Trawler questions

Discussion in 'Stability' started by alrod, Dec 5, 2008.

  1. Tad
    Joined: Mar 2002
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    Location: Flattop Islands

    Tad Boat Designer


    The internet is a dangerous place......I see I'm quoted on your website, presumably as some sort of expert? Inexperienced? You know nothing of my experience. But that's okay, you must defend your this case against nothing.

    The reason I post on this forum is to try and help folks understand something concerning naval architecture or boat design. I often have to clarify statements that are taken out of context or misunderstood.

    Boats are available in all manner of shapes and sizes, this is good and keeps us all busy. And everyone has an axe or two to grind (sell).

    When I stated........
    "Unballasted, lightweight cored construction, shallow draft, wide beam.....all these factors add up to a high sided box floating on top of the water. Motion in a seaway will be quick and exaggerated due to fast shifts of the center of buoyancy in a wide flat hull."

    I believe your website states Great Harbour's are unballasted?

    I believe a great deal is made of cored construction in your product literature? As opposed to say....all steel construction?

    I believe a great deal is made of shallow draft in your product literature?

    True you are careful not to say "wide", rather you state, "stable" and "roomy". But everything is relative, compared to my Passagemaker Lite 46' with 11'6" beam, the 15'10" beam of your GH47 is wide.

    I include the comparison drawing below to clarify my statement concerning a "box floating on top of the water"....folks can make up their own minds on that one....

    The comparison vessel is my design, the Ocean 55'. LOA is 55'0", LWL is 51'2", beam is 15', draft is 6'0", displacement about 75,000 pounds at half load, cruising speed is 7 knots with a 105 HP John Deere turning a 40" wheel through a 4:1 reduction gear.

    The GH47 is 46'10" LOA, LWL is 46'1", beam is 15'10", draft is 2'10", displacement is 70,000 pounds full load, cruising speed 8.25 knots with twin 75HP Yanmars.


    I believe that, referencing the drawing above, you should be able to understand that as each boat heels, the shift of B outboard will be quicker (and farther) in the GH than in the Ocean. What this implies is that motion (righting force) will be more quickly applied. Some folks are comforted by this rapid righting, others are worn out by it and would prefer the slower and deeper rolling of the Ocean type hull.

    Neither boat is right for everyone......
    1 person likes this.
  2. dskira

    dskira Previous Member

    In my humble opinion you should talk privatly with TAD.
    He has a great experiences in motor boat.
    You can even have him design the boat of your dream.
    To be precise: I know TAD by his work, I don't know him privatly and I never had any business with him.
  3. Guillermo
    Joined: Mar 2005
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    Location: Pontevedra, Spain

    Guillermo Ingeniero Naval

    I'm wondering how the GH's perform in really hard (a force 10, i.e) sustained oceanic conditions with their shallow draught and high superstructure.

    In my humble opinion they seem rather oriented to island hopping and anchoring in shallow protected waters, which probably they do nicely, but I may be wrong.

  4. Guest62110524

    Guest62110524 Previous Member

    all rather intrigueing
    could you put up a stability curve of the boat in question please
  5. apex1

    apex1 Guest

    They do´nt perform well Guillermo.
    There was a rather hot debate on another forum or blog about one year ago. Could´nt find it again.
    The result was pretty clear, Bahamas to Key Largo yes (but every bathtub can). Westcoast to Hawaii, as one of the boats made, was good luck and bad seamanship!

  6. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    The hulls are modelled after hard-chine coastal workboats. The interiors are modelled after waterfront condominiums. Serious blue-water crews tend to want more confined spaces (less room to get tossed around) and deeper-riding hulls, although that's not to say a GH couldn't be outfitted with sufficient hand-holds and tie-down points to handle getting tossed around offshore.
    I tend to agree that, based on the manufacturer's specs, and the owner reports and reviews I've seen, the Great Harbour boats are intended more for coastal passages and island hopping than for extended ocean passages. (Which makes sense- after all, coastal cruising is a much larger market, and one that tends to be turned off by true offshore features.) I won't pass judgement, though, until I've been on one myself.
  7. Pierre R
    Joined: May 2007
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    Location: ohio, USA

    Pierre R Senior Member

    I will caution what I say because in other forums in the past you have been very agressive against anyone who has posted anything negative in any way about the GH.

    The GH certainly does not have underwater design going for her in terms of a sea friendly design. What she does have going for her is Inertia. She's a tank and slow to get tossed around because of that but that does not substitute for underwater design. Waves are still waves and have their own physics associated with them.

    The GH is still a boat that is largely going to follow the surface of the wave patterns. The wave patterns where the GH shows a great deal of discomfort are not that uncommon in coastal waters or in the open ocean. I know people who you have trashed for saying the GH delivers a harsh ride in a beam on short chop of 2' to 4' waves. The kind of waves found in places like Lake Erie, the Chesapeake and Albermarle Sound.

    I do not think the GH boats are a bad boats if used as really intended by the designer but I think you oversell them and in listening to new owners, I think you are effective at that. Buyer beware. Sea boats make lousy houses and houses make lousy sea boats. You can have your house and a sea boat too but it starts at around 50'. Tad is one of my hero's and right on the money.

    I think the GH is a fine boat, a fantastic liveaboard boat and a fine coastal cruiser if you watch your weather. Then again, I suppose you are no different than the rest of the boat reps. They all seem to be trying to sell fair weather coastal cruisers as go anywhere boats. The GP seems think that if it looks like a trawler or a tug it must be seaworthy regardless of the real underwater design and dynamic stability parameters. If it looks like their house they like it. I cannot fault Mirage for that. The boats I really like woundn't sell cuz they are real sea boats.

    Now I expect you to trash me but not maybe as bad as others before me. I do like the GH within reason.
    1 person likes this.
  8. dskira

    dskira Previous Member

    Lets face it, the GH is a great barge with a lot of accommodation.
    You don't need experience when a hull looks like a barge, it is a barge.
    Be realistic, and the GH will be even a better boat without the selling speach of the sale manager.
    Joined: Oct 2002
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    FAST FRED Senior Member

    Most every sailboat has positive stability , and should come right side up after a roll.

    The mast may go but the basic boat will be intact. Loads of production cookies have circumnavigated

    There is loads of experience rolling USCG boats inverted and letting them right , if they can.

    Would be great fun to see this barge rolled, then salvaged.

    OR just the stabilty graph to compare to known ocean worthy vessels

  10. El Sea
    Joined: Aug 2006
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    Location: St Petersburg, Florida

    El Sea Junior Member


    Most boats are suitable for your ventures IF you choose the right weather window and feel capable with your own skills.

    "It's the voyage, not the vessel"
  11. Fish Catcher
    Joined: Oct 2014
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    Location: United States

    Fish Catcher Junior Member

    Eric you still watching this thread ? If so let me know for I would enjoy talking with you about the GH 47. We have been researching boats to find the best fit in a liveaboard to enjoy looping. I have found NO Matter what boat a person decides on there are many folks who will trash it and have a million and one rerasons why it wont work. I think Edison probably knew that one all to well. LOL

    Any way I hope to hear from you
    Have a blessed day
  12. Steve W
    Joined: Jul 2004
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    Location: Duluth, Minnesota

    Steve W Senior Member

    Ive got to agree with Eric that people should not contribute to a thread if they don't have actual knowledge of the boat in question, not just an opinion based on what they have read or heard second, third or fifth hand. I for example I have built dozens of boats in composite, wood and even Ferro cement over a 40 year career but i have the decency to stay away from steel boat threads unless im asking questions to further my knowledge because i don't have actual experience building or maintaining in the medium.

  13. Fish Catcher
    Joined: Oct 2014
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    Fish Catcher Junior Member

    The funny thing I have noticed is I have not ever built a boat from scratch. Now I have gutted many and redid them to better fit my needs and others and yet I find it easy to, lets say remove the wheat from the chaff to put it nicely with many post or replies. Why people have to feel they need to prove how smart or educated in things I will not ever understand. I mean give a humble honest reply and it will be taken well even if you dont get all these pats on the back claiming how smart you are.

    Another thing I have come to learn is there is NO such thing as "the perfict boat" even in an offshore or coastal cruiser or ocean runner. No one boat will be the best fit for every one. You will do well to find a boat that fits mostof your needs and learn to overcome any short comings you may find along tyhe way. Other wise we all would be running around in the Same boat doing the same things and You Know that aint gonna happen any time soon ! LOL

    I am not trying to upset anyone or boast of anything, just saying Relax and enjoy the boat.
    I can loop a kady krogen or a NT49 or defever or mainship etc just as well as a Great Harbor or lord nelson victory tug. That does not make any one of these boats a better fit for anyone. I could take ANY of these boasts and make an ocean voyage if I first research and grasp my limitatations with each boat and do all the best weather planning I could do. Now would I take a 500 mile out across ther open sea in any of these? Not hardly, but then again I dont desire to do such a thing.

    My point is I do not have a point.....just common sense.....serves me well and when in doubt, talk to those who actually have the boat in question.
  14. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    We shouldn't forget that pleasure boats have more emotional than practical value. Most people buy a boat to fulfill a dream, not because it makes sense.

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    FAST FRED Senior Member

    >Now would I take a 500 mile out across ther open sea in any of these? Not hardly, but then again I dont desire to do such a thing.<

    Thats why they make sailboats.

    20 ft on up have circumnavigated .

    A true ocean working motor vessel will by its nature be large and expensive.

    Fuel and water take room as does months of stores and perhaps some spare parts, so the interior volume suffers .

    Having a genuine offshore boat is great if it is operated that way.

    Be realistic in your Desirements.

    Just for strutting the dock ,UGH!!,, the brown water boats liveaboard far better.
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