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Iolaire
03-24-2007, 08:10 AM
I would like input about construction of a small (2 boat) dinghy dock. This would be "attached to shore" which is actually a beach and the depth is less than 5', tide rise about 2', and very slight windage. Preference would be a "floating" system, and easily removable for transport in the winter. Alternatively, some sort of "fixed" structure is possible.
In both options there are commercial systems but they are pricey. Is there "homebuilt" experience available here on the forum.

Tylerdurden
03-24-2007, 09:22 AM
I am a big fan of cheap and practical, 30 and 55 gal plastic drums can be had cheap or if you are really a scrounger check out the large hotels in your area. Most use 30 gallon drums for laundry chemicals and cannot give them away. Hospitals too.
Whenever I needed them for a project I would make the tour and in a short while I would have more than I needed.
Look around for scrap two or three inch pipe, galvy is good, Black iron oh well. Some chain or pipe hangers for the slides will do the trick for attachment . Good luck!

S.V. Airlie
03-24-2007, 09:29 AM
Tyler.. I pm'd him pretty much the same..
One thing that I found helped.. use a little bottom paint on the barrels... keeps them looking better.. no growth. OR.. less growth.

rbgarr
03-24-2007, 11:58 AM
I would like input about construction of a small (2 boat) dinghy dock. This would be "attached to shore" which is actually a beach and the depth is less than 5', tide rise about 2', and very slight windage. Preference would be a "floating" system, and easily removable for transport in the winter. Alternatively, some sort of "fixed" structure is possible.
In both options there are commercial systems but they are pricey. Is there "homebuilt" experience available here on the forum.

Is it a sand or shingle beach? Can you water jet piles in or set pipe stanchions onto it? How far out into the water would have to extend?

Tylerdurden
03-24-2007, 01:23 PM
Tyler.. I pm'd him pretty much the same..
One thing that I found helped.. use a little bottom paint on the barrels... keeps them looking better.. no growth. OR.. less growth.

The bottom paint is a great idea!

Martin Nelson
03-24-2007, 01:37 PM
The Hoofers sailing club at the University of Wisconsin had dinghy ramps for their tech dinghys. They didn't have to worry about the tide. The frame used something like 2"x10"x16' joists, and 4"x4" posts. The decks were panels made of 2x6 stock. All of them were removed in the late fall and installed in the spring. You might ask them about the design, they may have changed it in the last 40 years.

Ron Williamson
03-24-2007, 06:24 PM
Some of the portable docks around here use big steel spoked wheels from old farm machinery,on the deep water end.
Definitely aids the launch and retrieve if you can pull it instead of lift it.
R

katiedobe
03-25-2007, 09:10 AM
Hey Tyler and Airlie,
How do you attach the dock part to the old plastic drums? Strapping or do you build a small wooden cage around it? A simple drawing would be nice, pretty please?

S.V. Airlie
03-25-2007, 10:16 AM
Firstly, I'd just make a frame out of 2x4s that have skirts and fit over the barrels. Once in the water, the barrels will keep the frame in place and visa versa.. sorta like a cap.
Then, the top of the frame can be made of marine ply if ya want.. painted of course.
On each corner will be a "U" bolt.. sim to say a "U" bolt for a muffler.
This would be used to attach the 4x4s or pipes that are set into the soil,sand, mud.
Can also be used as attachments for anchors or what have you. The "U" bolt would allow for tidal fluctuations.
Then paint the bottom of the barrels with bottom paint. Again, I found that helps to keep flotsom, growth, from building up. As theorhetically, this thing should not be going anywhere.

I'd post a picture but I don't have one.. Sorry...I realize I am not being much help.

rbgarr
03-25-2007, 10:47 AM
Here is a good website for floats used by rowing teams. They float very low (by necessity) because the outriggers on a rowing shell have to overlap the dock in order for the rowers to get in and out of the boat and launch/retrieve the hulls.

The flotation used is layers of that blue insulating board available for foundation insulation.

http://www.truesport.com/row/dock/

Bruce Hooke
03-25-2007, 11:22 AM
I helped my father build a dinghy dock for his shore in Maine and it has now been in use for something like 15 years. The tide there can run up to 13 feet or so for spring tides. The area is well protected from seas, but does get some significant tidal current running past it. On the basis of our experience, here are a few notes:

1. Don't make the float too small. I'd guess that our float is about 8' x 10'. If two people get near one corner they can push it under. Also, if you go much smaller than 8' x 10' the float would, I think, simply start to feel unstable. I should say that our float could be as small as 6' x 10' ... I am going on memory here.

2. Our flotation is the pink bars of dock float foam that the local lumber yard sells. This is certainly more expensive than barrels but does come with a few advantages. Since the flotation goes right out to the corners the float, it is, I think, a bit more stable than a barrel supported dock would be. Also, the surface of the dock is, I think, lower to the water (maybe 6" if I remember correctly) than a barrel supported dock would be, which is better for getting in and out of small boats. On the other side of the coin, foam is more prone to damage. We have sacrificial strips of wood under the foam to protect it when it comes down on the bottom, which it does at most low tides.

3. The ramp to our float is a three part system. The first part is a fixed walkway about 16' long that goes out to a roughly 12' long box beam that goes between two bits of granite ledge. From there a roughly 14' long ramp goes down to a hinged connection to a small intermediate float and then from there a second roughly 14' long hinged-end ramp goes down to another hinged connection to the float (about at the center of the float). The box beam is attached to the ledge with two threaded studs that are set into the ledge. A pair of crossed ropes from the inside corners of the dinghy dock go to two eye bolts set into the ledge out beyond the box beam. Everything except the two threaded studs and the two eye bolts is brought ashore for the winter (ice is a serious issue in the winter). One advantage of this whole system is that everything below the high tide line is considered temporary (fudging a bit on the bolts set into the ledge), so nothing much was required in the way of a permit to build it. I think he has to pay a nominal fee to the town but that is minor compared with the process required to build a permanent dock!

4. To make the hinge points we typically used eye bolts and lengths of galvanized pipe with cotter pins in the end. This makes for a somewhat sloppy but very sturdy hinge. In some places the eye bolts are replaced with holes in the wood or with notches in the wood covered with steel bar stock.

5. There is galvanized pipe railing down one side of the hinged ramps but this is still not a system that would make someone who is unsteady on their feet happy. We only did a railing on one side because we needed to keep the other side open for carrying kayaks. The intermediate float in particular introduces some unsteadiness into the system. As I am sure you can tell, this is not a system that would likely please someone who likes everything look and work "just so," but it is a system to warm the heart of your average shade-tree engineer and tinkerer!

On a "soft" shoreline such as it sounds like you have, you will clearly need some other way to anchor stuff in place. I suppose you could look at burying anchors deep in the sand. How long a ramp do you need to get from dry shore to the intended location of the dinghy dock?

Keep in mind that beaches are dynamic systems so you either need a very solid system that can withstand shifting sand ($$$) or you need to plan for change and assume that you may occasionally have to reset your anchors. We used crossed lines to hold the float in place because we did not have that much spread between the eye bolts (maybe 20'). In your situation that might not be necessary.

You could obviously build a big fancy system, but if it were me I think I'd be thinking in terms of something more along the lines of what we built. Then again, with a sandy beach one might ask why you need a dinghy float at all, unless, of course, the sand gives way to mud at low tide, which would not surprise me at all...