T&T: size of anchor cable

[Rudy and Jill]

> I have a 63' shrimp boat converted to
> a pasagemaker with a drum winch and 300 lb anchor. Is 1/2
> inch galv cable sufficient or should I use 5/8? I want to be
> able to ride out really bad weather.


A typical 60 foot boat, in 60 knot winds can have up to 8,000 lbs of force on their ground tackle. A typical 70 foot boat can have up to 10,000 lbs of force on their ground tackle. 

These figures are minimums, but include wind force and surge loads, applied with the boat having the ability to oscillate. They do not include shock loads, which can triple the load on the ground tackle. 

The warning that we like to give, concerning shock loads, is that even with a snubber employed, circumstances can still combine to your disadvantage, allowing shock loads to occur. 

Yes, we know, if the gear is deployed appropriately, shock loads are not likely to occur. But it can happen, and since they are seldom thought of, we think that it is a thought that needs to be mentioned.

"Extra strong" will not let you down. Even if engineered to the forces that you can calculate, Mother Nature can, and often does, get a laugh by exceeding that which you spend so much time trying to calculate. The wind is stronger, two/three waves combine to gang up on you, that protected anchorage that you planned on is full of boats...

Remember that you are not sizing the cable's breaking load to the forces that your boat will encounter, but instead its working load. 

By the way, using a rope snubber to hold on your cable, the size you will need in harsh weather,  will be a challenging chore. One idea that you can try is the snubber braid", Rolling hitched, camel hitched (or one of the other variations of the rolling hitch) to the rode. 

We find that the snubber braid will hold on rope, or chain rodes, no matter the size of the line used for a snubber. I also use it on wire, when splicing the wire, and it holds good at this job; so I suspect it would work well on a cable rode.

Kind of wordy, we admit, but it reflects our thoughts. If you try a snubber braid on your cable, please let us know how it works out.

Rudy
Briney Bug, Panama City, Fl