Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
Wooden Timber Crib Dock #5271 11/29/04 04:32 PM
Joined: Mar 2004
Posts: 79
J
Joel Offline OP
Member
OP Offline
Member
J
Joined: Mar 2004
Posts: 79
Greetings...

I plan to build a Timberframe boat house. It will be approximately 30'x50'

The foundation will be 8'x8' cribs made from treated timber (6'x6' or 8'x8').

I would LOVE to communicate with anyone that has knowledge of building crib docks.

Joel

Re: Wooden Timber Crib Dock #5272 11/30/04 06:35 AM
Joined: May 2002
Posts: 218
E
Emmett Greenleaf Offline
Member
Offline
Member
E
Joined: May 2002
Posts: 218
Once upon a time (not a fairy tale laugh ) when I first learned timber frame deconstruction in the finger lakes (circa 1950) I observed several very old boat house underwater foundations which had lasted some time. The cribs were bolted together with about 1 foot extending from each corner to provide a right angle pocket around a pole driven in the lake bottom. The remaining center space inside the crib was(about 6' square) filled with large rock (1 cu ft or larger).The crib top was typically 3' above the mean water level. Walkway docks were then placed on the cribs on which the boathouse was built.
Based on the experience of the wooden submerged timbers used on the St Lawrence waterway they are of red oak and replaced at nominal 30 year intervals. These timbers can be dried and used in a new above ground timberframe. The problem of submerging wooden timbers is finding a preservative the environmentalists will let you use not withstanding any provisions of NYS law/building codes.
Good luck and work safe.

Re: Wooden Timber Crib Dock #5273 11/30/04 03:23 PM
Joined: Mar 2004
Posts: 79
J
Joel Offline OP
Member
OP Offline
Member
J
Joined: Mar 2004
Posts: 79
Thank you for your reply!

The poles sound like a good idea...I am very concerned about the cribs sliding on the river bootom...the TF would not like this!

Did the cribs have a bottom? Almost eveything I have read shows cribs with a bottom. Makes sense...something has to apply the weight of the rocks to the crib!

HOWEVER, I just met with a person who seemed very knowledgible. Since my river bottom has fat/jagged rock, he suggested using bottomless cribs filled with flat jagged rocks to "lock" into both the river bottom and the sides of the crib. I don't think this is the norm...but it sounds logical.

BTW, the waterfront is the St Lawrence River! Located in Morristown, NY.

Joel

Re: Wooden Timber Crib Dock #5274 11/30/04 04:58 PM
Joined: Sep 2003
Posts: 120
B
Bruce Chrustie Offline
Member
Offline
Member
B
Joined: Sep 2003
Posts: 120
Joel,

Not sure if you have done this yet but I would suggest you take a boat out and see how many cribs are still intact. Given the iceflows on the St L I would caution you to consider design alternatives. I have seen many a fine crib pushed away by an ice flow come spring! Most of the newer docks on the St L are attached to shore with some aspect of floatation, though would not apply to your boar house.

Bruce,

Re: Wooden Timber Crib Dock #5275 11/30/04 07:24 PM
Joined: Mar 2004
Posts: 79
J
Joel Offline OP
Member
OP Offline
Member
J
Joined: Mar 2004
Posts: 79
Hi Bruce...

Thank you for your reply.

You hit the treenail on the end! Cribs are notorious for moving, especially in the winter.

I planned to do a piling dock. About 2X the cost of a quality crib dock, but a better bet to survive winter. A contractor looked at my waterfront and felt thier was not sufficient rocks and stones on top of the bedrock to prevent a piling dock from moving. Drilling into the bedrock would be 50% more then simply driving the pilings. So...I go with a crib, or a drilled piling at 3X the cost. Yeeks! The good news is that this contractor in not a fan of cribs, but felt if there was an ideal location for a crib dock, my waterfront was it (little wake from ships, partially protected by a small bay, ice known to melt in the spring with little to no movement from water flow...). I thinking maybe an ice melter could protect the crib from vertical ice movement as the water level increases.

As an alternative, I'm looking at the possibility of having pilings with a plate on bottom end that could be pinned to the bedrock. It would be closer in cost to a driven piling than a drilled piling...I hope!

You sound familar with the St Lawrence river. Where are you from? I think I'm pushing being off topic with this thread...I'd love to continue talking via email perhaps?

Joel

Re: Wooden Timber Crib Dock #5276 12/01/04 03:28 AM
Joined: May 2002
Posts: 218
E
Emmett Greenleaf Offline
Member
Offline
Member
E
Joined: May 2002
Posts: 218
Another approach might be to do 2 concrete boxes, the outer box with drainage holes to maintain a constant water level. The inner box, spaced five or more feet from the outer box is the foundation for the boathouse. The space between the boxes is rock filled not unlike a crib. Anchoring both boxes to the bottom with drilled rod removes the threat of creep. piling rock around the outer box like rip rap helps protect this protector box from ice. The only unforseen is the massive flood which carries the boathouse downstream. This box in a box technique has been used in tidal waters in Europe for a long time.
What does a search for boathouse foundations yield ?
The St Lawrence is a cold water envirionment to work in but the fishing is great. Ever put a muskie on the barbie ?

Re: Wooden Timber Crib Dock #5277 12/01/04 03:02 PM
Joined: Sep 2003
Posts: 120
B
Bruce Chrustie Offline
Member
Offline
Member
B
Joined: Sep 2003
Posts: 120
Joel,

Feel free to contact me offline. As for where I am from....the other side of the St L! I have only done some swimming in it so am not that familiar with it, but dock cribs are a way of life in Canada for cottagers. I would seriously take a look at how many cribs are used in your area.

The concern is iceflow come spring and have seen many a dock twisted by a sheet of seemingly 'small' ice float on by with the wind or current only to demolish anything in its path. Cribs, piles, pillars can all suffer the same fate.

Re: Wooden Timber Crib Dock #5278 12/01/04 08:00 PM
Joined: Mar 2004
Posts: 79
J
Joel Offline OP
Member
OP Offline
Member
J
Joined: Mar 2004
Posts: 79
Emmett...

It is unclear to me what is the purpose of the inside box. Why not just fill up the entire outside box with rocks?

Joel

Re: Wooden Timber Crib Dock #5279 12/01/04 09:37 PM
Joined: May 2002
Posts: 218
E
Emmett Greenleaf Offline
Member
Offline
Member
E
Joined: May 2002
Posts: 218
Joel,
The inside box is the definition for your boat entry slip (to sling lifts I would guess), the foundation for the boathouse structure and the inner wall limit of the rocks between it and the outer wall. The rock mass between the concrete walls is to resist movement induced by anything moving in the river. Some of the very old boathouses in Europe used stone on stone masonry for this two wall system. Going this route calls for individual stones that weigh tons each. The concrete containers is the "modern" approach. Yes I know too that some of the oldest concrete structures have been around for 2000 years (the coliseum in Rome for example).

Re: Wooden Timber Crib Dock #5280 12/02/04 03:03 PM
Joined: Mar 2004
Posts: 79
J
Joel Offline OP
Member
OP Offline
Member
J
Joined: Mar 2004
Posts: 79
Emmette...

I'm suffering from spatial dyslexia on this!

Is there somewhere I can see a drawing or a picture of this?

In plan view, the dock/foundation for the boathouse will be U-shaped.The boat would enter the boat house through the open end of the U. Where are the 2 boxes placed? What shape are the boxes?

Appreciate your patience!

Joel

Page 1 of 2 1 2

Moderated by  Jim Rogers, mdfinc, Paul Freeman 

Newest Members
HFT, Wrongthinker, kaymaxi, RLTJohn, fendrishi
5134 Registered Users
Powered by UBB.threads™ PHP Forum Software 7.7.3
(Release build 20190728)
PHP: 5.4.45 Page Time: 0.025s Queries: 15 (0.008s) Memory: 3.2146 MB (Peak: 3.3984 MB) Data Comp: Off Server Time: 2024-03-29 12:39:20 UTC
Valid HTML 5 and Valid CSS