Hurricane! - Mangrove Trees or Mooring?

[landonshaw]

Living in Grenada with the hurricane season now upon us I am making my plans. As I see it I have four options:

1. Sail away – I don’t have that luxury to leave each time a storm is threatening us.

2. Put on the hard – The marinas have no space left.
3. Put in a hurricane mooring in Secret Harbour (Mt. Hartman Bay) – I will be contracting with a local company to put one 8-foot screw into the lower part of Secret Harbour for a permanent mooring. I have been thinking of using a 3 screw set up, all 8 feet, and have it as my hurricane mooring and done properly by professionals.
Secret Harbour faces due south and is protected by three reefs that you have to navigate to come and go. It has steep hills all around except for the ocean side. There is not an area to get out of the line of sight-of-the ocean. Some boats anchored here during Ivan and survived.
4. Move to a hurricane hole and tie up to the mangrove trees. The popular bay is Egmont, I will go one bay over, Chemin Bay for more privacy, and both face south. Boats where anchored in both of these bays during Ivan and survived. There is protection from the sea. can not put a hurricane mooring in this area.
I will be purchasing a Rocna anchor and possible a Fortress if I tie up to mangrove trees. I also have a 65 lb. storm anchor if needed. New ropes and whatever else is needed will be purchased.
So my question is of number 3 and 4, what are your thoughts and if I decide to tie up to the mangrove trees, how exactly do you anchor your boat and tie up. Example: all lines to the bow so that you can swing (anchors and mangrove attachments) or secure it so that there is no swing, side-ways to the mangrove or maybe bow out and stern to the mangrove trees?
I’m starting now so that when a storm hits, I will start with a plan and then make changes as needed.

[S/V Antares]

My thought would be to use the mangroves with many lines as many of my friends do. That said the real issue will be boats dragging onto you. I saw the damage in Culebra PR and it looked like a hundred boats were pushed up into a pile with a bulldozer. I would look for a narrow cut as deep into the mangroves with a turn to rt or left. Tie into the roots and leave plenty of slack for tidal rise/surge. Clearly others have more experience at this then I do and will look to see what they say.

Regardless, Good luck this season!

[seacap]

I have seen the eye of a cat4 and cat2 sitting in the mangroves. I use the Benners Bay area on the south cost of St. Thomas. I have always been tied along side to the mangroves. I put my primary storm anchor (a big fortress set for mud) out towards the direction of longest fetch I see. Then I put my next biggest anchor out abeam. I don't situate my boat so I am beam to my greatest fetch. Then I run my lines to the mangroves with hose slipped over for chafe protection around trunks of the mangroves. minimum of 4 lines. They don't have to be real long as you should be close. I finally put out my 3rd anchor and position it depending if the storm will pass N or S.

1) reefs will not be any protection as the storm surge will carry seas right over them. I like to find a place were I have no more than 200, max 300 yards fetch in any one direction. Most times no more than 50 yds. Well over 1000 yachts were lost in St. Martin becuase the inner lagoon had to much fetch to deal with during Hurricane
2) Mangrove channels are great. You are protected on 2 sides and can put out your 2 largest anchors towards the entrance to the channel. Then tie up along both sides.

3) Trying to set up multiple anchors so you can swing is tough. The proper way to put down sand screws for storm moorings is with a machine that keeps screwing them down until a certain pressure is achieved. This sometimes results in the screw going below the surface. if they just put them in with a pry bar to screw them down...they aren't pros!

4) Tighten up all lines and anchor rodes. The nylon will stretch a lot. After Marilyn My tight lines were all hanging down in the water.

I took a quick look on Google earth and marked where I would consider. If it is shallow, go in with your dinghy and lead line and do a sketch chart before hand so you know how tight you can get. There is no order to the numbers. See attachment.

After all your prep work, sit back and have a cold beer. You deserve it! Too few people do there home work when it comes to hurricanes.

good luck this season.

[landonshaw]

I will dingy over and check out each spot. Thank you

[roverhi]

The problem with storms is not the wind but the seas that could build up. With enough lines and anchors, you sit out the wind. Add waves and the pitching and hobby horsing saws through lines and elongates chain till it either breaks or pulls the anchor out.

Find a place that is as sheltered from the ocean as possible. Mangroves seem to be the anchorage of preference. Staying out of the way of errant boats that may be dragging is also a good idea.

Aloha
Peter O.
Pearson 35

[camaraderie]

I was in Grenada in St. Georges for Ivan and had many friends on the south shore. From what I saw...the mangroves were the safest place to be in what surely was the storm of a lifetime...way worse than the 2 Cat2's I'd seen before. Given the improvements in the land based storage w/ tiedowns, that would probably be my first choice, with mangroves the second and a "safe anchorage" last. NO one was safe at anchor in the last one. In St. Georges which was almost totally enclosed and free from big swell...only 6 of 41 at anchor boats were still there after the storm. I know it was much the same over at Mt. Hartman, True Blue and Prickly. Grenada Marine in St. Davids was less hard hit...but I think that was just luck as it is pretty wide open if the wind is right.
If you are on the boat...why can't you take off for Trinidad on every warning. It is only a days sail and VERY few storms/waves get on a path where you would have to worry. If I got into a 3 day cone of probablilty there...I would head south and be well out of it in plenty of time.

[s/v Jedi]

We were anchored in the east cove in Mt Hartman Bay during Ivan. There was actually an Irwin on a "hurricane" sandscrew mooring (built by "George") that survived the storm fine. All other boats on moorings (most from that marina) were set ashore, on the reefs or just sunk/lost. I think we were the only boat who did fine at anchor; the only real damage was caused by other boats dragging into us and our anchor chain. The marina was all but destroyed with many boats sunk and the ones that still floated with a lot of damage.

My advise would be to NOT use the hurricane holes as pictured on the chart earlier in the thread. Many boats had heavy damage there as the result of being hit by other boats; it will be very busy there with lots of un-secured boats. I would put a very heavy mooring (like 3 huge sandscrews) close to the mangroves in that cove so that you have the option to build a spiderweb of lines to the mangroves AND use the mooring to try to hold you off them. The NE corner of the cove seemed best to me but don't go to the north shore as there's rocks between the mangroves there.

On the attached picture: on the left they are salvaging a friends boat on the north part of that cove where the rocks are. The spot I recommend is on the right in the picture. See the hills in the background for reference. Another boat washed up in that spot and came off without damage (just looted over and over but no big hurricane damage).

cheers,
Nick.

[anjou]

Millions of years worth of evolusion have probably made mangroves the best anchors, all you have to do is get the right spot

[GordMay]

Originally Posted by seacap

... Then I run my lines to the mangroves with hose slipped over for chafe protection around trunks of the mangroves...
... good luck this season.

Obviously chafe protection is very important - at both ends of the line.

I like to use short pieces of chain shackled around tree trunks and rough pilings.
A 7' ➛ 8' piece of chain will circle a 1' diameter tree twice, or a 2' ∅ tree once. Shackle your anchor ropes (moused shackle & thimbled eye) to the chain.

[s/v Jedi]

Indeed, Gords method with pieces of chain is what we used to do. I changed to heavy straps now (like used on trucks to secure cargo: remove all metal parts and sew a loop on each end, first with machine (V110 thread) and then by hand (with a doubled-up waxed V346 thread)

After wrapping it around posts/mangroves etc. put a big shackle through both loops and tie to that. The advantage is that it doesn't rust. And of course the important thing is that it doesn't chafe.

cheers,
Nick.

[landonshaw]

I was in the construction business and we used straps on the tri-axle trucks that you might be referring to? Use those straps around the mangrove trees to secure the boat. They would take a lot of abuse, friction from the weather I believe. I can bring those straps down when I return in July.

[s/v Jedi]

Landonshaw,

I don't know much about trucks, let alone tri-axle ones... I used the straps that are 2 or 2.5 inch wide with a tensioning device attached to them as I see them in hardware stores here. I use only the webbing-part of them.

Do you understand the cove I described in Mt Hartman bay?

cheers,
Nick.

[GordMay]

I would never again undertake to hand-stich eyes into a Nylon web (truck) tie-down strap.
Instead, purchase a manufactured Cargo or Hoisting Sling, which comes with an attached load limit label.

I’ve used both; but prefer Chain basket slings over Nylon (or polyester) web.

Chain vs Synthetic Web:
Chain can rust & doesn’t stretch*; but doesn’t suffer from abrasion, or UV damage.
Nylon doesn’t rust & stretches; but suffers from abrasion & degrades in UV sunlight.
* Shock absorption isn’t essential at the tree sling, as long as the boat is connected to the sling by rope.

Hoisting Cargo Slings ➥ Lifting Sling, Nylon Sling, Rigging Slings, Flat, Round for Crane and Hoist

See also the Rigging with Slings information:
➥ Rigging With Slings: Basic hitches, Working Load Limits, Sling angle, Reach

Note the effects of sling length, and resulting basket sling angles, on sling load capacities. Longer slings (chain or web) are better, within reason.

[landonshaw]

Yes I understand the cove in the Bay. It is directly across from our apartment. We currently have the boat anchored out from the boat that went aground during Ivan. We live maybe 100 yards from that. Erie anchoring next to a grounded boat. Nice to get up and look out and see the boat. I guess I will add the sailing away to my list of options. We work at the University and will check and see what their emergency plan is when a hurricane is headed toward the island. I'd expect they will close a few days in advance so that students can fly home and then not open for a few days, assuming no direct hit so they can get back.

[s/v Jedi]

Ah, you mean the big steel schooner "Fool's Wisdom"? You must live near Inga, you know her?

Gord is right about the slings.... if you live somewhere you can get those ;-)

cheers,
Nick.