How to build a float

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Rachel
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How to build a float

Post by Rachel »

I'm looking for some kind of guidelines or instructions for building a float. I figured there would be something on the Internet, but it's hard to get around the nine-million sites that explain how to build a parade float! Floats aren't usually used where I'm from (except for rowing clubs, but those are huge floats), so I'm not that familiar with them -- perhaps there's another name for them that I don't know.

The reason I'd like one is so that I can keep my dinghy in the water and get to it more easily than I currently can. The tides here aren't huge, but the dock I have to use isn't a floating dock, so it can be awkward to get in and out of the dinghy (there's an aluminum ladder, but...).

I've seen work floats that are about 8' x 8' and I think it would be nice to have one of those tied to the dock, and then my dinghy tied to that. Then I could jump down onto the float before boarding the dinghy, there'd be an intermediate spot for getting the dinghy rigged, stuff in and out, etc.

I had been thinking of something 4' x 8' for the usual plywood reason, but a co-worker pointed out that if they're too narrow they're not stable enough. The work float I've seen is 8' x 8', by the way. I'm not intending to have a ramp leading down to the float; I'm picturing something with cleats at the four corners, then using two of them to tie the float to the dock, and the other two to tie the boat to the float. The location is very sheltered (minimal waves and at-most moderate wind).

So, are there particular tricks for constructing these floats? Know of any web resource that I couldn't find?

What do people use for bouyancy? (I have a source of plastic 55 gallon-type barrels, but those might be too high?) Any other tips? I'm looking for something that will be minimum investment for now (and not expecting it to last forever either).

Thank you,

Rachel
David

Post by David »

You can find bulk styrofoam at this site

http://www.marinefoam.com/styrofoam.html

and instructions for building a floating dock that probably apply to what you want to do, here:

http://www.canadianfishing.com/dock/index.htm

One cubic foot of styrofoam has about 55 pounds of bouyancy.

Good luck,

David
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Post by MikeD »

Rachel, I'm not sure what they're called, but I've seen this setup around here a few times. Basically, it's a loop of line running around a stake on the beach(so it doesn't get washed out) out to an anchor point below the low tide mark. The dinghy is attached to a loop on the line and can be pulled out into the water or back to the beach depending on which side you're pulling on. Could be a lot cheaper and easier to set up than a float...
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Rachel
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Post by Rachel »

The trouble is I've got mud. A medium amount of mud at high tide, and a whole lotta mud at low. So I'd rather go from the dock and keep the mud out of the dinghy. I've also got overhanging trees on shore so it's hard to rig the dinghy for sailing there.

The way I'm distinguishing a float from a dock is that the float's top is only about 6" or so out of the water (vs. a dock that sits up higher).

I'm sure I could figure out something, but I figured if someone had already done the figuring, I'd try to use that knowledge.

R.
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Post by sal's dad »

Hi Rachel -

I have been doing docks this weekend, so it is on my mind (I found free used docks from a local yacht club, on Craigslist - need som refurbishing, but a quick and easy solution!)

There is an OK book on the subject, I thought it was called "The dock book", but nothing turns up in google, so my memory must be failing.

The easiest way to build your dock, assuming you don't need to drag it around a lot in the off-season:

Build a simple frame of 2x4s or 2x6's. Treated lumber and long stainless deck screws are well worth the money. So you need, say, 4 2x6's for the rim, and 5 or 6 2x4's for the joists. Bolt in heavy metal angles or a big post at the corners to hold it together, there is a lot of stress there. No need for joist hangers or other fancy stuff to hold the rest of it together, screws will be plenty, if you do the corners right.

Build the frame upside down (or flip it over now) and put in your flotation. The big pink or orange foam dock billets work best, but almost any big slabs of foam will do. (Yes, your barrels are probably too big, and will complicate the framing. ) If you put the foam across the joists, it will float the dock higher. Getting it between the joists will lower the dock, and make things more secure; of course that means measuring before you build the frame. The best way to secure the foam is with a massive frame, but you can also hold it in place with a couple 2x4's along the bottom, bolted, wired or tied through the foam to the framing above.

How much foam? As noted, a cubic foot will float 55 pounds or so, so figure 6 cubic feet for the dock (which will be submerged all the time) and a bunch more in reserve, above the "waterline". Get the flotation as far out to the corners as you can.

For decking plywood is a bad idea - it will be a mess in no time. Use 5/4x6 treated decking. You'll need 16 or so.

Instead of cleats, I like wood posts at the corners, extending from the lowest part of the framing (or the mud!) up through the deck about 3' Round them off a bit, and equip your boats with permanent dock lines with spliced eyes. That way guests, kids, drunks can all secure the boat with no knowledge of knots.

Old carpet scraps or garden hose works fine for edging.

Lumber and fasteners, about $200. Foam is expensive, maybe $150 or so (google "flotation billet"). Have fun!
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Post by Steve'O »

If you use Styrofoam be sure to encapsulate it. Nothing is worse than seeing those little white balls fouling up the shoreline
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Post by Rachel »

I'm with you there, Steve. I wouldn't use any foam that would do that (hate that stuff floating around).

Sal's Dad: Thanks for the tips. At this point, unless I hear input to the contrary, I'm thinking that it has to be at least 8' x 8' for stability (although I don't need it that big for my use). I took at look at the yard float I mentioned that's painted plywood, and upon closer inspection I see they fiberglassed over the top of the ply before painting, so perhaps that explains the longevity.

I won't be starting on this immediately, so if anyone has further tips please post them.

Rachel
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Post by sal's dad »

You can go smaller, but with some loss of stability, and no great savings on material or labor (except for hauling it in and out!). You might consider 6x8 or 6x10, I have floats about 5'x16' that do fine. Just keep the flotation at the extreme corners. For stability, the heavier the better - if you do go with your plastic drums, filling them halfway with water will lower your deck, and increase stability quite a lot.

I found the book - The Dock Manual by Max Burns - not real sophisticated, or useful in rough ocean/tidal situations, but a good reference.
http://www.amazon.com/Dock-Manual-Desig ... 1580170986
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Rachel
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Post by Rachel »

Thanks for the additional info.

Filling the drums partway sounds like a great idea - I can procure those easily, too, so I can experiment without spending an arm and a leg. I don't know how long I'll have this dock situation, so I'm trying to keep it cheap and easy.

Rachel
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Post by sal's dad »

I would try to get the spacing between the joists just right to cradle the drums, then lash them in place. Almost all the pressure is upward, forcing the assembly together. The only problem may be in the whole weight of the dock resting on the drums at low tide...

If there are 2 openings in each drum, put one at the top, one at the bottom. Open the bottom one, and let in water by venting the top slowly. When all 4 are just right, close up the bottom bungs.
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pvc dock

Post by petemarkey »

I built a swim platform using 8' lengths of 4" diameter pvc pipe, with caps on the end obviously, covered them with 1X6 Pressure Treated decking. with 1X1's running opposite the 1X6's holding the deck together and keeping the pvc in line. used galvanized hvac strapping as well to keep the pvc in place.

Works awesome, use it form swimming and can run the sea doo up on to it to keep it dry.
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Rachel
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Post by Rachel »

That sounds interesting, and "one or two trips to Home Despot" doable. Thanks for the specifics.

I put my potential float project on the back burner, and have been dragging my dinghy up into the mud instead. Definitely not as nice!

R.
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Re: How to build a float

Post by Chesapeake Bob »

Rachel,

Not sure if you ever built your float, but a freind of mine used plastic barrels for floatation. I think they were pickle barrels.
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