What's up dock?

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What's up dock?

Postby hectoretc » Tue Dec 13, 2011 9:39 am

Season's Greetings all,
I need to expand my dock area next spring so my DSII has a place to sleep, and so planning in that direction, I bought a dozen 55 gal plastic drums a few weeks ago. I need some guidance/suggestions from anyone who's built a floating dock (using drums) previously, or knows the hydro-mechanics of floatation vs. weight and stability kinds of things. Where better to get that info from a sailboat forum. I realize this question isn't directly about DaySailers, but I guess it falls in the same category as trailers. What to do with the DS when it's not sailing.

First question - Does anyone know now much weight (generally) an empty 55 gal drum will support?
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Postby ctenidae » Tue Dec 13, 2011 11:50 am

8*55= 440, so I'd say, not accounting for the weight of the drum itself, you get 440 pounds of floatation per drum, give or take.

As for stability- just remember, they roll. That's about all I know.

Oh, double check your drum size- a standard barrel is 42 gallons. a "55 gallon drum" isn't always a 55 gallon drum.
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Postby hectoretc » Tue Dec 13, 2011 12:18 pm

Thanks!
Assuming I'm staring at a "big" plastic drum, now do I estimate the volume? Dimensions? I'm hoping there isn't a 1 gallon bucket and a lot of water involved in this solution... :-)
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Postby ChrisB » Tue Dec 13, 2011 1:03 pm

Assuming the "big plastic drum" is cylindrical, the volume = pi x square of radius x height. Once you have the volume in cubic inches, you can convert to gallons by multiplying cubic inches by 0.00432900433.
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Postby ctenidae » Tue Dec 13, 2011 2:14 pm

ChrisB wrote:Assuming the "big plastic drum" is cylindrical, the volume = pi x square of radius x height. Once you have the volume in cubic inches, you can convert to gallons by multiplying cubic inches by 0.00432900433.


Pi R Square.
No they're not- Pi R Round. Brownie R Square.

The volume is probably embossed ont eh drum somewhere- just double check it to be sure of the size. 55 gallons is a standard size for many things, but just because it looks like a 55 gallon drum doesn't mean it is. That's all.
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Postby GreenLake » Tue Dec 13, 2011 7:12 pm

I've seen discussion of dock designs - try a search.

Here's one I found: http://www.instructables.com/id/Floating-Dock-with-Barrels/

What I like is that he uses a rather wide platform to provide as much stability as possible for the dock part.

Later, when he builds the ramp, I would seriously question the way he uses the barrel length-wise. In fact, it would probably have been more stable to give the ramp some "flare" where it meets the dock (giving it a wider base) and to use a hinge. The hinge would have to allow more than usual play to handle waves, but not so much as to allow the ramp to twist around its long axis.

There are probably other designs as well worth comparing.
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Postby hectoretc » Tue Dec 13, 2011 7:53 pm

Thanks ctenidae and Chris B for the math.

Thanks GL for the link. I like that idea, simple design. I was aiming toward a 4 x 8 foot wide sections with a barrel at each end, but rotated the other way from his ramp, but I can see how that would be unstable as well... High center of gravity with a small footprint. An 8 foot wide dock is big (wide), but might have to be the way to go. If I did two 8 x 16's (32 total length) it would be like a pier.
I'll have to give that some thought, it would not do to dump grandma in the lake. Especially our lake... (yech.. bottom... yech...)

I'm headed up tomorrow afternoon for a couple hours (only 45 min away) so I'll look for stamps or labels on the barrels and bring my tape measure.

Thanks, Scott
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Postby Bob Hunkins » Tue Dec 13, 2011 8:03 pm

Wow, a dozen drums?! That 's a lot of flotation for a ~600 lb boat. even if you want to stand on the dock with a crew. Guess you don't have to use them all. :)
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Docks

Postby kokko » Tue Dec 13, 2011 8:10 pm

They use barrels for mt dock on white bear lake. You may give the boatworks a call.
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Postby hectoretc » Tue Dec 13, 2011 8:46 pm

Bob Hunkins wrote:Wow, a dozen drums?! That 's a lot of flotation for a ~600 lb boat. even if you want to stand on the dock with a crew. Guess you don't have to use them all. :)


Hi Bob,
Yeah... I wasn't sure what I was going to have to do, and they were really inexpensive. The way everyone is converting them to rain barrels I figured I could sell 3-4 and recoup my investment.

But today I was reading about float docks online, and found a link to floation boat lifts (look out... another potential project).
People are taking these barrels and basically building a floating dock (that they sink) with boat rails like a trailer, and then blow air into the barrels to lift some pretty big boats out of the water. Should be a breeze for a 600 lb sailboat. Maybe I'll build one into the dock.. maybe not... we'll see.
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Postby GreenLake » Tue Dec 13, 2011 9:09 pm

There's a guy near here who does this with his motor boat. Has a sun cover and the floats are stainless or aluminum. Every spring he launches it from the ramp and drives it to his mooring with a small outboard.

If your lake has lots of powerboats, not tying your DS to a dock might be gentler. I know a lake here where the wakes are so bad I have to use a cats cradle of lines between some pilings to prevent the DS from being driven underneath the dock (not my own, alas).

I would make sure to make the side of your dock wide enough that the stern of the DS can't be pushed underneath - the stern is pretty low in the water.
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Postby hectoretc » Tue Dec 13, 2011 9:44 pm

GreenLake wrote:I would make sure to make the side of your dock wide enough that the stern of the DS can't be pushed underneath - the stern is pretty low in the water.


That is a very good point. The one thing I've noticed about the Drum based float docks is that they seem to ride pretty high. When (if) I get there I'm already wondering if I'll need to either allow some water into the barrels to bring it down (maybe a fitting with an air hose so they are adjustable) or a center low bumper of some kind. Something to keep in mind.... great point.. Thanks
DS #6127 - Breakin' Wind - From the land of 10,000 lakes, which spend 80% of the year frozen it seems...
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Re: Docks

Postby hectoretc » Tue Dec 13, 2011 10:09 pm

kokko wrote:They use barrels for mt dock on white bear lake. You may give the boatworks a call.


Hi Kent,
How wide are they (floating docks), if you can estimate? I'm assuming they pull them out of the water for winter, are they (Boatworks) open year round? I would imagine they just stack them on the ground. WBL isn't too far, maybe I'll pop over and take a look. Just off 61 at Cty Rd F? sound about right?

Say, White Bear Lake just registered with me... you guys had some seriously low water this year didn't you?

Thanks,
DS #6127 - Breakin' Wind - From the land of 10,000 lakes, which spend 80% of the year frozen it seems...
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Postby K.C. Walker » Wed Dec 14, 2011 12:59 am

Check out http://www.rollingbarge.com/ there is definitely lots of info there.
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Postby hectoretc » Wed Dec 14, 2011 9:35 am

Thanks K.C.
Great ideas for docks, and plans too!
Wow... love the party barge. Probably have to save that for next winter's project. :)

Thanks again! -Scott
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