OCEANS APART AD#3 QUESTIONNAIRE
1. Many builders say their boats are built to ABS, Lloyds or ABYC standards – what does that mean?
One of the interesting challenges of building luxury yachts for the world market is getting a handle on all the different boat building standards, rules and regulations that are out there. Most countries subscribe to some published set of guidelines, codes or laws that a boat builder must follow in order to sell a boat in that country. Some of the most familiar to Nordhavn owners are USCG, ABYC, CE, AS/NZS and ABS – and all of these will be discussed in some detail.
Thankfully there is a great deal of parity between many of the different international regulatory bodies that create these standards, so in most cases there are more similarities than differences. However, there still are many differences a builder has to be aware of depending on where in the world a boat is going. While it might seem simpler to just build every boat to satisfy every different international standard there is, one doesn’t have to wade too deep into the details to quickly learn how foolish such an approach would be. The more pragmatic approach – and the one Nordhavn uses – is to offer the ability to build to any published standard there is. After building yachts for the world market for more than 30 years, Nordhavn has gained an enormous wealth of experience in this area.
Before taking a look at some of the more familiar standards organizations, it’s important to understand there are some notable differences between building boats that are labeled “in compliance,” “certified,” or “classified.” In some cases, like in the U.S., it’s mostly up to the builder to voluntarily comply with the published guidance – which is certainly in a builder’s interest to do. In other cases, like in the European Union, by law a boat has to be inspected, documented and certified that it meets the published guidance. This understandably adds to the cost of the boat in terms of hiring outside inspectors and creating documentation. Then there is a whole additional level of scrutiny for any boat where a pleasure yacht or commercial charter yacht classification is desired, which typically involves ongoing inspections throughout the build, extensive documentation and the use of materials and equipment that is held to a higher standard.
In the States
In the U.S. there are a few laws within the Code of Federal Regulations (CFRs) with regard to the construction of recreational boats. However, these requirements are mostly limited to small boats less than 20-feet in length with gasoline engines. There are also requirements for fire extinguishers, lifejackets, navigation lights and visual distress signals (click here to see the Federal Requirements Brochure www.uscgboating.org/fedreqs/default.html). For the most part, however, the government in the U.S. has left it up to private industry to create a body of guidance for building safe recreational boats.
Enter the American Boat & Yacht Council (ABYC – www.abycinc.org), which was formed in the ‘50s in response to the emerging recreational boating market. Its focus was, and continues to be, on developing safety standards for the design, construction, repair and maintenance of recreational boats. Its first book of standards, published in 1956, only included guidelines for life saving equipment and battery chargers. The current book includes more than 65 different standards covering nearly every aspect of boat construction.
Nordhavn, and many others, voluntarily build boats to comply with ABYC standards. And ABYC is very clear about what it considers necessary. In its standards it uses “a builder shall” for anything that is a must-do to be in compliance with a specific rule, and “a builder should” for recommendations that are not considered items for compliance. The standards themselves are in a continuous state of evolution and are revised and updated at regular intervals to keep pace with changing technology and improved building practices.
There is no such thing as an “ABYC Certified” boat – and ABYC does not employ boat inspectors who verify that builders are following its standards. It is up to the individual builders to ensure they understand and follow the standards if they want to be in compliance. What ABYC does do is offer education courses where builders can have their engineers and technicians certified. These folks can then use that knowledge to ensure their boats are in compliance with all the latest ABYC standards. Nordhavn keeps its boats current by sending its people to these courses and ensuring the latest standards are adhered to. The benefits of building a boat to ABYC standards include greatly enhanced safety for the owner and a very high measure of liability protection for the builder.
An additional benefit of building a boat to ABYC standards is that doing so covers the majority of requirements for most other countries. In fact, some countries have simply incorporated the language of the ABYC standards into their own book of rules or codes. And, in some of these countries, they have built these standards into their actual law books – so they obviously have a very high degree of confidence in the guidance ABYC is putting out there.
Across the Pond
In 1996 countries in the European Union adopted the Recreational Craft Directive (RCD), which is a single set of “harmonized” essential requirements for boats sold in any member country. Unlike the ABYC standards in the U.S., compliance with the RCD is required by law in the European Union member countries – and third-party inspections and certifications are required as part of the process. The boat is given a CE mark at the end of the process, which confirms that is has passed muster and is legally valid for sale in the European Union. In house we typically refer to these as “CE boats.”
There are at least 60 standards that have been developed to support the requirements of the RCD, and each points to a specific International Organization for Standardization (ISO) document that contains the detailed requirements for that particular standard (such as ISO 10088: 2009 Small Craft – Permanently Installed Fuel Systems). Like ABYC, these standards are revised and updated at regular intervals.
The good news for builders like Nordhavn is there is little real difference between the RCD standards and the ABYC standards. The biggest difference is actually all the documentation and inspections that are required for building a CE boat. At Nordhavn we use special software that basically creates a massive checklist of items that must be confirmed for RCD compliance. In each case we note how we satisfy the specific requirement, and once complete the software compiles a large technical file that is given to the inspector. The inspector reviews the file, inspects the boat and makes note of any additional actions that are necessary for compliance. Once he’s satisfied that all the requirements of the RCD are met, he issues a certification that the boat is worthy of a CE mark.
A Type Certification can be issued for production boats that do not change from boat to boat, and Nordhavn typically does this for its smaller CE boats – that way only the first boat has to be inspected. The larger Nordhavs, which typically change a substantial amount from boat to boat, require individual inspections and certifications for each CE boat.
There’s also the MCA Code of Practice, which is a set of rules that applies only to the UK and other “Red Flag” UK overseas territories (Bermuda, Cayman Islands, Gibraltar, Isle of Man, etc.). MCA is shorthand for the UK Maritime and Coast Guard Agency – and vessels certified by the agency fly the red MCA flag. The MCA Code, which publishes its own set of construction and safety rules, is only for commercial vessels used for sport or pleasure. Even though these are often pleasure yachts, they are crewed working boats and are not considered recreational pleasure boats. The process for building an MCA boat is similar in nature to building a classed boat, which is discussed later in this paper.
The Land Down Under
Nordhavn does a brisk amount of business in Australia and New Zealand, which have published their own set of rules with regard to electrical installations on boats. The most recent version of the Australia/New Zealand standard (AS/NZS 3004.2:2008) was published in 2008 and borrows heavily from ABYC. So again, a builder that is already up to speed with ABYC can easily include the few additional requirements for compliance with the Australia/New Zealand standard.
Compliance with these standards is mandated by law, but there are no special requirements for documentation or inspection like there are for CE boats. It is up to the builder to be familiar with the Australia/New Zealand standards and be prepared to prove that the standards were followed should a regulatory inspector in Australia or New Zealand require evidence of compliance. Nordhavn does this by using internal checklists, noting specific Australia/New Zealand requirements on the electrical schematics and inspecting the boats for compliance as they are built and upon delivery.
Classification of pleasure yachts is a very different animal compared to what has been discussed so far. All the major classification societies, including the American Bureau of Shipping (ABS), Lloyd’s Register (LR), Bureau Veritas (BV), RINA, Det Norske Veritas (DNV), etc., are much more involved with commercial shipping than they are with pleasure boats. Classification as a pleasure yacht or commercial charter yacht is normally the target here, with the charter classification being more intensive and expensive. And anything smaller than a mega-yacht or super-yacht is probably not a candidate for classification. ABS, for example, does not classify vessels smaller than 24 meters (79 feet).
When an owner does request a classified boat the classification society gets involved at the very beginning of the design process by reviewing and approving drawings. The classification societies have their own books of standards, which tend to be much more rigorous than ABYC and the others that focus on smaller recreational boats.
In addition to all the documentation and design scrutiny, classed boats receive repeated visits to the factory for ongoing inspections while the boat is being built. All of this will obviously add to the cost of the boat. Nordhavn has built a number of ABS classified N86 yachts, and the additional cost of ABS classification is estimated at more than $300,000 for one of these boats. And once classed, the boats must receive ongoing inspection surveys throughout their lifetime to maintain their status as a classed boat.
What’s It All Mean?
There seems to be this notion that the more acronyms one can attach to a boat, the better it must be. Boating magazines like to try to list as many impressive-sounding endorsements as they can when writing about a boat, but they often miss the mark and create confusion while they’re at it. Here’s one from a boat report written about a 67-foot yacht: Their boats “are certified by ABS and Lloyd’s Register and have achieved the Bureau Veritas ‘unrestricted navigation’ category. This means they also carry a CE Category A ‘ocean’ rating and meet NMMA/ABYC standards.” What?!? ABS is very clear that it doesn’t “certify” boats and does not even look at boats smaller than 79 feet, CE is only for boats going to Europe, and NMMA is not a part of ABYC. We’ve asked magazine editors to be on the lookout for such loose mention of these standards organizations.
The truth is there is little real difference in a boat built to comply with ABYC standards in the U.S., or built to satisfy the RCD requirements for a CE mark so it can be sold in the European Union or built to meet the electrical requirements of Australia/New Zealand. In fact, unity seems to be the current trend in pleasure-boat building standards for boats less than 80 feet in length – with ABYC leading the way in many areas of construction.
For larger boats – we’re talking about mega-yachts and super-yachts like Nordhavn’s N86/96 and N120 here – it makes more sense to go with one of the classification societies if an endorsement is needed. One can say that classed boats are built to a higher standard than boats built to satisfy CE or ABYC because the classification societies are more-often focused on approving boats for safe commercial usage, which means they have to be ready for years of heavy daily use. Some classification societies do offer non-commercial pleasure boat classifications (like ABS), with the main difference being a much higher level of scrutiny for commercial classed boats.
At Nordhavn the first line of every boat order lists the model of the boat to be built, and the second line notes whether it’s a standard ABYC boat for the U.S. market, a CE boat for Europe, an AS/NZS boat for Australia or New Zealand , an ABS boat for international classification or something else. That way we know from the very beginning what special steps we need to take to make sure we satisfy the particular needs of whatever standard the boat has to be built to.
We can say with easy confidence that every Nordhavn is built to our own high standards of safety and quality, and we’re equally glad to say we have years of experience offering the necessary compliance, certification and classification needed for selling boats to the world market.
2. What are the benefits of a fiberglass yacht?
Nordhavns feature a heavy laminated fiberglass hull and deck built off of finely finished molds resulting in a long lasting gel coated finish that can last for decades. In fact many early Nordhavns, now approaching thirty years old, are still getting service out of their original gel coated surfaces.
No Nordhavn has ever suffered a structural failure not resulting from wrecking or fire. The strength of the structure has proven itself in some of the most extreme conditions on earth – including the highest northern latitude ever achieved by a pleasure yacht, the most world circumnavigations, a successful transit of the ice laden Northwest Passage, cruising of the Antarctic Peninsula, South Georgia Island and numerous roundings of Cape Horn.
Steel vessels can offer advantages in terms of construction cost without investment in tooling, production times can be reduced and a stronger structure can be produced in steel where ice breaking, constant deck abrasion from fishing or freight operations, or extreme service is contemplated.
Historically, fiberglass yachts built from polished molds and produced in quantity have proven to have greater resale value and unlike metal vessels, can last almost indefinitely without the significant expense required to maintain the structure. This benefit plus the historical service record of Nordhavns in extreme use around the world leaves little doubt of the capability and suitability for world cruising. This, along with the extraordinary retention of value combine to make the Nordhavn brand “Oceans Apart from the Rest”.
3. What is the ultimate limit of positive stability of your brand and can I see the vessel’s stability curve? What about down flooding, scupper sizes, and other standards of compliance for certification under CE Category A?
What is a stability curve and what is the limit of positive stability?
A stability curve plots the righting arm (GZ) vs the angle of heel. The righting arm is the horizontal distance between the Center of Gravity (CG) and the Center of Buoyancy (CB) as shown in the first figure below. The righting arm multiplied by the boats displacement is the righting moment at that angle of heel. The righting moment counter acts heeling moments, which roll the boat, and bring the boat back to upright. When plotted at various angles of heel the plot is called the stability curve. The range of stability can be shown graphically on a plot of heel angle on the horizontal axis and righting arm (GZ) on the vertical axis as shown on the second figure below. The range of stability is defined as that range of inclination from upright equilibrium (where the boat is upright, level and stable) through the heel angle where the boat maintains a positive righting arm. The magnitude of the righting arm is dependent on the beam, freeboard, watertight integrity of the deck and superstructure and location of the center of gravity. Within the range of stability the righting arm is positive. At angles of heel in excess of the point of vanishing stability the righting arm is negative and will theoretically result in a capsize.
The stability curve shows, theoretically, the results of very gradually heeling the boat in calm, motionless water (which in fact never exists). The angle at which the transverse righting moment reaches zero is defined as the angle of vanishing stability or the limit of positive stability. It should be noted that a positive righting arm doesn’t preclude the chance of a capsize in the real world where dynamic factors play a large role.
The stability curve also shows the maximum righting arm, the angle it occurs, the initial stability and the area under the curve (which represents righting energy), which are all evaluated when accessing the stability of a yacht.
There isn’t a single stability curve for a boat. Every loading condition, trim angle and initial heel angle will produce a different stability curve for the same boat. For this reason stability standards define particular load conditions to be analyzed which typically are worse case conditions. All stability curves must be associated with a load condition.
In analyzing the stability of a ship or boat, the seaworthiness of the design and the stability curve is compared to several criteria, or minimum requirements, to determine how stable the boat is. For yachts the standard stability criteria is the International Standard ISO 12217, Small Craft Stability and Buoyancy Assessment and Categorization. The standard is divided into several design categories recognizing that more stringent requirements are dictated by the sea states and wind conditions found at sea as opposed to sheltered conditions. All Nordhavn’s are certified to the highest Category A standard.
The following criteria are tested in the evaluation process for Category A:
- Downflooding openings: This requirement insures that the level of watertight integrity is maintained. The locations and construction of all openings into the boat including hatches, ports, seacocks, exhaust, and ventilation are specified and inspected.
- Downflooding height: This requirement determines that any opening into the boat has sufficient height to prevent flooding. Nordhavn pays particular attention to the large engine room ventilation ducts insuring that they are high and inboard as far as practical.
- Downflooding angle: Each opening into the boat is tested to determine that the angle of heel when flooding occurs is sufficiently high to prevent significant quantities of water from entering the boat.
- Offset load test: This test determines that if all aboard were to move to the rail on one side, the boat would not exceed maximum allowable heel angles. Vertical locations of the crew are also considered – crew rushing to the side rail on upper decks is more serious than lower decks.
- Resistance to waves and wind: This requirement determines if there is adequate reserve righting energy to right the boat if were healed due to wind force and then rolled due to waves.
- Recess sizes: The volumes of recesses (areas capable of containing water on deck) are accessed. Scuppers and drains must clear the decks of trapped water before stability is affected. Nordhavn’s freeing ports and drain sizes exceed requirements.
- Detection and removal of water: This test insures that alarms are in place to detect high water and that the water removal system in terms of pumps, drains or scuppers is adequate.
Only after all the requirements are met and the boat is surveyed to assure compliance is the boat awarded a Category A certification.
4. How has your brand’s hull form developed over the life of the brand and what empirical knowledge has been used in that development?
Using the experience gained over the past 40 years we have a pretty good idea of what works. A new Nordhavn design takes what’s good from our past builds and improves upon them. This is a constant process with complete continuity, resulting in an ever improving yacht. Naval architecture evolves along with mechanical, electrical and plumbing systems – all improve with this process that has gone uninterrupted now for forty years. PAE is managed daily by the original founders and owners which has made this evolution possible.
In 1987, the first Nordhavn was designed in house by our Chief of Design and PAE co-owner, Jeff Leishman. Jeff has designed every subsequent Nordhavn with the help of an ever-growing team of talented in house engineers and project managers. While other competitors talk about “design integrity” we’d suggest that is Nordhavn’s greatest attribute.
For the past 15 years Nordhavn Owners have successfully cruised their yachts to the far corners of the world and the recorded cruising miles have now exceeded five million. Many of these experiences are well documented in their blogs, books and videos. In Nordhavn’s early years we lacked this input from our customers and took every opportunity to gain the experience firsthand.
For the first Atlantic crossing of a Nordhavn 46, PAE’s co-founder co owner, Jim Leishman, was aboard and from 1989 through the present, the ownership team made up of PAE president Dan Streech along with Jeff and Jim Leishman still take as many opportunities as possible to experience our Nordhavns in open ocean conditions. Hundreds of thousands of miles have been accumulated by PAE owners, designers, engineers, project managers, sales staff and other members of the PAE team.
One of the greatest examples of this is the 2001/2002 Around the World voyage of our Nordhavn 40. Virtually every key person at PAE participated in that great event. Dan, Jeff, Jim, as well as Project Manager Dave Harlow each skippered major legs of the trip. Project managers, sales people, and commissioning staff – all learned volumes and gained firsthand experience of what is required to make a major ocean passage. Company employees that stayed ashore participated and learned the logistics of fueling and provisioning in foreign ports, medical support and assistance, parts shipment and inward and outward clearance procedures of a dozen different countries. The trip taught us all teamwork and contributed to a camaraderie that exists to this day.
Our goal with the ATW was to get around the world in one season which required perfect timing and a schedule that had to be maintained. Fortunately everything went just about perfect and the record still stands – Nordhavn circumnavigated the world faster than any production yacht in history.
Experience gained aboard during the ATW along with the experience of escorting 18 yachts (16 Nordhavns) across the Atlantic during the Nordhavn Atlantic Rally (NAR), the maiden voyage or crossing the Pacific, north of the Aleutians on our first 120, along with countless other passages dating back to the late seventies aboard our Mason sailboats all have combined to create the Nordhavn brand and reputation as it is today. It has been our lifelong passion and work.
At last review Nordhavns have crossed the Atlantic and Pacific over one hundred times, have completed over ten circumnavigations, reached the highest northern latitude ever reached by a production powerboat, transited the Northwest passage, rounded Cape Horn eight times, reached the southern reaches of Antarctica, called upon South Georgia Island; it’s a record that eclipses virtually all production Passagemaking yachts produced by other builders – combined.
5. What is the benefit of a single propulsion engine plus wing for back-up vs. driving the main propeller with a generator hydraulically? When are twin engines advantageous over a single?
Starting with the original Nordhavn 46, a single engine was selected for numerous reasons;
- Ultimate efficiency and range
- Protected propeller
- Strong attached rudder with large surface area suitable for low speed control
- A long keel for ultimate protection against floating debris and grounding, plus the directional stability provided by the long keel with attached rudder
- The ability to carry ballast as low as possible for ultimate stability
A requirement of the original 46 design was the ability of the yacht to travel at least 2,500 miles with adequate reserves (in case of adverse weather) at a speed length ratio of at least 1.0 or in the case of the 46 – a bit under 6.5 knots. The yacht could travel efficiently at speeds up to 8 knots but for the longest of ocean passages, the speed must be reduced.
It was concluded in this design the single was the only viable option but some method of auxiliary propulsion was desired and an alternative method of spinning the main propeller did not seem like a viable option. A loss of the main engine is only part of the potential problem that can strand a boat in mid-ocean. The failure of a transmission causing a lock-up, the failure of a shaft coupling or the most likely problem, the fowling of the main propeller, are not addressed with a get-home drive which just spins the main propeller. Additionally the potential engine failure due to fuel contamination would soon render a generator-driven get-home useless.
So – what was desired was a completely redundant propulsion system. The wing engine was developed which spins its own separate shaft and folding propeller, uses its own isolated fuel tank, starts on a separate starting battery and then produces its own electricity to keep vital systems alive on the yacht. This concept has proven itself the very best solution for hundreds of Nordhavns over almost thirty years.
The wing engine can be started instantly from the wheel house and provide power to get out of a tight spot if the main dies and in open ocean it can generally keep the yacht going indefinably at more than half of the yacht’s normal cruising speed.
The second Nordhavn designed and built was 62 feet and for this model, too, a single was selected. Ultimately the newer models – the 40, 43, 47 and 52 were all designed with singles and starting with the 55, twins were available. Now the 60, 68, and 76 are offered with twins but, by a wide margin, the single engine configuration has been the most popular. When fitted with twins these models all feature long protecting skegs with attached rudders and protected propellers. These are all lovely boats and steer well with the skegs and large rudders and can maintain speeds with one engine approaching the normal cruising speed. They are still very efficient but less so than the singles. Our observations show that the loss of efficiency in the twin verses single of the same model is at or in excess of 20%. On a small Nordhavn this loss was unacceptable and would limit the cruising range to an unacceptable level however the larger models have excess capability so the twin versions can still accomplish the long passages.
Of course as we get into the 80-foot Nordhavns and above, the twins are the reasonable solution as the yacht’s range and speeds are suitable for worldwide cruising, the redundancy of twins are attractive, and the draft of the vessel can be kept to a reasonable level.
6. Are any of your models available with dry-stack exhaust if I prefer that instead of wet exhaust?
The diesel propulsion engine is the reliable heart that beats in the chest of every Nordhavn. More than any other piece of machinery, the exceedingly dependable diesel makes the Nordhavn way of life possible. However, it does present some issues that have to be dealt with along the way. One of the chief challenges is what to do with all the hot, loud and smelly stuff that comes out of it as it merrily chugs along.
There are two main camps of thought when it comes to marine exhaust systems for recreational boats: the wet and the dry. While wet exhaust systems are much more common for recreational boats in general, many builders of deep-sea passagemakers – including Nordhavn – like to take advantage of dry exhaust systems on a number of their models.
As their “wet” and “dry” monikers suggest, the differences between the two systems are substantial – and the main advantages and disadvantages of each system are equally distinct. Either way, the objective is the same: To safely carry away the byproducts of combustion along with no small amount of noise and heat. Engine cooling is closely tied to the exhaust system, and each type of exhaust will influence how the engine is cooled.
Wet exhaust is called wet because seawater is mixed with the exhaust before it is routed out of the boat. Injecting seawater into the exhaust stream does a couple of things. It dramatically lowers the temperature of the exhaust run, so the fiberglass tube or rubber exhaust hose used to carry the exhaust away is not a threat in terms of burns or fire. And exhaust noise is suppressed as the water expands into steam and mixes with the exhaust.
The water is provided by a dedicated seawater pump that typically routes seawater through the engine lube oil cooler, gearbox cooler, and main heat exchanger before being injected into the exhaust downstream of the exhaust manifold exit or turbocharger exit. After being injected into the exhaust the mixture is often routed to an inline muffler or water-lift muffler for further noise reduction before being ejected overboard. In some cases a water separator muffler is also used, which quiets the exhaust even more and allows the gas portion be discharged above the waterline and the water portion to be quietly discharged below the waterline. Nordhavn includes these on its generators to eliminate the splashing noise created by the discharged cooling water, which quiets things down at night while on the genny.
A craft with a wet exhaust system is also often called a “heat exchanger” boat because a heat exchanger is being used inside that boat to cool the main engine. On the primary side of the heat exchanger a mixture of freshwater and antifreeze is being used to pull heat away from the engine block, on the secondary side seawater is being used to pull heat away from the freshwater and antifreeze mixture (this is the same seawater that is later injected into the exhaust).
The main residual of dry exhaust is heat – and lots of it. Diesel engine exhaust gas temperatures can reach 1,200°F, and the surface of mufflers and exhaust pipes can reach between 400°F and 900°F. This means serious measures have to be taken to protect people and any surrounding equipment and structures from burns or heat damage. Special lagging, insulated exhaust pipe lockers and even forced-air cooling blowers are all used to shield people and the area around the exhaust pipe from the extreme heat.
The heat is only present while the engine is in operation or while it is cooling down, and a system that is subject to large temperature swings from an ambient 75°F or so at rest to 900°F while running must be designed using components that will operate without cracking or breaking due to thermal contraction and expansion. This requires a great deal of thought during the design stage to ensure the system – from the engine all the way to the top of the stack – is safely secured yet is allowed to expand and contract time and again without failing. Slip joints, bellows and special pipe hangers all come into play here.
Because no water is used in the exhaust, the dry exhaust setup creates options in terms of engine cooling. Of course the heat exchanger method could be used, and the seawater simply discharged overboard instead into the exhaust. Or, a common alternative for passagemakers is to basically move the entire heat exchanger outside the boat where the passing water will carry away the heat much like a radiator does for a car.
In this case the heat exchanger is now called a keel cooler because it is mounted on the outside hull surface below the waterline (but not really on the keel) – giving us what most refer to as a “keel-cooled” boat. With a keel-cooler heat exchanger on the outside of the boat there is no longer a need to bring seawater into the boat – so a keel-cooled boat does not need the thru-hull fitting, sea strainer, seawater pump, secondary piping and other components that are required by a heat-exchanger boat.
Dry Up or Get Wet?
The decision to use dry exhaust or wet exhaust is almost always made at the design stage and is not typically something a buyer can pick as an option. Any boat where high speeds are a top priority – and certainly any planing boat – is going to favor wet exhaust because the drag of a keel cooler would slow things down too much. This covers the vast majority or recreational boats. Dry exhaust is lauded for greater reliability, so it is often the system of choice for slower-moving commercial workboats that see a lot of daily use – and, as it turns out, for a number of recreational passagemakers.
Like the workboats that inspired them, recreational passagemakers prize reliability over speed, so in many cases dry exhaust is the system of choice if it makes sense on the whole. A quick look at the main pros and cons of each system will help here:
- Far fewer heat issues with exhaust runs
- More interior space
- Easier to design and install
- Seawater pump failure could destroy engine
- Sea strainer, pump, injector elbow maintenance
- Exhaust can blow into boat in following wind
- No seawater pump to maintain (or fail)
- No seawater strainer to maintain (or clog)
- Exhaust released well above deck
- Dangerous heat
- Space accommodations for stack
- Complex design and construction
It’s clear what the main issues with the wet exhaust system are. It requires a hole in the boat for the intake, a strainer to filter the water and a pump that must be powered and maintained. Remember that this is the main source of cooling not only for the exhaust, but also the entire engine. A clogged thru-hull or strainer, or a pump failure, will almost immediately manifest in extremely high exhaust temperatures that can destroy exhaust hose and fiberglass exhaust tubes, and loss of cooling to the engine can quickly cause the engine to seize and result in catastrophic damage. Many boats with wet exhaust will include an exhaust temperature alarm and/or a loss of cooling water alarm to give the operator a few seconds to shut the engine down in the event of a loss of cooling seawater. These are not alarms to silence and causally inspect. If you get a high exhaust temperature alarm or a loss of cooling water alarm, shut the engine down NOW! Even a few seconds without cooling water can result in irreparable damage.
Another issue with wet exhaust is the potential to flood the engine with seawater when over cranking. While cranking the engine during starting the seawater pump is pumping water into the exhaust, and if the engine doesn’t start the muffler and exhaust tube will begin to fill up with seawater. Too many unsuccessful starting attempts could dump enough water into the exhaust to where it spills over back into the turbocharger (if installed), exhaust manifold, and cylinders, which can cause catastrophic engine damage. The recommendation here is to open the valve or plug at the bottom of the muffler after 30 seconds of continuous cranking to drain the water before attempting to start again – this will ensure seawater doesn’t backup into the engine while starting. This is especially a concern with Nordhavn generator engines, all of which use wet exhaust systems.
On the dry side, most of the frustrations are with the system design more so than with operation and maintenance. The exhaust run needs to be designed and constructed to allow for thermal expansion, and it needs to be properly shielded to prevent burns and heat issues. Also, the exhaust locker will have to be included in the interior accommodations design and will eat up some space inside the salon, galley or other compartment. Once all these issues are sorted out, however, there’s really not much for the owner to worry about or maintain – and after 25 years of building these systems, Nordhavn has perfected the process to ensure the necessary safety while minimizing the impact on interior space accommodations.
Low maintenance and reliability are top priorities for Nordhavn owners, which makes dry exhaust the system of choice for many owner/operators. They might have to sacrifice a small slice of interior space and put up with a little more radiant heat, but the payoff includes no strainers to clog, no impellers to break and no belts to fail – all of which add up to a nice increase in reliability. And all appreciate the added benefit of releasing the exhaust gas out the stack high above the water where it can’t be blown into the boat by a following wind.
While there are some situations where wet exhaust makes the most sense on a Nordhavn – typically on larger boats with twin engines – we always recommend dry exhaust anytime we can. There’s less to maintain, there’s less to worry about and there’s no smelly exhaust getting blown into the salon – all good reasons to go dry.
7. Is shipping and exchange rate fixed in the contract purchase price?
Each purchase agreement is unique and is written specifically for the circumstances of the sale and what the Buyer and PAE/Nordhavn have agreed to leading up to the signing of the agreement.
All Nordhavn sales are made in US dollars. The Buyer has no exposure to any exchange rate risks which could affect the purchase price in USD. Many Nordhavn Buyers of course are not Americans as Nordhavns are purchased by Buyers from different countries from around the world. Those Buyers do need to think about and plan for any anticipated exchange rate movement between their currency and the USD.
All published Nordhavn pricing includes shipping from the Asian factory to the delivery location that has been agreed to in the purchase agreement. All ancillary costs of shipping such as insurance and port fees and discharge fees are on PAE/Nordhavn’s account. From time to time, Buyers will elect to take delivery of their new Nordhavn at the factory and begin their cruising in Asian waters. In those cases, the cost of shipping is refunded to the Buyer.
8. Can I work with an outside interior design firm to customize the interior and what wood and joiner styles can I choose from?
A lot of things can be done in-house but we do often work with outside interior design firms, particularly with the larger boats.
For Nordhavns under 86 feet, we recommend a buyer work with the salesman and project manager to capture the look and feel they desire for their boat. We have hundreds of photos of layouts and options of every model we’ve ever produced. A buyer can pick and choose arrangements, elements and style details that best suits their desires and needs.
There is no limit to the types of wood and joinery styles a buyer has. We have built yachts with very traditional interiors, very contemporary interiors, and everything in between. Wood options and joinery work is all up to a client’s personal tastes.
When it comes to design, almost anything is doable but custom comes at a price. Buyers need to take into consideration increased costs as well as the impact on re-sale value that ultra-custom details can impact.
9. Are electronics installed during the build or during commissioning and what role does the builder play? How good a value can be offered?
Modern Nordhavns.. even the smallest models.. tend to have electronics packages which are quite complex. “Electronics” includes navigation, autopilots, radars, communication, cameras, computers, AV and more. In most cases (and it is PAE/Nordhavn’s preference) the electronics package is supplied by a competent vender after that vendor and the Buyer have developed the package that is appropriate for the budget and the intended use of the boat. Using milestones developed by the builder and the PAE/Nordhavn project manager for the build of the Nordhavn, the electronics components are then shipped to the Asian factory for installation concurrent with the build of the boat.
It is a requirement of PAE /Nordhavn that the electronics vendor create detailed installation instructions for the electronics package along with electrical and logic drawings that will guide the builder and later provide documentation for the Nordhavn owner if maintenance is required in the future.
Builder installation of the electronics packages gives a spectacularly beautiful result as there is a harmonious blend of boat system wiring and electronics wiring. Additionally, the builder can provide matching wood work, metal work and fiberglass work that may be required for the installations.
When the boat arrives at the commissioning location, the electronics vendor will then confirm the installation, set up and program any of the equipment which requires it and complete the work quickly and without any drama or trauma to the boat.
10. Can I take delivery directly from the factory or any location of my choosing? If so will someone from your company be on hand for the initial voyage?
As part of the purchase process, PAE/Nordhavn and the Buyer will agree on the location where the Buyer will take delivery. We have office locations in Portsmouth, RI, North Palm Beach, Florida, Seattle, Washington, Dana Point, California, Hamble, England, Gocek, Turkey and Brisbane, Australia. Typically, a new Nordhavn will be shipped from our Asian factory to one of those locations for final commissioning and delivery. We can and often do, however, ship new boats to other locations which are more convenient for the Buyer and from time to time a new Nordhavn is delivered to the Buyer at either our Taiwan or China factory locations or in Hong Kong. With nearly 600 Nordhavns now delivered, we have gained the experience necessary to deliver Nordhavns nearly every place in the world. Additionally, there is another factor that is unique to Nordhavns. Because Nordhavns can easily travel at the rate of 1,000 miles per week or more, it is not unusual for a new Nordhavn to be commissioned at one of the traditional locations and then travel on her own bottom to an agreed delivery point. No matter where a new boat is delivered, Nordhavn staff or representatives will be part of the process and will make sure that the new owner has been trained and is comfortable with the boat.
11. Do you provide a comprehensive, customized electronic and printed Owner’s Manual that is specific to the yacht as built?
For each new Nordhavn that is delivered from the factory, we develop a personalized three-ring-binder filled with descriptive explanations detailing every system aboard, accompanied by a full set of systems drawings. The Nordhavn Operators Manual is essential on board equipment and has been described by more than one Nordhavn owner as the “gold standard” in the industry.
Our technical writer spends time aboard crawling all through all spaces to double-check how everything has been assembled and cross reference systems with the CAD drawings used to install them. He personalizes the details of each new Nordhavn in order to provide an accurate inventory and description of every new Nordhavn – not only what equipment/gear has been installed, but how to operate it. What could be more important?
The concept of this Operators Manual is to try to have it written in terms a person coming aboard can easily understand. And while it is geared to a more novice boat owner, it is equally invaluable to a seasoned power boat veteran (every boat is different no matter how many similarities they seem to share). We keep the writing clear and plain speaking.
Another key to the success of our manual is the inclusion of numerous CAD drawings. Every manual includes a full set of plumbing, electrical, and other systems drawings that are updated for each specific boat. This gives the owner and any technicians who might work on the boat a quick, at-a-glance reference that is truly reflective of that actual boat.
We put a lot of time and energy into creating a highly useful, comprehensive, and accurate manual. Countless professional captains and owners alike have told us our manuals are the first place they go if they have any questions about the boat systems or operation. And when we get calls with those kinds of questions, we always start by checking the manual. Often we find the answer we’re both looking for – so the manuals actual help us help owners! Please see the link below for an example of a recent Nordhavn Owner’s Manual and drawing set.