Hurricane Survival For Small Boats

[ffiill]

In the Caribbean if boats are still sailing and a hurricane is forecast they will go into the mangroves preferrably in a lagoon. Then tie the bows to the mangroves and put out three anchors. One heavy storm anchor direcly behind the stern, then one each at 45 degrees each side of the boat. One of the anchors is generally the bow anchor and all should be on chain. We had that kit on board but only came close to using it in Spanish Waters, Curacao. What was expected to be a direect hit passed 50 mile north. I was doing the cruiser net weather forecasts so was keeping everybody up to date every hour from midday to midnight.

A couple of questions/comments.
Why bow in and not bow out facing the storm surge?-In Earl Hinz book Anchoring and Mooring he reccomends bow out two anchors plus stern lines to the mangroves.
Why chain?-8mm chain for example will distort/break on a snatch load of under one ton wheras 28mm Seasteel rope commonly used in the fishing and oil industry for moorings etc has a breaking load of 12 tons plus its very abrasive resistant.
Using the aprox. calculations in Hinzs book I have estimated that my 9 ton 34 footer in 130 knot winds with a 15 to 20 foot snatch loading wave pulls a little under 2 tons.
The book is worth reading as this Pacific based US author(ex USN ccommander) also covers anchors tests;chain strength etc.

 

[binch]

chain cable

One of the things that is hard to get across when teaching is that the anchor itself is only part of the holding. The important part is the cable.
If possible lay out enough chain cable so that even in the strongest wind, you do not lift it off the bottom . This can be done in extremis by bending on a second anchor one third of the cable length from the main anchor. If and when the cable lifts, the anchor will soon follow.
Wire rope cable is valid for ordinary anchoring especially if it reels onto a wire rope reel. We used it for choice on landing craft when loading over a beach, for then the ship is lower in the water on leaving than when she arrived. The pull required is enormous and a self reeling geared winch at very low gear will haul her off better than chain cable.
I have used SWR in long lengths in bad storms but not to an anchor because then the anchor is the weak link. It is best made fast to something firm on shore.
One can get the relationship wire/chain in perspective by considering an ocean tow that I did once. A huge floating dock We had 1000 fathoms of 10" circ SWR out. in two lengths and as the wind rose so did the wires and they twanged like guitar strings. The solution was to put 3 shackles of chain cable (1 shackle is 12 fathoms, the links were 3" dia steel) in the centre of the tow. This stopped the tow coming up and twanging.
Scale that down, and you see the important feature of chain: its weight acts as a spring.
I was mate in that tug and I learned more about the sea in her than the whole of my life elsewhere.