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Old 08-04-2016, 04:49   #61
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Boats Do Survive Cyclones + "Where I was"

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Originally Posted by sailorboy1 View Post
What difference does it make? I was in Cancun for Wilma and hurricanes don't even care about buildings. If you think a few extra 100 pounds makes any difference to the power of a hurricane feel free to be silly.
Supposedly, typhoon Yolanda was the most powerful storm ever, however, US Airforce data contradicts that.

When I was on Okinawa, in the mid 90s, the US Airforce clocked THREE HUNDRED KILOMETERS AN HOUR coming off the hillside at Futenma Air Base.

We lived not far from the hill at that time and survived fine in a concrete house with shutters. And, more to the point, so did ALL YACHTS on the island.

In Okinawa, the boats at Kadena Marina are hauled ashore and they tie themselves down to stainless rings embedded in the marina concrete. Other yachts tie up next to each other in the Higa River (along with commercial barges and fishermen) then spider-web the whole lot to trees on each shore. Lots of old tires alongside, of course, and lots of music playing and beer flowing. The whole event ends up like something of a 2 day party.

Bottom line is that there was not a boat lost in what may well be, if not the most violent storm on record, very close to it.

Would have to go back and check, but, if I remember correctly, the phoon killed 200 or so folks in the Php on its way up, then around 50 in Taiwan, when it ended up there. In Okinawa, we lost two service members who came to watch the waves as the typhoon moved away and got a bit too close to the breakwater.


I knew the service member who was tasked with identifying the one, recovered body.

Just my experience,

G2L
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Old 08-04-2016, 05:01   #62
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Biggest Worry is Other Boats ... And ...

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Are you talking shock loading or steady-state forces?

1" nylon 3-strand line has a safe working load of over 2,500 pounds and a breaking strain of over 20,000 pounds, and 50 feet absorbs a lot of shock.

So assuming the mooring base is the "immovable object", for a cruising yacht it sounds good enough to me. Then the biggest thing to worry about is other boats getting loose.
... if your boat's cleats can handle the load as well as your rope.

That's my big worry at the moment, but I have heard that tying off to the stepped mast is always a last ditch option.

What think thee?

G2L
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Old 09-04-2016, 00:13   #63
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Re: On "stolen" moorings - how to prevent?

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Hi again,

Yeah, I understand the mushroom concept, but it would definitely be a logistical challenge to get something like that done here. Would have to figure the actual size needed and make the mold somehow, then figure out what how much cement it might take to get the necessary weight, and then figure how to deliver and sink it, hoping that after all was said and done, I'd have enough money left to eat.

Not to mention, I might have to buy a pistol in order to get the local fishermen off it : )

Better, I think, to tie up to a bunch of palm trees or mangroves and hope for the best.

No insult meant, just thinkin' aloud.

G2L
Get an 8' x 4' sheet of 1/2" structural ply and cut it into 4ea 2' x 4' pieces.
Fix them together along the 2' sides and then reinforce the top and bottom edges with 4" x 2" timber. Get a piece of weld mesh 4' x 4' and bend it in the middle to 90 degrees and put it in the plywood mould as an inverted V. Take a piece of hose big enough to take about a 1 3/4" rope and double it down through the weld mesh and tie the ends together. Fill mould full of concrete. Thread 1 3/4" rope through hose and splice as endless rope.

We made 12 of them and placed them using a Roberts 50s anchor winch and 4 part blocks. Cost about A$150 each.
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Old 09-04-2016, 21:51   #64
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Re: On "stolen" moorings - how to prevent?

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Originally Posted by RaymondR View Post
Get an 8' x 4' sheet of 1/2" structural ply and cut it into 4ea 2' x 4' pieces.
Fix them together along the 2' sides and then reinforce the top and bottom edges with 4" x 2" timber. Get a piece of weld mesh 4' x 4' and bend it in the middle to 90 degrees and put it in the plywood mould as an inverted V. Take a piece of hose big enough to take about a 1 3/4" rope and double it down through the weld mesh and tie the ends together. Fill mould full of concrete. Thread 1 3/4" rope through hose and splice as endless rope.

We made 12 of them and placed them using a Roberts 50s anchor winch and 4 part blocks. Cost about A$150 each.
Interesting. What does each one end up weighing? And are you inferring that each serves a different mooring and a number of boats, or do you use more than one block at a time to moor a single?

Thanks for sharing,

G2L
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Old 09-04-2016, 23:07   #65
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Re: On "stolen" moorings - how to prevent?

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Interesting. What does each one end up weighing? And are you inferring that each serves a different mooring and a number of boats, or do you use more than one block at a time to moor a single?

Thanks for sharing,

G2L
The buoyed weight of each block is about 4,000 lbs.

The resulting moorings are in a tidal river which floods about every two years. One block constitutes a single mooring.

If I was building a cyclone mooring and had the room in say 10m of water I would place at least 4 blocks in a square pattern about 100 metres from the central position of the boat. It is important to keep the angle of the mooring lines low so that the vector components produce little uplift on the blocks. Provided that care was taken to prevent chaffing of crossing lines the individual moorings could be interlaced to provide multiple moorings. However I would try to keep the boats at least 70m apart.

The energy absorption capacity of nylon pretty well exceeds all other synthetics except the Spectra stuff and nylon does not tend to float so depending on the location I would either bring the four mooring lines together with two riser lines to the bow to allow the boat to swing to the wind or if in narrow waters 2 forward and 2 aft and run breast lines to anything I could tie a rope to.

We don't design boats specifically for living in cyclone or hurricane prone areas but if I did I think I would favour a metal boat because of their general toughness, which could take the bottom and I might even consider a telescoping or fold down mast to allow me to get under bridges and as far up creeks or rivers as possible.
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Old 10-04-2016, 09:28   #66
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Thanks - Re: On "stolen" moorings - how to prevent?

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Originally Posted by RaymondR View Post
The buoyed weight of each block is about 4,000 lbs.

The resulting moorings are in a tidal river which floods about every two years. One block constitutes a single mooring.

If I was building a cyclone mooring and had the room in say 10m of water I would place at least 4 blocks in a square pattern about 100 metres from the central position of the boat. It is important to keep the angle of the mooring lines low so that the vector components produce little uplift on the blocks. Provided that care was taken to prevent chaffing of crossing lines the individual moorings could be interlaced to provide multiple moorings. However I would try to keep the boats at least 70m apart.

The energy absorption capacity of nylon pretty well exceeds all other synthetics except the Spectra stuff and nylon does not tend to float so depending on the location I would either bring the four mooring lines together with two riser lines to the bow to allow the boat to swing to the wind or if in narrow waters 2 forward and 2 aft and run breast lines to anything I could tie a rope to.

We don't design boats specifically for living in cyclone or hurricane prone areas but if I did I think I would favour a metal boat because of their general toughness, which could take the bottom and I might even consider a telescoping or fold down mast to allow me to get under bridges and as far up creeks or rivers as possible.
Thanks Ray,

Very helpful and truly appreciated.


My boat is a light, 4ton Tri, with only a 3 foot draft on the main hull and a foot on the side hulls. How do you think that effects the length of rode needed?

Wondering if the light weight and three hulls would make the boat harder to hold in a storm, or easier than say, a typical monohull with lots of ballast.

Whaddayou think?

G2L
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Old 10-04-2016, 10:35   #67
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Re: Riding out a potential hurricane in the Bahamas

concrete weighs right at 4000 pound per cubic yard (3' X 3' X 3'). Just info for planning. Also check into legal implications of putting a mooring on public waterway. Make sure the water is deep enough at extreme low tide to allow safe passage over it.


Ken
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Old 10-04-2016, 10:44   #68
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Re: Thanks - Re: On "stolen" moorings - how to prevent?

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Originally Posted by Gone2long View Post
Thanks Ray,

Very helpful and truly appreciated.


My boat is a light, 4ton Tri, with only a 3 foot draft on the main hull and a foot on the side hulls. How do you think that effects the length of rode needed?

Wondering if the light weight and three hulls would make the boat harder to hold in a storm, or easier than say, a typical monohull with lots of ballast.

Whaddayou think?

G2L

Most probably your tri take off like a kite in a bad blow... Landing somewhere else.....
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Old 10-04-2016, 11:12   #69
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Re: Thanks - Re: On "stolen" moorings - how to prevent?

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Most probably your tri take off like a kite in a bad blow... Landing somewhere else.....
I've had two tris., and like them. I think this assessment is correct. One that I had sold, ended up upside down, after a hurricane when having been in a slip.
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Old 10-04-2016, 15:08   #70
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Re: Riding out a potential hurricane in the Bahamas

There was a thread on here last year regarding a cat which had sheltered in Island Head Creek for a cyclone (hurricane) and had been 360'd into the mangroves from the wind force. I would guess that what happened was the wind force on the mast was enough to lift a hull and the wind then acted on the windward hull and underside of the bridge deck to roll it further. This incident tends to suggest that light weight multihulls should be ballasted down in really severe blows. If you had time getting a crane and lifting off the mast and rigging might be an alternative.


At the moment I have a steel boat which has four pretty monster cleats bolted into the deck with 4 x 1/2" SS bolts each cleat so having somewhere solid to tie off on is not a problem. However, since I am getting old and lazy and the maintenance is getting on top of me I am going plastic and am off to inspect a boat this week. One of the items on my inspection list is cleat structural integrity. With a really light weight multihull having solid enough places to tie off stern and breast lines might be a problem and I suspect that if there was room I would opt for allowing the vessel to swing to the wind from a single mooring at the bow. I think I would also try to take the mast down and stow it securely if this was possible.


One of the things I now do when in cyclone areas is use Google Earth and the charts to try to identify potential cyclone holes along my proposed route.


On the rode length item.


What one is attempting to achieve is hold the vessel against the horizontal forces generated by the wind against the vessels above water structures whilst allowing some "spring" to allow it to respond to wave action without generating excessive loadings on the moorings. If the water is deep enough the catenary formed by a relatively heavy chain provides both these functions however in shallow, whilst the horizontal translational resistance is there the spring effect may be insufficient to allow the boat to respond without badly snatching at the mooring. Using longish synthetic rope rodes tends to maximize the holding capacity of the mooring anchors as the forces on them are predominately horizontal and because synthetic rope is very stretchy it can absorb a lot of energy when cyclically loaded without generating high stresses at attachment points. Also, in a multi restraint situation allowing sufficient stretch on one restraint will often allow other members to take up some of the load.


I also think that if I was preparing to moor a light weight multihull for extreme weather rather than fasten around hulls and beams with rope I might lay in a number of webbing straps with rings in the ends to fasten rodes to.
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Old 10-04-2016, 15:31   #71
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Re: Riding out a potential hurricane in the Bahamas

Could you flood the Amas?


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Old 10-04-2016, 15:49   #72
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Re: Yeah, but ...

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Europe.
Not true. The Bahamas gets hit more often than S Florida. S Florida gets hit 20 times more than N Florida, etc
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Old 10-04-2016, 16:16   #73
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Re: Riding out a potential hurricane in the Bahamas

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There was a thread on here last year regarding a cat which had sheltered in Island Head Creek for a cyclone (hurricane) and had been 360'd into the mangroves from the wind force. I would guess that what happened was the wind force on the mast was enough to lift a hull and the wind then acted on the windward hull and underside of the bridge deck to roll it further. This incident tends to suggest that light weight multihulls should be ballasted down in really severe blows. If you had time getting a crane and lifting off the mast and rigging might be an alternative.


At the moment I have a steel boat which has four pretty monster cleats bolted into the deck with 4 x 1/2" SS bolts each cleat so having somewhere solid to tie off on is not a problem. However, since I am getting old and lazy and the maintenance is getting on top of me I am going plastic and am off to inspect a boat this week. One of the items on my inspection list is cleat structural integrity. With a really light weight multihull having solid enough places to tie off stern and breast lines might be a problem and I suspect that if there was room I would opt for allowing the vessel to swing to the wind from a single mooring at the bow. I think I would also try to take the mast down and stow it securely if this was possible.


One of the things I now do when in cyclone areas is use Google Earth and the charts to try to identify potential cyclone holes along my proposed route.


On the rode length item.


What one is attempting to achieve is hold the vessel against the horizontal forces generated by the wind against the vessels above water structures whilst allowing some "spring" to allow it to respond to wave action without generating excessive loadings on the moorings. If the water is deep enough the catenary formed by a relatively heavy chain provides both these functions however in shallow, whilst the horizontal translational resistance is there the spring effect may be insufficient to allow the boat to respond without badly snatching at the mooring. Using longish synthetic rope rodes tends to maximize the holding capacity of the mooring anchors as the forces on them are predominately horizontal and because synthetic rope is very stretchy it can absorb a lot of energy when cyclically loaded without generating high stresses at attachment points. Also, in a multi restraint situation allowing sufficient stretch on one restraint will often allow other members to take up some of the load.


I also think that if I was preparing to moor a light weight multihull for extreme weather rather than fasten around hulls and beams with rope I might lay in a number of webbing straps with rings in the ends to fasten rodes to.
I've lived in Florida since 1966. Best advise is to leave, unless you feel ok playing the odds. However playing the odds with your life is much different than playing the odds with your money. You can always make more money. Because thats the bottom line, you're playing the odds of being there when a big one hits. 150 to 180 mph winds - forget about it, hopefully you left the boat and got out, or you loose. Problem is that by the time you know whether it's a really bad storm or not, it might be too late to leave. Storms change quickly! I guarantee you would only do it once, if you survived.

Someone else said that hurricanes hit everywhere, so might as well stay in the Bahamas. Boat yards in N Fl and S GA fill up for a reason during hurricane season.
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