Storage shed on pontoon frame

[clowry453]

I just set our 14' by 10' storage shed on a 8' by 24' pontoon boat deck. It is centered on the pontoon frame. I have had our shed get flooded and tip over 1/2 a dozen times. I live on the Susquehanna River and it floods like all rivers. To keep the shed and pontoon frame from floating away when it floods I put two concrete ballasts (2 tons each) flush in the ground about 30' upriver from the pontoon frame. I have a 5/16" grade 7 chain connected to the concrete ballast and I will connect the other end to the pontoon frame. Here is the question: I am unsure where I should hook the chain to the underside of the pontoon frame. If I put it too far forward I am afraid the front of the pontoon frame will submerge when the water gets too high. I could put it in the middle of the pontoon frame but I'm afraid the pontoons won't track with the flow of the water and it will go sideways and tip over. I need to have the 30' of chain because the river can rise 20' here when we get a flood. Any advice would be helpful.

[GregH]

Interesting solution but marine craft all has a weight capacity rating.
Have you checked to see how your shed weight compares to the pontoon capacity?

Also, weight distribution is a component of weight carrying ability and a shed center of gravity being much higher than people standing on a deck could make it prone to tipping.

Have you allowed for this?

For it to be as stable as possible two chains at the front of the craft with the anchor points spread wider than the front of the pontoons would be most stable.

[Tolyn Ironhand]

(Not an expert) The chain mounting point will not be as critical as how the pontoon is loaded. I would attach the chain to the front of the pontoon where it is designed to have a winch attached when putting it on a trailer (not a scissors trailer). Then, you should put the shed slightly to the rear of the pontoon. This will keep the front of the pontoons up on top of the water and tracking correctly.

Good luck! I am interested to see if this works. Any chance of posting a picture?

[clowry453]

I have the shed placed slightly back from center on the pontoon frame. I can add some weight to the back end of the shed to have the stern sit slightly lower. placing the chains apart would have been a good idea. I guess I should have posted this prior to placing the concrete ballast as it now cannot be moved; therefore there is only one attachment point. The weight should be fine as I did the calculations of the pontoon cylinder displacement and the shed + pontoon frame weight plus contents of the shed. If high water is anticipated I plan on moving any heavy objects, i.e. tables and other non sliding items to the floor of the shed in the center to help reduce any elevated weight. If there is an easy way to transfer pics from my iphoto to the forum let me know and I'll get some pictures up.

[GregH]

You will need to upload your images to a free host like Photo Bucket and either provide a link or use the buttons above the reply box to have them appear in a post.