Looking for a N.A. for 85' passagemaker

WE have been using it for over 20 years, when required.

So long as you ensure the corrosion between the two metals, locally, is addressed, and that you dont design the structural joint using steel weld strengths at the joint, and pay attention to local stress concentrations and fatigue, just as with any deisgn, it works very well indeed.

 

Ad Hoc thanks for the info.

I guess, in my continuing quest to lighten the overall weight of the proposed mono-hull passage maker, I was hoping that the deck could be aluminum.

In the use of Triclad could you please comment on special design and construction considerations of the following:

Steel Hull + Steel Deck + Aluminum superstructure.

Steel Hull + Aluminum Deck + Aluminum superstructure.

Being involved primarily with Aluminum vessel design and construction I would like to know about first hand use of Triclad.

Thanks,

Mark

 

The first option shall be heavier.

Other than that, what can be said of one is the same for the other.

 

Though Tritonsubs might argue that technically anything can be done, there are several reasons why I wouldn't go for a steel hull + aluminum deck combination in this particular case (just my personal preference, ok?):

• As Tad has pointed out in the post #41, this hull's girder appears to be pretty slender and the main deck is to be considered a strength deck. It will be subject to cyclic bending and torsional loading during oceanic voyages, so imho the design and plate/stiffeners dimensioning needs to take fatigue into account. It means that the maximum allowable stress (the one to be used in the calculations) of the aluminum deck plating/stiffeners might be up to 2.5-3.5 times lower than the max. allow. stress of a steel deck plating. Considering that steel is around 3 times denser than aluminum, it leaves a too little (if any at all) weight advantage of the former over the latter. It is also true if the max. deflection is used as scantling parameter. Only if higher deflections for aluminum deck are allowed, a significant weight saving would be possible.
• You also have a problem of obtaining the hull girder structural continuity, to ensure a correct transmission of loads across different materials forming the hull-to-deck joint. Like I said, I have used the Triclad transition joints in the past with very good results (zero cracking or corrosion problems), but it was done for joining the aluminum superstructure to the steel deck plates and framing. Though I like Triclad and consider it a great idea which saves a lots of time and headaches, I wouldn't feel comfortable using it along a hull-deck joint line because I don't have sufficient data on the fatigue behaviour of the explosively-created bonds under both accross-thickness tension stress and shear stress. Perhaps Ad Hoc or someone else with decades of experience on their shoulders have more data and can reassure us on this aspect.

I'm anclosing here a technical brochure for Triclad bands, which also graphically shows it's correct usage for plate and frame joining.
Cheers!

 

AH, don't know if the weight saving is worth the other problems which the second option brings in...
But I might as well be wrong, as you certainly do have more long-term case-study data about possible problematics during the vessel service.
Cheers!

 

D et al,

As you point out there are many issues to address when making a vessel out of “composite” materials. But I would add that once a Class wave bending moment has been applied, whether the deck is steel or ally, the stresses and thus the scantlings, must be addressed accordingly.

I’m not sure how other NAs etc design their hulls, but if I were thinking of the possibility of a steel v ally deck, I would design the deck & plate for each case, address the stress and fatigue and SCF for each option accordingly. Then work out the difference in weight and potential savings of man-hours/labour as well as weight, cost etc. Once that has been done, an answer usually pops out. I never assume a solution; I let the numbers speak first then address any particular nuances if a stalemate.

Being heavier may not be ideal, but if the boxes are ‘ticked’ and everyone is happy, then why use Triclad. However, if the boxes are ticked and it appears ally is better solution, then go with that.

 

Thanks to Ad Hoc and daiquiri for your input on Triclad.

Perhaps Bruce could provide us with specs concerning operational area and proposed classification when available.

----------

When I look at the proposed vessel in terms of potential, given the commitment to a steel hull, I would tend to look at high latitude operation (general expedition and sub exploration) and an overall passenger/commercial classification as a way to cover future uses (and possible sale) of the vessel.

So in the structural analysis I would also be interested in capabilities for sea ice (not breaking) and how this would factor into strength, weight and cost. The proposed very slender design could lend itself very well in addressing sea ice operation.

----------

I am very interested in learning more about high latitude vessel design, and the special requirements for sea ice mitigation and effective topside de-icing.

Mark

 

The preliminary design and bid package for this now 95' passagemaker has been completed.

Basic specs are:
LOA 28.95m
LWL 28.95m
BWL 4.5m
Bmax 5.3m
Draft 1.52m
Persons 8 max
Displacement tons
Lightship 49.6
Half load 63.6
Full load 77.5

Speed
12.5 knots cruise
14.5 knots max

Stabiliser Seakeeper M2100 active gyroscopic
Watermaker TBD, 3000 litres/day
2 x John Deere 6068AFM75 6 cyl. marine diesels 231hp cont.
Combining gear (TBD) driving single CP propeller
2 x Northern Lights 16 & 20kW
Fuel 19,500 litres 5151 US gallons
Water 5000 litres 1321 US Gallons
Range 9020nm at 9.0 knots
5025nm at cruise
2450nm at max

Images & details can be downloaded:
http://www.tritonsubs.com/images/triton95.pdf

 

I'll assume you're looking for criticism.......I understand this is only preliminary and lot's will change IRL.......

You and Mr. Bury have come up with a clever arrangement that holds some promise of working quite well....of course I have a bunch of nits to pick....

The first surprising thing is the hull form in plan view, I gather this is styling but bunching all the topsides curvature in one place appears odd and I'd rather see smooth transitions.......

At the published half-load and power the top speed will be just barely in reach.....big boats always gain weight....I would build in a bigger cushion....

It appears the engine room and interior are accessed through 4' high doors from the main deck? The only full height interior access is through the pilothouse.....This needs revision.

I assume the workshop is the engine room ventilation trunk?

I'm going to bang my head on the pilothouse-saloon stairs...I hate that....

The curved corner glass in the pilothouse windshield will be expensive and confusing/awkward to see through at night......change that to a flat plate. Also in the pilothouse....when coming alongside I want to stand as far to the side as I can and get my head out the side window (so I can see the whole side of the boat) and be able to reach throttle/clutch and jig steering lever. This appears scary on starboard with the stairs right there and impossible on port.........

I assume the big Seakeeper goes in the tank room?

The RIB on the transom blocks aft deck access to the engine room and the sub storage...I would re-think that, two ways out of all spaces is a good thing....

Finally I'd extend the PH roof over the outside galley/dining area.....and arrange isenglass to enclose it.......

Otherwise it's a good start.....

 

Submarine Support

Tritonsubs,

OK, I give up. How do you get from the saloon/galley to the aft guest cabin. I can see the spiral stairs going down to the lower deck and the step up to the aft guest level but the steps then seem to go on up to the pilot house in the same sweep. I must be having a senior moment, any help is appreciated.

Cheers,
Graham

 

Unfortunately at sea my internet connection is so weak , slow and expensive that downloading files is prohibitive. I have not seen the boat and its file.

Im curious...How much does a submersible mini sub weigh ? And once loaded on deck what is its maintenance cycle ? How many days per year will this sub be deployed ? Deployed at sea or in a coastal environment ?

From the discussion I understand that the vessel is long and thin. I also have sailed light displacement ,long thin vessels at sea...fast, seaworthy, not uncomfortable , but tons of water cascading down the decks . Little buoyancy in the ends of a narrow boat, they punch straight thru the wave. To control this rushing water I frequently am bow down at 2 knots in heavy conditions. Be careful with any structure or equipment on deck and fanatically prune all weight forward...for example make it possible to dump the chains then reload , redirect , the ton of anchor chains and ground tackle well aft into a dedicated locker before putting to sea.

The difference in sea keeping abilty is dramatic.

 

Graham,

I think the idea is that the circular staircase starts at the lowest level (forward cabin under saloon), turns up through 50+ degrees to arrive at the mid level (aft stateroom level under PH), up through another 45+ degrees to land at the saloon level, and finally up another 50+ degrees to end at the pilot house. A quick mockup will tell you if it really works.......

Numerous other thoughts occur looking further at this preliminary.......

I think the custom combiner gear (two engines into one output shaft) should be dropped in favor of one heavy duty commercial rated 6 cylinder engine.....more reliable, parts are readily available, and lower cost initially and long term......If a get home system is required that can be fitted via hydraulics, with it's own shaft and prop or without.

I do think the sub garage below deck is a very good idea but I don't think the loading system will work in any sea. The vertical (open) doors will be smashed if the sub swings at all in it's davits, plus the side loading on those davit arms will be a problem setup as currently drawn....not to mention getting two separate arms to function identically?

The sub this boat is designed to support has a published weight of 8800 pounds, of which 3600 is fixed ballast....it's listed at $2.59m...just for the sub.......The support vessel is about 110,000 light ship and was supposed to cost $2.5m complete........

This is the puzzling part.....the mothership is to be built in China at around $22-23 per pound. The sub's lead ballast might be $2 /lb so deduct $7500 from the $2.59m for the ballast, you then have 5200 pounds of sub at very close to $500/lb! Do sub builders get paid a lot more than boat builders? The highest quality composite luxury yachts currently built in the USA are running $50-70/lb....why so much more for the sub?

So that brings me the biggest question....Will the individual spending $5m + to own what is really an occasionally (rarely?) used bauble, be happy with the accommodation supplied by this vessel......my guess is no....but I've been wrong before and will be again.....

 

Apologies if this has already been covered, but what is the rationale behind having only two guest cabins?
Now, I realise that many owners wind up using their 3rd cabin as little more than a store room, but there's a reason why the vast majority of builders go to great lengths to cram at least 3 cabins into boats that are as small as 40 feet... it's what the market thinks it wants...

 

Whoa ! launch,retrival and storage of a fragile 9000 pound sub ? from a 95 ft boat at sea will be a challenge .

 

Thanks for all the comments.

First, I should reiterate that this is a purpose built design for the CEO and senior management of the largest civil submarine group in the world. We may sell one or two to our clients who are sub-centric owner-operators and as shadow boats to super yacht owners who want access to a sub but we don't expect this to appeal to a wide range of buyers. We're experts when it comes to at-sea sub ops and launch and recovery, so LARS ops from a gyrostabilized vessel will not be a problem and subs, especially ones that dive to 1000 meters, are not fragile. In fairness, the LARS system is overly simplified in the drawings and lateral control lines and tensioning winches are used to minimize sub motion during the process.

Tad, you make some good points a couple of which I'll address.

I like the styling. Bridge windows will open, but we'll have a remote panel to control gears, throttle, CP prop, rudder & bow thruster from anywhere on the vessel.

The doors are 5' and you step down into the superstructure. Not ideal, but workable. The RIB can be moved on to the main deck and will be for long passages.

I'm adamant about the engine/drive configuration. At cruise, one engine is running at optimum power for maximum efficiency. In those instances where more power is needed, the second engine comes on-line and the CP prop is adjusted. The system is redundant in case of an engine problem and engines can be switched for at-sea maintenance/oil change, etc. And while there is a strong trend to overpower displacement hulls, I reject it.

We are having a problem finding a combining gear. The Finnoy system, which would work, is massively heavy. We're still looking and also considering diesel electric. Not surprisingly for sub guys, the vessel will have a very large battery bank.

With respect to sub cost - you wouldn't want to go to a 1000 meters in a cheap submarine would you? The main ballast is not fixed lead but the weight of water in the MBTs. There is very little fixed lead ballast present in the form of a drop/trim weight. I don't have the space and time to go into the complexities of deep submersible construction but I can tell you that it is nothing like building a yacht. And if you think this model is expensive, you should see the price on the new 11,000 meter capable full ocean depth Triton we are building, or the 65 m Phoenix 1000 diesel electric luxury sub ($90 million).

And finally, my wife and I will run the boat (she's done one circumnavigation) and we're the clients, so it only has to meet our needs. Frankly, I couldn't be more pleased with the design and Paul Bury (formerly Chief Designer at Tripp Design and Wally Yachts) is a terrifically talented and personable bloke with whom to work.