Cable Ferry

BC Ferries is proposing to replace the existing vessel on Route 21, Buckley Bay to Denman West, with a cable ferry of the same capacity. A petition opposing this plan, which was signed by half of the population of Denman and Hornby Islands, has been sent to BC Ferries executive and has been tabled in the legislature, with no discernable action other than a denial of any concern from BCF.

The authors of this article decided in October 2011 to merge their experiences as a ship's captain and a project manager to review the proposal on its technical and financial merits. We view this as a pre-feasibility study - gather all the information you can at no cost, and see what is missing. We have not had access to any BC Ferries inside information. Everything here is in the public domain or has been heard on the street. The following is what we have learned so far.

News and Updates

16 April 12: The Authors section added

27 March 12: Total update and formal issue The link to PK cable memo update (PM3) is slow - will sort that out later.

Preliminary Conclusions

1. It is technically feasible to build and operate a cable ferry across Baynes Sound. Whether this is an attractive investment is not at all certain.



2. Four potential deal-breakers have been identified, which ought to be resolved before any more work is done:
   
   a. Design wind speed.
   b. Capital cost differential.
   c. Cost of cables.
   d. Loss of flexibility in the fleet.
   
   
3. The design criteria wind speed which is supposed to represent the once-in-50-years occurance has been greatly exceeded twice in the last six years. It is set too low. This will impact on cable size and possibily viability.



4. No justification has been presented for the statement that a new 24 car replacement for Tenaka will cost twice as much as a new 50 car cable ferry plus two new loading ramps. Our calculations suggest that there may be an exta capital cost of $10 to $20 million for a cable ferry.



5. The major contributors to the operating cost savings identified by BCF in its presentations are fuel and manpower. There is in fact a third major factor which will reduce or eliminate the projected savings: cost of cable replacement. We cannot estimate this until BCF releases more data on projected fuel savings and confirms the projected manning.



6. Cable sizing is a critical element of the viability and the risk of this project. The guide cables must resist the force of wind on the side profile of the vessel. This means that the maximum expected wind must be estimated, and the storm of 11 December 2006 is a candidate. The side profile must balance the needs of passengers, including school children, and structural considerations, against cable cost.



7. The introduction of a limited use vessel to replace the all-purpose Tenaka will further restrict the flexibility of the fleet, which seems to be under constant strain anyway.



8. There is considerable risk involved. This project represents an extrapolation in several factors, including tide range, length of cable, and probably depth of channel. There is concern about the fact that this is one of the few cable ferry installations in the world which represent unique access to an island. There is also risk of having bidders underestimate cable needs for competitive reasons.



9. The cautious route to establishing this risky technology would be to keep the exisiting loading ramp at Denman West (or its replacement) in service.



10. There is no comparable installation anywhere in Canada or North America. One wonders where the expertise lies to judge bids and to train crew.

Summary of the Project

BC Ferries needs to obtain one new vessel for the North Island fleet to replace the Tenaka, now on the Quadra/Cortez Island route, which is due to be retired next year. Cable ferry technology has been raised as a possible way to reduce operating cost, specifically fuel and possibly personnel.

The proposed cable ferry (which we have designated Cable Queen for brevity) is thought to be best suited for the run from Buckley Bay to Denman West (Route 21). Cable Queen would be a 50 car ferry, the same as Quinitsa which is currently on this run. Instead of being pushed by a propeller, it will be pulled along a cable. The drive engine, and a spare, will be located on board the vessel.

There are three parallel stationary cables, which normally lie on the bottom of the ocean to allow shipping to pass overhead. They are raised up to the ferry vessel as it passes overhead, and then drop to the bottom again. The two outside cable are the guide cables and serve the same purpose as railway tracks for a train. These cables run through sheave blocks on the four corners of the vessel. The centre cable is the drive cable which runs over a drum mechanism on board. The vessel will have controls for speed and braking, but not steering. This picture, of the Needles ferry on Lower Arrow Lake, BC, shows the three cables and the sheaves.

The installation will include a new vessel, new loading ramps at Buckley Bay and Denman West terminals, possible changes to the marshalling and parking areas, facilities for storage and handling of spare cables, plus any maintenance facilites which may be required. The present loading ramp at Buckley Bay will be maintained. The existing loading ramp at Denman West will be demolished - this was planned anyway.

The project is justified on savings in capital and operations. The capital savings is based on the Cable Queen costing $18 million less than a replacement for Tenaka. The operating cost is based on a 2/3 reduction in fuel cost, along with a reduction in manpower. We do not have numbers for these items.

Capital Costs

Following is our own data. If and when we get any real information from BC Ferries, we will update this.

The only information that BC Ferries has provided is that a replacement for Tenaka will cost $35 million, but the new cable ferry for Route 21 will only cost $17 million, so that the cable ferry will cost $18 million less. This is attributed to the use of new technology and smart design such as not having an AC generator. (We trust the operating people will sort this out.) We are asked to take this on faith and any question about this on Hornby evoked a response of "Don't you want to save $18 million?"

Yes, we would like to save $18 million, but we do not believe this. New technology should apply to both options. A 50 car ferry should cost 50% more than a 24 car ferry build to the same standards, not half as much. Both vessels will have hulls, two engines, a reinforced car deck, similar passenger facilties and similar electrics and electronics. One has propellor shafts c/w bearings and glands. The other will have some means to transfer power to the cable: we can postulate a hydraulic system and an enormous drum of some kind which will probably take extra deck space.

Do we have other data? Yes. A 2006 report prepared for the Government of Newfoundland and Labrador contains cost estimates for vessels with 6, 20 and 40 car capacities. Graphing these costs, creating a logarithmic trendline and extrapolating to 50 cars we get values of $21 million for a 24 car ferry and $28 million for a 50 car ferry. Adding 25% for escalation since 2006, gives us values of $26 million and $35 million for 24 and 50 car vessels respectively. This is for the vessels only.

There are minimal onshore costs for the Tanaka replacement, but for the 50 car cable ferry, there is at least one extra ramp to be built. There is also the cost of the original and one spare set of cables and miscellaneous shore works including cable anchoring, cable handling and storage. Also the changes to the parking area at Denman West which have been outlined in BC Ferries presentations. Let us assume $1.5 million for the cables, $3 million for onshore works, and $10 million* for an additional ramp. The cost of the cable ferry is now estimated at about $50 million. These figures should be accurate within +/- 25%. Thus:

$26 million for a straight replacement all purpose 24 car vessel
$50 millon for a dedicated 50 car cable ferry
additional cost for cable ferry = $24 million
straight line depreciation of $24 million over 40 years = $600,000 per year
if the money is borrowed, this cost will double
which will outweigh any potential savings in fuel and manning

*The latest available Quarterly Report says the two new ramps on Route 22 (Denman/Hornby) cost $18 million. This involved two ramps built at the same time with the same general design and shared setup costs. The new ramp at Denman West should be designed for more violent weather conditions than at Buckley Bay.

It may also be that some of the shore costs are being charged to another account, but if so it is still being wasted.

The cable ferry will need two new ramps. There is an argument that one would have been needed anyway to replace the existing structure at Denman West. There is also an argument that a secondary ramp should stay in service at Denman West with a cable ferry. The existing ramp at Denman West is said to be in need of replacement. So there is the possibilibty of an extra 5 to 10 million for a third new ramp.

As a check on the above numbers, BCF recently had a new 120 car vessel built, the Island Sky. The 2007-08 financial reports indicate the cost of that ferry was projected to be $45.5 million for the vessel, and $57 for the project. Factoring these numbers by a power factor of 0.6, this is equivalent to $30 and $17 million respectively for a 50 car and a 24 car vessels. Scaling down the project costs from 57 million gives $34 million and $22 million respectively for the 50 and 24 car vessels. These are consistent with the numbers above.

This is the Tenaka. Note the three decks above the car deck. A replacement vessel does not need this sophistication. In fact a replacement vessel could be the model for several small vessels in future - an all purpose vessel which could be used on any small route. The design for a single-use cable ferry and the experience gained with building and operating it have no ongoing value for any other vessel or route in the fleet.

This is the Needles ferry, a 30 car ferry on Lower Arrow Lakes, BC. There are no visible foot passenger facilities. The low railings and lack of passenger lounges and facilities are not suitable for the conditions on Route 21, with a lot of walk-on traffic, especially the school runs, high winds and salt water spray. We hope that this is not being used as a model for the Cable Queen.

Fuel

A fuel reduction is to be expected. It stands to reason that pulling on a cable is more efficient than pushing with a propellor. The Glosten report indicates a savings of $100,000 for two ferries. The vessel on Route 21 runs more trips per day than that on Route 22, so let us assign $65,000 to Route 21, which is accurate enough for now. The surprise here is how low this number is compared to the other two.

Manning

This is totally up in the air. The official word is that the cable ferry will be run by a crew of 3, but we hear rumours that the number is now 4. Quinitsa has a crew of 6 as mandated by Transport Canada. The crew size is related to the passenger load and depends on an actual test abandonment of the vessel. The Glosten report claims that a cable ferry will not be subject to Canada Transport regulations, which is a scary thought.

Following is a quotation from Glosten report under Risk Assessment and Crewing Requirements. We are not sure what this all means.

Standard manning requirements from Transport Canada (TC) do not apply to cable ferries, so BC Ferries extrapolated the standard TC manning requirements to a cable ferry (i.e., minimal propulsion system so, therefore, minimal engineering watch crew) as an initial assessment of the appropriate manning level. Subsequently, BC Ferries looked at manning from both the basic ship operational level as well as potential emergency operational levels for the various shipboard emergency scenarios. Both sets of analyses support a crew of three (3) for the cable ferry. Glosten has experience with small conventional car/passenger ferries (up to 149 people) with crews as small as two (2) people that have operated safely for many years; therefore, a crew of three (3) is reasonable.

The only justification we have seen for crew reduction is that an engineer will not be needed because it is technically not a ship under the regulations because it is still connected to the shore. (If the cables break does it revert to being a ship?) This leads us to wonder how fast and how well mechanical defects will be dealt with. Other reductions are related to vague suggestions of better vessel design. We have to wonder if other potential ideas for crew reduction have been saved up to be applied to this project.

We also wonder why the same new technology would also not lead to a lower manning requirement for Tenaka II

We also question whether the proper comparisons are being made. If we address the situation fleet-wide, the Tanaka is being retired and the cable ferry added. If we consider the spare vessel, which one assumes is not normally running, the Tachek becomes active and the Kaholke is idle. If you ask any of the crew whether the planned move of the Quinitsa to the Denman/Hornby run will happen, they say no way. Ask them where the Quinitsa can be used, they shrug. Maybe BCF should make use of the expertise in their own backyard instead of hiring compliant consultants.

Actually which vessels are on which route and which are spare is an operating decision which will be made after the construction is ocmplete.

One operating condition on that route requires 3 more persons - 14 shifts/week @ 5 per person. We have assumed a wage rate of $25 per hour and 25% benefits to arrive at a cost of $200,000 per position. This is easily scaleable.

Cable technology

The cables to be used in such an installation are encased in plastic, and therefore cannot be spliced. They have to be delivered from the factory as continuous 2+ km lengths, so transportation methods and cost are important considerations. At any diameter over about 2¼" one cable will exceed the weight limit for highway travel

There are many cable users in British Columbia - boats, ski lifts, logging - but there is a maximum size which is made here. Cable over 2½" diameter must be imported. One can expect a three month delivery delay from local sources, more from overseas. Spare cables should available on site for quick access at all times.

The amount of slack in the cable affects the amount of force it can withstand - the more slack, the more force. But the more slack there is the more wear there will be from abraision on the ocean bottom.

Cables are a consumable item, and operating cost. The life may be one or two years. In New Brunswick there was a case where a cable on a single-cable vessel broke and the vessel drifted away. The province has now mandated life spans for all such vessels. In this case the cable broke after 400 days, so the replacement interval was set at 9 months.(Transportation Safety Board Marine Report-1996-M96M0150). This was an 11 car vessel on a 500 m crossing where there was abraison of the cable apparently due to slight tidal motion. The cable which failed was 1⅛" diameter. Scaling up to 50 cars from 11, gives an estimate of 2.4" diameter. this is not a design numbeer, but a valid estimating number.

The effective tensile strength of cables will be reduced every time they pass through a sheave or around a drum. To limit the loss to 10% the radius of any such device must be 16 times the cable diameter, i.e. for a 2¾" cable that means 44 inch diameter sheaves.

Further information is available in the two documents prepared by Pete Kimmerly which are accessable from this page. These memoranda draw on the knowledge and exoperience of 5 qualified professionals - Mechanical Engineers, Civil Engineers, Structural Engineers, Naval and and Civil Architects.

Storm of 11 December 2006

Just after 4:00 pm on Monday 11 December 2006 a violent wind storm hit the islands of Denman and Hornby. Mature trees and utility poles came down. It was 8 days before power was restored to Hornby Island. Roads on both islands were cleared of debris by snowplows. The same weather pattern caused a similar storm to hit Parkesville/Qualicum on Wednesday and Stanley Park on Friday.

When the storm hit, Kahloke, on the Buckley Bay/Denman run, was was part way across with 50 or 60 high school students on board. Here is a recollection of that trip from one of the crew:

It was the school run. When we left Buckley Bay the Kahloke was encountering following winds. Very strong, deep valleys between the crests of rolling breakers. By the time we were half way across the tops of the waves were being chopped off by the wind, visibility was almost zero with spray.

It took the captain about 7 minutes to dock the boat once we were inside the slip. Both engines were roaring. School kids who had come out on the deck for the fun and exhilaration 15 minutes earlier, were now crying and hanging on to each other and vehicles. When docked, I was about to head up the ramp to put in the pin, but could not physically walk up the ramp. I hung on to the railing on the apron and could not make forward progress for 30 seconds at least. As I finally made it to the crank to put in the pin, I heard a crash. A metal lamp standard on the trestle had come down in the wind, crashing onto the causeway, smashing the lamp assembly and then crashing overboard and into the water. If I had been at the gate I would likely have been hit and likely killed. Parents waiting for their children in the parking lot and waiting area were screaming. We unloaded all the students and cars, only to find there were several cedar trees down on the ferry hill. We canceled the next 2 sailings.

Was this a Qualicum? Probably, but the name does not matter. It had the attributes of a Qualicum: came up without notice, was fierce, blew for short time and then abated quickly. The important thing is that it happened, and can happen again. A local long term resident at Shingle Spit says such a wind is infrequent but not unique. We all seem to remember this storm in detail.

How strong was the wind? Doug has a record of press reports that winds (presumably at Chrome Island) exceeded 170 kph. This is 92 knots (106+ mph). He was involved because he was at that time involved with the operation of the Hornby Island Resort property next to the ferry property at Shingle Spit.

Where did it come from? The trees broken or uprooted at Shingle Spit fell to the NNE. On Denman there were many trees and utility poles down at the west end of MacFarlane Road, which suggests a similar direction – from the Alberni Inlet.

Naysayers are saying that Qualicums do not enter Baynes Sound. Readers can draw their own conclusions.

Vessel profile

The load on the guide cables depends on the side profile of the vessel. The vessel cannot have just a flat deck with ropes in stanchions as an external fence. This is a vessel which carries a significant number of passengers in the rain in winter. Closed passenger accomodation is required. Vehicles on the deck have a profile, and this includes delivery trucks, campers, cement trucks, log trucks and busses. We do not feel that this profile can be much less than half of that of the Quinitsa.

This is of concern because the pictures in the three PowerPoint presentations from BC Ferries do not really indicate a committment to allowing sufficient heated enclosed space for foot passengers. Look at the pictures of Needles and Riverhust.

This needs further review.

Cable selection

We understand the value which is being used in the BCF calculations is about 1¾" diameter. There is a huge difference in the project viability between these two estimates.

A 2000 km 1¾" cable will weigh 18 tons and have a breaking strength of 154 tons.
A 2000 km 2-5/8" cable will weigh 42 tons and have a breaking strength of 348 tons.

For more details please refer to Peter Kimmerly's two project memoranda which can be accessed from the links at the top of this page.

Wikipedia Cable Ferry List

In their various presentations, BC Ferries have emphasized the following points:

Cable ferries are proven technology.
This technology has low complexity and is very reliable.
Systems are simple and redundant. (not sure what redundancy refers to - cables?)
There are hundreds of installationa around the world.
There are experts available who will help evaluate bids.

We thought we would check out where the expertise lies. Our primary source is an article on Wikipedia titled Cable Ferry. It covers cable ferries in North America, Australia and Europe except Russia, plus a few from Africa. It seems to represent a fair sample of what we should be looking at for examples and expertise.

There are 195 cable ferries on this list, of which 163 (84%) or more cross rivers or lakes. No more than 32 are in tidal water of which 23 are in Finland. In terms of cable ferries being the unique access to an island there are 31 (both fresh and salt water), of which 23 are in Finland, and one each in Canada (NB), the US (LA), Norway (passenger only), Sweden, Denmark, and Australia.

It is hard to make the case that there is a pool of experience in North America in ferries operating in tidal water. There are only three such routes, all in Nova Scotia. Two are at river mouths, and one is a shortcut across a bay in Cape Breton Island.

There is some doubt as to whether some of the individual routes in Finland are in fresh or salt water, due to some strange terminology. Thus the question marks.

There may be a pool of expertise in operating small fresh water ferries in Canada. We have the most cable ferries of any country except Finland. British Columbia has 11 cable ferries, which is 6% of the world wide total, and 38% of Canadian installations. But five of these are 2-car reaction ferries which are of no interest to us.

The proposed Cable Queen is to have a 50 car capacity. In terms of comparable size ferries BCF lists two routes in England at 49 and 73 cars respectively, and one in Finland at 36 cars. The largest cable ferry in BC is at Needles, at 30 cars.

The length of the run proposed for Route 21 is 1.9 km. This would be the longest in the world, the closest others being one in Finland at 1.6 and one in Saskatchewan at 1.5 km respectively. (Page 23 of BCF's Supplimental Information). This is not much in terms of world wide expertise. BCF claim to have contacted three other routes - we do no know whether this included a visit or just a phone call.

Depth and bottom countour are other factors we would like information on, but we have no informationon which ferries offer examples.

Risk

There are three types of risk to concern us:

Risk to life and property,

Economic risk,

Risk of degradation of the mobility of the fleet

The attributes which are different from most conventional ferries or existing cable ferries in Canada are:

This would be the longest cable ferry service in the world,
providing unique access to two populated islands,
in a shipping lane with 16' tides,
and a deep and unusually contoured ocean bottom,
in an area of erratic and strong cross winds,
in weather conditions which may included cold, rain and snow,
and routinely carries walk-on passengers,
including up to 60 school children on some runs.

BC Ferries claim that the length of the cable has "no effect". This may be true as far as tensile strength is concerned, but there are two issues which may cause effects, the amount of slack cable and the weight which may be suspended from the ship at any time. This run will be longer than any other in the world, and the cable weight effect is exaggerated by the depph of the channel.

The longest open ocean cable ferry run in North America seems to be the 125 metre crossing of St Ann's Bay on the north coast of Cape Breton Island.

Unique Access to an Island

This route provides the only access to two populated islands. If it fails, commuters and other travellers cannot get to work, school, medical specialist, any specialty store, etc. We do not know what is done about alternate service in other jurisdictions but most of the experience seems to reside in Finland. Has this been checked? There is a good argument for ensuring that Denman Island can still be accessed by conventional vessels for as long as the cable ferry exists.

BC Ferries has suggested that the Gravelly Bay dock on the east side of Denman Island can be used as the alternate dock, but we do not believe the fleet is big enough to carry the peak load, even if all spare vessels are deployed. In addtion, only certain vessels are suitable for the trip around Chrome Island: in an exchange of vessels over the weekend of 10-11 Marcch 12, two of the three vessels involved were damaged by wave action to the south of Denman.

Tides and Bottom Contour

This route seems to be unique in terms of tidal range and depth of the channel. The tidal range will accentuate the erosion of the cable along the bottom along the Denman shore, which is presumably rock. The depth of the channel will increase the weight of cable hanging from the vessel at the deepest point Which will affect the vessel design. The tidal force on the hull must be added to the wind load when selecting the cable size.

Erratic and Strong Winds

We have written a separate document to cover this topic. Link to come.

Winter Weather and Walk-on Passengers

The matter of carrying a relatively large number of passengers with no vehicles means that the vessel must have significant passenger lounge space, which increases the side profile of the vessel and therefore the wind load on the guide cables.

Worst case scenarios

One worst case scenario is: imagine a 4 pm sailing with 60 school children on board, a sudden fierce storm with 170 kph sustained wind from the south. This is exactly what happened on 11 December 2006. But if the project vessel were in service that day, the 1¾" guide cables on a 50 car vessel may not withstand the force and they break, first one and then the other. The ferry drops its anchor, which does not reach the bottom because the water is 85 m deep. So the ferry drifts off toward Comox and finally grounds where the water is shallower, perhaps off Tree Island. Worried parents are gathered at Denman West to pick up the children. BC Ferries is frantically trying to find a tug boat and a small passenger vessel which can rescue the passengers. Fortunately there is a tug available in Powell River, but it would not arrive until morning. The CTV helicopter beats it to the scene and gets good footage of the stranded vessel before heading for Denman Island to gather the residents' opinion for national coverage, just as the children are finally delivered to the island. Shear panic in the BCF PR department.

Other options to consider:

One cable breaks and the other does not. The weight of cable is suddenly released from one side of the ferry, A cement truck in one of the centre lanes slides to the side and traps passengers inside the cars beside it.

One sheave seizes up and the vessel cannot move.

The ferry is laid up for a month awaiting a spare part from overseas. This would be a part chosen by the supplier to lower its cost to win the bid. Even worse, there may be a delay to re-engineer the problem.

The Authors

Peter Kimmerly is retired from the position of Senior Master on Route 22 (Denman-Hornby). Prior to joining BC Ferries he had been master of ain icebreaker in the Arctic Ocean. He has also done a number of special tasks for BCF.

Doug Christie is retired propcess engineer with 50 years industrial experience in operation and project studies and mangement. He has successfully completed over 40 projects in Canada, the USA, France and Southeast Asia.

Both are residents of Hornby Island.