Battening down for heavy weather
With the recent unpleasantness off Cape Horn (as well as reading Lin and Larry Pardey's Storm Tactics) it occured to me that I have seen little on the topic of outfitting for heavy weather on this site.
During that catastrophe the vessel had a forward hatch stove in and was dis-masted. To me, those are all quite forseeable events far offshore. John Vigor refrains, "think inverted" and it seems sensible to me.
Sailboats enjoy one characteristic that ships do not; they are generally self-righting. That imparts a huge survivability factor and I wonder if ti is exploited to it's fullest.
I am more interested in your thoughts than expressing mine, as my offshore experience has been on very large vessels, but I cannot help but wonder about a few things. Most hatches I've seen on foredecks seem to be designed for sail stowing, ventilation, and light. The fact we're cutting a big hole in the boat, that should be as strong as the deck around it, seems to go by the board. If such a hatch is stove in, where is the dunnage for damage control use? One would think that such material would come with the vessel, perhaps per-fabricated and stowed in it's own locker. I do not hear much talk of carrying a wooden spar lashed on deck-little imagination is needed to see how this could be put to use. Certainly a sea-anchor and storm oil would be carried.
We've seen two instances in the last month where sailors departed their vessel while the vessel was still afloat. In either case I suspect that Capt. Bligh would have found either vessel to be far superior to that to which he was consigned. Is all of our attention focused on rescue, to the detriment of giving up the ship? From those who venture far offshore I'd be interested in what you've outfitted in these areas and others. Thanks in advance.
Most Monohulls are self-righting to some degree... Most multihulls are not... However, most multihulls have positive buoyancy, and even if inverted are in little danger of sinking, where most monohulls would be.
Plywood, preferably 1/2", should be kept aboard to cover the hatches in case of them being stove in.
Storm oil is a violation of many international treaties and not as effective as you would think. Instead of a sea anchor, I generally recommend a Jordan Series Drogue for small sailing craft.
Leaving the vessel, if it is in no danger of sinking is often the most dangerous thing to do... which is why they always recommend that you only "Step up in to a liferaft."
oil on thr water
goodday all;many a time i would have had my butt handed to me while shark fishins 50 miles out in the gulf of maine had it not been fot the fish oil emenating from my chum buckets..i fish offshore in a 19 foot mako. when the seas roll up i use 3 -5 gallon buckets bridled off the bow because i have a cut down stern with only 9 inches of freeboard.in any good tackle shop you can purchase bulk fish oil however'if you chum they will come'
Storm oil is very effective and is still, as far as I know carried by merchant ships. The dispenser is still sold by the ship chandlers. This snippet published in a 2005 article might be interesting,
“Sailors who traditionally dumped barrels of oil into the sea to calm stormy waters may have been on to something, a new study suggests. The old practice reduces wind speeds in tropical hurricanes by damping ocean spray, according to a new mathematical “sandwich model”.
As hurricane winds kick up ocean waves, large water droplets become suspended in the air. This cloud of spray can be treated mathematically as a third fluid sandwiched between the air and sea. “Our calculations show that drops in the spray decrease turbulence and reduce friction, allowing for far greater wind speeds – sometimes eight times as much,” explains researcher Alexandre Chorin at the University of California at Berkeley, US.
He believes the findings shed light on an age-old sea ritual. “Ancient mariners poured oil on troubled waters – hence the expression – but it was never very clear what this accomplished,” says Chorin. Since oil inhibits the formation of drops, Chorin thinks the strategy would have increased the drag in the air and successfully decreased the intensity of the squalls.
The researchers suggest that, during a tropical storm, aeroplanes could deliver harmless surfactants to the ocean surface – reducing surface tension in water and stopping droplets from forming – perhaps preventing a hurricane developing.
But some climate physicists remain unconvinced. “I am very doubtful about this approach,” says Julian Hunt at University College London, UK. He has studied turbulence both theoretically and in the laboratory and thinks that the high wind speeds are caused by an entirely different mechanism.
In a paper submitted this month to the Journal of Fluid Dynamics, Hunt suggests that variations in the turbulence between different regions of the hurricane cause sharp jumps in wind speed.
Chorin stresses that his team has not carried out experimental tests on the application of this work with tropical storms, but feels that it could be explored in the future.
Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0505209102)”
Tartan- I don't really doubt the science or the conclusions for that matter, but can you imagine the amount of oil you would have to carry onboard to have any affect on hurricane windspeed!!! Most boats are doing good to have the tankage for need fuel. We would all have to be sailing something that had EXON written on the side. Isn't this a practice that started with whaleships that had huge amounts of sperm oil on board??? (G- just let it go, please!)
This time I will be serious. (I can be when need to).
I read Sail's post, and all subsequent ones. (I needed T's help with some meanings, thanks T).
Opening a hatch or a port for sail handling or light is a common thing today and is required, however it needs to be done properly.
Here some points:
One is that today, boats without light inside don't sell, look at the raise in numbers of deck saloons and other large deck houses surrounded by windows produced today. There is a trend there. Unfortunately, the larger the hole, the weaker the structural integrity of the surrounding structure. Add that to the decrease in construction performance, to decrease production costs and the ingredients are right for catastrophe.
Second the hatch construction itself. There are several types of hatches and they have to respect certain codes (Lewmar I know does), because when deciding on my hatches we were offered a multitude of hatches that went from light less resistant to slim line for aerodynamic qualities to oceanic types. Unfortunately, the most expensive are the oceanic (due to heavier materials and type of construction) and the aerodynamic, due to their cost in research. In parallel, you may acquire a hatch that fits the job, at a lesser cost, but not suitable for oceanic conditions. Albeit the weight, I decided on oceanic hatches, mainly for safety, but also because they will take more abuse. I had however a 45% increase in cost due to that. And I only built one boat, Imagine production houses that build 60 or more.
Third we have the rules of each Country. Over here, you have a minimum requirements as far as hatches and ports go, to prevent bad quality and construction, however, it does not cover replacements and modifications. And I know that some production get away from this…..
In my particular case, we had to reinforce (and they inspected it) the cabins structure around the hatch to satisfy the inspectors, but I know that many builders here and there do not do this. I don’t believe that what will fail is the cabin structure, but the hatch itself.
Initially, my boat was going to have nice hull windows and we soon decided, absolutely not. The boat will race, will hit pontoons, other boats etc, and even on a cruising boat, the occasional “love rub” in inevitable, then water starts getting in.
As far as procedures to improvise and cover a hatch hole. I think you may hit a good point. As far as I know, there are none here for oceanic passages. I know however, that a friend that sailed to Macau, decided to cover one of his ports and had makeshift boards to cover the hatches form the inside.
So at the end of the day, we are relying in one’s experience and seamanship to succeed and cover all bases for maximum safety.
Truth is, if one of my hatches goes, and the weather hits, I am done. So after this, I am going to make wood plates for my hatches, just in case.
Very very good point here Sail.
I wasn't stating that dumping large quantities of oil on the water wasn't effective... but it is highly illegal... the MARPOL treaty makes it so.
Part of the problem with the idea of pouring oil on troubled waters is that it takes a fair amount, and you have to keep doing it as the boat moves/drifts/blows out of the area the original oil slick is working on.
Yes it’s not considered practical for something like a hurricane. But only a few quarts are needed if you want a slick for maneuvering. I have not used oil but have sailed with people who sailed on commercial sailing ships and they have used oil. Their description of its use and its influence on the waves was very interesting.
In the old days it was recommended to flow oil if you were lying a-hull but boats today are designed differently and forreach much faster so oil is of no practical use in that situation today.
I also think this is the type of subject that deteriorates into nonsense very quickly and should be dropped
All the best,
The sea anchors found on merchant ship lifeboats carry a cone shaped dispenser designed to dispense vegetable or fish oil, neither of which is harmful. The amount held is approximately 1 gallon, the point being that it does not take a great quantity to acheive the desired effect. The response to this surprises me-I thought this information was common knowledge.
Marpol's opinion on this, being in a life/ship saving situation, can be left to another thread, let's stay on the topic of keeping positive buoyancy.
The Pardey's say, to Tartan's point, one must eliminate fore-reaching to create a "slick" to windward. They also seem to be big fans of the parachute sea anchor, cautioning against running too long before the wind.
Keep it comin'.
|All times are GMT -4. The time now is 08:06 PM.|
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2015, vBulletin Solutions, Inc.
User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
(c) Marine.com LLC 2000-2012