Building a new dock

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pontchartraintoon
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Building a new dock

#1 Post by pontchartraintoon » Mon Jan 02, 2012 9:24 am

Well, I am going to have some new tie backs installed next month on my sea wall, and also a new dock. There isn't quite enough room in the budget for a lift yet, but am debating between another fixed dock, or maybe a floating dock.

We are in a cul-de sac lagoon with no wakes, and on Lake pontchairtrain so only between 1-2 foot normal tide, with larger depending on wind.

What are your thoughts fixed versus floating?

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Ron Burgundy
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Re: Building a new dock

#2 Post by Ron Burgundy » Mon Jan 02, 2012 9:42 am

Floating hands down, but make sure you build it so that there is enough room to raise if you have a big storm surge. I currently am tied to a fixed dock where tide swings of 4 feet are an everyday occurance, and while it is manageable I am going to try to build a floating dock as well. The problem is that you have to tie your lines loose enough so you don't get hung up on low tide. This means on high tide you have loose lines. If you can tie off on all 4 corners it's not that bad.

I don't know what your budget is, but if you can build a fixed dock far enough out into the water so that you don't have to use those long arms that extend off the seawall/bulkhead it will be much stronger. You can then use the verticle poles that are bolted directly to the pyling, and your dock will ride up and down on those. I'm not sure if that description lets you visualize what I'm talking about so I'll see if I can find a photo somewhere.
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GregF
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Re: Building a new dock

#3 Post by GregF » Mon Jan 02, 2012 10:11 am

The problem with floating docks in places with surge tides is keeping them where they belong. When they float off the pilings you locate them with they tend to become rafts, going out to sea.
We had one here that only escaped half way and was turned 270 degrees, sticking out in the channel when they got out to look at it, hanging on by the one piling that it hung up on and pulled up about a foot.

If you are thinking about a lift, most of the floating dock advantages start to disappear. Lake guys have different issues and they seem to make more sense there. Lake levels can vary greatly year to year.

Whatever you do, be sure you wrap the pilings.
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Re: Building a new dock

#4 Post by badmoonrising » Mon Jan 02, 2012 10:41 am

Ron Burgundy wrote:Floating hands down,
Agreed.
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Ron Burgundy
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Re: Building a new dock

#5 Post by Ron Burgundy » Mon Jan 02, 2012 12:24 pm

GregF wrote:The problem with floating docks in places with surge tides is keeping them where they belong. When they float off the pilings you locate them with they tend to become rafts, going out to sea.

The floating docks I have seen around here have stops at the top to prevent them from floating off.
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pontchartraintoon
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Re: Building a new dock

#6 Post by pontchartraintoon » Mon Jan 02, 2012 1:51 pm

I'm going to get the dock guy out and see what his thoughts are. I've seen some affordable hoists on eBay, and know what 4 pilings cost. I think around us, the roof, shingles and everything else adds a good bit. I may see if he can put the 4 poles in, and I can take it from there. It's times like this I can apprecaite that map that shows where everyone is. It makes it easy to see who to invite for the weekend of lift installation.....ahem, I mean beer drinking. :drink4

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Re: Building a new dock

#7 Post by Ron Burgundy » Mon Jan 02, 2012 2:25 pm

I know Greg built his own lift so he can probably give you some pointers. If you can swing it a lift that is probably your best bet, although they can be sketchy during a big windy storm, or hurricane. BoatUS rated lifts as one of the worst types of 'docking' during a hurricane, and rated a floating dock with tall pilings as one of the best. Maybe there is a way for you to do both :donno
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Re: Building a new dock

#8 Post by Bamaman » Mon Jan 02, 2012 5:59 pm

You should look around to see what your neighbors are using. I'd also talk to the marine contractors to get their opinions. Floating docks can be such a headache during bad weather--and something we seldom even see on our lakes. They can require elaborate cable tie systems and winches to adjust the cables. And, storms can be tremendous on Lake Ponchatrain and the New Orleans area.

I take it that the bottom of your lake is mud bottom. Is there any bedrock under the mud? How deep is the mud?

Our marine contractors come in with a pile driver on a barge, and they drive two rows of five 4" diameter steel pipes into the lake bottom until they hit bedrock. My bottom has 4" of rocks and gravel, and approximately 3 1/2' of chert. They use 20' pipe, and cut it off level with the other poles. A fixed boat house usually needs a 4" channel iron frame at 12' off the normal water level. A 4" channel iron is welded inside the boathouse approx. 3' off the water level--at dock level. I've built two boathouses, and think the last one cost about $4K for the steelwork, including a 2800 pound Ace boat lift.

The steel pipe can be driven with a sledge hammer easily--after you get through the gravel. It's really something a good handyman could do off a pontoon boat with a 10' step ladder. Welding skills would still be required, however. I added on to my boathouse last year for a Waverunner.

Our local contractors are glad to throw up the steel work, as they're not carpenters.

Most boats are now slung under a big concrete deck (12' off the water), and beside a concrete dock (3' off the water.) My neighbor had a single lift built 2 years ago for his Harris Flote Boat with 150 Verado for $58K. The tritoon was $38K--total $96K investment. Ouch!

I personally prefer fixed boathouses on a lake that just goes up and down 3' per year. But, water level variations, the type of lake bottom and governmental regulations are to be considered. Many mountain lakes go up and down dramatically (30'-40'), which obviously requires floating piers.
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Re: Building a new dock

#9 Post by GregF » Mon Jan 02, 2012 6:52 pm

Ron, if that floating dock hits the top of the piling it will pull it right out. There is really not much holding a piling down except the weight of the pole itself and they float somewhat anyway. That is why pilings always stick up so far. Even a wood dock can float up if the water gets over it.

It is best to have your lift before they set the piles so they know where they go.
Once you get your 4 pilings for the lift set, there is not a whole lot to do. It is best to let them sit a while to be sure they are stable but you want to tie them together with 2x4s or something so they don't move on you. Driven piles are more stable than "jetted" piles that really need to be stabilized.
Assuming you are using the kind that has I beams on the poles and a cradle ...
Once you are happy that the piles are good to go, you cut off the tops level, mount the I beams on top if the pilings and hang the rest of the hardware.

My lift us a cable lift without a cradle. I am picking up the boat with the lift rings and no I beams I have a single lift plate with a pipe that goes across the stern. Two of the 4 cables from the pipe go forward and catch 2 pulleys that lift the bow. Everything is framed up with 2x12s in notches cut in the top of the pilings. Fore and aft is a girder made with 2 2x12s and a zig zag of 2x4s to stiffen it up. It keeps the pilings separated with the strain of the forward pulleys lifting the bow.
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Re: Building a new dock

#10 Post by Bamaman » Mon Jan 02, 2012 7:16 pm

I made the mistake of using 4" heavy nylon straps across the front and rear. After about 20 years, I got a slight stress dent about 3' long on one toon. It doesn't affect performance, but it does bother me to see it. My Starcraft uses the U shaped foam filled toons, which I think are not as strong as the cylindrical toons.

I see most boathouse owners mounting their boats and pontoons on channel steel cradles, with long bunks custom fitted to their boats. These take up about 2' of water, so it takes a pretty deep mooring to use them. I think that I beams mounted crossways with wood bolted lengthwise would be adequate for most people's use.
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Re: Building a new dock

#11 Post by GregF » Mon Jan 02, 2012 10:40 pm

The guys around here just use 2x10s on the I beams of a regular cradle and the toons sit on them. One of my neighbors also has bunks for a deck boat that sit between the toons so the lift can be used for either boat. He keeps his pontoon on it in the winter and in the summer when he is in Ohio a friend keeps his Hurricane on it
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Ron Burgundy
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Re: Building a new dock

#12 Post by Ron Burgundy » Tue Jan 03, 2012 2:32 am

Fortunatly, I haven't had to deal with a hurricane storm surge yet, but the study by BoatUS last year clearly found that more damage claims were filed for boats on lifts than for boats secured to a floating dock with tall pilings. They made a point to differentiate between floating docks with short pilings. Those did not perform well for the reasons Greg talked about. I suppose at some point any system will fail if mother nature is raging. I figure if a storm surge is big enough to raise the dock 8-10 feet and then another 8-10 feet to pull the piling out of the sand...mother nature wins, and I probably have bigger things to worry about than a floating dock.
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Re: Building a new dock

#13 Post by ROLAND » Tue Jan 03, 2012 3:03 am

about a year ago my uncle, who lives in the Branson, Mo. area got hit by a tornado. The tornado destroyed thier community boat dock and all the boats in it. The new replacement dock is one of the nicest i've ever seen... it has stone or hard tile flooring...12 slips all equipped with electric lifts, each slip is independantly lit, large storage bins at the front of each slip. When I was up there last week I asked my uncle ( who by the way replaced his destroyed deck boat with a 2008 tritoon ) if he was concerned about rising water levels damaging his boat in the slip... He told me the new dock is a floating dock so it all rises and falls together.. not sure how it's anchored but it's one helluva a nice boat house. I can remember years ago when I first moved to Lousiana, my father in law had a couple of small boats on a lift at his place on lake Bistineau. I also remember one of his boats getting all jacked up because the water rose so much it forced his boat up against the underside of the boat house roof...just remembering that makes me think a floating dock is the way to go...
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Bamaman
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Re: Building a new dock

#14 Post by Bamaman » Tue Jan 03, 2012 8:16 am

It all comes down to how far the water goes up and down. Our lake cannot go up and down more than 3-5' due to the 1920 design of our dam--a 5000' 100' high all concrete dam. Some of the mountain lakes in the southern mountains (E. TN, N GA & W. NC) go up and down 40'--and require floating docks. Lake Lanier's down 12.5' right now, and they have to use floaters.

Anyway you look at it, boathouses are a major expenditure. I just happen to think that if your conditions warrant a fixed boathouse, they can be much more affordable if you get the metal frame installed--and finish the roof and decking yourself. The worse part about the job is just getting the wood and supplies down the hill to the boathouse.

What's amusing was that many boathouse owners on our lake built their decks relatively low to the water--2' above normal summer pool. A few years ago, a big storm came up, and washed all their jet skis/ personal water craft away--and beat them into the seawalls.
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Re: Building a new dock

#15 Post by GregF » Tue Jan 03, 2012 9:10 am

The covered lifts here are not really boat houses, They just put a frame and canvas type cover over the lift. Usually people take the cover off in front of a storm or the wind does it for them.
We have a few truss, plywood and shingle roofs over lifts but these are pretty old, before building codes.

Two of my neighbors just had covers put on their lifts and they paid around $4k for them. The cover on mine is about $30 worth of PVC pipe and a silver trucker tarp.
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