There are basically two ways to make Nitrox: partial pressure blending and using a membrane.  For practical and safety reasons we stick to membrane systems.  And for reliability and maintenance reasons I stick to German-made compressor equipment.

To make Nitrox (officially ‘enhanced air nitrox’, you first use a low presssure compressor to pump air through a membrane which takes out part of the nitrogen and produces an ‘enhanced’ airmix that contains typically 32% or 36% oxigen.

It is then brought up to 4.500 psi (31o bar) with high pressure compresssors and put into the Nitrox storage tanks.  See the schematic drawing below. 

The problem with making Nitrox is that by compressing air with a low pressure compressor to push it through the membrane it gets a lot warmer.  In fact, some membrane filters need you to even heat the air before it enters the membrane.  This mean you can end up with Nitrox that’s warmer than the manufacturer of the high pressure (HP) compressor recommend it to be.  And hot Nitrox also shortens the service life of your filters pretty dramatically.  So how do you keep that Nitrox cool so it won’t ruin your compressor or loosing your warranty on your HP compressor? 

Another issue is getting the oil out of the air before it gets into the membrane.  Oil and nitrox membranes are not good friends: the first one shortens the life of the last one considerably.  I’ll be trying to find out how to take the most oil from the air before it reaches the membrane and how many hours I can expect from the membrane with a certain minimum oil content in the air.

Different companies, different solutions.  I’ll ‘dive’ more into that in my next post when I have received feedback from all the different providers.   I’m looking both into after market “yacht” products and adaptations as well as off-the-shelve industrial /commercial solutions.   And I checked into water cooled compressors – both after market like those of ‘Nitrox’ Bob Olson and industrial breathing air compressors.  It’s going to be an interesting comparasion.

My latest  such experience is with Manta Maritime,  a British company headed by Anthony Gradwell.  Anthony is a naval architect, professional engineer, former Lloyds Register surveyor and worked 5 years with he Cayman Islands Shipping registry (the largest registry for commercial yachts)  most of it as lead surveyor. 

Since 2006 he runs his own company - Mantra Maritime - dedicated to providing “effective yacht safety solutions through innovative and practical guidance”.

When looking for some info on SOLAS and MCA issues I ran into Anthony’s site and spend over an hour reading the information he had available for download on his website.  While I consider myself pretty well informed about the issue his site really brings it all together.   Handy compliance charts and guides clarify many of the issues that have a lot of people confused.

Then I sent him a note of appreciation for setting up such an informative website and that started another round of very informative e-mail exchanges.

Among the things I was made aware of is that the Cayman Island Shipping Registry is far advanced preparing a 13-36 guest code.  It’s still under wraps but it will be discussed at the Superyacht Forum in Amsterdam next month (at the METZ tradeshow).  It will most likely be a consolidation of all the requirements in SOLAS for small (<36) passenger ships, plus some standard equivalent arrangements.  And excellent slideshow presentation about the 13+ guest/passenger issue can be found on the Manta Maritime website.

Since we plan to make our yacht MCA LY2 compliant and will be able to take more than 12 guests, we’re very interested  in any new regulation regarding this topic.  When Peter went over my website and general arrangement he came up with a host of other helpful suggestions showing an in-depth knowledge on a wide range of issues.

If you have a project where you need expert guidance on regulatory issues, I highly recommend you contact Anthony Gradwell.  Start by visiting his website www.mantamaritime.com.

Our initial idea was to basically add plating to the inside of the tank  walls and hull to create the cofferdam space (about 20 cm wide)  and make this hull inspectionable with an inspection camera like this one from Ridgid .  Making the cofferdam wider to allow access would mean ending up with almost no fuel storage space and rules require you can inspect a cofferdam but don’t specifically say how big it has to be.  But how to keep corrosion at bay and what about not being able to weld this plating on both sides? 

So we started looking at other solutions like a tank we could remove.  To store about 3 to 4 m3 of jet fuel (780-1038 gl.), one big tank would not be practical (how to get it in there?)  Several smaller tanks?  To start with, that would clearly violate the KIS principle.  But then we learned about bladder tanks and we came accross the website of Australia’s Turtlepac and thought, if they can do that kind of stuff with a bladder tank – like throwing filled tanks out of helicopters - it will work for us!  The obvious advantage of a bladder tank in our application is that when empty, you can easily remove it through the manhole and inspect the outer tank!

Unfortunately, there was no information whatsoever available on the Internet about yacht applications approved by a class society so I decided take my case to always very helpful gentlemen of Lloyds Register in Ft. Lauderdale to see how they felt about the idea.  I met with one of their surveyors and the news was good.  Yes, there was a precedent of the use of bladder tanks on (classed) yachts.    But we had to make sure the tank would not collapse while being emptied because they want fixed connections to the tank for filling and venting.  Flexible hoses – not normally visible as they are hidden in a cofferdam – that could  move and possibly allow parts rubbing into each other, resulting in some kind of failure were a no-no. 

Mmm…  a bladder tank that maintains its shape?  How then would we get it at its intended location or remove it for inspection.  But they mentioned there are companies that manufacture a foam specifically for use in fuel tanks (also called fuel cells) that could be inserted into the tank to keep it from collapsing, maintain its shape and allow fixed connections.

A little more Googling and we ran into so-called explosion suppressant foam made by  Crestfoam among others.  To see why this foam is called ‘explosion suppressant’, it’s enough to watch the video below.

So thanks to the helpful advise of Lloyds Register and with a little planning from our side and a lot of ball-shaped foam pieces from Crestfoam it looks we have now overcome the major hurdle to create jet fuel storage that will meet class requirements.

As you can see from the picture below, these fuel cells can be made in any size of shape to fit the particular needs of your yacht.  Of course, they will have to be pressure tested by the class society but the pressure is not that high and as you can imagine, these tanks can meet those requirements easily.

Being a former marine engineer I have no probleem seeing the advantages of scheduled maintenance and you can look at my earlier post on this topic where I discuss several software packages that make managing this process a lot easier.

One of these packages, Idea Yacht from Sprectra – my favorite - just got an new ‘light’ version.  For only Euro 490 (almost USD 750) you now get the basic but essential modules to run a solid planned maintenance software package. See the image below with the main menus of each package, illustrating the differences.

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Still, this is a package that needs a lot of planning and a solid engineering background, not something common on many smaller yachts (60-100 ft. range) where often it’s just the skipper doing all the engineering besides running the boat.  For those captains and/or yacht owners that need practical, hands-on advice or a little more hand-holding to get properly schedule maintenance going, I found a very good alternative in Superyacht Support Inc., a Ft. Lauderdale-based company.   

Founded by John Vergo, a former Royal Navy engineer, an experienced megayacht captain and engineer and a former fleet manager for Camper & Nicholsons, he knows a thing or two about scheduled yacht maintenance.  This firm specializes in helping yacht owners setting up custom planned maintenance schedules, safety training manuals and mini ISM systems.

Check out his website or drop him a line. You’ll find him very helpful, friendly and his in-depth experience can potentially safe you a lot of money, headaches and avoid lost charters.

So I decided to dedicate a post to comparing these 3 models.  Of course, there are  also the SeaMagine submarines which I have covered in an earlier post.

The most affordable entry in this field is C-Quester 3.  At about Euro 550 K you get a 3-seat  sub that is certified by Germanischer Lloyd.  The Quester 3 can also be configured to take the pilot and 3 passengers but while making this attractive in commercial use, I doubt it will be very comfortable. 

There’s also a 340 kg payload limitation so ideally this 3rd passenger is a kid and the airconditioning needs to work.    With its new lithium batteries it now has a very practical 6 hours of autonomy and 96 hours of life support. 

With a maximum operational depth of 100 m. (300 ft.) you can cover any area where you typically would like to make recreational dives.

Weighing only 4.500 kg and relatively small, this is the only personal sub you can put on a big yacht as an afterthought.  You may need a bigger crane but not much more.

The main drawback of the Quester models is its limited downward view forward due to the  seat location.  It won’t be a major issue for general sightseeing when you’re between a shoal of sharks or passing by a coral reef wall as you can see on the picture in an earlier post.  But for but more serious work, including picking up things you’ll have a problem.  But then again, you save almost $ 1.5 -2 million  depending on the configuration compared to the next in line, the SeaMagine Triumph.

The Triumph is one big serious submarine that can take you all the way down to 153 m. (500 ft.) it its standard version and to even 914 m. (3000 ft !) with upgrades.  The Triump  can take a pilot and 2 guests in comfort and offers an extraordinary good view all around, providing probably the most exciting ‘immersion’ experience.  It’s big, heavy (6.800 kg, 15.000 lbs), bulky and not very fast due to it’s un-streamlined shape but for serious personal diving and scientific work, this is one an awesome sub that’s hard to beat. SeaMagine also offers a smaller ‘Ocean Pearl’ model.  It only takes one passenger so you get no shared ‘ohh and ahhh’ or practical commercial use.  But, if you don’t have the space or the crane capacity on your yacht this may be an acceptable compromise and save you some money with standard pricing at $ 1.4 million.

For real serious ‘personal’ submarine work, lots of capacity and a host of unique options taken straight from the professional submarine field the VAS subs fit the bill .  Like the Seamagine this is a submarine you have to plan for during new-built or have a dedicated ’sub carrier’. 

Starting at $ 2.6 million for the 4-person entry model you get a sub with a military heritage.  The VAS is the only private submarine available with an optional diver lockout which allows you to exit the submarine underwater and investigate firsthand found objects of interest!  The diver lockout also acts as a recompression chamber in the event of a diver medical emergency.

The VAS passenger compartment is made of 5cm (2”) thick steel and the viewports are a minimum of 15cm (6”) thick.  All of this is wrapped in an extremely tough composite hydrodynamic envelope (you can actually tow this sub behind your yacht!).  Historically, the VAS had to meet military standards of AK47 assault rifle fire. So if you want to go diving of the cost of Somalia you want a VAS .

Compared to the SeaMagine model you get an 8-hour range (versus 6 hrs) and more speed (or staying-at-location-capacity when there are currents), more interior volume, an extra seat, less weight (5 tons versus 7) and a smaller form factor. Like the Seamagine its classed (RINA) and meets the latest Cayman Islands standards for 96-hour live support.

Since the length is relatively adjustable, you can also easily request a VAS sub with more seat capacity.  A longer hull also gives you better handling, speed and battery efficiency. 

BUT, but, the VAS doesn’t offer the ’immersive’ view of the Seamagine.  To  their advantage they use large flat, distortion-free optics.  This perfect vision will be essential when utilizing manipulators and close quarter maneuvering, as there is no guesswork in gauging distance.  But then again, you’re still in a metal tube with windows versus a transparent shere you can’t even see when you’re looking upward in a SeaMagine.

The situation is different for every yacht and budgets differ too but I hope this post will help you make a decision about this sub is best for your yacht. As for ourselves, we had originally planned for a Seamagine Triump but we’re also giving thought to the VAS.  But we will probably start out with a Uboatworx for budget reasons . 

As you can see, the deck extracts almost 3 meters (10 ft.) allowing sufficient rotor tip clearance.  Our situation is shown in the drawing below.  Even when landing partly outside the forward area of the ‘H’-circle  (1/2 D) we’re still OK.

By the way, after a lot of consulting with experts and pilots, the helicopter we plan to have on board eventually will be a Eurocopter EC130B4.  It allows the best guest experience, is silent, safe and has great capacity.

The MCA Large Yacht code, paragraph 13.2.2.3 states that for vessels of less than 85m in length, or those complying with 13.2.1.3 (which applies to yachts over 85 m. in length), a sufficient number of liferafts should be provided so that in the event of any one liferaft being lost or rendered unserviceable, sufficient aggregate capacity remains on either side of the vessel for all persons on board. This may be achieved by transferring liferafts from one side to the other. Where liferafts are transferable, this requirement may be met by the ability of the rafts to be transferred within 5 minutes, as below:

• Liferafts of 6 – 15 persons capacity to be carried by 2 persons
• Liferafts of more than 15 persons capacity to be carried by 4 persons

So we could have a setup with two liferafts on one side and one liferaft at the other side and comply with the rules. But we think that carrying a 185 kg liferaft container isn’ t much fun under normal circumstances, let alone in rough seas and emergency circumstances.

Our initial liferaft racks would look like the pictures on the the right below.  However, the Viking ’stacked’ rack (center picture) is a better solution and made possible by moving the rack away from the ship’s centerline so the falling raft won’t hit the ship’s hull.

And as the most left drawing shows, having two of these Viking racks with capacity for 2 x 2 rafts takes about the same deck space as two original 1-raft racks.  Interesting detail: the containers of the 20-person and 25-person liferaft not only have the same size (OK, that can be explained) but also the same weight. I hope a VIKING rep. can explain that soon.

We’re also required to carry a rescueboat but this can be a non-SOLAS approved properly equipped tender.

For an informative discussion about liferaft and liveboat requirements, see this forum discusssion on PMY.

We’d like to create a little bit extra space for our dive tender.  We were looking at 7.5 m. Humber Inflatables (2.8 m. wide offshore model) and 2 extra feet of boat deck would be nice. We’ve now decided to go for a custom aluminium tender design (see post (…soon).   It would also give two extra feet of tip clearance if we have to land with a helicopter.   That’s about a 25% more than we have now although since we wrote this post, we decided (September 2009) to create an extractable helipad.

Click on the image to see it bigger and let us know what you think.

When we started asking feedback on our galley design from chefs, the response was overwhelming.  It lead to suggestions on laundry equipment, tableware and a lot more.  So, we’re going to dedicate a section of our blog to crew-related issues such as crew accommodations, crew management, crew-guest relations and a lot more.

Of course there are online forums dealing with these issues.  There are Dockwalk forum, YotCrew.com and Yacht Forum to name a few and please visit them if you are crew. But our purpose is to get back specific feedback and there are things we cannot do on these other forums like posting questionaires or posting images.

We appreciate your visit and we love your feedback.

Here are some direct links to crew-related topics:

• General crew feedback & forum
• Galley design
• Bridge lay-out and equipment
• Helping the stewardesses
• Crew spaces

We look forward to hearing from you.

Thorwald Westmaas
Project manager

So captains, mates and other navigators, please share your thoughts and your experiences to guide us in the right direction for a bridge on this go-anywhere expedition yacht.

What would you like to see? Which (additional) equipment do you like and why? What’s your favorite radar, electronic chart system and radio brand and why?  What were the 5 most annoying things you encountered on a bridge?  What did you like most of a bridge you worked on?  Just through it all out. And if you have pictures of bridges you’l like to share, please send them to thorwald @ expedition yacht . org

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