Stability of Strange Canadian Boat (pictures inside)

Discussion in 'Stability' started by CatBuilder, Sep 11, 2010.

  1. gilberj
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    gilberj Junior Member

    I am not interested in studying the photo's and trying to assess the boats shown. way too little information and no way of verifying suppositions.
    This is a vessel type, which has proven successful. I have had a close look at about a dozen of these boats, and another three that have been converted to yachts.
    the working vessels shared most of the characteristics I spoke of in the last post.
    One of the boats I have seen closely, was the ubiquitous floating coffin mentioned in a previous post. There are always people who operate marginally, letting the boat run down in various ways. The hatches into the lower part of the hull were far from watertight, the electric wiring was hanging loose, the free-board was even less than the usual. it was a disaster really trying to happen, and it almost did.
    Other than that, the other boats were pretty similar in the main details. They all I think had large scooped freeing ports, The one I sailed a little on had three per side approximately 8" x 14" in the bulwark with the scoop opening being about 8" x 8".
    The down flooding point, entry into the engine room was almost 3 ft above the deck, in the wheelhouse and only about 4 ft off the centre line, the entry into the engine space. The engine room vents were on the top of the shelter deck.
    I am sure there were boats lost in the past. Door county (really beautifull country)as mentioned in a previous post, had a large fleet. perhaps trolling through old newspapers might offer insight to pre-war statistics. The steel boats I am familiar with are all post war, and share many principal characteristics.
    Lake Erie had the largest fleets on the Canadian side, between Kingsville, Wheatley, Port Stanley, and Port Dover. Lakes Huron and Superior, Georgian Bay and the North channel had smaller fleets and continue to have small working fleets.
    Pleasure boat conversions I have seen have generally been pretty good. Part of the shelter deck area becomes fully enclosed, the upper works needs to be strengthened in that area, as it is now enclosed space. the C of G will rise and care needs to be taken to not loose track of it.
    Someone mentioned stability tests. I was told by a Transport Canada Navel Architect that tank testing was performed on a type model, which apparently performed far better than expectations....I don't know the details so I cannot vouch for the information, I do not know who did it or when. The comment does confirm my personal experience.
    Fishing vessel all over enjoy the highest casualty rate in the marine industry. I still do not know of one of these vessels foundering, or rolling over.
    JG
     
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  2. Tad
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    Tad Boat Designer

    "far better than expectations" is a meaningless statement......better than expectations of what?

    Generally speaking test tanks have nothing to do with static stability studies....they were studying something other than static stability in the tank. It could have been anything, dynamic stability perhaps, or maneuvering, or resistance, or handling in waves....who knows?

    Below are current stability standards for Canadian Fishing vessels, I believe any Great Lakes "tug" will have difficulty meeting any part of these standards.......

    STANDARD: STAB 4
    STABILITY STANDARDS FOR FISHING VESSELS:

    OPERATING CONDITIONS WITH NO ACCUMULATED ICE
    1 The following minimum intact stability criteria are to be used in the approval
    of stability data for the above vessels:
    (i) The area under the righting lever (GZ) curve should not be less than 0.055
    metre-radians up to Æ = 30° angle of heel, and not less than 0.09 metre-radians up
    to Æ = 40°, or the angle or downflooding Æf if this angle is less than 40°
    Additionally, the area under the righting lever (GZ) curve between the angles of heel
    of 30° and 40° or between 30° and Æf if this angle is less than 40° should not
    be less than 0.03 metre-radians.
    (ii) The righting lever GZ should be at least 0.20 metres at an angle of heel equal
    to or greater than 30°.
    (iii) The maximum righting arm should occur at an angle of heel preferably
    exceeding 30° but not less than 25°.
    (iv) The initial metacentric height(GM) should not be less than 0.35 metres.
    WORST OPERATING CONDITION WITH ACCUMULATED ICE
    2 Using the ice accumulation weights and vertical centres of gravity requires by
    the appropriate fishing vessel inspection regulations:
    (i) The area under the righting lever (GZ) curve should not be less than 0.04
    metre-radians up to 30 degrees angle of heel and not less than 0.058 metre-radians
    up to 40 degrees or the angle of downflooding if this angle is ,.less than 40 degrees.
    Additionally, the area under the righting lever (GZ) curve between the angles of heel
    of 30 degrees And 40 degrees or between 30 degrees and the angle of
    downflooding, if this angle is less than 40 degrees, should not be less than 0.016
    metre-radians.
    (ii) The righting lever (GZ) should be at least 0.15 metres at an angle of heel
    equal to or greater than 20 degrees.
    - 2 - STAB 4
    Modification No. 20
    October 1, 1987
    (iii) The maximum righting lever (GZ) should occur at an angle of heel not less
    than 20 degrees.
    (iv) The initial metacentric height (GM) should not be less than 0.23 metres.
    3 Hydrostatic and stability curves should normally be prepared on a designed
    trim basis. However., where the operating trim or the form and arrangement of the
    ship are such that change in trim has an appreciable effect on righting arms, such
    change of trim is to be taken into account.
    4 The calculations may take into account the volume to the upper surface of the
    deck sheathing, if fitted. In the case of wood ships the dimensions should be taken
    to the outside of hull and deck planking.
    5 Cross Curves of Stability may take the following into account and a note to
    this effect must be shown:
    (a) Enclosed weathertight superstructures and enclosed weathertight
    deckhouses of similar construction,
    (b) Weathertight trunks, and
    (c) Hatchways having regard to the effectiveness of the closures.
    6 Definitions for paragraph 5 are as follows:
    SUPERSTRUCTURE means a decked structure on the bulkhead deck
    extending from side to side of the ship, or with the side plating not
    being inboard of the shell plating more than 4 per cent of the
    maximum moulded breadth of the vessel measured at mid-ships. A
    raised quarter deck is regarded as a superstructure.
    WEATHERTIGHT means that in any sea conditions water will not
    penetrate into the ship.
    7 In cases where a ship would flood through an opening, the stability curve is
    to be cut short at the corresponding angle of flooding and the ship is to be
    considered as having entirely lost her stability at that angle.
    8 In the calculations for loading conditions an allowance is to be made for the
    weight of the wet fishing nets and tackle.
    9 In all cases the cargo should be assumed to be homogenous unless this is
    inconsistent with practice.
    10 The following conditions are not considered as operating conditions.
    Therefore the above criteria are not applicable and the standard to be obtained in
    these conditions is a positive.GM:
    - 3 - STAB 4
    Modification No. 20
    October 1, 1987
    (a) Lightship
    (b) Port after discharge of cargo with 10% of fuel, fresh water and stores
    remaining and accumulated ice on top-sides and rigging.
    (The lightship condition is defined as the condition of a vessel ready for sea
    with no stores, consumables, fluid ballast or crew on board).
     
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  3. Guillermo
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    Guillermo Ingeniero Naval

    I'm with Tad here. Most probably those boats do not comply with the present FV intact stability criteria with such a low freeboard. And those freeing ports (first photos) do not comply at all with anykind of minimun area requirements. As Tad says, if there are not freeing ports and volumes over main deck can be considered as part of the watertight zone for stability calculations, then superstructure has to have adequate resistance. But in our country even if a FV has a closed superstructure as those, but has openings in it to allow for the working with the fishing gear, even if temporarily, then we cannot consider the volumes as watertight and cannot be included for stability calculations.

    Those boats are probably good for work in sheltered waters and I don't doubt they have been able to survive harsh conditions, although I'm wondering about what the official accidents reports are. I'm also wondering about the height of the the hatches' sill, as gilberj relates one boat was flooded through an open hatch. Over here requirements are 60 cm for seagoing vessels and 45 cm for sheltered waters. Very small boats can go down to 30 cm.

    Answering Catbuilder first questions:

    1) Given the shape of the hull, how would these boats react to rough, open ocean conditions relative to a Nordhavn or some other trawler?
    Those forms do not look like being adequate for serious seagoing. Too flat.

    2) Do you think stability would be compromised if you were to add a yacht's worth of interior fittings (wall partitions, berths, galley, water tanks, etc...) and such to one?

    I do not know if compromised is the word, but certainly it will have an important effect. You should ask for a proper stability calculation to a naval architect. If those boats are obligued to have an stability booklet, then he can estimate things without the needing of getting the lines and performing an stability test, which you would need to do otherwise.

    3) In general, do these seem seaworthy, or not? I can't quite decide...

    They do not look seaworthy to me. Bottoms seem to be quite flat and freeboard is not good enough, as said, and not only at the middle of the boat. Also at the bow (first photos). It looks too low.

    4) How could I do basic stability calculations for one of these boats, given I have no plans and all that steel up high has to have an effect?

    If there are no stability booklets, you can get a hint about initial stability by performing a rolling test. If found period in seconds is equal or less than the beam in meters, then the initial stability is high enough. The lower the period the more the vessel is able to admit overdeck loads. But you will not get information on ultimate stability (big angles) unless you perform proper stability calculations.

    Cheers.
     
  4. gilberj
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    gilberj Junior Member

    I am not disagreeing, but suggesting there are other ways to skin a cat.....
    First a comment on the general form....These boats are deep V bottom, and are not shallow boats. Normal draft being in the order of 4 to 5 feet with the larges being more like 6 or 7 feet.
    I am well aware of STAB 4 and inclining, static stability and damage stability. Most of these Great Lake boats will not pass STAB 4 mainly due to their low freeboard. The freeboard is much like older tugs ( perhaps that is why they are referred to as tugs ) older tugs have the low freeboard and low bulwarks and no upperworks. The bulwark is of the same scantling as the rest of the hull, but the upperworks is much lighter. The bullwark and upperworks are not part of the watertight enclosure. The wheelhouse, engine room entrance, and occasionally a bunk room, are part of the enclosure. They are located along the centreline, to the extent that if the upperworks was removed the vessel would indeed look like an older style tug. the bullwark has large scooped freeing ports and without them the boat would indeed be dangerous.
    Curiously I think many of the boats, the smaller ones at least would pass ISO 12217, as an enclosed vessel with a watertight deck. I have not tried the calculations as I do not have data to work with, but the main elements of concern are addressed in the type.
    The real point is not arguing numbers, or details. The real point is these boats have a remarkable safety record in this industry, pretty much unsurpassed in the developed world where the fishing industry has the highest casualty rate of any major sector of the marine business. I still do not know of a casualty relating to the seaworthiness of a single boat . Assuming there was a few sinkings the record would still be very good, recognizing these waters are not sheltered, or insignificant, this record is very telling. Tad you are quite right when you point out TSB only began in the early 90's, but that means we still have 15 to 17 years of data. How many West Coast boats have been casualties in the same time, and what were the causes??
    I am supposing we are dealing with approximately the same demographic with regards to operators, so I would not guess this is a significant factor in the survival of these boats.
    As far as converting these boats to a pleasure boat.....I agree with what you say. They clearly perform well in their intended job. The normal load of fish is insignificant relative to the weight of the vessel. They are not designed to carry a load. To fit one out as a pleasure boat is to completely change the beast. Careful track of weights removed and added, attention to understanding the enclosed watertight envelope, is critical. I'd recommend a naval architect be consulted, throughout the project. I have seen 3 good conversions of these boats to yachts, that were done well. I have seen varying attempts at other conversions, on the east coast, west coast and one on the lakes that were not done well in any sense of the word.
    The guys I have spoken to fish year round unless the ice is too thick to get away from the dock. On Lake Superior that is longer, about 3 months, but further south there are some who fish, at least a little in 12 months of the year. I don't know how much experience you guys might have with the conditions on the Lakes but mill pond does not apply.
    JG
     
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  5. gilberj
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    gilberj Junior Member

    converted Canadian Fish Tug

    http://www.flickr.com/photos/54416556@N04/5147131597/
    If I have done it correctly this is a photo of a Great Lakes fish tug which has been converted to a pleasure boat. This boat is quite successful, having been converted more than 20 years ago. It is on Lake Superior...
    JG
     

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    Last edited: Nov 4, 2010
  6. Tad
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    Tad Boat Designer

  7. Tad
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    Tad Boat Designer

  8. gilberj
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    gilberj Junior Member

    thanks Tad, it kind of confirms my point when you have to go back to 1934 and 1940. I never suspected there were no losses. I have trolled through the TSB reports and once found American reports to troll through. Id say the boats in the photos, much earlier than any I have looked at appeared less well developed, but you can't tell much from an old photo.
     
  9. Guillermo
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    Guillermo Ingeniero Naval

    Well, gilberj is right when he says those were no low draught boats! If all hulls were shaped like that one, they are pretty draughty (and awfully lined!) boats, indeed. See the attached image from Tad's first link. Low freeboard is still a concern.

    And if Richard H was 40 feet in length with a beam of 12 feet, and weighed 19 tons, she had probably a nice draught also.

    BTW, we cannot say Jean R.'s is a typical lack of stability accident, as the boat was stopped and pounded for hours against the thick ice at the entrance of the harbour, in my opinion.

    The Richard H faced 60 knots winds and 40 foot waves, under steam power. Perhaps the loss was rather due to a propulsion failure leaving the boat with no hope against the storm.
     

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  10. gilberj
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    gilberj Junior Member

    If you go to a web site called boatnerd. in addition to lots of photos of Lake Freighters and tugs and work boats there is a few hundred pictures of Great Lake Fish Tugs, in all stages of condition for wrecks to some really fine vessels. At least one of the boats shown was one of the first responders looking for the Edmund Fitzgerald, sorry I have lost track of the name. The weather that night was force 10 or so, not for unseaworthy toys.
     
  11. apex1

    apex1 Guest

    gilberj

    no matter how we turn it,

    this:
    [​IMG]

    at sea, is a floating coffin. period

    that:

    [​IMG]

    is a different animal, but was not part of the OP´s question. (and is not what he could use either)

    Why must every other thread be drivelled down to death, just for the sake of contradiction?:mad:

    Richard
     
  12. troy2000
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    troy2000 Senior Member

    Relax a little, Richard. In the course of the discussion we've gotten some interesting pictures and history in this thread; I'm enjoying it.:)
     
  13. gilberj
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    gilberj Junior Member

    Richard,
    I have specifically avoided commenting on the specific boats in the photo's. I think any unsubstantiated conjecture without at least a passing nod to the larger context is poor judgement. These boats as a type have a fine safety record. They like every other group of vessels range from very well maintained boats to "floating coffins", but very few losses due to seaworthiness or stability, even the sort exacerbated by human foolishness. The OP's question was can boats like this be turned into a pleasure boat. The answer is yes. A clear understanding of why they are successful as a working type, is necessary, because on these, more than other types, weight creep can be really dangerous. I recommend he consult a Naval Architect familiar with the type.
    No-one is asking you to buy one. You are welcome to your opinion, but it is at best an informed opinion and not fact. My informed opinion is based on some personal experience with the type.
    If you think the forum has been driveled to death, perhaps you should stop following the string.
     
  14. Tad
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    Tad Boat Designer

    The larger context is safety at sea......As a naval architect with 25 years of experience in stability studies, I'm saying these boats (as built) are unsafe. We have your "unsubstantiated conjecture" that they are perfectly safe and have "a fine safety record". Your statement does not negate their poor design.

    As with almost every type of fishing vessel in the world, the great lakes fish tugs evolved with no input from naval architects. Fisherman are the most conservative people in the world when it comes to boats, they are only interested in boats that look like those their grandfathers fished.......the boats get bigger but basic design does not change. It is only very recently that actual stability of fishing vessels is beginning to be addressed.....and that's a double-edged sword tieing up some boats which cannot meet standards.....

    Of course (as with any boat) they can be rebuilt and turned into something else (as your picture shows). Taking a tug and filling the available interior with furniture is still not recommended.

    Yes, their are lots of photos of fish tugs at boatnerd, so what? That also does not negate their poor design. A study of those photos can educate us though. None of the small "tugs" are presently in use for fishing. Just as on this coast most of the large boats are presently tied up with no sign of currently fishing (paintwork is perfect). The ones still in use are big, 60+ feet long and 18'-20' wide. None of them have open scuppers, and any that are pictured underway are in flat calm conditions. So how many days a year fishing do they actually get?

    Good design? I don't think so.....

    L&R7-07-08a.gw.jpg
     

  15. apex1

    apex1 Guest

    Oh I am relaxed Troy, thank you.

    But I cannot understand why our statemets, that the boat shown in CatBuilders first post, was unsafe and could not be used in:

    were contradicted.

    Nobody denied that there are possibly other vessels of that era (area), which could be safer. Even those though, would not be safe enough for the intended use.

    CatBuilder does not longer play with the idea btw.

    Regards
    Richard
     
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