Since the last Ft. Lauderdale Boat show I’ve “dived” into the question of how to make Nitrox on board. I visited the stand of Brownie’s at the show where they had the Triton sub on display and we got talking about their Nitrox solution. 
Getting home I started doing a little more research.
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.
Occasionally when doing my research and preparation for this project I run into a company or person that really stands out when it comes to helpfulness, speed of reply, in-depth knowledge and last but not least, an informative website. Recent examples of such an experience were the people at Palux in Germany (galley equipment), Triton water (sewage treatment plants) and Lift Emotion (elevators and dumb waiters for maritime use).
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.
Continue Reading »
Being an expedition yacht able to carry a helicopter you tend to end up in places where jet fuel for your helicopter is not readily available. So we decided early on we wanted to be able to carry some extra jet fuel to be able to refuel the helicopter. In an earlier post about this subject, we wrote we had planned to adapt two former diesel fuel tanks for this purpose. Class rules require a cofferdam to surround the jet fuel tank as well as a double hull if the tank is on the outside like in our case.
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!
Continue Reading »
Scheduled maintenance of the machinery and equipment on yachts is not a topic you read very much about. Ads for crew uniforms outrank those for yacht maintenance services of software a factor 100 to 1 it seems. Given the expenses you will run into if there’s no regular servicing of your equipment on a yacht, this is surprising or maybe telling about the way maintenance on yacht is planned - or not.
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.
.
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.
We’ve been looking for a yacht sub for some time and recently ran into the VAS submarine models from GSE Subs srl in Italy, a mostly military contractor with a 30-year pedigree of building submarines. In the US they are represented by Nautilus Underwater Systems. The people at Uboatworx in the Netherlands also upgraded their design recently. Add the line of personal subs from SeaMagine in California and you now have some real choices when looking for a certified personal submarine from companies that have gone well beyond nice 3D models or unstable models with very minimum freeboard.
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.
Continue Reading »
We finally found an elegant and safe solution to create even more space on our helideck in our effort to comply with the latest CAP 437 (North Sea off-shore helicopter operation guidelines) and MCA guidelines on helipads. Although we are not required to comply on a private yacht, and we already had an acceptable clearance, the solution shown below makes a good thing even better.
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. Continue Reading »
As we are looking to make some changes to the top wheelhouse deck, we started reviewing our liferaft setup. The amount of ‘life safety appliances’ on yachts is regulated by flag state authorities like the British MCA while passengerships must comply with SOLAS Chapter III passenger ships regulations. We had originally planned for a total of 3 SOLAS-A package life rafts of 25-person capacity each.
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.
You’d think 132 ft. (40.2 m.) is enough but, it’s never enough 
.
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.
