Interlake New Construction Unloading Arrangement

[Guest]

When the Canadian Navigator ( Algoma Navigator ) was converted to a self-unloader a single cargo hold conveyor was set on top of the bottom of the cargo hold. No modifications of the cargo holds occurred. The belt was enclosed of course, with gates on top. To get an idea of how it looked, look at the recent cross section pictures of the new Interlake build. You see the cargo tunnel belt space running down the centerline of the hold, its set down the way most self-unloaders look, now imagine that sitting on top the bottom of the hold instead. It was another unique ULS design. When the Canadian Navigator unloaded cargo the gates were opened and once as much free flowing cargo was removed as possible, two pay loaders, one on each side scooped up, lifted and dumped the cargo into the open gates. Of course the unloading process took longer, seemed to be about 10-12 hours for the Navigator.

Now for the Ryerson I would think such a self unloading conversion would possible work. She would still be able to haul taconite pellets and the new dri pellets. With her low cubic capacity holds and a conversion as I described, she may still lose some carrying capacity for regular pellets and may not be able to achieve her maximum 28'4" design draft, but she could only hit that draft during periods of high water anyway. Normal lake levels do not allow that draft. The dri pellets are a little denser than regular pellets, so I believe they would be able to load her to max draft with those.

Of course it all comes back to sad reality. There are too many lakers chasing too little cargo and after this recession has run its course there will be even less cargo available, so its all a mute point.

[Guest]

Decreasing the size of the side tanks in order to increase cubic capacity would only make sense for cargoes such as grain or coal. The only trade where such a configuration makes sense is the grain down and iron up from the Gulf of St. Lawrence, but most US ship owners have never seen themselves competitive in that trade, when operating and labour costs are compared to Canadian shipowners. That's why companies like Hanna formed Canadian subsidiaries such as Carryore and Pickands and Mather formed Labrador Steamship.

And yes I do know that a few US fleets did use the St. Lawrence Seaway on a fairly regular basis in the 1960s, especially the early years. And US Steel did so with their Supers into the Fall of 1981.

So were they short-sighted? Well, yes and no. If I was a person in charge of designing a new US 730-foot ore carrier in 1958, knowing that American labour costs, as well as other factors would make my vessel uncompetitive in the St. Lawrence Seaway, I would use the design that they used. Perhaps they should have designed their new ships with more versatility in mind, but they were designing for what they needed at that time. And 1960 was the era of the straight-decker in the ore trade and no thought given to a future self-unloader conversion.

[Guest]

It would not. There is no room under the holds on the Ryerson for a belt.

Isn't the bottom of the cargo hold raised during a self-unloading conversion anyways to accommodate the tunnel? I think the primary problem in this case is limited cubic capacity due of the Ryerson's cargo hold that is optimized for the carriage of iron ore. If I recall correctly this constraint is due to larger than normal ballast tanks but I may be wrong. Is it possible that a conversion not involving the sloped sides of the cargo found in the cargo holds of most self-unloaders would minimize the loss of cubic capacity? I don't know how close to the hatch coamings the Ryerson loads taconite too but I would guess that it would take up more volume than in a conventional ship designed with larger cubic dimensions to also carry lower specific gravity cargoes such as grain, coal, and stone. There was a cross section drawing of the Ryerson's cargo hold arrangement online some time ago, but I can't remember on what site it was on.

[Guest]

In any self-unloader conversion, the tank-tops are lowered in the area of the center-line conveyor. From drawings I've seen over the years it's around 3-feet. So there is room for a center-line belt, with modifications. The issue is her large ballast tanks, though they'd either be recessed or ripped out in any self-unloader conversion. Cost is the big factor in a conversion of the Ryerson.

Enclosed is a drawing from a SNAME paper I have, showing mid-ship drawings of various vessels, including the Edmund Fitzgerald and the Edward L. Ryerson.

[Guest]

Whether it be the Ryerson or Fitzgerald or Homer I'll never understand why they were made with such low cubic capacity and before people say cause all they carried was ore well as stated the Quebecois and all the other 730s could do both equally well so short sighted!

[DCN]

I think the Pathfinder originally come out of her conversion with an unloading arrangement where they needed to use loaders to clean her out, but was converted to a more traditional sloped hold arrangement after a year.

I seem to recall comments at the time describing her belt setup as if the unloading belt was installed sitting on the old tank tops on the center line of the hold, and the cargo space either side of the belt was also the old tank tops and were thus lower than the belt and so they had to literally dig out the last of the cargo with equipment and raise it up to the belt to unload.

I don't know if that is actually the arrangement of what was installed in the Pathfinder or not, just what I remember hearing at the time. Either way she got more traditional all gravity unloading arrangement rather quickly. Perhaps Interlake saw enough promise in the equipment vs gravity set up to keep it in mind for the future, all be it in a more refined manner.

DCN

[Shipwatcher1]

Th Ryerson was built to haul only ore, so her holds were not designed with cubic capacity in mind. Thats why she never has, and likely never will be converted.

[Larry64]

The problem is the Ryerson has no system. It has to be unloaded with shore equipment.

[Guest]

What's the problem with the Ryerson's system in the first place?

[Guest146]

It would not. There is no room under the holds on the Ryerson for a belt.

[Guest]

The flat-bottom for a self-unloader is fairly common on Canadian self-unloaders on the 1970s, where a traveling reclaimer is used to move the cargo to the center-line belt from port and starboard outboard sides.

The trend nowadays is to dispense with the reclaimer and use gravity to discharge most of the cargo to the centre-line belt then bucket excavators or front-end loaders to move the rest to the centre-line belt. The later is what the CSL Assiniboine uses. It could be what the newbuild self-unloader Mark Barker will use, but I haven't seen any drawings of a cross-section.

The problem for the Edward L. Ryerson is that either a sloping side tank to the hoppers, or a flat bottom to a center-line belt still means she has a significant reduction in cubic capacity, and traditionally vessels were selected for self-unloader conversions based on the condition of the tanktops (as they would be replaced during a conversion anyway) and the cubic capacity of the existing cargo-hold. The Ryerson has large ballast tanks so a flat bottom cargohold vs a sloping cargohold would mean less loss of cubic in a conversion, but she's still not the ideal candidate for a conversion. A ship like the Edmund Fitzgerald had a cubic capacity of 883,125 cubic feet and the Ryerson has 761,000 cubic feet. a 14% difference. Now you take a Canadian ship like the now scrapped Algoma Montrealais, and her cubic capacity is 1,162,180 cubic feet. That is a difference of 35%.

[Guest]

It looks like the new ship being built for Interlake will have a flat bottomed cargo hold feeding the unloading belt. Doesn't the CSL Assiniboine have something similar? Would such an unloading system be a possible solution for the problems with Ryerson's cargo hold arrangement?