line with float, and partial view of windlass

Ok let's review - we have the spot to drop the anchor marked on the GPS, we plan to use 70' of rode, we are confident the area is deep enough at low tide, and the trip line is rigged.  Now to plan the mechanics of actually dropping the anchor. We prefer to approach the drop site from direction C'est la Vie will drift once the anchor is set.  Thus noting the other vessels are drifting  west we will approach from the west.  Now we are GTG (good to go) for dropping the hook.