Sticks and Stones
A Traditional Les Cheneaux Crib Dock Replacement Project
By Alex Watson
Last year, we decided to replace our aging cedar crib docks. They had withstood 44 years of rain, sun, snow load, Lake Huron ice flows, winds, wave action, and record high Great Lakes levels. (And the occasional bump by a boat.) – Also remember you can click on any of the photos in todays story to enlarge them – Texx
Because crib docks are a characteristic of our area — The Les Cheneaux Islands (Hessel and Cedarville, MI) — it was a given we would replace them with new cribs. The alternatives — seasonal wood or aluminum docks — look too contemporary in this rustic area. Nor could seasonal docks offer us the protection we needed from winds and waves.
When work began last winter, I realized this project would make an interesting Woody Boater story. Most lakes do not allow crib docks, so this would be something new and different — the first dock story. And, lets face it, all of us here have a thing for wood, right?
Replacing the docks from scratch offered us the equivalent of a do-over. We could replicate what we had, or try to improve on it. We took over a year to ponder options and map out configurations.
We chose a local dock builder, Bob Dunn of Breezeswept Docks to spearhead the work. Bob is a handshake kind of guy, and his reputation is excellent.
We decided the main dock would be shaped as it was before, like an “L,” because this offered the ideal protection from the prevailing, mainly West winds and waves. It would measure approximately 82 feet long x 7 feet wide, with a 90-degree angled section 41 feet long x 11 feet wide, creating slips sufficient for our longest boat, the 25’ Sportsman. The new dock would incorporate five 15 x 7 foot stone filled cribs and two 7 x 7 foot ones.
The project would also include dredging a harbor approximately 80 feet x 55 feet, 3 feet deeper than the existing level, removing approximately 300 cubic yards of hardpan (the dense layer of clay, rock, and sand under the sediment). Why dredge? Lake Huron was over a foot below chart datum, fast approaching its 100 year low.
Yet the new docks would be built to the same height as the old docks which, at the time, were about 5 feet above the water. Why rebuild 5 feet above? Because in 1986, 24 years before, Lake Huron hit its 100 year high, water level (5.92 feet above datum — the normal high water level is 2 feet above datum), swamping many crib docks built too low.
This kind of water level range (about 6-1/2 feet!) doesn’t happen on smaller inland lakes, but it must be accounted for with fixed docks on the Great Lakes.
Lake Huron had been falling precipitously in recent years. Let’s run the numbers on this…
• Lake Huron has a surface area of 23,010 square miles (which, by the way, includes 30,000 islands).
• 1 square mile of water 1 inch deep is 2,323,200 cubic feet of water.
• If you multiply these two figures, you get 53,456,832,000 cubic feet of water in just one inch of Lake Huron depth.
• Now if you multiply that figure by the 72 inch (6 foot) drop in water level since 1986, you get 3,848,890,000,000 cubic feet of water that has vanished.
• What’s that in gallons? Well, since 1 cubic foot of water contains 7.4805 gallons, then it’s 28,791,600,000,000 gallons.
It’s hard to imagine how nearly 29 trillion gallons of water could disappear, and how (and when) they will return. So we didn’t. We banked on science. Yes, there are theories of an over-dredging cover-up, or excess water diversion down the Mississippi, or excess drawing of water from aquifers for bottling. And there’s plenty of global warming opportunism too (“you never want a serious crisis to go to waste,” right?). But the fact is, whatever role those things play — even in cumulation — the rising and falling of Lake Huron has happened several times in measured history, before any of those things. And all records were made to be broken, right? Who’s to say breaking an all time low is “caused” by anything, and not natural? Who’s to say the all-time low wasn’t lower, before we started measuring less than 100 years ago?
This is not to make light of the low water situation. It’s dire for many communities, including ours. It’s just my 2 cents relating to the low (and high) water we needed to consider, given the projected 40-50 year life span of the new docks.
The improvements we decided to incorporate into the docks were:
a) A greater number of cedar log piles (65 total), spaced closer together, offering more protection from the ice. (Incidentally, a single one is called a pile. A structure of them is called piling.)
b) 11 feet of width for the 41’ (90-degree angle) dock instead of the previous 7 feet, offering us room to entertain on the dock.
c) Higher capacity electric power. Enough to install a hot tub on the docks, should our ship come in. (Message to my wife… No, dear, this doesn’t mean I want to buy a bigger boat.)
d) Plumbing to the dock, for washing the boats.
e) Decking screwed in with galvanized screws, rather than nailed.
We elected to use pressure-treated, beveled lumber for the decks instead of cedar. Pressure-treated boards would last as long, or perhaps longer, than untreated cedar, and would weather to the same lovely shade of grey. Bevelled boards would be easier under foot and less likely to splinter.
Though the contracts we signed spelled out the job in basic terms, we had no idea how involved the process would be and how much talent it would take to build the dock right. As you’ll see, there’s a lot more to this than banging logs together and filling them with rocks.
So here we go…
Step one of the project was behind us — the drawings. Step two was all legal. Beyond signing contracts with the contractors, we needed to pull permits with: a) the local township; b) Michigan Department of Environmental Quality (DEQ); and c) Army Corps of Engineers.
The DEQ permit introduced a complexity. Removal of the old docks and any dredging would have to stop by April 1, whether completed or not, because digging around and disturbing the lake bed could harm fish during spawning season.
Once the permits were in hand, there was a lag of a few months before work began in February. You might think demolition, dredging, and installing the new cribs would be more difficult in the winter. But the opposite it true. The crew needed the thick winter ice (about 15”) as a foundation, so they could drive the excavator much further out from shore.
Here you’ll see the excavator laying out a canopy of hardwood logs, all strung together with steel cable.
The excavator positioned the logs on the ice, then drove on top. The weight pushed the logs and the 15” of ice beneath them down to the lake bed and voila, a temporary island was born.
Demolition of the old docks happened remarkably quickly. The dry wood (above water level) was either burned or cut up for firewood, while the wood beneath the water was hauled to a landfill. The rocks which filled our old cribs were pulled out and piled on shore, where they would be reused in the new cribs.
The next step required an interesting talent. The man running the excavator had to dredge our harbor and make way for the new docks. He operated basically blind, feeling his way around through the ice fragments, floating pieces of old dock, and stirred up water. (It was months later when the project was nearly completed that we could see in clear water how effective he had been at getting everything pulled out to the prescribed depth.)
Once dredging was done, it was time to position the new cribs. They had been built and floated over before the ice to rest on our beach.
Surveying equipment, construction string, t-squares, and neon spray paint were the tools used for siting them. Each crib was towed over, positioned, submerged, nudged into place, and filled with rocks.
Once the cribs were set, they were left to settle about 6 weeks. Settling can be significant or slight, depending on lakebed composition — it’s not something that can be controlled or rushed.
After checking to ensure no crib had materially shifted from its intended position, the next step was to “build up” the cribs to the prescribed level above water. As each crib was built up, more rocks were piled inside. The tallest cribs ended up about 9 feet high (combining underwater and above water height).
You can now get a sense of how heavy these cribs are. The 9 foot high ones (each measuring 7 feet wide x 15 feet long) consist of a few dozen green logs each, and are then filled with rocks piled about 8’ high! We used a total of over 120 cubic yards of rocks.
Even so, moving ice can be merciless and shred even crib docks under certain conditions.
At this point, a running change was made to our design. We realized we had an opportunity to cut steps down into one of the 90 degree end cribs, making it easier to walk to boat level in the low water. (These can easily be built up when the water returns.) Here you’ll see them cutting into the crib to make space for the steps.
The next step was to install pressure treated 6” x 6” stringers.
The crew used chain saws to cut into each of the crib logs as needed to ensure the stringers were perfectly level the entire length of the dock.
Once our wire conduit and hosing was strung throughout the docks, the deck boards were installed and the stairs finished.
It was now time to install the 65 cedar log piles. The rings of the logs indicated they were approximately 100 years old.
Specs called for these to be driven in 4 to 7 feet, if possible, unless there is “bottom refusal.” (I swear I didn’t make that up.) In the tight 90 degree corner and near shore, a large drill, a high powered water-jet, and downward hydraulic pressure were all used.
In deeper water, pile driving equipment was used to pound the logs down.
The crew was able to install the piles vertically, with fairly even spacing — no small feat! Where the piles would not go deep, they were collared to the dock with galvanized straps. (None of the piles is attached to the dock, because ice periodically lifts piles. Lifting piles would lift dock components too, causing damage.)
Finish work was next. Remaining piles were cut down to prescribed, uniform height, excess cedar bark was peeled, and the top of each pile was leveled and beveled. Bob assured us each would be smooth and level enough to hold a drink. (No plans to line up 65 shots, incidentally.) Next, the ends of the horizontal crib logs were all trimmed to uniform protrusion and the edges of all the deck boards were beveled to reduce the risk of cutting oneself going off the dock. And lastly, the stairs to Slip 1 were completed.
That’s it. The new crib docks were finished!
But the total job wasn’t.
Because we had more boats than before, we needed more slips. This is where our greatest improvement over the old docks came into play. We had ordered custom, 4’ wide floating docks from Flotation Dock Systems to be incorporated with the fixed crib docks.
Flotation docks are engineered, commercial strength, and can be found at many Michigan marinas. Many do not need to be removed for winter. They are free to rise and fall with water levels, yet they will not twist or sway. Even their stairs self-adjust, keeping every step level, regardless of water fluctuations.
On the heels of the crib dock completion, Flotation brought in two pre-made dock fingers (one 28’ and the other 25’ — factoring in the various lengths of our boats), a massive aluminum connecting beam, steel piles, two stair sets, and the related hardware to assemble their product. To help blend with the look of the crib docks, we specified round cedar posts, rather than Flotation’s standard, square, pressure-treated ones. In just a few hours, the dock sections, stairs and connecting beam were offloaded from a large barge, assembled, and moved into exact position, and the steel piles were forced down. It was slick.
The Flotation component added to the total project cost, but it was well worth it when you consider they expanded our “protected” (from the winds and waves) docking capacity from 2 boats to 5, and made entering and exiting 4 of those 5 boats far safer, because they are always at the right height. (Recall the 5th boat is accessed via the stairs cut into the cribs.)
There was one last step to be done. We had a 40’ x 4’ pressure treated ramp built to lead to the docks. This covered a dirt path, ensuring less dirt would be tracked onto the docks (and into the boats). Because this new ramp was wider than the ramp it replaced, this also reduced the risk of a fall onto the rocks which border the land leading to the docks.
Cost of the project — drawings, permits, demolition and hauling, dredging, crib fabrication, crib installation, crib build-up, wiring, plumbing, decking, floating components and installation, and the 40 foot ramp — came to about $80,000 in total.
Now the job was all done. We had the best of all worlds.
1) The 40+ year longevity, protection, and authenticity to the area only crib docks offer.
2) The practicality and safety (for boarding and disembarking at varying water levels) only self-adjusting floating docks can offer.
3) Significantly more protected docking capacity than before.
What mistakes did we make? We’re only aware of one. To allow for drainage and air circulation, we spaced the deck boards farther than the norm. As the boards began to dry, the surface became painful when barefoot. We were also concerned a small child could catch toes between the boards, or a dog might catch a paw. And so we had each and every board unscrewed, re-positioned the customary “nail-width” apart, and refastened to the stringers. Removing thousands of tightly driven screws and then re-driving them was labor intensive. And of course, closer boards meant more boards were needed. Still, it was the right thing to do.
We are very pleased with the end result. And we no longer have to be concerned with fluctuations in Lake Huron water level. Unless of course levels drop from the current (2013) record low to a much lower low, rendering the dredging we did insufficient. If that happens, more dredging will be required. (It also offers a perfect excuse to buy classic I/Os and classic outboards with trim.)
We hope you enjoyed learning about this project. As with a total boat restoration, it was a bit of a letdown for us when it was finished. The process was a big part of the fun. Still, the best is yet to come. In a few years, the wood will have mellowed to grey and we will blend back in with our beloved area.