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Old 12-22-2014, 07:57 AM   #101
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>Although the FPB has 135 deg of static stability, and zero dynamic stability because it's around bilge with no flat lifting sections which stabilise the boat when underway, it's a well know fact that long slim hulls roll like pigs in a beam sea..<.

The shape of the hull is NOT what stabilises the boat to make it come upright , the difference in where the center of buoyency and the center of gravity does the work.

The boat does not have zero dynamic stability it is not an empty coke bottle.

The longer roll in a beam sea eases the ride , as the quick jerky roll of a chined boat is what creates a Vomitorium.

Safety and comfort are different requirements .

Safe and comfortable is known as Seakindly.
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Old 12-22-2014, 08:20 AM   #102
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>Although the FPB has 135 deg of static stability, and zero dynamic stability because it's around bilge with no flat lifting sections which stabilise the boat when underway, it's a well know fact that long slim hulls roll like pigs in a beam sea..<.

The shape of the hull is NOT what stabilises the boat to make it come upright , the difference in where the center of buoyency and the center of gravity does the work.

The boat does not have zero dynamic stability it is not an empty coke bottle.

The longer roll in a beam sea eases the ride , as the quick jerky roll of a chined boat is what creates a Vomitorium.

Safety and comfort are different requirements .

Safe and comfortable is known as Seakindly.
I'm very happy to accept your explanation as correct.

Personally I've never been out for a long trip in a small boat in anything stronger than a F 6 or 7, and that was too much for me.

But I have experienced storm force winds on a RORO ferry on the Irish Sea.
I wanted someone to come and shoot me to put me out of my misery!
It was so rough the ferry couldn't dock, and we circled for 18 hours before the storm passed through.

My comfort zone is close inshore, in sight of land, no more than an hour from a safe haven.....call me a wuz if you like!
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Old 12-22-2014, 09:40 AM   #103
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Not quite. They are designed to shear and do without a drop of water leaking. That's exactly what happened to a 55 nordhavn just south of Bermuda on a run to Antigua a few years back. Roll increased 10% according to the owner.

Via iPhone.
With only a 10% increase in roll, why have in the first place. It would be hard to notice such a small difference.
I suspect it was closer to 30% based on common sense
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Old 12-22-2014, 09:42 AM   #104
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I'm very happy to accept your explanation as correct.

Personally I've never been out for a long trip in a small boat in anything stronger than a F 6 or 7, and that was too much for me.

But I have experienced storm force winds on a RORO ferry on the Irish Sea.
I wanted someone to come and shoot me to put me out of my misery!
It was so rough the ferry couldn't dock, and we circled for 18 hours before the storm passed through.

My comfort zone is close inshore, in sight of land, no more than an hour from a safe haven.....call me a wuz if you like!
That's why I don't have a gun on board
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Old 12-22-2014, 10:04 AM   #105
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That's why I don't have a gun on board

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Old 12-22-2014, 01:30 PM   #106
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I come to the conclusion from my life experiences listening to others and reading the multiple posts above that smallish motor boats (40-60 feet) stabilization or not are not a comfortable place to be in any kind of significant wave condition. For those who get sea sick it can be hell on water. I believe most trawler types and family oriented power boats are used primarily in flattish water. There are the adventurous people who go off shore and many report with careful planning few incidence of big waves and really bad weather over many years of adventure. I can relate to all reading this from first hand experience that being out in a big storm with big waves and really high winds is a humbling experience. My experience happened in the late 1960s in the North Atlantic. I and the rest of The CG cutter crew did not want to be there,but we had duty and orders and five souls to rescue. If you have not been there don't ignore the power of the Sea when it gets uppity. The hull design and the type of stabilization may be very important for comfort in moderate seas but in my opinion of little use or significance when the sea kicks up discomfort and dangerous motion is what you get.
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Old 12-22-2014, 02:28 PM   #107
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I come to the conclusion from my life experiences listening to others and reading the multiple posts above that smallish motor boats (40-60 feet) stabilization or not are not a comfortable place to be in any kind of significant wave condition. For those who get sea sick it can be hell on water. I believe most trawler types and family oriented power boats are used primarily in flattish water. There are the adventurous people who go off shore and many report with careful planning few incidence of big waves and really bad weather over many years of adventure. I can relate to all reading this from first hand experience that being out in a big storm with big waves and really high winds is a humbling experience. My experience happened in the late 1960s in the North Atlantic. I and the rest of The CG cutter crew did not want to be there,but we had duty and orders and five souls to rescue. If you have not been there don't ignore the power of the Sea when it gets uppity. The hull design and the type of stabilization may be very important for comfort in moderate seas but in my opinion of little use or significance when the sea kicks up discomfort and dangerous motion is what you get.

Wise words indeed.
We are talking semantics : in a life or death situation stabilisers aren't going to save your life., that's for sure!
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Old 12-22-2014, 03:50 PM   #108
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Wise words indeed.
We are talking semantics : in a life or death situation stabilisers aren't going to save your life., that's for sure!
Thats not entirely true, in EXTREME conditions the lack of stabilizers may tire the crew to the point of exhaustion. Extreme exhaustion can cause the crew to make decisions that could be life threatening.

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Old 12-22-2014, 07:56 PM   #109
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Thats not entirely true, in EXTREME conditions the lack of stabilizers may tire the crew to the point of exhaustion. Extreme exhaustion can cause the crew to make decisions that could be life threatening.

Hollywood
Hollywood what you say assumes that stabilization would do something significant in extreme conditions. What I say is having been there I strongly doubt that any form of stabilization on a small boat will be effective enough to make a significant difference. Our ship at 311 Ft crewed by very experienced CG personnel was getting tossed around violently to the point that there were personnel injuries. The five people on the boat in distress were experienced ocean travelers and their boat was a good sound vessel and was not sinking at the time of rescue, but the seas had smashed ports and the rudder was broken. I was ships surgeon and examined and interviewed those rescued and had first hand information on the nature of their experience. They were delighted and much relieved to get on our ship where the motion was just plan violent and according to them a big improvement compared to what they experienced.
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Old 12-22-2014, 08:27 PM   #110
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60 foot pacific rollers are different than 35 breakers in the gulf stream.

Like most "extreme condition" ,big wave discussions...heck most TF discussions...people often are talking apples and oranges.

Even large vessel/small vessel in the same conditions can be good for one and and for another... change something just a tad...and the tables swap.

I agree stabilization may redude fatigue..and yet I have been in conditions where fins would be coming out of the water and be potentially ineffective.

Heck, one captain of a 210 foot USCG Cutter was contemplating cutting the chains and letting my helo roll over the side to improve stability in a Gulf of Mexico hurricane. The wave pattern was so random it was hard to find a reasonable course to steer.
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Old 12-24-2014, 02:16 PM   #111
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http://youtu.be/hxTW0rU1JLE
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Old 12-24-2014, 03:24 PM   #112
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Good video a taste of what can be, but no where near the peak of violence the sea can express.
I very vividly remember sliding back and forth across the floor of the empty officers mess applying a quick splint cast to the elbow of a crew member who was violently thrown out of a sea berth. I was on my knees he was on his back and we would slide to port hit the wall with a short lull , I would wrap gauze franticly and then the slide to starboard repeating the process back and forth until the job was done. Without actually having been there in that storm and those conditions it is hard for me to see how I or others could really appreciate the awesome power of a riled up sea.
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Old 12-24-2014, 05:33 PM   #113
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It doesn't take seas that big to scare the hell out of you. Having a plan with the next safe anchorage, a drogue (even an old tire on a 100' line) and common sense will take that scare from panic to safe operation. Sailors know that by the time you think about reefing a sail, you're already late. When seas build, head to a safe landing now.
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Old 12-25-2014, 12:56 PM   #114
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60 foot pacific rollers are different than 35 breakers in the gulf stream.

Like most "extreme condition" ,big wave discussions...heck most TF discussions...people often are talking apples and oranges.

Even large vessel/small vessel in the same conditions can be good for one and and for another... change something just a tad...and the tables swap.

I agree stabilization may redude fatigue..and yet I have been in conditions where fins would be coming out of the water and be potentially ineffective.

Heck, one captain of a 210 foot USCG Cutter was contemplating cutting the chains and letting my helo roll over the side to improve stability in a Gulf of Mexico hurricane. The wave pattern was so random it was hard to find a reasonable course to steer.
There seems to be an assumption that bigger is better, but that does not seen to fit the data.

I noticed in Ireland that maybe 85% of the trawlers and fishing boats were in the 40 to 50 ft range, 10% 90 to 120 ft & 5% 150+

Now, clearly there are economic reasons for this, but there is also an issue that more bigger boats succumb to the north Atlantic.

And to compare any military boat, with their portionly narrow beam, is not apropos.
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Old 12-25-2014, 01:41 PM   #115
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WXX3 That "more bigger boats succumb " if true is a difficult statistic to wrap my mind around and get a meaningful conclusion. Maybe bigger boats stay out in bad weather and take bigger risks while the smaller boats seek shelter earlier. On another note I would also like to point out that the size of waves is not nessaseraly the major determinant for how badly a boat will get tossed around. I have been in four and six foot seas that were confused and really washing machine in nature and very dangerous.
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Old 12-25-2014, 06:10 PM   #116
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WXX3 That "more bigger boats succumb " if true is a difficult statistic to wrap my mind around and get a meaningful conclusion. Maybe bigger boats stay out in bad weather and take bigger risks while the smaller boats seek shelter earlier. On another note I would also like to point out that the size of waves is not nessaseraly the major determinant for how badly a boat will get tossed around. I have been in four and six foot seas that were confused and really washing machine in nature and very dangerous.
Fishing boats are not an accurate presentation of what is considered safe boat design. (at least not in the US where boat design is UN regulated) Here the fishing boats are routinely designed by a marine architect, made to conform to a particular fishery. Then, as the fishery goes bust, the owner takes it to a shipyard and has modifications done to change fisheries. These often make fishing boats come of of a rebuild looking NOTHING like they originally were. What started out as a stern trawler, may end up as a side scalloper, then be changed to a suction dredge clammer. Many, Many instances of missing, capsized and roll overs evidenced on East and West Coast fisheries. Think of all the converted alaskan fisheries vessels you see on the TV shows. They have all been modified. Most with just Gus and Frank and a torch and an idea!

Regarding the use of stabilizers. They only work when at speed. At slow speeds (when hove to, or stopped) stabilizers are useless. I cannot imagine any vessel with stabilizers getting any benefit in seas that would preclude being hove too, or stopped. Hanging on a drogue would seem to be the best alternative. BUT, People keep mentioning how a comfortable roll makes the difference. No such idea exists in large seas.

Once a decision is made to 'alter course' because of impaired seakeeping ability, you have altered the wheres' and whys' of boat operation. This becomes less about difference in GM and more about slowing down/altering course for the vessels safety. When heaving to, or making minimum headway to ease the ride, NO one puts their boat beam too. What has been discussed is the pitching head into, or fairwind. The video that started the discussion was most definitely not about beam seas. But the conversation morphing into the expensive boat and how well it rides is not germane. Those little boats with vertical windows stand -0- chance in any seas where the bow will be dipping, taking green water over the stem. And with no shear, that will happen after about 6' or so. The size of the wave and the hull shape on the bow and speed is what will make a boat ride comfortably in a heavy sea. If you can operate running a specific course, with no regard to sea direction then you are in a capable vessel (in that sea condition) The larger the seas, the smaller the boat (also the worse the hull shape) the lower the ability to make way.

Sort of makes the need for accurate weather predictions even more important. How the heck did 'we' do this before satellite weather, and 36, 24 and 12 hour prognosis?


There's two kinds of heavy weather boat operation. The kinds of boats that can GO out and deal with whatever comes. The second are those kinds of boats that have to keep a weather eye out, and plan around weather. The staying put 'till the storm passes kind of boat!

I am not sure the current discussion is about the second type of boat. The OP asked about the type of seas that a 'capable' vessel can operate in, in the context of small boat seamanship. Using pictures of 300', or 400' navy vessels isn't really comparable. (IN all truth they are so narrow they don't ride so well anyway!) That seems to be the 'apples and oranges' referred to about 6 replies back.
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Old 12-25-2014, 10:01 PM   #117
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Your Experience in Really Rough Weather?

It easier and cheaper to over build a small boat and the boat is also more nimble. Those captain and crews in those latitudes are fearless and have skills that very few people have. Those skills are pass down in a hands on training at early age. A poor boat can do more in the hands of skilled crew then a well design boat with poor crew. The debate about what type of boat can put up with what conditions is really about what you are made of and what resource you have to take to the sea.
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Old 12-26-2014, 06:38 AM   #118
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>I believe most trawler types and family oriented power boats are used primarily in flattish water.<

The build scantlings of most rec boats is the main reason they work best in lakes bays and rivers or close inshore.

>Extreme exhaustion can cause the crew to make decisions that could be life threatening.<

Another reason to have a couple of sailboat style bunks , instead of a double bed or lubbers bunk.(Sleeping athwartships) ,
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Old 12-26-2014, 08:51 AM   #119
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Interestingly enough, When I started out looking for a trawler to buy I was contemplating buying an insurance total. One of the boats I found was Steeleaway Steel Away

Imagine my surprise when looking for info about the incident I found a link to this forum.

Anyway: I can't find it now, but I found an official report on the sinking. I can't recall if it was an insurance report, or a USCG report. But similar to the current discussion, the boat was doing well (abeit uncomfortable) in 6' to 8' seas, head on after exiting a river off the Chesapeake. Then once out in the 'open' Chesapeake the owner wanted to turn back and run for shelter.

Apparently she made the initial run INTO the seas fine. It was when she turned about that she had trouble. The owner reported two knockdowns. The first Steeleaway recovered from. The second she didn't.

Upon lifting (30 days or so later) the only damage they found was the lower salon window blown out. AND a missing large flat panel TV. The deduction was, upon being thrown on the beam, the TV went through a salon window. The second knockdown then allowed massive water ingress. Thus the swamping.

So, although there are no snappy videos to show, There is evidence about how seas knock trawlers out of commission. Not even the massive stuff shown in the OPs example!

I will keep trying to dig up the reports on the Steeleaway sinking.
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Old 12-26-2014, 08:19 PM   #120
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Rough Rough Weather, Long Thin Designs

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I'm going to stir up more trouble.......

The Dashew isn't available without stabilisers; they're a compulsory fitted item.
The reason is this: the hull has a very slim length/ beam ratio with a round bilge just like on a sailboat: without stabilisers the boat would turn turtle and have an dangerously high degree of lean. Of course sailboats have a massive weighted keel to stop this very thing happening.

What happens if one of your stabilisers get hit by a floating object when you are 200 miles offshore in bad weather......?
.!
I think all Dashew FPBs and Artnautica LRCs have paravanes - so in the case of the FPB if the stabilizers go out - they will use the Paravanes.

For the Artnauticas - they use the paravanes all the time.







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