DIY Danbuoy

pcatterall

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My orginal (made 7 years ago) now sinks!!

I made 2 danbuoys 7 years ago using pvc pipe wieghted at one end a water bottle filled with foam gap sealer and a flag on top.

It has been tested every year but recently has started to slowly sink which I guess is not to good!

I believe that the gap sealer has become porous.

We were just going to replace with a smart new one but noted the price at £160 plus.

As the DIY jobby worked so well ( for at least 5 years) I thought I might have another go at making one.

The MK version would be basically the same but I will value suggestions as to a more durable foam/polystyrene filler.

I guess there will be the usual howls " penny pinching on safety critical equipment" etc but I think that the one I made was quite safe!
 

doug748

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Penny pinch away, I'm with you.
I think there was a fairly recent thread on this very subject.
However, I made one ages ago using a bit cut off one of those spaghetti/noodle things kids use in swimming pools.
 

rogerthebodger

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I made floats for my motor boat from 110 mm PVC pipe with end caps glued on each end.

A Dan Buoy float could be made in the same way. It a 20 mm conduit box joiner was glued top and bottom 20mm conduit could also be used for the flag and weight mount. To make the 20mm conduit more rigid I fit 15mm aluminum tube inside which stops it bending.

All items obtained cheep from your local B & Q.

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I have also used to same PVC pipe fittings to make screw lid water proof containers for flares and first aid kits.
 

Hydrozoan

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I cannot remember exactly what happened to them (UV degradation?), but when the end caps on a danbuoy failed I used a pair of this type of pipe fitting to replace them. https://www.screwfix.com/p/floplast...V7rXtCh3wkgAoEAQYBSABEgKU7PD_BwE&gclsrc=aw.ds

The rubber ‘bellows’ for the small pipe (minimum 32mm, maximum 50mm) are offset from the centre of the 110mm section, but the hole through the foam block was large enough for the pole (a glass fibre tube) to pass through them without much distortion, and if one was making the foam from scratch it could be could be designed accordingly anyway. The foam also had to be slightly modified to allow the large ribbed section to be worked down into the ends of the 110mm pipe. I carried out only a relatively short float test, but reasoned that a seal which works for waste pipes should be satisfactory in this application (and I have not found rain getting in to the body).
 

fisherman

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There are plenty of dedicated plastic floats with a hole through for doing this. however, in theory you should be able to use a pipe, closed both ends, with a suitable weight to render it upright, then attach a thin mast with flag. Stability is important, you don’t want it laying flat just when you are trying to find it. White plastic pipe may go brittle.
https://www.gaelforcemarine.co.uk/en/Buoys-and-Floats/c-43.aspx
 

pcatterall

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Thanks all. ( and no comments about penny pinching)
Thanks ( on the competing thread!) for the links to the floats and buoys with holes. I just need to check the proposed pole outer diameter and the weight/stability factor.
I will try to use similar PVC pipe to my original one ( it did not go brittle after 3 years in med) The original weight was via a bit of rebar with a tight fit into the pipe and a 'bonded' end cap.
Incidentally the 'light' we used was a manual little led bike light ( the sort that wrap around handlebars/danbuoy poles) after 2 years on deck in the med it still worked. Of course the switch has to be pressed before you chuck it in but better than no light at all.
 

rotrax

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If you can find a copy of "Do It Yourself Yacht Improvements" by Reg Minal, all will be clear.

On page 8, Reg shows a clear diagram/drawing of his excellent Danbuoy.

Required bits are as follows:-

1x2 metre length 15mm plastic pipe or conduit.
1 large plastic cola or lemonade bottle
1x empty baked bean tin or similar
2x38mm galv. clout nails
Small quantity of ready mix cement
Enough fibreglass mat/tape/resin/hardener to cover and seal plastic bottle and bean can
Reflective tape
Material for flag and lanyard
Paint-your choice of colour

The plastic bottle is bored 15 mm to take the pipe. 450MM from the end of the pipe is the place for the base of the bottle.

The nails are pushed through-after drilling-the bottom of the pipe -at 90 degrees to each other. These will be inserted into the bean can -which is filled with concrete as a weight -in place.

When the bottle and weight are fixed in position and the concrete is set, cover the bottle and weight with the fibreglass mat/tape and resin, overlapping by at least 1 inch at the top of the bottle.

Make the flag and attatch, use an eye bolt to affix to a lifebuoy and cap off the open pipe end. Paint.

Simples.

Reg was a member of our Winter Talks Club. He was also a member of the South West Shingles Yact Club, which, as some here might be aware, is invitation only.

Enough said.............................
 
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pcatterall

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Sorry about the competing thread. I should have done a search first.

Since the weighted pole would appear to be off a Dan Buoy I may well push the boat out (So to speak)and use this:

https://www.gaelforcemarine.co.uk/en/Polyform-Yellow-Purse-Float-C1/m-2716.aspx

Between 2 threads we seem to have accumulated plenty of tips. I note that the purse float above is for a 35mm pole. My 'pole of choice' is still the white waste water pipe I used before, rigid enough for the purpose and has survived UV exposure for 4 Mediterranean summers. This has an OD of 22mm which I hope will accept the other pole buoys with the stated 21mm hole(soapy water?)
I need to calculate buoyancy against the weight I can get in the pipe and of course length above or below water of the pole. I used black ribbed re-bar in my last version.
 

fisherman

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Those purse floats, unless they have changed, are foam, coated with hard plastic and they eventually split and degrade in sunlight. Also much bigger than you need. You want a hollow hard plastic float, say 75mm-100mm.
 
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