Full Displacement of semi

Discussion in 'Boat Design' started by tdamico, Jul 31, 2003.

  1. Guest

    Guest Guest

    in my experience cats seem to be more of a hard jerking type movement compared to a monos gentle roll. but if going into wakes directly cats (especially air entapment cats on plane) provide one of the smothest rides ive had. Driving a cat is a dream as they turn like they are on tracks. But docking is an issue due to thier width. they have tons of room and are very nice to live on. They generally have much better fuel efficentcy as well as higher top speeds than monos.
     
  2. tdamico
    Joined: Aug 2003
    Posts: 33
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: NC

    tdamico Junior Member

    I agree that much more investigation needs to be done before we are anywhere near our decision. We will also charter several boats before making our final decision. Michael, is a 7' clearence enough to counter effect the pounding you mentioned earlier. I actually communicated with the owner of the company you mentioned and he feels that the Island Hopper is not only a deep water boat, but is sailing one from China to Miami for promotional purposes. He hopes to have this boat at the powerboat show in Anapolis in October. Is the hard jerky movement analogous with the way a pontoon boat handles?

    Regardless, despite all the upsides or downsides to ride, seaworthiness, etc. if you can't find a place to dock it from time to time, its worthless. From what I can see, beam for monohulls that I am looking at run around 16' and beam for the cats I am looking at run around 21', is this extra 5' really critical?
     
  3. Portager
    Joined: May 2002
    Posts: 418
    Likes: 13, Points: 0, Legacy Rep: 325
    Location: Southern California

    Portager Senior Member

    If you are talking about the way a pontoon boat reacts when it is hit by a wave from the beam, then yes. When a wave encounters the pontoon, the water level relative to the pontoon suddenly increases causing a sudden increase in buoyancy force. When the wave hits the Catamaran head-on the affect is distributed over time, but when the wave hits broadside the force is sudden and since it has a large lever arm relative to the ships center of gravity, it creates a high angular rate.

    The beam of the Island Hopper 43’ is 22’, which is 1 foot wider than the Nordhavn 72’. Since the maximum air draft to clear a bridge in Chicago is 19’, boats the size of the Nordhavn 72’ are unable to complete the great loop. Enough said?

    Next time you talk to TrawlerCat ask them what the minimum air draft of the Island Hopper 43’ is. If it is greater than 19’ then the Island Hopper 43’ and the Great loop are mutually exclusive.

    Regards;
    Mike Schooley
     
  4. Willallison
    Joined: Oct 2001
    Posts: 3,590
    Likes: 130, Points: 0, Legacy Rep: 2369
    Location: Australia

    Willallison Senior Member

    Have you considered something like our very own Tad Roberts' "Passagemaker Lite " series of designs ( http://www.tadroberts.com/ )
    Air draft is low, stability, comfort, economy etc are all good..... and I'm sure Tad would be only too happy if you were to commission one!:D
     
  5. Portager
    Joined: May 2002
    Posts: 418
    Likes: 13, Points: 0, Legacy Rep: 325
    Location: Southern California

    Portager Senior Member

    Did you get your questions ansered or just get anoyed?

    I hope the former but if not I am sorry. I just want you to make sure the Cat is really what you want before you make a decision that cost a lot of money.

    Regards;
    Mike Schooley
     
  6. tdamico
    Joined: Aug 2003
    Posts: 33
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: NC

    tdamico Junior Member

    No, Michael. I was away on a business trip and just got home this evening. Brutal trip, I'm going on about 2-3 hours of sleep in the last two days. Anyhow.

    I am really torn. I can't wait until September and October to visit TrawlerFest and then the Power Boat show. I really need to climb around these boats.

    I am drawn to the cat, but I wonder how hard it really will be to find a slip. Some say that 90%+ of the time is spent on the hook, so finding a slip every month or so for a few days is really not a big deal. I really have no way of knowing if this is true or not. Hopefully, at the boat show I can meet some owners. If I pick a cat that is under 19 bridge height, then am I correct in assuming that I can navigate the great circle route? Will I find anchorages along the way or will the 22' beam really be a huge factor? If I choose the monohull trawler, will the greater draft limit me when I want to explore those out of the way places?

    Also, how realistic is it, really, to find free anchorage or inexpensive moorings in the islands and the east coast?

    I just have so many questions!!!

    Thanks to all. :confused:
     
  7. Portager
    Joined: May 2002
    Posts: 418
    Likes: 13, Points: 0, Legacy Rep: 325
    Location: Southern California

    Portager Senior Member

    I think the people who spend a high percentage of their time on the hook are the ones on a tight budget. Those who can afford it tend to spend about half their time in slips. The reasons are to eat out, to gun the AC without running the generator, use shore facilities such as access to phone lines to catch up on email, …

    The Catamaran I tried to sleep on was on an end tie. I never realized how unprotected end ties are until that night. Every passing boat produced enough of a wake to wake me up. Maybe that’s how it got its name? A ferry went by ever 2 hours and produced enough wake in a no wake zone that I’d go airborne. When the wake hit the first hull we would bob up, but then the wake hit the second hull the boat would reverse direction while we were still going up. I’d wake up in mid air, just an instant before impact. I spent the second night in a Motel 6.

    If your air draft (with mast lowered) is less than 19’ you should be able to navigate the Great loop, although you might trouble on some of the narrower channel systems. I’m not sure how wide the locks are.

    I think you can find abundant anchorages in sparsely populated areas, but the closer you get the population centers the harder anchorages will be to find. There are also long stretches on the inland rivers that have been widened and dredged for barge traffic where anchorages are rare.

    If your interested in gunk holing maybe you should take Willallison’s advice and consider Tad Roberts designs http://www.tadroberts.com . The Passagemaker Lite 46 has the following specifications:
    LOA 46’0”
    LWL 45’0”
    Beam 11’6”
    Draft 2’10”
    Displacement 29000 lbs
    Fuel 860 gals
    Water 200 gals
    Power (2) Perkins M65
    59 HP @2600 RPM
    Top Speed 11.5 Knots
    Cruising Sp. 10 Knots
    Vertical clearance (boat plus 14" grd. clearance) 13'2"

    With a draft of only 2’ 10” it is 2” shallower draft that the TrawlerCat Island Hopper 43’ and it looks a lot better. Best of all it could be transported without a pilot car.

    If that won’t do, try the Passagemaker Lite 56:
    PL 56
    LOA 56'0"
    LWL 55'0"
    Beam 13'0"
    Draft 3'6"
    Displacement 51000 lbs.
    Fuel 1100 gals
    Water 400 gals
    Power (2)John Deere 4045DFM 75 HP @2400 RPM
    Top Speed 11.5 Knots
    Cruising Sp. 10.5 Knots

    The draft is a little higher but it is much larger inside.

    Regards;
    Mike Schooley
     
  8. tdamico
    Joined: Aug 2003
    Posts: 33
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: NC

    tdamico Junior Member

     
  9. gonzo
    Joined: Aug 2002
    Posts: 14,132
    Likes: 538, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    A large wake will move a monohull or a multihull. I can't see the difference in that situation. I suppose some people aren't able to sleep at sea. I agree that live-aboards have a setup not far from an RV park. However, most talk about sailing the seas and seeing the world. I wonder what they'll do with the plants in the cockpit and the phone connection. Anchoring out is a choice that has nothing to do with money. I prefer peace and quiet to the commotion at the marina.
     
  10. Portager
    Joined: May 2002
    Posts: 418
    Likes: 13, Points: 0, Legacy Rep: 325
    Location: Southern California

    Portager Senior Member

     
  11. gonzo
    Joined: Aug 2002
    Posts: 14,132
    Likes: 538, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Is A/C really a necessity?
     
  12. tdamico
    Joined: Aug 2003
    Posts: 33
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: NC

    tdamico Junior Member

    Gonzo, your posts are great, as a counterpoint. If you can find some time, I would love to have you elaborate on some of your opinions. Are you familiar with cats? Are there any "real" issues around finding dock space when you really need it, regardless of whether in the "Ditch" or sea? How realistic is "living on the hook" I agree with you that it has more to do with a lifestyle than it has to do with money. Is this a naieve point of view?

    Michael:

    As regards high speed internet access, I will be installing a KVH TRACNET Service.

    This system uses a slow speed "uplink" (landline, cellular, or satphone) to request information from the internet, then the requested files from the internet are sent to the boat using a high speed connection to the DSS TV satellite. Special installation connections are made to the KVH sat TV antenna so that it will interface with the new data system. In order to use this system, the vessel will need to have both KVH satellite TV antenna, and the new Tracnet "uplink" antenna. There will be a monthly charge for the high-speed downlink service, and a per minute charge on the "uplink", which will depend upon which uplink service is needed. The "downlink" speed will be very fast: 400kbps.
     
  13. gonzo
    Joined: Aug 2002
    Posts: 14,132
    Likes: 538, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I have sailed and fished the Atlantic from Argentina to Canada, worked in the islands for a while and cruised the Amazon basin. There are all kinds of different approaches to cruising, and as long as they fit your life, they are equivalent. I am sailing the Great Lakes now, where the water is frozen half the year ( iceboats are fast). Once you leave the more touristy areas, boat facilities are scarce. A problem many people have, is that their boats and lifestyle depend on continuos supplies. It is limiting as to the areas available. I think that a boat with less systems gives me more freedom. However, it is at the expense of confort. Boats designed for A/C, and I have built a few, have little or no provision for natural ventilation. In my opinion, they make poor long range cruisers. A wind scoop can cool down a boat to a confortable level. If 65-70 degrees is required at all times, then an A/C is necessary. But then, what is the use of going to the tropics?
     
  14. Willallison
    Joined: Oct 2001
    Posts: 3,590
    Likes: 130, Points: 0, Legacy Rep: 2369
    Location: Australia

    Willallison Senior Member

    This is developing into a very interesting thread, I must say. :D
    Now I don't profess to know a great deal about the 'great circle' route, living on the other side of the world as I do, however much of this discussion is relative to any long-term cruise.
    As far as choosing to anchor out vs berthing o/night in a marina, I'll take the anchoring out option any day. I've never understood why people who go boating to 'get away from it all' go straight to the nearest marina where there's less peace and quiet than if they'd stayed home. Sure, you might spend a night tied up here or there in order to go see the local sights, or to eat out once in a while But otherwise there's few things as pleasant as waking up in a secluded bay with nobody else around and watching the sun come up to burn the morning mist off the water. Or to step straight from the bed into the water for a morning swim.
    On the other hand, if doing the circle means having to anchor close to a riverbank, whilst other boats and ferries can pass by continuously: or if that secluded bay is so full that it resembles a parking lot, then the marina starts to look pretty good!

    Back to the cat / displacement / semi displacement debate. I've not spent much time aboard cruising cats - they definitely have the advantage when it comes to efficiency at higher speeds (15 - 20 knots or so). Berthing is widely regarded as a problem. Where I live there a 7 marinas nearby. A few contain largish cats, but visiting multihulls are generally forced to take end-ties. Living spaces tend to be nice and roomy, but cabins tend to be rather more confined than in a monohull. Ventilation to these cabins is often not what it could be either.....
    Unless you have a very fat wallet, I'd forget the semi-displacement boat. We operate a 48ft Offshore yachtfisher. With a pair of 320hp diesels it tops out at around 18 knots. We haven't owned the boat for very long, but at that speed, I can tell you that you can visibly watch the fuel guages fall!!:!: Fine for short runs, but for any longer cruise it simply limits range too much. We usually operate the boat in the 9 - 10 knot range.
    A displacement boat operating at or near these speeds will be more economical - partly as a result of hullshape and partly because its engines will be sized for the job. Further, if there's one simple rule that applies to all hulltypes, it is that the more weight you add, the more power you need to drive it at a given speed. Cats & planing hulls are most sensitive to weight, then, semi-displacement and least affected of all is the displacement vessel. As you plan on cruising long term, plan on taking lots of stuff - plan on adding lots of weight. Lastly, I gather that much of the circle is speed / wake restricted. So after all that, the displacement vessel is the one I'd go for.

    Regardless of which type you choose, you must decide what kind of boater you want to be. Do you want a floating condo - where you have all the 110v domestic appliances - electric cookers, air con, heaters etc etc. If so, you'll want good shore connections and an appropriately sized, big genset. Most US boats are set up this way. Alternatively, you can go the 12 / 24 volt route. This requires more careful power management and different systems, but can generally provide most of the same comforts - just in a different way. The advantage here is that you aren't as reliant on shore power or running a generator every time you want to do something. Both have their pro's and cons, but you really need to choose one type of the other.

    The most valuable advice I could give, would be to go to as many boat shows as you can. Clamber all over the boats. Forget about the shiny topsides - check out the living spaces: is the boat easy to move about on: is there sufficient storage space (you'll need at least twice as much as you think...): will you be able to handle the boat with your expected crew. The list goes on.
    Talk to as many people who have completed the circle as possible. What kind of boat did they operate: what would they do differently the next time......
    Lastly, don't be fooled into thinking that one boat - or type of boat - can do it all. Better to buy a boat that suits your needs now - to complete the circle if you choose - and then replace it with something more suitable for offshore cruising if and when the need arises. There's no more sure-fire way of having a mutiny than to send the wife to sea in a riverboat!;)
     

  15. tdamico
    Joined: Aug 2003
    Posts: 33
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: NC

    tdamico Junior Member

    [QUOTE...As far as choosing to anchor out vs berthing o/night in a marina, I'll take the anchoring out option any day. I've never understood why people who go boating to 'get away from it all' go straight to the nearest marina where there's less peace and quiet than if they'd stayed home. Sure, you might spend a night tied up here or there in order to go see the local sights, or to eat out once in a while But otherwise there's few things as pleasant as waking up in a secluded bay with nobody else around and watching the sun come up to burn the morning mist off the water. Or to step straight from the bed into the water for a morning swim.

    While we will want to utilize our boat for a number of diferent activities, the above statment is bang on. This is our thinking exactly, but there is a lurking doubt that this is practical. Some, not all, but quite a few boaters that lurk on the various sites all seem, somehow, to make it seem that this community of boaters is really a community of RV people, just on boats. This is NOT what we are looking for in our lifestyle change. Reading posts like this gives me hope, that I won't have to live in a marina most of the time.

     
Loading...
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.