Looking for a N.A. for 85' passagemaker

Discussion in 'Boat Design' started by Tritonsubs, Jun 18, 2011.

  1. Luc Vernet
    Joined: May 2004
    Posts: 56
    Likes: 3, Points: 0, Legacy Rep: 31
    Location: Vietnam

    Luc Vernet Senior N.A.

    Could not agree more!

    Besides that, a catamaran of the same displacement (we buy boats by kilograms/ pounds, don't we?) will be some 60/65' long. Then the long, slender hulls which are at the root of catamarans performance, although rather deep will be almost useless corridors where even "modern" 6L. engines would be tight, not to mention the sturdy ones our friend is thinking of. Then, the "gain" in space would only exist if there is a top deck above main deck.
     
  2. Mark Cat
    Joined: Jun 2011
    Posts: 115
    Likes: 4, Points: 0, Legacy Rep: 66
    Location: Michigan

    Mark Cat Senior Member

    Bruce,

    Steel mono it is.

    The challenge with boat CG/CB with sub management is an interesting. I am hoping at some point you can share the retrieval approach.

    Just some thoughts on my CAT approach. Obviously, compared to you, I am a sub retrieval newbie.

    After doing some sketches, my solution for the Al CAT was to use a minimalist approach to the center bridge deck area between the hulls. Where a slightly elevated enclosed bridge and sub retrieval cutout (receiver) were the only real structures.

    The sub area was set into the aft portion of the curved enclosed bridge, both being set further back from a traditional CAT layout. The focus was on accommodating the sub CG and how the sub and the boat would be designed to mate together, with an overall bridge deck height of 48 inches. The hulls have cross connected forward beams, and max hull beam set further back than normal. So essentially, I shifted a lot of the structure into high shouldered hulls. Because of its simplicity in sloping the cabin ,deck, and work platform, it would be possible to address any hull icing for high latitude operation. There was a small roof extending over the front portion of the sub (location of the sub hatch), on top of which I put 12 solar panels.

    And I am sure you are tiered of my CAT ideas, so I will say no more about it.

    Now on to some more interesting stuff:

    Engines and Gensets - Cooling and exhaust design.

    For the steel hull design you have the opportunity to design in keel cooling for the Diesels from the onset. Coupled with the use of dry exhaust(s), you can venture into higher and colder latitiudes without having to unfreeze seachests or use 0C raw water.

    If though out ahead of time location of the dry exhausts can be effective and not soot the deck or back draft.

    Things not to leave for last:

    Galley design.

    Meet early with the master cook to find out how to layout the Galley. For a boat that rolls, the cook must "strap in", and be protected from hot liquids or surfaces using guard rails. Also things cannot move around. One trick is to glue a large sheet magnetic to the bottom of the SS316L work surface. So when you put a knife or something ferrous on it it stays put. There is a ridge around the work surface to facilitate easy cleaning, with the surface sloping down to the sink and drain. There are ears the extend slightly from the ridge rail, that allow a set sized SS rack to be placed on the counter so it cannot move around. The racks have build in handles (cutouts) and are also stack-able.

    Food storage and garbage management.

    Tender design.

    A lot of the tenders that I looked at, IMHO did not perform the role of tender very effectively. So for the 74 ft AL work boat I designed my own, it was also a CAT.

    It came down to the how to quickly move supplies between shore and ship. The easiest way was to use standard sized containers (Plastic Jerrycans, and other reusable plastic water tight holders of produce and food, with provision for reusable ice packs), that would fit into covered storage holds on the tender, with similar standardized compartment holds aboard ship. So transfer was to move full containers on-board and empty containers out to the tender. This included garbage containers, that were also standardized but were larger and different in color.

    So going ashore, garbage off, food on.

    My primary responsibility was in electrical design, so if you have any question about this let me know.

    Mark
     
  3. Tritonsubs
    Joined: Jun 2011
    Posts: 20
    Likes: 1, Points: 0, Legacy Rep: 14
    Location: Twin Lakes, Idaho

    Tritonsubs Submarine design & build

    Hello Mark,

    Thanks for your thoughts. If you PM me I can send you more info on the 20m cats we are building and how we dealt with the LARS issues.

    When we've finalized more of the Triton 95 design, I'll post the details here, including the LARS design.

    We'll fit underwater exhaust to the Triton 95 and standard heat exchangers. It's what I am comfortable with and while I never considered your issues with high latitudes, it's food for thought.

    Nice idea about the magnetic sheet & ss. It makes sense. We intend to fit the boat with the Seakeeper 21000 gyro system, so, hopefully any rolling will be minimal. I've done a lot of "strapping in" on sailboats and those days are hopefully over for me.

    While I grew up on commercial tugs and jack-up rigs and lived on a 68' Defever for many years, sailing it through Asia, Indonesia, Australia and the South Pacific back to Seattle in the early 70s, I married a woman who had just finished sailing around the world. She was 24 and I was 30 and that was 25 years ago. We always had sail boats, but a few years ago, while living in Florida we had a Beneteau that we would often sail to the Bahamas. I managed to make one trip so utterly miserable that she suddenly acquiesced and told me I could buy another passagemaker. So, she's now a willing accomplice.

    As for the tender, I would like to know more about what you designed. I would normally just do a RIB, but I am certainly open to suggestion.

    Thanks for your time.
     
  4. daiquiri
    Joined: May 2004
    Posts: 5,371
    Likes: 258, Points: 93, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    That's visually a nice design, but I'd like to say my opinion about those huge vertical windows on the front of the superstructure. Imho they don't marry well with a low freeboard combined with plumb unflared bow and a wet deck. That's if your concern is beating into head waves during (possibly stormy) oceanic operations, as it appears to be the case from your previous posts. In such conditions big windows might occasionally get subject to high peak pressure loads from impacting green water.
    Just my two cents worth.

    Cheers!
     
  5. Tritonsubs
    Joined: Jun 2011
    Posts: 20
    Likes: 1, Points: 0, Legacy Rep: 14
    Location: Twin Lakes, Idaho

    Tritonsubs Submarine design & build

    We'll soon begin construction on a full ocean depth submersible capable of diving to 36,000 feet, the deepest spot in the ocean where the hydrostatic pressure is 16,000 PSI. The passenger compartment is composed of- you guessed it, glass. We build conventional and large subs with acrylic viewports that dive to 3300 feet and 1000 feet. We're building the world's first undersea resort and many of the rooms have exterior pressure boundaries that are 70% acrylic.

    Properly engineered and appropriately sized glass in the location you mentioned is absolutely not a problem, even if it defies conventional thinking.
     
  6. daiquiri
    Joined: May 2004
    Posts: 5,371
    Likes: 258, Points: 93, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    If we want to take it to the extremes, men have also walked on the moon - so that's not impossible either. But not everyone finds it convenient or attractive to use spacecraft technologies for pleasure purposes. :)
    I didn't understand that you are one of those guys who will rather go upstream than downstream. My fault.
    Cheers!

    P.S.
    I'd be curious to learn more about those acrylic viewports for subs. What size are they, and how thick? How much do they deflect at 3300 ft?
     
  7. Tritonsubs
    Joined: Jun 2011
    Posts: 20
    Likes: 1, Points: 0, Legacy Rep: 14
    Location: Twin Lakes, Idaho

    Tritonsubs Submarine design & build

    A bit thicker glass is hardly rocket-science. One need look no further than the Dashew FPB series to see this in use.
     
  8. Mark Cat
    Joined: Jun 2011
    Posts: 115
    Likes: 4, Points: 0, Legacy Rep: 66
    Location: Michigan

    Mark Cat Senior Member

    Bruce,

    Diesel raw water cooling:

    Raw Salt water = Corrosion, Repair and Money.

    Keel Cooling with polypropylene glycol + Deionized water = Long Life, routine maintenance.

    Go to BoatDiesel.com and just read about the same problems over and over with heat exchangers and after coolers and galvanic corrosion in the use of raw salt water cooling. I have come to the conclusion that the worse thing you can do to your expensive diesel engine is run salt water through it.

    ----------

    In dealing with small beam hulls (relatively speaking) it is a challenge to address all of the propulsion needs due to space constraints in the engine room.

    It is very hard to argue that an effective system is a single large engine and single prop. Engine room layout for a midships longitudinal row of engine and genset(s) is very attractive.

    One possible approach:

    Main propulsion:

    KTA35 See attached. Continuous rated big and slow with good fuel economy.

    Main Genset 3 Phase (208/120) 60 Hz:

    50kW I6 Diesel

    2nd Genset 1 Phase (240/120) 60 Hz:

    25kW I6 Diesel

    Emergency propulsion:

    30Hp 3 Phase induction motor with controller, uses secondary drive input on transmission.

    Notes:

    In discussions with People like Dave Gerr and NAs, the question of engine reliability for large diesels like the KTA38 is not an issue. So from an engine stand point we do not need to design for redundancy with engines like the KTA38. With some fine print that I will discuss in a moment.

    If you were to have paying passengers on board there are the CFR 46 and other rules about secondary propulsion, dead ship, etc. One approach is to use a 3 phase AC Motor, lets say 30 HP and a controller, as emergency propulsion powered by the Genset, a mini hybrid approach.

    For reliable diesel engine operation I would propose (short list):

    1) Keel cooling.
    2) Polishing all fuel before coming into use not matter where it is purchased. Continuous in the day tank, and polished through transfer pumps as it is brought on board and stored in wing tanks.
    3) Keep up with oil changes. It is best to have an oil change system on-board using tanks, pluming, manifolds and pumps, to change oil while in port, and provide a way to move oil between the engine room and topsides.
    4) Proper fuel filtering.
    5) Keep up with maintenance.

    Keel Cooling System Description:

    Every manufacturer has special needs for the exact keel cooler design, so for the KTA38 consult Cummins. Basic set up:

    All engines use a dry exhaust, or forced air cooled dry exhaust.

    There are two large keel coolers one port and one starboard recessed into the steel hull, with a central main reservoir (non-integral tank) sized to service all three diesel engines through their normal raw water systems. The reservoir can be segmented and/or pressurized if needed.

    Two electric pumps + main engine driven mechanical backup (Clutch controlled), are used to circulate polypropylene glycol between the coolers and the reservoir. The pumps are reservoir temperature controlled and are usually staged about 5C apart. The operating sea water temp for the system is based on 30 to 85 degrees F.

    Mark
     

    Attached Files:

  9. Mark Cat
    Joined: Jun 2011
    Posts: 115
    Likes: 4, Points: 0, Legacy Rep: 66
    Location: Michigan

    Mark Cat Senior Member

    Bruce,

    Catamaran Aluminum Tender design (15 feet). Center console design, cross between a CAT and a tunnel hull design for the hulls.

    The CAT had several uses. It could be heavily loaded for supply, or run very fast light for moving 1 or 2 passengers (in addition to the pilot) between shore and ship. The outboard was behind the driver/console in the center section, with a jack plate, in a recessed pocket (below the bridge deck). Supply holds were in the hulls with hinged sealed tops providing seating for moving 3 to 8 passengers.

    For one or two passengers (high speed mode) seating was in front of the console side-by-side. There were water tight compartments in the hulls at the bow and stern which would prevent sinking upon capsize. I wanted to fill these water tight compartments with pure Nitrogen at a set pressure, to monitor integrity after welded and over time.

    The tender was designed to be beached. For shallow low speed operation you could jack up the out board with the jacking plate.

    I have attached a sampling of what we reviewed for standardized storage of supplies on-board the work boat. The Gerry cans and Acro-Mills totes fit into dividers in the hulls. They were under hinged seats each having a slam latch and seal to keep out water.

    Screw Top Garbage cans were wedged (ears down from the center console step) on the center section for transport. You could line up 4 on each side. For a total of 8.

    ----------

    Bruce you are in a unique position of being able to design you own custom aluminum tender. Because you understand how to deploy vessels at sea, so it would be fairly simple for you to design a custom receiver for the tender for disembarkation/embarkation stability and bringing the vessel aboard for transport.

    I am sure you would be able to move beyond the basic crane approach to something more clever. With a custom tender design there is a lot you can do.

    ----------

    Anyway this is the basic tender/supply approach.

    Mark
     

    Attached Files:

  10. Mark Cat
    Joined: Jun 2011
    Posts: 115
    Likes: 4, Points: 0, Legacy Rep: 66
    Location: Michigan

    Mark Cat Senior Member

    Bruce,

    Yes its me again.

    I just had a long discussion about how to best attached the aluminum cabin/deck/superstructure to the steel hull/frames/flanges.

    And one approach I would look at would be bonding and riveting.

    I think I would have the structural engineer create a mock up and test shear at elevated (max deck) temperatures.

    I am assuming an aluminum deck. Obviously, in addition to the approach here there are the more traditional approaches for dealing with the two dissimilar metals.

    So for example:

    Hull is completed and right side up ready to be mated to the superstructure which will be lowered by a huge overhead crane, in a temperature controlled assembly house.

    The steel hull flanges would mate to the aluminum superstructure flanges. Both on the steel side and aluminum side prep the surface, which may include priming (isolating and prepping) the steel and cleaning the aluminum using a solvent, to remove oxidation, clean and dry surface. Then a bonding adhesive is applied to the painted steel flanges. Obviously a lot of adhesive with a very long cure time. The super structure is then lowered onto the hull and clamped in position. The aluminum structure is then riveted to the steel using two rows (or more depending upon joint and strength) of offset SS304 or SS316L high shear strength 120 degree flush mount rivets. Excess bonding is removed from the joint. The rivets could be installed wet using the same or slightly thinner bonding adhesive. The riveted deck area would eventually be epoxy painted along with the hull which would cover the riveted areas and blend the two surfaces.

    Anyway I think I would give this a look.

    Mark
     
  11. Tad
    Joined: Mar 2002
    Posts: 2,321
    Likes: 214, Points: 73, Legacy Rep: 2281
    Location: Flattop Islands

    Tad Boat Designer

    A long skinny hull with low freeboard (small cross section) will require global bending to be addressed early. The light scantlings and break in the main deck may be problems.....the break will be an issue.....she may require a steel deck with big longitudinal girders/flanges......

    Lloyd's SSC rules address global issues reasonably well......
     
  12. daiquiri
    Joined: May 2004
    Posts: 5,371
    Likes: 258, Points: 93, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Hi Mark,
    please take a look at the Triclad site: http://www.triclad.com/
    That's what I use when alu/steel bonding is an issue. They are explosively bonded alu/steel bars which are placed in between aluminum deck/superstructure and steel hull frames, and then welded each side to it's similar metal.
    Cheers!
     
  13. GAZZABO
    Joined: Mar 2006
    Posts: 36
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Whangarei,n.z.

    GAZZABO Junior Member

    One of my designs was built here in NZ about 18 years ago and proved very soccessful. Called ADVENTURE it won the Tall Ships Race Boston to Europe I think in 1994 .
    ADVENTURE was 123 ft oa 18ft beam and 4ft draft board down 14ft twin 120hp Fords 3 masted schooner.Displ 93 tons it was based on my original design but extended by my client ( have you heard that before!) the 0riginal one was 100ft 18ft 4ft and 75 tons no motor but with a 18ft 60hp Tug for pushing around in port. 4 masted schooner all the same mainsails. 30t cargo hold/workshop. Steel of course.
     
  14. GAZZABO
    Joined: Mar 2006
    Posts: 36
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Whangarei,n.z.

    GAZZABO Junior Member

    Sorry ,please ignore my last post. I have since followed thru all the posts . Seems you are well on the way.
     

  15. Mark Cat
    Joined: Jun 2011
    Posts: 115
    Likes: 4, Points: 0, Legacy Rep: 66
    Location: Michigan

    Mark Cat Senior Member

    daiquiri,

    Thanks for the link.

    Ernest Sims briefly talks about Triclad in his book Aluminum Boatbuilding Third Edition. This was one of the traditional approaches I was talking about. However, never having actually used the material, inspected weld quality or performing any preproduction sample/weld stress analysis, I am very interested in how it performs in actual use.

    Could you comment further on the performance of Tricald joints and how the transition point between steel to aluminum was chosen per the overall structure?

    It seems a challenge in providing access to the joints (Both sides continuous welds) while also achieving a pleasing cosmetic quality at the transition.

    Thanks,

    Mark
     
Loading...
Similar Threads
  1. Nathan Hill
    Replies:
    3
    Views:
    211
  2. Boatyboatboat
    Replies:
    13
    Views:
    1,342
  3. fpjeepy05
    Replies:
    13
    Views:
    677
  4. Allen thomas
    Replies:
    15
    Views:
    1,299
  5. Fisher Heverly
    Replies:
    22
    Views:
    2,163
  6. Thule
    Replies:
    18
    Views:
    1,541
  7. John Torelli
    Replies:
    8
    Views:
    977
  8. Michael Vankevich
    Replies:
    3
    Views:
    1,016
  9. mjozefo
    Replies:
    8
    Views:
    1,597
  10. Daniel Mazurkiewicz
    Replies:
    41
    Views:
    4,059
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.