Buoys

[Raydee]

I am making up some buoys for my local lake and wondering if I should add some lead ballast weight to the bottom section of my pvc pipe? I am not sure if it will need it or not. The bottom pipe will have a cap with a eye hook and the line will be attached to a 3lb brick. The counter weight wil be a 1lb pvc pipe. Its a small man made lake so there is not a lot of current. The buoys will be in the lake all year round.emycnoodlebuoys.jpgBuoys.jpg

[Panther6834]

I think adding additional weight to the bottom of the PVC tube is probably needed. The rope & counterweight idea is fantastic for automatically adjusting as the water level of the pond roses/sinks...but, it would probably also slow to buoy to lean, as the top of the buoy would be heavier than the bottom.

In order to keep the buoy as perfectly upright as possible, the bottom of it NEEDS to weight more than the top. Since the bottom of the PVC pipes will be capped off, I'd suggest adding something with 'weight' (shotput, sand, metal BBs, etc) inside the pipes, and capping off the top end of the pipes (which I see you've already done). The foam you're using is lightweight...but, the added weight inside the PVC pipes should weigh approx 2-3x as much as the yellow/orange foam pieces.

While the added weight inside the PVC tubes needs to be as heavy as possible (to keep the buoys perfectly upright), the total weight still needs to be less than the weight of the displaced water. Believe it, or not (and, if you don't, look it up), there used to be ships made with concrete hulls. That's how they were able to float - they still weighed less than the water they displaced. ANYTHING can float...as long as it weighs less than the displaced water...but, unless the bottom weighs more then the top, it'll either "lay on it's side", or it'll flip upside-down.


~ More peace, love, and kindness would make the world a much better place

[Raydee]

Makes perfect sense. I guess I will have to head to the pond and experiment and see how much weight I will need to keep the buoy upright. I am thinking I can also add something like a larger round disc to the bottom of the buoy to give it a little more surface area to float on.

[Panther6834]

I am thinking I can also add something like a larger round disc to the bottom of the buoy to give it a little more surface area to float on.

All that would do is add additional weight higher up, making it even more top-heavy, which, in return, would require even more weight needing to be added at the bottom of the PVC pipes. Adding weight "at" the waterline won't make any difference. The point is, additional weight needs to be added 'below' the waterline. Furthermore, the further below the waterline said weight is added, the lower the CoG, and the more upright the buoys will be.


~ More peace, love, and kindness would make the world a much better place

[NativePaul]

I would say no, but you also need bigger weights.

We used the same system at our roving multi lake lake club, the big weights were 6" plastic pipe 12" long filled with concrete (no real idea of what they weighed maybe 30lb), and the small weights were 3" pipe about 6" long filled with concrete (maybe 5lb).
These weights were enough to keep our bouys upright, but a good bouy strike would often move the buoys far enough to need moving back before the next heat which was a PITA, but when dropping and lifting them from the rescue boat on race day for a new venue it was about as much as most people can manage to lift over the side.

FYI we also ran a PVC pipe through the centre of our bouys, but switched to a copper pipe for durability, if you use PVC make sure you either have spare bouys and a way to get the line up off the bottom, or spare complete buoy systems.

My current club has a small purpose built lake, and we do it a bit differently. The bouys are essentially the same, but the rope goes down to a pulley bolted through a 41kg (near 100lb) paving slab and gets tied off to a stake at the lake edge, which allows us to easlily and quickly raise and lower bouys as needed for scale, sail and power boat events that use different courses. Our lake was dug 1m deep so while it is be impossible to lift a paving slab from our rescue boat, anual maintenance can be done with waders. We have marks on the perimeter fence that align with where the bouys should be for ease of yearly maintenance. With this system I have never seen a buoy strike powerfull enough to visibly move a bouy far enough to need attending to during a race event, but during anual maintenance we often see that they are not aligned perfectly with the marks anymore.

[Peter A]

What we have used for the last ten years are the large yellow net floats ( used on fishing trawlers) with an aluminium 25 x25 square tube through them and a D shackle on the bottom which the rope runs through. Our bottom weights are old car rims and the counter weight is around 1/2 kg. These bouys can survive a full noise strike by large gas boats. In fact we used these to discourage hitting bouys and so boats would be driven around them, previous bouys were regularly wrecked and a lot of time and expense was had replacing them. Boats have been broken on these.
This year we cut the bouys in half to reduce their height above the water and this has worked better to allow boats to ride over them instead of imbed into them. They are bright yellow and once or twice a year we have to scrub them and paint them. For paint we get aerosol cans of yellow road marking paint from a local road marking company.
Regardless the bouys are there to go around not through!

[Raydee]

Thanks for the info guys