Port Hinchinbrook before and after cyclone Yasi

Port Hinchinbrook marina had around 250 marina berths, with floating pontoons sliding up and down pylons with the tide. Postcard-pretty part of the world.

Just how much of the pylons were above high tide I'm not sure, but when Category 5 cyclone Yasi crossed the coast nearby it delivered a storm surge reported to be 7m. So the pontoons and attached boats simply floated off the top of the pylons, and were driven ashore by the wind, which was over 200km/hr strength.

The question is, how many boats would have been damaged had the pylons been tall enough to retain the pontoons? I'm guessing very few....

Local resident and live-aboard Rob Leydon moved his 43' yacht from the marina to a nearby small creek and tied up to the mangroves, along with 5 other boats. They were all grounded slightly but have freed themselves. Some have a little damage from flying debris but are better off than the ones in the marina as shown in the pictures taken by Marc McCormack of the Cairns Post.

Here is one of the news stories
http://www.cairns.com.au/article/2011/02/04/147851_cyclone.html

I guess a lot will be repaired, but I'd be pretty worried about stress fractures, particularly in FRP boats, triggering future laminate failure. Can such damage be detected even if covered up some paint over quick and nasty repairs?

 

I'd guess you're probably right. If the floats had stayed where they were supposed to be then some of the boats would have come untiled and grounded, but most would probably have been OK. That said, how high is high enough? do you need to make all pylons 10 meters above the high water line? 15?

I think the guy in the mangrove swamp had the right idea. Those trees will absorb a LOT of the energy from the waves.

 

Here in Eastern North Carolina we have had a number of major hurricanes damage our coast. The practice here is to remove your boat from the water before the storm arrives and secure "on the hard". An older feller once told me that "it is easier to pick your boat off of the ground than off of the bottom"

 

Well, if today's news article is right then 1 to 2m higher may have been enough. As the article notes, a previous cyclone had the pontoons near the top of the pylons so there was prior warning of the risk.

Here's the news story
http://www.couriermail.com.au/news/queensland/boaties-furious-at-marina-design/story-e6freoof-1226001119942

and here's an extra picture that was in the paper.

And yes Carteret, the boats that ended up in the carpark will be easier to retrieve than the ones on the bottom of the marina! And there were a few of those. Hauling out would have its own issues and risks. I suspect many of the boats are owned by folks who live far away. Would you fly or drive to a marina in such a situation, and put you life at risk?

 

There is also the issue that with that rather impressive seawall they probably felt their boats were well protected. Live and learn.

 

TV News last night showed a crane lifting boats onto grass 'dry dock' areas, but also showed one happy boat owner. He had been tied to a pontoon where the owner of a large boat had extended the pylons by 2m. The boats on this finger pontoon basically rode out the cyclone undamaged and the pontoon remained in place.

The attached newspaper story is saying the storm surge was only 2-3 m at the port, which makes sense as Hinchinbrook Island protects the port from the open ocean, and the fetch between island and port is relatively short.

It seems that the privately built marina installed shorter than normal pylons, perhaps for aesthetics, but probably as a cost-saving measure also. Longer than normal pylons would clearly have saved a lot of damage.

And I'm guessing that the 12m marina berth I saw for sale (lease to year 2040) at $60,000 is now going to be re-priced!

 

Is anyone interested in some facts about the "Port Hinchinbrook" marina, Breakwater Marina (Townsville) and cyclone YASI? heights of piles etc? Photos?

This is about marina design, insurance thinking, and the appropriateness of abandoning marinas full of boats every year on the NQ/FNQ coast, where there are no regulations related to cyclone-design for marinas.

Yasi's dome was 500-600 kilometres in diameter.

Sea surge height was 5.5 to 6 metres at Cardwell, 4 metres within Hinchinbrook Passage, close to 3 metres at Townsville. Occurred about an hour after low water. Fortunately!

Public piles in PH were barely above HAT, I took photos last year. Some private piles were higher AND some boats on these piles were damaged but despite the extreme sea surge height were not swept ashore. Winds were in excess of 200 km/hr. No piles in NQ/FNQ marinas are tall enough for a sea surge of three metres at HAT.

The water is not quiet when this is happening, wave action in Cleveland Bay (Townsville) was recorded at average of 5 metres continuously over some hours (ie maxima of 10 metres) so sea surge + wave action is a serious challenge to marina design. Wind-and wave-driven pontoons will apply huge forces on very tall piles at high water. Will piles gradually lean in the mud until the pontoons slide off? Even if not in line of ocean wave action, local wind-driven waves generated within the fetch of a marina can quickly reach one metre in a Cat 2 cyclone, and strong "joggling" energy will penetrate from outside.

Insurance companies have changed their thinking. 15 years ago commercial boats were directed (on basis of insurance policies) to leave Breakwater Marina and take shelter in the Hinchinbrook Passage. This time they said "your call", and are paying out on boats abandoned in marinas.

In a marina your boat is at the mercy of the standard of management and other boat owners.

For some of us a boat is not merely a fun plaything. Mine is my home (since 1984). I'm not impressed with my costs going up sharply because of others who abandon their vessels in a marina and (further) don't secure them adequately. During last season's cyclones Anthony and Yasi (and this was after ??Ilui) I was faced with securing a larger Melbourne-owned boat upwind of mine, which was leaning on the pontoon between our boats and was tied up with literally rotting rope. Its decks were littered with metal tools, lengths of chain, ropes and other articles. It was local yachties who tidied the boat, secured it with additional lines, used my heavy line to haul it back off the walkway to cyclone rings further to windward, and repaired its cockpit drains which were open into the body of the yacht. Not that anyone got any thanks for it.

This attitude of "I'm insured, too bad for everyone else" is new in my world and I don't like it. What happened to "take reasonable precautions" that used to be in insurance policies?

There is currently a push to get a marina built out in the open off Mission Beach, a wide-open lee shore where Yasi's winds, unhindered, reached 300 km/hr. There is such a level of ignorance, even after Yasi and the example of "Port Hinchinbrook", that people believe a rock wall will protect a marina. For adequate height, at the standard 30% slope, you can easily estimate the footprint of an adequate rock wall for (say) 4 or 5 metres above HAT, in water depth of 5 metres.

Any ideas? I have more info and photos if there is interest.

 

Thank you for the useful interesting information. There is a lot to consider when choosing a berth.

 

Choosing a berth: an article published in a cruising magazine recently stated that a blow-on berth is ideal, in a cyclone. I do not agree. A boat is free to settle on its lines, appropriately adjusted (lots of long stretchy springs) when hanging OFF a pontoon, and take the forces in ways that best suit the vessel, rather than the blow-on situation of heeling hull pressed onto pontoon edge in strong winds and active water. The longer ropes and distribution of lines of the vessel hanging off allow for smaller shock loadings on the pontoon as well as on the vessel.

Blow-on and blow-off vessels DO NOT heel together - and the pontoon is doing its own thing. Further, the leaning-on vessel can get its toe rail caught under the edge of the pontoon, and I've seen it happen: the vessel, a small sailing yacht, was damaged despite being tended right through the cyclone.

When buying a berth one has to make choices for convenience and safety. Some boaties and managements say that blow-on is best, because you get blown onto your berth most of the time when entering/leaving. This sounds to me like an assumption based on poor vessel-handling skills. My choice has always been for a blow-off berth, for cyclone safety, should I have the misfortune to be trapped in a marina for a high-category cyclone.

Does anyone have experience overseas re marina design and management for cyclones and hurricanes?

To accommodate even a 4 metre sea surge and relevant wave action piles would have to tower at least 5 metres above HAT. Add 4 metre tidal range and 5 metre depth at LAT = pile height of 14 metres above the bottom and 9 metres visible at LAT. How much extra length must be buried in the sea bottom? What are the engineering constraints? Do such tall piles have to be thicker or thicker-walled?

For us in the tropics climate change and more El Nina seasons means that more of the cyclones we normally experience will be higher intensity. Is anyone interested in what this means for NQ/FNQ coastal boating? Qld is not including this in its inquiries into last season's disasters (95% of the state was declared disaster area).

 

About "the port" - no port, it's just a canal estate

News account was inaccurate. "Port Hinchinbrook" is not a port. There is no port there. All really shallow water - the navigable gutter of the Hinchinbrook Channel occurs along the Island side. It is mostly 3-4 metres in depth, some 7 metres, with a few isolated holes of 15-20 metres. Two very long bars at the southern end of Hinchinbrook Channel (Lucinda, and Dungeness) - the outer bar is over 7 km.

"PH" is a privately built canal estate and marina, the site is an old mangrove island (acid marine mud). A 1977 Qld Harbours and Marine Study pointed out the site is unsuitable for a boat harbour, citing no natural deep water, catchment location, and severe siltation (the latter because of its location on the Hinchinbrook Channel, a drowned valley where the bottom moves back and forth driven by strong currents). Nevertheless, in 1994, in the absence of any Qld coastal legislation, the State supported this development because of some old permits.

Hinchinbrook Island is about 3 to 4 kilometres across the Channel from the mainland. The Island provides good shelter under its lee, but not much use for boats on the mainland (western) side of the Channel, specially at the exposed northern end. The cyclone winds roar down those steep western slopes of the Island (think about "bullets" and how they occur), and during Yasi carried terrestrial trees and branches over about 30 boats anchored safely in the mangroves (chainsaws were later used to remove branches from their lines). The mangroves stood and broke the wave action. These were well south in the Channel, not near "Port Hinchinbrook".

The "Port Hinchinbrook" canal estate/marina is less than a kilometre south of the small township of Cardwell, and Cardwell looks out at the open sea towards the Brook Isles. Hecate Point on the near (NW) tip of the Island is low lying.

The sea surge at Cardwell has been determined (Prof Jon Nott, JCU) as being around 5.5 to 6 metres. BOM has similar data. I have taken photos repeatedly starting about 3 weeks after Yasi, including the eroded foreshore and the channel-front houses on "Port Hinchinbrook", many of which now look as if they have been abandoned. The sea surge went through the lower storeys of these large sea-front houses, and the wave action took out a good deal of their seafront artificially raised "land".

The so-called sea surge is caused by the low atmospheric pressure, so width of "seawall" will not help - the sea simple rises as the atmosphere gets less weighty towards the cyclone eye. Being in the dangerous SW quadrant adds it own effects as 300 km/hour winds near the centre drive surface water towards the coast. Anywhere that the sea gets onto, due to sea surge, is then subjected to the destructive wave action of the cyclone.

For those who have never experienced a cyclone, at a little distance (eg Cairns in this case) the northern side (on this coast) has remarkably fine weather compared with the fury on the southern side.

By the way: the "PH" marina is well-silted up (utterly predictable - nothing to do with cyclones) . The developer has not responded to berth owners and block owners agreements. The STATE govt says it will dredge it and bill the developer. I say the developer will not pay - or they would have done it already. So will taxpayers foot the bill? OUCH.

 

There was no excuse for boats to have been caught in a Marina there.
Owners had plenty of notice of impending storms and had no shortage of the best cyclone shelters in the country only a few short miles away.
Any responsible owner would have had there vessel far up a mangrove creek.

 

Sabahacat - yes, I agree with you! And at least one yacht was berthed in PH precisely so it could be quickly moved to the Channel. But Club Marine paid out on about 30 other boats which were destroyed inside PH Marina. I understand that these boats were buried.

That's part of my concern - that insurance companies are now allowing some kinds of "irresponsible" owner behaviour and will be putting up the insurance premiums for the rest of us. Part of the problem may be that the State government now makes "compulsory evacuation" orders. The Port Authority can also order "no movements in port". Then what does the boat owner do?

On the other hand, Club Marine has recently sent a letter saying that boats left "permanently" on moorings or their own tackle off Airlie Beach or in Shute Hbr will not be insured by them (no argument here, Airlie a lee shore and bad in strong northerly winds) (but I don't know how they determine "permanently"). Inadequate and unmaintained mooring arrangements may be part of their story.

Townsville is about 9 hours' sailing from Lucinda (need to cross 7 km bar at/soon after LW in strong SE preceding cyclone, to avoid bad "weather tide"), with another 1/2 day to area of suitable mangrove creeks.

New low level bridge over Ross River (built after Yasi) has stopped masted vessels accessing mangrove creeks in Townsville. It's marinas, Hinchinbrook Passage 12 hours away, or nothing. Hauling out here may not be much of an option in a high cat cyclone. Breakwater Marina piles are only about 1.5-1.7 metres above HAT, except for the new B finger (shorter, only 37 mm left above Yasi's sea surge according to those who stayed) but the marina site is good because of having very broad and very high protection all round from high-energy cyclonic wind waves which can easily penetrate the marina in Ross Creek.

Unlike Townsville, Cairns has good Cyclone Plan organised by Port Authority, all boats are directed which creek to go to, according to type of vessel.

House owners are also discovering that some insurance companies are backing out of insuring houses in NQ/FNQ, or charging much more than in the past. It may be that some of the channel-front houses at "Port Hinchinbrook" which became uninhabitable after Yasi have actually been abandoned. Some look it - tarps over tiled roofs now disarranged and obviously unattended. And a house in the township has been advertised "where is as is" - rebuild or wreck, your choice.

 

the lesson from storm damage is that damage to your boat is almost always caused by your neighbor hitting you. The harbour Im presently moored is often blasted by force ten winter storms . When forecast, Fishing boats move to the windward side of the harbour , put their sterns into the gale then stand watch. If possible always move out of the leeward side of a densely packed harbour then be vigilant.

Concerning Insurance...It encourages poor seamanship and we all pay the penalty.
Last winter in this port, the elecrtricy was disrupted for three weeks due to construction. My next door neighbor started his generator to keep the ship alive then went on vacation. That generator ran three weeks ,unatteded, until it finally ran out of fuel. Only insurance makes you that dumb.

 

I have to agree, Michael! Here on the NQ/FNQ cyclone coast it is sails, sail covers, awnings - all easily removable - which are left out in cyclones, to be shredded and then replaced by insurance. I'm always amazed that insurance companies pay up.

A wise man now deceased, Andy Martin of Middle Percy Island (50 nm off Mackay) wrote to me in 1985: don't waste your money on insurance, buy good ground tackle instead. That was in the good old days, when there were lots of good places to anchor. Ports and marinas have now taken up so many good anchorages here. Boaties have fewer and fewer options outside of marinas which have not been built to withstand much more than a high Cat 2 cyclone. In our marinas you cannot readily change your berth or move your boat to some other spot inside it.

And there is a new breed on the water - marina-hoppers - who drive by GPS, don't like anchoring, don't read paper charts, and expect to be rescued. Many regard their vessels as something to be abandoned in an emergency.

 

Sometimes the damage will be overwhelming no matter how wisely you prepared. The damage portrayed here was more the force of nature than lack of preparation.

http://www.youtube.com/watch?v=TduvuKna_-o