Huricanes Don"t Destroy Boats Marinas Do

[Brian Degulis]

Hello All The insurance thread reminded me of something I wrote in 2005 on another forum thought it might be of interest

--------------------------------------------------------------------------------HURICANES DON"T DESTROY BOATS MARINAS DO

The recent postings by fellow listees that used common sense and forethought
to protect there boats from hurricane Dennis caused me to write this. I
don't claim to have any special expertise on the subject these are just my own
observations and I welcome any criticism or comment. HURRICANES DON'T DESTROY
BOATS now think about it unlike many buildings the superstructures and hulls
of our boats are more than adequate to withstand 100+ MPH winds so that
shouldn't be a problem. If you plan to stay at the dock take a good look at your
location if your in an exposed area were the wind can create a sea condition
your chances of avoiding major damage are minimal. Look at the dock itself is
the structure built heavily enough to secure a boat of your size and weight?
many are not is it in good condition? Many are not so what should you do if
your dock is inadequate?

If your on a narrow canal your in luck these are perfect hurricane holes
with a little cooperation from your neighbors you can run your lines to the
opposite side of the canal and tie off in such a way that your boat is positioned
well away from your dock. With good heavy line secured to strong tie off
points on the boat and docks or sea walls this will work just great. The length
of the lines provide lots of stretch to accommodate storm surge and yet still
hold the boat securely. The most common mistake I see people make in
preparing there boats is leaving the lines much to loose in anticipation of storm
surge. The forecasted surge is less than the reality in most cases the farther
inland you are the less it will be. If the lines are left to loose the boat
will allowed to move violently in the wind and the peak loads created by the
weight and momentum of the boat can cause a piling line or cleat to fail
usually starting a chain reaction that destroys boat or dock or both. Nylon line
stretches quite a bit and keeping the boat from moving is important long lines
are always best they provide lots of stretch and minimize angles as the boat
rises. Remember chafing gear for the lines and remember what we have learned
recently about heat build up caused by using hoses as chafing gear.

So why do we lose so many good boats in storms the answer is simple MARINAS
ill conceived marinas have destroyed more boats than any storm ever could. I
live in the Tampa Bay area and in 2001 the West side of the Twin Dolphin
marina was ripped to pieces by a September tropical storm/ minimal hurricane
about a 70 MPH wind. Now it wasn't that boat owners and marina personal didn't
prepare it looked like they secured and tied off pretty well. The problem was
everything that they tied to fell apart in weather that should have been
expected. There breakwater collapsed concrete floating docks broke lose and
millions of dollars worth of boats were destroyed by the marina not the storm. The
entire marina was rebuilt shortly after that and it held up much better in
the storms of 2004. Once again Tampa Bay was spared the full wrath of the
storms with winds in the 70-80 MPH. Still the new breakwater although in tact is
bent up like a pretzel and it's obvious that it would never withstand the
forces of a real hurricane. And yet millions of dollars worth of boats are kept
there.

Tampa Bay didn't see much of hurricane Dennis peak wind of about 50 MPH yet
directly across the bay from where I live the Vinoy marina came apart
destroying a few boats in weather that should have been expected. There are similar
stories on the East coast of FL and probably everywhere effected by
hurricanes. I woke up this morning to my local news channel talking about how the
horrific storm destroyed the Vinoy marina horrific negligence on the part of the
marina owners would have been more accurate. My point is that if you keep your
boat at a marina you are probably amongst the most vulnerable in a storm.
Your dependent upon good construction and maintenance by the marina owners and
responsible preparation by your fellow boaters both of which can be woefully
inadequate. Well, that concludes my rant for this morning lets hope this over
active hurricane season calms down.

Good Luck To All Brian

 

[Genesis]

Maybe someone can tell me why I have to have a gate that is "kid proof" around my pool but a marina can have pilings that are totally falling apart yet keep its operating license from the county or state where it is.......

Hmmmm....

 

[Jaxfishgyd]

There was a write up (think it was by David Pascoe) about how most marinas got wiped out by Andrew in S. Fla but one had no damage.

Difference was the one marina had 4 poles for the each slip (2 front, 2 aft) plus left extra distance between slips so the boats were not shoe-horned in.

I've been a telelphone repairman since 1970 in Florida, worked the aftermath of 7 hurricanes the latest being Katrina. Plus been thru 2 (Cleo in 64 and David in 79).

I have my boat 35 miles inland, a mile off the St Johns River at a marina that is basically in a minor cove. I am protected on 3 sides and the 4th side is only 1/4 mile wide.

Plus we are a fairly new marina (built in 1999?) and the pilings are 16' above high water. I can run lines to two pilings in the back and will run two lines to the concrete pilings in front even though they are holding the floating dock and on the opposite side of the main dock.

I bought a spool of 300' of 3/4" line so I can cut off what ever lenght I need and tie off to anything and everything I can if we should get hit.

So "basically" I am as secured as one can be. But I think about being hit by a hurricane 52 weeks a year.

In today's local paper it stated that several million Floridians have zero plans on what to do if a hurricane should hit their homes.

 

[Pascal]

oh they have plans... demand help after the storm to make up for their lack of preparation ! a week after MINOR huricane Wilma, i remember going to the local supermarket to to get my groceries, everything was back to normal.

that same day, 20 blocks away, i saw a mile long line of cars waiting at a fema distribution center for free ice and water...


back to the original topic... narrow slips, low pilings, floating docks and too few pilings are a receipe for disaster. I can understand the beam issue since wider slips would significnatly reduce the number of slips... but there is no excuse for large slips (40 or 50') that have only one pair of piling at the bow...

 

[thoward]

I so totally disagree! There is no dock structure with boats attached that can withstand the kind of forces that a major hurricane produces. IMO it is not the marinas job to secure/store a boat in a hurricane.....

 

[captddis]

I know people that had boats at both marinas Brian talked about. The damage was predictable. It boils down to location, location. If you moor in a exposed location, You are a goner. Moor in a protected spot that can take the surge, you have a good chance. I told my friend at the Vinoy that his boat would be inside a downtown building in the event of a storm. Exposed floating docks fail everytime. Isla del Sol marina and Tierra Verde marina are two other examples of exposed marinas that will have massive destruction in even a tropical storm.

 

[StratPlan61]

I weathered Hurricane Frances on-board for 6 days at Marina Bay on St Rd 84 in Ft Lauderdale. The biggest problem was there were NO pilings, everyone was tied to the fiberglass floating docks. About 0200 on Day 2 Dock 6 (about 20 yachts per dock) had swayed enough out-of-position to hole it about half way to the end. The dock starting sinking, pulling all of boats down with it. Several days of pumping and patching by 24/7 crews kept it barely afloat, while another dock section was brought over from the other side of the marina cove.
It may not be the responsibility of the marina to provide safe moorage during a hurricane, but I sure would have preferred tall, fixed pilings and plenty of them to run lines to. I had 20 lines out, 10 fenders and was lucky. The flying debris was a larger worry!

Bear'
1984 61' MY Strategic Plan

 

[Brian Degulis]

"I so totally disagree! There is no dock structure with boats attached that can withstand the kind of forces that a major hurricane produces. IMO it is not the marinas job to secure/store a boat in a hurricane."....

It certainly is not some tech logical feat to construct a marina with enough heavy pilings standing high enough above the high water mark to secure a boat in a hurricane. The saddest part of all is that relative to the cost of waterfront property and considering what slip rent is today it's not even all that much more expensive to build right. You need only take a quick look at most marinas accommodating large boats and you can see that no thought at all was put into providing an adequate mooring in weather that should be expected.

I'm certainly not suggesting it's the marinas job to secure your boat I'm only saying that the marina should be providing you with an adequate structure to secure to. The idea that it's just not possible to drastically reduce loss with better construction and maintenance is just plain silly.

Brian

 

[Jaxfishgyd]

Several places here in jacksonville have gone "private" and offer slips for sale. Just down from me is the "OLD" Ortega River Boat Yard that was torn down and rebuilt.
You can buy a small slip for only $130,000. And the sad thing is, they didn't even put in a center piling!. Am guessing that must be a cost extra

 

[Genesis]

To those who say you can't build a dock that will take an EXPOSED direct strike and survive.

Horsecrap.

My dock has SEVEN MILES of exposed fetch. It took eleven hours of pounding from Ivan with 10' breaking seas.

The sum total of damage to the dock, deck and lift structure?

Two boards missing and the under-deck freshwater feed line was broken. Nothing else, including the electrical, was damaged.

The picture below is from AFTER the sun came up, EIGHT HOURS beyond the peak of the storm. When it finally settled down I found a 2x6 from someone ELSE's dock NAILED into my pilings at CHEST LEVEL, with the nails buried all the way to the hilt - I needed a crowbar to get it off.

Build it right or build it twice. With even MINIMAL protection (my dock has ZERO - as I said - SEVEN MILES of open fetch) you could easily moor a big boat to that structure and it would NOT fail.

By the way, of the docks that are up and down my stretch of the bay, mine was the ONLY ONE left standing and undamaged. I have a video taken from the top sundeck a day after the storm with a 360 panaromic view of the destruction.

Any questions?

Click here for the video: http://www.denninger.net/Ivan.wmv

 

[captddis]

Sooo why did you not keep the 45 there? The comments were about keeping BOATS tied up to exposed docks. Leave your boat there and see if you still claim bullcrap.

 

[Genesis]

The water depth did not permit Gigabite to come in there.

At any time - hurricane or no.

That video was taken more than six hours after the peak of the storm - Ivan's landfall was at approximately 2:00 AM.

The windage of that total structure (including the top deck) exceeds that of any boat that would have fit there. Point being, there was ZERO movement. Why? Because of how the dock is built.

All pilings are upsized and pylocked. The entire dock structure is unitized so that forces taken at any given point are transmitted and buffered through the ENTIRE structure, instead of being able to wrack the point of impact loose, causing a progressive failure of the structure.

If I had the depth to keep Gigabite there, I would have, and would have upsized the structure even more (I had it designed, engineered and built to my specifications.) Since dock structures (residential anyway) cannot be insured, and knowing that I live in an area that, on average, takes a Cat 3 hit every 10 years, I built my dock to survive such an impact.

Again - that was the only dock on this part of the bay which was standing and intact. The rest of them were destroyed, with many being reduced to bare, twisted poles.

We didn't even lose the DECKING nor was any of it loose due to wracking forces. In short the dock simply did not move. The video afterwards was LITERALLY the first full day after the storm - ZERO repairs made. We still use that dock daily.

Interestingly enough, if you look at that video again, you'll find that the boathouses are all still there. Why? Because there's a code for those, you see, as the county gets pissed off about whole roofs flying around at 140mph, so they actually have a code for those and inspect.

There is no code for the actual dock strength, however.

By the way, the MARINA where Gigabite was moored (and which we moved her from previous to the storm), was far better protected than my home's dock is; it has spoil islands on all sides but the inlet which faces another land mass less than 1/2 mile away to the northwest (not a high-risk direction for storms.) It is less than 2 miles away by water. They evicted many boats prior to the storm's arrival.

Nonetheless, huge parts of those docks were utterly destroyed - just as were the other residential docks in this vicinity.

Why? My opinion, given what I observed there over the years I was present, was that the structure was weak and severely deteriorated by the passage of time, lack of maintenance and inadequate design up front.

Point being, properly built docks do not automatically fail when storms come, it is entirely possible to build them that won't, and the difference is simply a matter of whether you wish to spend the money on proper design, engineering and maintenance.

It is not an unsolveable problem nor an "Act of God" when they DO fail.

You cannot sell a car in this country that kills you in a 5mph frontal collision or one that has seat belts made out of toilet paper. Why marinas are allowed to operate with dock structures that are so badly wasted that they move noticably under HUMAN traffic, or which have pilings that are WAY short of the expected tidal surge in a storm that is otherwise surviveable, thus GUARANTEEING that your boat will be destroyed if it is there when the storm comes, is beyond me.

 

[thoward]

We are talking about marinas with boats attached! What you fail to take in to mind is that if you have slack lines your boat is going wrack that dock and I am pretty sure 100,000 pounds of repeated pounding is going to tear any dock apart. Also lets not forget the surge where your boat is going to lift those loose pilings up and go for a ride. My boat went through Katrina in Mississppi and that is exactly what happened. She pulled the entire dock and went for a ride. You guys are expecting way too much for a structure that has a million pounds of shifting weight pulling it apart. If a 3000lb car can snap a telephone pole at 20 mph then it does not take much of a step to understand the damage a 100,000 lb boat can do.

 

[Brian Degulis]

I don't think anyone would suggest that all huricane damage can be prevented but I bet 80% could be.

A common sight at todays marinas is to see a slip for a 60 footer consisting of a floating dock and 2 pilings about 70' out and that's it. Do you think thats OK? I think any structural engineer would tell you that with a typical 60' boat in that space the safe working load on that structure would be exceeded in winds of about 40 MPH.

The Tampa area saw 2 marinas completly destroyed and one almost destroyed from winds that never exceeded 80 MPH. Would you consider that exceptable.

I stayed at one of those marinas over the weekend it's been rebuilt with nice heavy concrete piers but the pilings where so short that the rub rails on my 61 MY where above the tops at high tide.

My point is this every time a huricane strikes there's a lot of damage that could easily be prevented if marinas where designed and maintained corectly.
Crapy designs and poor maintenance destroy more boats than the storms themselves.

Brian

 

[Genesis]

In a word, nonsense.

If you're improperly secured then your boat goes under!

I've seen it happen - the pilings do just fine - you're literally held down and sink.

People think this is rocket science. It is not. If I can stick a boat on the end of a rode in a hurricane and have it hold, I can also stick it in a slip at a marina and have it hold, provided that the pilings and structure are built properly for the loads contemplated.

"Loads contemplated" include storms. You guys never get severe weather? Where do you live? You think it requires a HURRICANE to get 100mph winds? Ha!

How come my little bitty house stays together in 130mph winds with flat sides that act like sails and catch the wind? Its because the structure of the house is unitized. This is also why if you lose a window you're hosed - the structure is not designed to take pressure loads from the INSIDE so once the wind gets in the roof comes off.

This is an engineering problem guys and it CAN be solved. Yes, the boats have to be properly secured, but these are not snatch loads - there is tremendous stretch both in the lines and the pilings.

How many of you have actually been through a hurricane with a boat? After Ivan Gigabite (which was moored AT A DOCK guys!) had the chafing gear showing BURN damage in a few places. The dock it was secured to held and so did the deck hardware. But the evidence of extreme stress was present in the lines used (they were all discarded after the event, natch.)

This is NOT an impossible problem to solve. I know a lot of people think it IS impossible, but its not, any more than its impossible to build a dock that will survive breaking seas far above the deck height.

Now look - if your deck hardware is inadequate, if your lines are inadequate, if you get holed by someone who gets loose, if you're improperly tied, ok. There ARE marinas and slips that cannot be made safe for YOUR boat, mostly because the slip is too narrow to permit proper line setting (you can't set up for the surge without banging the pilings and/or simply have insufficient clearance) or the pilings are too short which is how you get speared and sunk from the bottom.

But having gone through this both as a dock and boat owner, more than once, I will say this - if your marina is sited in a place where it has several MILES of unbroken fetch it shouldn't be there! That permit should NOT have been granted - period! Some sort of break should have been mandatory to cut the breaking seas down to size, or if that couldn't be done, the permit should have been denied. Absent a HORRIBLE location the rest of the problem is one of inadequate design, engineering and most of all maintenance.

After Ivan I can't tell you how many pilings I saw that were snapped off at the bottom. Upon inspecting the broken pieces what was seen was clear evidence of wastage. Those pilings did not fail due to storm loads, they failed due to deterioration - they should have been replaced BEFORE they failed! I also saw stringers that were NAILED, which are GUARANTEED to come loose under load, instead of being through-bolted. I saw "bolts" that were so wasted you could have snapped them with a 1/4" drive socket IN YOUR HAND.

Never mind floating docks on pilings that are 3-4' above the water - gee, what do you think happens when a 6' surge shows up? They all float off and......

I have ALSO seen properly-designed docks RIGHT NEXT TO structures that were NOT properly designed, such as my NEXT DOOR NEIGHBORS dock and mine. HIS came apart because of the sins of original construction. Mine held. There was ONE HUNDRED AND FIFTY FEET separating them. Same conditions guys.

 

[Pascal]

we had about 100kts here during wilma in 2005 and most boats, even the most exposed, held just fine on two pairs of pilings. I have no doubt that with one or two extra pairs, they woudl have held up much higher winds.

it's all about preparation and spreading the loads. floating docks and insuficient pilings are not going to cut it.

same with homes... When my house was built on St Barth in the late 80s, it was built like it shoudl be on a hurricane prone island. Blocks with reinforced concrete pilars at every corner, door and window, with reinforced concrete at the top of every wall, and a roof structure that was all thru bolted.. no nails. Roofs are anchored into the concrete with threaded bars bent around the steel

after strong and slow (36hrs) near cat 5 Luis is 95, there was no damage. Even teh 8' galleries in front of the house stayed on.

compare that to local florida building codes where roofs are nailed and "luxury" homes built out of nail matchsticks....

it's all about anticipating the loads...

 

[thoward]

Nonsense? So what works up there will work down here? Sorry boys but geology has a lot to do with how the dock is going to hold up. Pilings in mud/silt are not going to hold like those in sand. My marina for instance has 6 pilings for the smaller boats and 8 for my class set in a sandy bottom. The dock is screwed together and crossbraced but twice(once it was only 1 year old) was broke off at the ground. We are directly in the inlet so I am sure it had a great deal to do with it. You may be able to have one hold up great in some areas but there are some areas that there is no way it is going to hold up. You are also going to have a darn hard time setting your lines when the surge is 8-10' or more in some areas. I will lay dollars to doughnuts those 8 pilings will not hold our boat in a Cat 2 + hurricane and I will not take that chance.

 

[Genesis]

If you have enough width surge is not a problem; take lines to FURTHER DISTANT pilings so as to both give you a smaller angle AND more stretch (less snatch loading.) This was the strategy we used for Ivan with excellent success.

If you don't have enough width and are forced due to piling configuration to run short scope on the lines then you're unsafe in that location.

The biggest problem with a properly-configured dock structure is providing fairlead and chafe protection on your lines in a severe storm; you can't use long chafe guards that have no permeability because of the tremendous HEAT generated internally in the lines - nylon will literally melt under hurricane loads! The water (from the rain in the storm and windblown water) is actually an essential part of maintaining line integrity. While old fire hose makes excellent chafe protection its lack of permeability can be a problem for this reason, especially if you try to get cute and use a longer length of it than you really need.

Ideally you want the chocks/fairleads CLOSE to the cleat where the line terminates so that the stretch and thus motion to that point is small; this allows you to use smaller chafe guards and allow cooling water to get to the line under the guard.

 

[Jaxfishgyd]

Here's a portion about properly built marinas.... The entire story is at http://www.yachtsurvey.com/huricane.htm


The Coco Plum Experience This private marina at the south end of Coral Gables gave us an excellent lesson in hurricane protection in the aftermath of Andrew. Most of the boats in all the marinas to the north and south of Coco Plum were destroyed, even though all these marinas directly front Biscayne Bay. And yet, incredibly, not one boat at Coco Plum was lost, and only a few had significant damage.

So what distinguished this marina from all others? First, the entrance channel to the marina has a sharp dog leg that greatly reduced wave action. Next, the marina was protected by a buffer zone of dense mangroves. But just as important, the concrete docks at the marina have very wide slips with heavy, tall pilings. This allowed boat owners to tie their boats well off the docks. Even with a 10' storm surge, not one boat came down on the pilings, and hence none were lost. Whereas at Diner Key, Matheson Hammock and Black Point, nearly all the boats were lost because all had narrow slips and inadequate pilings. The lesson for boat owners with boats in narrow slips is that your chance for survival is very slim indeed.

 

[Pascal]

many boats suffered rub rail damage at DKM during wilma because the slips are too narrrow. I had to adjust my lines a couple of times during the storm to stay off the pilings as winds shifted.

pilings are too low too, even though surge was only 5' or so i got a few scratches as the rub rail reached 2' above the piling tops.