Principles of yachts design,plywood alternative for boat decking,boat dealers long island ny 2014 - Plans Download

Published 23.11.2015 | Author : admin | Category : Free Fishing Boat Plans

Over the last couple of years we have had a number of discussions about the mechanics of stability and capsize risks. Our goal is to convince you that heavy weather risks, while remote,  should be taken seriously.
This photo is from the 1979 Fastnet Race in which 23 yachts were abandoned and numerous crew lost their lives. This is a tough part of the world to cruise, worse yet if you are scheduled to race with no precedent for postponing due to weather which is almost always bad at some point  in the race, with 98 being especially awful. OK, time for some basic principles of naval architecture. Stability, capsize resistance, and recovery, is a complex subject.
The next factor is the buoyancy and added stability provided by the hull and any structure mounted on the deck as the boat heels. Every vessel has a stability curve, the shape of which determines how it reacts to waves, how far you can heel before losing the ability to come back, and the restoring force required to get the boat upright again if capsized. It is quite possible to have a design which will float on its side, not capsize, and not recover from a heel past the point of positive stability.
In order to have heeled buoyancy work for you the windows, doors, and vents need to stay water tight. Free surface effect of liquids in fuel and water tanks can be a major contributor to capsize, if the tanks are not well baffled, or filled. For sailboat designers, builders, and buyers, analyzing stability is at the top of the list. Let’s start with a modern sailboat stability curve, this one for the Halberg Rassey 40 (German Frers design). There is some inverted stability and wave energy will be required to right the capsized vessel (but not a lot). The graphic above is from a research project done to investigate commercial trawler safety as a result of numerous capsize incidents and the associated loss of life. Although the FPB 64 specifications call for 130 degrees this shows ultimate stability remains positive until 150 degrees. There is virtually no stability below the line indicating little wave energy is required to right the boat in a full capsize. When designing a beamy yacht, relative to a narrower configuration, for a given roll period (or comfort level), the VCG has to go up. Avoid adding weight high (likes solid fly bridge tops, extra roller furling sails, and oversized rigging. The images which follow are derived from the FPB 64 hull shape, basic house volumes, and a variety of heel angles. What the heeled shape looks like relative to how it will skid, or trip, when impacted by a breaking wave crest on the beam (skidding is a highly desirable reaction). The fish eye view shows the skeg and rudder still immersed, but rapidly losing their grip on the water. 90 degrees and we are just now immersing the Dorade vents, which is why they have closure plates adjustable from inside the boat. Do the weather and sea state risks warrant our concern with stability and capsize, especially with modern weather forecasting? Conditions affecting sea state such as bottom topography, surface currents, and lee shore wave bounce.
Possibility of secondary and tertiary wave trains interacting with primary wind driven seas.
Secondary destination options if the situation deteriorates, or the primary goal becomes to risky. Primary and secondary destination approach considerations (lee shore, difficult navigation in adverse conditions, breaking bar). Possibility that it may be necessary to stand off in deep water until seas calm down and allow shelter. We are expert enough in weather forecasting to feel confident in our ability to avoid most severe weather. If you are buying a yacht, ask to see the stability curves (something common with commercial vessels and yachts built to code, and most sailing designs). We started with Fast Yacht, the first of the 3D hull design programs along with its VPP code, mid 1980s. Everyone would benefit, the insurance folks, the Coast Guard, the boat owners and the ocean. We are curious of the roll period of your 64’ and did you make some seas trials without Naiads ? Both the FPB 83 and FPB 64 have natural roll periods of about four seconds due to their relatively high polar moments. As to comfort without the NAIAD stabilizers, the boats will roll a bit, but between the slow roll period and the location of the living space so close to the roll center, the motion is surprisingly pleasant. One of my employees had a night job building seats for a whale watching motor vessel intended to operate in Hawaii.
First of all thank you for contributing to my ongoing education, how much impact would going to a lighter stronger metal, like grade 5 titanium make in lowering your VCG, if you used it when possible in your designs.
Thus looking at the curves, the maximum working heel angle is for type 1 and type 11 is much less than 24 degrees and for the Halberg Rassie less than 65 degrees. Now, of course, this instability is dependent upon the external heeling moment being sustained and in reality once the angle of heel changes the load can be taken out of the sails and the vessel will then fall back to a more stable heel angle. My conclusion is that as well as the GZ curve its SLOPE will give a better indication of stability under sail . I have been reading your blogs for years and have been debating the traditional trawler versus more contemporary designs.
In my quest to find the perfect vessel, I have been also following another build, a Northern Marine 85. I am curious to know whether you find any of the study’s numbers present a glaringly obvious problem, or whether their recommendations of having someone onsite to evaluate during launch was sufficient given the numbers stated. It is moments like this when people like me appreciate people like you being involved in the marketplace.
Hello – I have for my 1980s designed boat boat a paper lines plan with a table of offsets. Tiara Yachts, a division of S2 Yachts, is recognized throughout the industry as a builder of high-quality powerboats. Founded in 2002, Meridian Yachts has quickly become one of North America's foremost builder of bridge boats. Establishing a new leading edge in naval architecture, propulsion and liveaboard comfort, the 541 Sedan more than succeeds at the core principles that define the fleet's legacy - livability, maneuverability and cruisability - it sets new standards for each.


The 541 Sedan is the first Meridian to come standard with Zeus, one of the most technically advanced propulsion systems in the world. Impeccably designed living spaces and sleeping quarters create a welcoming, relaxed atmosphere onboard. Sea Force One Motor Yacht is and Admiral 54, designed by Luca Dini and produced by AMY, stands out in the international panorama as being a really unique yacht.
The hull is polished black, the shape is pleasant and imposing, the outside lighting is impressive and also includes the part underwater. Conceived to accommodate 10 passengers in five cabins and up to 12 crew members, the yacht is 54 meters long, 10.50 meters wide and spreads over four bridges. The sundeck is a huge relax area with Jacuzzi and sushi bar, whereas the upper deck hosts a wide dining room that can accommodate up to 30 people and a gym.
Harmonious lines and one of the largest flybridges in its class, for incredible moments of open-air relaxation. Recently these issues have come up again, and we thought this might be a good time to revisit this fundamental safety issue. And that sailors and powerboaters should be realistic in assessing the capabilities of crew and vessel.
The two vessles are running with the seas, but the breaking crest which capsizes the lead trawler is from the beam. It is of an RNLI lifeboat out on a rescue mission after the seas had substantially flattened.You can download the post race inquiry here.
Yet we know for sure that in spite of all our efforts to the contrary, one of these days we will get caught again. Refer to the lead photo of the Japanese car carrier in the Gulf of Alaska for a good example of this. Once there is a major inrush of water, perhaps just an off center vent, the situation quickly becomes grave. Almost all sailboat design and sea trial articles will publish a stability curve. There seems to be less concern from the power boat end of the spectrum, which may be acceptable in protected waters, with shelter close at hand.
The type one design(blue line) is a traditional moderate freeboard trawler while the type two (magenta line) is a high freeboard enclosed deck design.
There is a complex relationship between form stability from hull shape, VCG, the way weight is distributed (polar moments), where you live and work relative to the roll and pitch centers, and how this impacts comfort and cargo security.
For example, if you have four fuel tanks and carrying half your fuel capacity, it is better to put the fuel in two filled tanks than four half full tanks. The deck edge is clear of the water, and there are no air intakes, hatches, doors, or other items about which to worry. Note that the house and just a touch of deck are required for floatation, with the deck barely immersed This means the hydrostatic pressure on the entry door and deck hatches is low. If you have raced planing dinghies or catamarans you know that when the wind is puffy, and you are occasionally overpowered on a reach, pulling up the centerboard (leeward fin on a cat) allows the boat to skid sideways with the puffs, dissipating the wind energy.
If the boat is heavy, with a deep hull or keel, immersed surfaces and inertia of the mass, tends to hold the boat in place, allowing more energy from the wave to be transferred to the topsides.
If these are not available, there are naval architects who will check the righting moment, and then using this plus a set of lines, calculate a stability curve. It is a lovely winter day in Tucson, Arizona, we are starting to think about some testing we need to do with Wind Horse, including a gale or two in the Gulf Stream. Stayed with it, or more properly George Hazen and Bruce Hays, as various defense contractors bought and sold their company.
I can not honestly say I understand everything but I know enough to know that you know what you are talking about and I really appreciate you putting it all together for us to absorb and grasp over time.
This is a strong well designed and built alloy boat that comes as close to your philosophy as I can afford at the moment. The main thing is to go cruising before it is too late and waiting around trying to earn additional funds for a more costly vessel, versus going now, never makes sense.
I assume power or sail boats will react similar with regards to the stability calculations?
There is may be a difference in how sail and power react based on their immersed hull shapes and if they skid off with the wave impact or sit there and absorb all the energy. We also don’t know if she had any free water affects from liquids sloshing in her tanks.
If we were starting a long passage and lost the stabilizer system, we’d not hesitate to continue. The vessel had passed its USCG stability test, was fully certified to carry passengers and was awaiting shipment by barge to Maui. Compared that to the 60 meters French luxo motor yacht (designed and built in 2010) that just capsized and sunk today in the Aegean sea after some mechanical failure in a not very stormy sea. The classical GZ curve obtained from a simple STATIC analysis, gives the maximum angle that a vessel can recover from providing there is NO EXTERNAL HEELING moment; thus if we look at Fig 14 the type 1 boat can recover from an angle of heel up to 90 degrees, while the type 11 boat can only recover from a heel angle of about 50 degrees and the Halberg Rassie 40 can recover from an angle of heel of 130 degrees. But Murphy’s law will ensure that the main sheets will get stuck and the load will increase! I think this is important because my feeling is that the so called angle of vanishing stability- when the GZ curve has a value of zero-is misleading and can give an false impression of security, when in fact, dynamic stability occurs at a value MUCH LESS than half of this angle.
I have really enjoyed reading the two books you recently released on Weather and storm survival. Ranging from thirty-four to sixty feet in length, Meridian yachts are designed to deliver comfortable livability and exceptional value.
So at nearly 54 feet in length the 541, with its twin independently articulated Zeus pod drives, feels effortlessly maneuverable and intuitive to control. The three-stateroom, two-head layout provides berths for six passengers, while a convertible dinette can accommodate two more. If you continue without changing your settings, we'll assume that you are happy to receive all cookies on this website.
The typical shipping construction principles, which were new for the yachting sector, were used right from the first designing phases of the steel hull and light alloy superstructure and the results are excellent.
The stern is organized to offer an unsurpassed'terrace on the sea': the garage was decorated with a sofa and a table so that when the platform is open it becomes a real patio Tenders and water jets here reside in a side-accessed garage.
Particular attention has been paid to the comfort of guests thanks to stringent standards for soundproofing and noise reduction. Aside from a tragedy, this race was a seminal event in yacht design, and gave rise to a variety of research on capsize mechanisms. Hence, the emphasis on understanding the mechanics of what creates problems in heavy weather and how to mitigate them. High initial stability can be good for sailboats as it allows more sail area, but can be a negative for motor vessels because of quick, uncomfortable motion associated therewith.


Offshore, with wind and wave risks factored in, one could argue for a more proactive approach to stability analysis. Note that both reach maximum stablity at around 25 degrees and then righting force drops precipitously. The final shape shall remain quietly secured – there is a limit to how much information we want to give away. Raising the VCG at small angles of heel has little impact, as hull form stability is dominant.
There is little in this combination of hull and fins to resist skidding sideways with wave impact and with most of the resistance to skidding aft (skeg, rudder, and hull), the tendency will be for the boat to rotate on its axis bow down the wave. Modern, relatively light keelboats with high freeboard, will skid on their topsides when knocked down due to being overpowered, typically with a spinnaker flying.
If the boat skids off to leeward with the wave impact, then the wave crest cannot impart the same force to the hull. This article took some time to work up, but so many folks are crossing oceans and taking risks of which they are unaware, that we thought we owed them the effort.
Sailboats also have a rig which contributes to polar moments, more of which are better than less when it comes to absorbing roll energy. They are running with the power skiff, (about 10,000lb.) on deck which is a complete no-no in rough weather.
If the wave period is the same or a harmonic of the vessel’s, then it can get uncomfortable in a hurry. And, you need the polar moments of some of these heavier high items to slow down the roll period. However, if there is an external heeling moment, as there is due to the wind in a sail boat, then a DYNAMIC analysis will show that stability is governed by the slope of the GZ curve.
While a full dynamic analysis involves inertia forces and moments, the important information is obtained from the slope of the GZ curve and this is readily obtained. You can usually find these settings in the 'options' or 'preferences' menu of your browser.
Two Caterpillar 3516B engines power the Admiral 54, reaching 17.5 knots and achieving around 5,000 nautical miles at economical speed. These are worth watching as they will give you a feel for the real world risks involved, albeit small, in this watery world for which we all share a love. However, waves coming from a different direction than the norm are not at all unusual, and if there has been a frontal passage you will get a 90-degree wind shift with its accompanying new sea direction. Author (and good friend) John Rousmaniere was in the race and wrote an interesting piece on the 20 year anniversary which you can read here. Of course there have been other gales and the occasional storm, like the 55 knots we saw one long evening on our way to the Austral Islands, but these all took place in deep water, unaffected by wave steepening counter current.
More stability is always faster, hence the pressure on increasing keel draft, and keeping weight low in the boat.
There are numerous computer programs that will roll a 3D model through specified heel angles, calculating the new waterplane and stability at each point. The traditional design loses positive stability at 50 degrees while the design with more superstructure will go to 85 degrees. But as the boat begins to heel, the VCG assumes greater importance, to the point where it is a major determinant of ultimate stability. In our opinion the closer the bow is to heading up or down wave, and the further you are from having the waves abeam, the safer you will be. Fully inverted like this the hull is highly unstable, meaning very little force is required to get the boat rolling right side up.
These boats should never run in that configuration in anything but relatively calm weather. For those folks who think they can ride out all situations heading into the waves, this should be a wake up call. To those aspiring to design we’d advise first to get some offshore passages under their belt, then to live with a yacht or two over time, and then to periodically head offshore. As one can see the slope of the curve is zero when the GZ curve is maximum, after this point the resistance starts to fall off and if the EXTERNAL HEELING MOMENT IS SUSTAINED the angle of heel will continue to increase until the masts are in the water! One is at the level of the main hall and thanks to a royal staircase that connects it to the water, it becomes an access way for guests. For power vessels, pleasure and commercial, the combination of high initial stability and a low VCG is uncomfortable, and can be dangerous, to the point where freighters will shed deck load if stability is too high with the accompanying snap motion. The other part of this is the VCG and that is a spreadsheet exercise, albeit in some detail, to determine where the weights which make up the boat are located. Passenger liners and many freighters have ballast tanks up high to reduce stability and lengthen the roll period. One of the areas we study are the shapes of the hull at various heel angles, and how we think the boat will react in a breaking sea.
Think of this like a boxer rolling away from a punch, taking the sting out of it as it were. The ability to skid is a primary safety factor in dangerous seas. Yet we know that there is always a risk, especially on passages of more than two days, that the weather models, the professional forecasters, or we, will be in error.
There are more of these sneaker waves than one would think and you need to be able to deal with them as well as those on the bow. The vessel is unstable whenever the working angle of heel is such that the slope is zero or negative.
The owner’s cabin has two, which create exclusive spaces right onto the sea to fully enjoy contact with nature. We will also go into some detail on the process used to evaluate stability in the design phase. However, we can assume that it met the minimum stability levels required by authorities, which are typically much more rigorous than for pleasure craft.
Of course their ultimate stability is compromised (we refer you to the lead photo in this regard), but for the ships, their odds of meeting a sea large enough to capsize them are reduced by their scale.
Smaller yachts obviously do not have the scale effects working for them like the big ships and are more at risk.. Bottom line is neither of us likes worrying about what might happen if the voyage does not go as anticipated.
We want to be emotionally secure, knowing if (or when) we are caught in truly dangerous conditions, our vessel is going to give us the best chance of success.



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