I apologize if this is a stupid question but...is there a way to increase the stability (or diminish the rocking motion) of a floating dock?

Some quick background: We’ll be building either a 12x24 or 16x24 dock to go with a new 2 acre pond. Originally, the intent was to make it stationary for stability reasons (due to a degenerative disability), but given that my neighbor’s dock currently ends 20’ before his pond begins, we’re re-thinking the plan. I just received the Mar/Apr 09 PB back issue with the dock article (thank you, Esshup, for suggesting both it and Catmandoo’s thread) but a few questions remain:

Does orientation affect stability? More specifically, can “sway” or rocking be decreased by placing either the shorter/longer side parallel to the shore and does direction (north to south or east to west) matter (do I need to consider wind/wave action on a small BOW)? Also, are there other mitigating design ideas that we can incorporate? Thanks!

I am sure that there are ways to deminish rocking, but a better plan may be to include structures on the floating dock to hold on to (railings).

There are very long floating piers built in the saltwater bays around San Diego. They have concrete posts that go thru the pier, and there is a roller attached to the pier for every flat surface that is on the post. Because of the stiff concrete posts, they cannot sway from side to side. The piers are at least 6' wide IIRC. Wide enough for a fish cart to pass another fish cart on the dock. I estimate that some of those carts had at least 1,000# of weight in them, either taking supplies to the boats, or offloading fish.

IIRC, a member built a floating dock and didn't have a very wide "T" section at the end. They said that it was very rocky.

Generally, the wider the pier, the less rocking will happen. Lateral structures coming off the main pier at 90° angles will also help reduce the rocking provided they are anchored very tightly to the main pier to eliminate any movement at tht 90° junction. Piers with more flotation will sway up and down less than a pier with less flotation.

If you have unlimited latitude in placing the pier in the pond, it will have the least movement if placed on the lee side of the pond. (the side from which the prevailing winds come from). A head or tail wind will move a pier less than a cross wind.

I am not going to drive any type of vehicle on the pier, and my floating portion of the pier will be 4' wide, by 16' long. At the end of that 16' section, there will be a 12' wide, 8' long section. Think of a "T" with a fat top that is 12' wide.

If you look on this page, those tubes going from the end of the dock to shore, and the guy wires criss crossed are there to stop the dock from swaying side to side. I'm assuming from boat wakes.

esshup - Thank you - exactly what I was looking for!!

I you intall guy wires, as I also did, be sure to install them at the same elevation as the gangway so that they will maintain the same tension as the water level changes. I used chains and included a turnbuckle so I can tighten them as needed. I still have quite a bit of rocking but do not have any posts at all. Originally there were no railings on our dock at all, but a couple spills later from kids, I installed railing on the water side of the fixed dock and on the gangway. In the attached photo (taken from the floating portion of the dock), you can see that the railings on the gangway are parallel with the gangway and fastened with a single lag so they can move with the water level. The turnbuckles are under the gangway. The railing have prevented further spills.



second photo from the side

Thank you, RAH, for the feedback. The pictures are very helpful. We’ll incorporate the rails and wire.

A couple of ther things you can do to stabilize a floating dock are: 1) If you are using plastic barrels for floatation, partially fill each barrel so that it sits lower in the water. Imaginge a totally empty barrel and how it will be very tipsy on the water surface versus a 50% filled barrel that is partially submerged. 2) Add ballast to your dock. Hang an engine block off each corner of the dock 2-3 feet below the surface. This accomplished the same end result as adding water to each barrel. Both methods "plant" the dock a little lower in the water increasing stability. If you chose to partially fill each barrel, you'd want to do this during the construction phase. If you chose adding external ballast, you could determine how stabile your dock was first, then add ballast until you get the desired stability you want. With such a large floating dock, it may be more stabile than you'd think.

Oh, my mind must be very sick. I'm thinking the 1970 Cadillac 500 cubic-inch, 400 hp V8, which I believe was the largest production engine ever used in street-legal passenger cars. Although, there were some other Ford, GM, and Chrysler engines in the 1950s that probably rivaled it in weight. If the ropes ever broke simultaneously from all four blocks, the dock would probably launch well into the sky like Sputnik.

Anyway -- ballast is good.

I will say, that my dock with 12 barrels underneath it, and with a 12-foot "gang plank" anchored to the shore with gate hinges, my dock moves very little. Even with 3-5 people on the dock, it just makes minor waves. With just me, it barely moves. It must be fairly stable, because even my 85 year-old aunt enjoys coming down and sitting on a deck chair, near the edge, while she fishes for bluegill.

I did find that not all 55 gallon plastic drums are the same diameter. I found a nearly 2-inch difference. In the middle of the summer I had to re-arrange my barrels to make the dock level. Because my fish feeder is on one corner, I put the larger barrels closest to the corner with the feeder.

As always during this time of year, in this area of the country, the pond is down at least 12-15 inches below full pool. It was as much as about 18 inches above full pool shortly after we built it this past spring. The dock has been perfect through it all. We've had some pretty major weather events to include lots of big wind storms and heavy rain storms. I've seen no problems due to the lack of ballast or anchors. I just need to device a better ladder for next season. Currently, I have an old cheap extension ladder tied to the dock with rope.

Thank you for the input. We’ll definitely incorporate a ballast structure. Typically, there will be 2 people and a Polaris (I use it as legs but it’s a blast, too) but I want to allow for those times when the kids come to visit (large family, 4 generations, rambunctious sons – I think we had 18 people for Thanksgiving last year). Anyway, we’re designing with 12 people in mind and I am thinking that using barrels (or series of) as an external ballast may just work. The idea is that we could just empty and fill as needed –any thoughts? Again, thank you – you all have been extremely helpful.

Full Circle,

Check out this link after reading below to see what I am talking about with regard to crossing cables.
http://www.midwestlake.com/pond_lake_management/docks.php

We like to criss-cross galvanized or stainless cable to prevent lateral movement and to prevent the dock from moving out into the pond. To prevent it from coming in, we secure the front edge of the gang way on each corner with a small loop of cable that goes around the angle iron and through the eye of an auger-type earth anchor that we screw in to the bank. We do this as close to each corner of the gangway as possible and then cover with gravel to dress it up and conceal it.

Earth anchors are also used for the main criss-crossed cable supports but they are typically secured in the water instead of on the bank. Again, this is just to conceal them.

Another option is to only secure the front edge of the gangway, either by attaching it 6"x6" posts which are secured 3' plus into the earth with concrete and upward another 2-3', or we've actually poured a concrete footer/pad on the shoreline and embedded a bracket that sticks out of the pad on the side facing the water. This heavy duty bracket then gets pinned to a bracket that we've welded onto the gangway. Both of these methods work great in most pond applications and do not usually require support cables. It depends on how long the gangway is, but there is usually not too much side to side stress with these types of systems in a pond. Doing this without cables in a large lake with heavy fetch and boat wake is a different story.

You can also drive steel pipes off each corner of the dock through sleeves and into the pond bottom, but my opinion is that it doesn't look good. Further, with time it always seems the pipes end up leaning.

Shawn - those are nice docks! If I may ask, what are you using for flotation? I appreciate the thorough description – I’ve cut and pasted the entire thread for future reference. Again, thank you to all.

Ken, in the woods of Wisconsin not too far North of Stevens Point I came across an old car that had a 12 cyl engine between the fenders and a couple of 8" dia trees growing between the engine and the firewall/fenders. I'll bet that engine would have given the caddy engine a run for it's money in the weight dept. I have no idea what car it was, the body was mostly rotted away. This was in '77 or '78. I can't begin to imagine how many years that car sat in the woods, nor how it got there. Not a road or 2-track to be seen near the car.

Just to clarify, when I say use an engine block for ballast, I mean just the bare block, no shortblock, no longblock, etc. The cylinder bores can even serve as cover for small fishies.

FullCircle,

We use poly encapsulated foam floats. Essentially they are a polyetheylene shell that is made in a rotationally molded process. They are then filled with polystyrene, which is steamed and then sealed. Several folks on this site buy them from dock builders out of Florida, but I recall finding a manufacturer in Arkansas, which is closer to you and should help on shipping. You would have to do a little google work to find them, but I think key words like dock floats and Arkansas should find them- or maybe they were in Louisiana, but it was definitely one of the two. We have a manufacturer up here that I buy from directly, and this should be the case with the Arkansas boys for you.

This style of float is really attractive, durable, and easy to attach. Sure, they cost more than an empty barrel, but.......it just depends on what you want and what your budget is.

Thanks for the comments about our docks. They are a source of pride with us. Most of them get entirely powder coated after we fabricate the frame work. Others get galvanized, and some get both. We like the powder coated finish- it makes for a nice look.

I second using the foam floats. They are easier to work with, and I think they might last longer too (or at least have less of a chance of leaking and filling with water). I'm using barrels just because of the cost factor.

Thank you, Shawn – I found them shipping out of OK about 400 miles away.
One benefit of pre-planning the house and pond is that I have been able to shop some of the sales and specials in advance and we are well under budget for now (nice change) so I could justify spending a little extra $$ toward the pond...

Full Circle, did you use Beaver Docks out of Norman?

No, I found the floats at dockbuilders.com. According to their “locations” page, the dock floats can be shipped out of Sallisaw.

There is a new product out on the market called a dock stabilizer and it is manufactured by .............

Robert:

Here's what the forum owner has to say about advertising. If you want to advertise, call the Pond Boss Office and take out an ad in the resources guide.

"Quite often, we'll see a new member (or existing members) selling their wares or services.
We only allow that of our approved advertisers. We are careful to make sure our advertisers are quality and meet our expectations.
If you have a product or service you'd like to promote on the forum, please send an email to info@pondboss.com and get permission before you promote or add information to your signature line or add a link to your website.
We'll protect our paying advertisers and people we know.
For our approved advertisers, you guys already know how to play.

If someone breaks this rule the moderators will delete all links and references to your business."

Usually whan a persons first post is about a product or service, that raises red flags with us moderators. Then an even bigger red flag is thrown up when we find out that the person who posted is affiliated with the company. If you are an advertiser with Pond Boss, and your information hasn't made it to the electronic copy of the resources guide, then I apologize.

You are absolutely correct...I will do as you suggest and inquire regarding a paid ad.

My Apologies...