Stability of Strange Canadian Boat (pictures inside)

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

  1. robm
    Joined: Feb 2012
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    robm New Member

    Collision and sinking of Great Lakes fishing boat

    There were some earlier references to searching for incidents.
    I had come across one earlier - here it is. PDF/LINDA_E_(2).pdf

    I've spent a bit of time on these, scuba diving. A few observations.
    1) The great lakes can be EXTREMELY rough. These boats are far kinder than planing and/or semi-planing hulls. Are they blue-water capable in all conditions? Doubt it.
    2) The Linda - mentioned in my pdf link above sunk after being hit broadsides by a much larger barge - and sunk, according to the report in 2 seconds. This is because the turtle is not water tight, there are typically no/few watertight compartments or even bulkheads, and no longitudinal bulkheads.
    3) It appears from the report above that the hull itself was not compromised by the crash, but was probably downflooded and forced under.
    4) These things can carry far more than the 500lbs of fish quoted earlier. Obviously this depends on the size of the vessel but a 50 footer can easily carry 25 men, each with 100lbs of gear (tanks, lead plus body weight) which would be over 3 tons, and while I didn't measure the change in draft, they did not appear to be heavily loaded. These are heavily build, industrial boats, at least the one's I've been on.
    5) They are sparse of any creature comforts (eg. no head you would want to use, sometimes just 'over the side')
    6) They are dry exhaust, deafening and vibrate like crazy. These real mens' boats!

    I've seen a few conversions, the one pictured earlier looks neat - but at what cost compare to a new build?

    Currently you can get a 60'x20' shell+engine+genset+some equipment and old electronics for $30K. Plan to spend God knows how much to make it a pleasure craft. (Don't forget the sound proofing and vibration control!)

    These boats are a part of Great Lakes heritage for both Canadians and Americans. Honestly if I was out on the lake in rough weather, I'd feel pretty safe in one of these as long as the opening to the engine room was sealed properly. Safer than any twin engine go-fast yacht of the same vintage. Cross the Atlantic? I'll fly, thanks.

    Last comment, the Ontario Gov recently purchased one or two new models, built 'similar' to the fish boats (but I'm sure designed to modern standards) and I think they were in excess of $2M each if I recall the press release. They will be used for 'fish research'. Each boat probably exceeds the value of the commercial fish caught by all the remaining commercial fishermen combined I'd bet. ;<
  2. ghostrider42
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    ghostrider42 New Member

    One of the first jobs I had was working on a Great Lakes fishing tug - smaller than most at 12m, but it work in all kinds of weather from March thru January on Lake Huron. Built of mild 6mm steel on the hull and 9.5mm on the keel. Keel cooled with dry stack the 12V92 can't be beat.

    I wish I had one of them over here in the North Atlantic
  3. sharpii2
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    sharpii2 Senior Member

    With all due respect for a pro (you), I think there is a lot of shooting from the hip going on here.

    Certainly the angle of vanishing stability for these vessels will be low, but I differ on whether it vanishes as soon as the rail goes under.

    Certainly with the high sides and the deck above the weather, deck the boat does look top heavy. Just remember, though, the engines, tanks, fish holds and most of the other heavy gear is probably on the actual weather deck or below. This could make the VCG a lot lower than it appears.

    My guess is that it would have to be pushed over as much as 45 deg. before it loses stability (the Coast Guard now requires that number to be 60 deg., IIRC). And all that worry some weight also has a lot of inertia, so the weather it usually operates in, may make such an event, though definitely possible, highly unlikely.

    Due to the low free board, down flooding would be my biggest worry.

    I would probably enlarge the scuppers, if I were to make one of these a personal boat, and maybe even make them one way.

    As for the bit about water getting on the low weather deck and being trapped there due to the scuppers being plugged and the crew being blissfully unaware of such a fact, I have two problems with that assertion.

    1.) I think it is highly unlikely all the scuppers will get plugged at once, and
    2.) If they did, and water was trapped on board, the motion of the boat would change. I firmly believe that people who make a living off such vessels, though they may not understand calculus, or even have a high school diploma, know their boats and would quickly notice something amiss.

    Even more likely, in any kind of a storm (which can spring up quite suddenly on the Great Lakes), the skipper will do what any rational powerboat skipper will do; turn the bow into the waves.

    Obviously, compromises to sea worthiness were made on these vessels to facilitate the job they were designed to do. I think that is true for all fishing vessels.

    But I wouldn't exactly call them floating coffins.

    If you look at oil rig supply boats you may also see an uncomfortably low weather deck surrounded by seemingly tiny scuppers.
  4. Tad
    Joined: Mar 2002
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    Tad Boat Designer

    You waited 18 months to say this.....after the original pictures (on which the thread is based) have disappeared?

    Go back and re-read the first post......"rough, open ocean conditions" are mentioned.......

    What I wrote was "they run out of reserve stability as soon as the rail (main deck edge) goes under water"......While that's not a particularly clear statement, it does not mention AVS. I was trying to draw attention to the fact that stability (righting arm or moment) decreases once the deck edge is immersed.....This immersion happens at low heel angles for vessels with low freeboard, coupled with high wind-heeling on high freeboard, the reserve righting energy becomes minimal......See the TC requirements for required areas below the righting arm curve(reserve stability).......

    And how is this statement not "shooting from the hip?"

    So you send people to sea with a "It's unlikely you'll drown".......Sorry I can't do that.

    Well I've been there and it wasn't pretty. Bucking a big steep sea, trying to quarter into it, took a wave wrong. Big coil of double-braid nylon sitting up high on the hatch cover. Washed straight into the scuppers, they were large and ran the entire length of the deck....perfect fit, plugged them all on one side. I waded in and pulled it loose, and slowly she came upright....but if it had happened at night it might have been a different story.

    And without power?

    So perfectly safe in "rough, open ocean conditions"? Or is it that they "seem seaworthy" to you, even though the original pictures which the questions are about, have disappeared? I think you might be shooting from the hip there........:D
    Last edited: Mar 20, 2012
  5. ghostrider42
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    ghostrider42 New Member

    Tad: You would be interested to know that Purvis Fisheries launched a new fishing tug in Canada in 2004 (left). They are built in the same manner, with the same specs as previous "tugs". I saw her last season in Gore Bay (center). Also the L&R Jackson mentioned earlier in this thread was seen at Port Stanley in Nov 11 (right) - seems she's holding up well. Note the addition of the life raft.

    Attached Files:

  6. sharpii2
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    sharpii2 Senior Member

    Hi, Tad.

    I did manage to track down the pictures.

    I didn't see any freeing ports at all.

    And the sliding door seemed quite well reenforced with about two or three inch deep steel webs every six to eight inches. It's almost as if the doors were meant to keep the sea out.

    I would almost suppose the idea was to seal them shut in bad conditions making the space between the weather deck and the top deck more or less water tight.

    I can imagine that would only work if the doors weren't stove in or knocked off their tracks.

    I imagine the biggest risk is that it's a judgment call on just when conditions are too rough to continue fishing operations. I can also imagine this judgment is often based on economic considerations more than safety ones.

    Sorry for the "shooting from the hip" comment. Other than being an ***, I was somewhat upset about the "yakking in the pilot house..." comment on the post I commented on.

    It came across to me as a disparaging remark about fishermen in particular and working men in general. As If they are too dumb to realize the hazards they face and cannot survive even one day without more educated people holding their hand.

    After reading your reply, I saw that wasn't the case at all.

    Just for curiosity. How would you make these vessels safer?

    Or, failing that, what would you propose as replacement for these vessels?

  7. Tad
    Joined: Mar 2002
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    Tad Boat Designer

    Sharp.....'s hard to get this internet thing just right every time......

    There are (at least) two conversations here; the conversion of a fishing "tug" to an ocean cruiser, and the seaworthiness of "tug" type great lakes fishing vessels.

    My reasons why these boats would make a poor choice as an ocean cruiser is outlined in posts above. As a static houseboat or protected water cruiser one of these could be just fine, but that was not the original question.

    As a currently certified Canadian fishing vessel I would be very interested in seeing the stability booklet and finding out how these boats are brought into compliance with regulations.

    As with any vessel, it can be made safer by dividing the hull with watertight bulkheads, adding watertight volume above the waterline, extending engine, vent, and access trunks well above the main (bulkhead) deck, limiting free surface volumes above and below deck, and installing adequate freeing ports and high hatch sills. I would assume all of this is done on the "tugs" currently fishing.
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