3.28.2009

Anchor Rode Marking - Reasons and Method

Marking your anchor rode at specific spots will allow you to make sure you let out the proper length of rode to get the required scope.










For my land lubber friends I will give a few quick definitions of these nautical terms.
Anchor Rode:
The line or chain attached to the anchor and secured to the boat.
Anchor Scope:
Technically, the ratio of length of anchor rode in use to the vertical distance from the bow of the vessel to the bottom of the water. Usually six or seven to one for calm weather and more scope in storm conditions. It is critical to let out the proper length of rode so that you will not drag your anchor.
We have two CQR anchors on Mary Rose.
Anchor number One configuration consists of the anchor attached to 75 feet of 3/8 high tensile grade galvanized chain which is attached to 150 feet of 5/8 inch, three strand nylon which is attached to 100 feet of 3/8 inch polypropylene rope. The poly is tied to the Sampson posts at the base of the anchor locker. This anchor locker is lined with 1/8 inch vinyl to protect the hull from the chain. The polypropylene is not strong enough to hold our boat and the reason we have polypropylene at the boat end, is because it floats. If we ever have to cut our anchor loose from the boat then we will be able to take a GPS position and we will be able to find the polypropylene rope floating on the surface if the depth is less than 100 feet. We use anchor Number One in high wind conditions or if there are bottom conditions that will chafe or cut a nylon road.
We braided each end of the three strand nylon around a stainless steel thimble to prevent chafing.



Anchor configuration Number Two consists of a CQR anchor, 15 feet of 3/8 high tensile grade galvanized chain attached to 250 feet of 5/8 inch, three strand nylon which is also attached to 100 feet of the floating poly. We use this anchor as a day anchor, or in light to medium wind and sea conditions, shallow depths and where bottom conditions are safe for nylon rodes without chafing hazards.
We marked both anchor rodes with strands of poly tied through the chain and nylon strands. The method we used is one poly strand at 25 feet, two strands at 50 feet and increasing the strands each 25 feet up to 150 feet of depth. After we reached the 150 foot mark we started counting down with the strands. So at 175 feet there are 5 poly strands. This photo indicates 75 feet or 225 feet if we have passed the 150 mark.


The very last mark on each of the nylon rodes is a weave of yellow poly approximately 24 inches long. There is also a weave of poly near the end of the 75 feet of chain on anchor #1. The reason for these weave markers is to let you know that you are literally at the end of your rope! This will give plenty of notice so that the rode can be made fast before the poly exits the chain locker through the bronze chain pipe.

In extreme conditions we can attach the three strand nylon rode from anchor #2 to the nylon rode on anchor #1. This arrangement would give us maximum scope and the nylon stretches well which diminishes the shock of high winds and waves when at anchor. In very extreme conditions both anchors may be attached in line on the chain with anchor #1. The nylon rode on anchor #2 will also be attached to our sea anchor when conditions require us to deploy it.

Please leave your comments and questions.

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