Using a builders bag as a sea anchor or drogue - how?

[peter2407]

I have a couple of builders bags that were used to deliver 1 ton of gravel in each. How would I use them as a sea anchor or drogue?

 

[robertj]

ive tried this but found it useless. I suppose if i removed the sand first would have helped!!

 

[srp]

Roger Taylor has used one in anger and describes it in his book.

 

[omega2]

rig it on a four way bridal, to keep it open, cut a hole in the centre/ bottom end, attach a recovery rope at that end as well or you will never be able to pull it back. Very good for holding you in the tide when the wind is over it.

 

[Simondjuk]

I've tried this and it works very well. I used one to stabilise a boat with broken steering gear whilst under tow. It could even be used to steer to some degree by rigging the bridle such that the bag could be hauled to either side. Based on that experience, I suspect they would also perform reasonably well as a sea anchor or drogue, or for that matter to provide some directional control to a vessel with steering failure making way alone.

 

[sarabande]

the bags are made to a budget, and the material is very susceptible to UV radiation. Keep in a very dark place.

You definitely need the hole in the base to help the bag stabilise when in use, otherwise it will spin round and round and...

 

[oldbilbo]

I have a couple of builders bags that were used to deliver 1 ton of gravel in each. How would I use them as a sea anchor or drogue?

A couple of thots....

The polypropylene they are typically constructed from deteriorates rather swiftly under UV irradiation - not that we've had much of that this year - but you should be aware of how long they've been out in the sunshine in the builders-merchant yard, then yours. That's one of the reasons they are now non-returnable. The tougher ones, 'Hippos', cost rather a lot of beer tokens but may make better bets.

Most of these bags now have 6" umbilical tubes at the bottom. Untying the cord to open these would help to a small degree with the severe instability of such shapes. ( think early parachutes ). The bigger problem is the bag collapsing in a tumbling crest, and there are enough of those about in frisky weather. You need to arrange that the bag is held open, and one way is to have a length of plastic water pipe ( or similar ) about 38mm diameter, which is long enough to be fed through the four lifting handles/loops right around. Have a rope through this pipe. Tie the ends together to make a stiff ring ( stop sniggering there at the back! ), tie a double bridle to the four loops/lifting handles, tie on a 300' or longer rode ( 150' if only in the Channel 'cos the water ain't deeper than that, most places ), add on a weight such as your No2 anchor to keep the whole kit 'n caboodle down where it should be, and throw the whole lot off to leeward. ( If you're able to throw it to windward, you're not giving it a real try-out )....

....Oh, don't forget to tie the end to your boat! Oops, too late.....

 

[MASH]

a four way bridal

Sounds fascinating. Is it some sort of sex-game?

 

[Simondjuk]

Just for interest, I tried one with and one without a hole. The one with gave a little less drag but still worked and spun a couple of turns. The one without had more drag, but was a little more prone to spinning, although to my surprise not badly at all. About six turns in the same distance as the other, about 5 miles at about 6 knots.

 

[HunterWanderer]

Put two lines through the handles of one bag and secure a large loop in each with a bowline. Secure the lines , one to each stern cleat. The drag is enormous so doubt if you need to deploy 2. To recover the bag just put engine in reverse and take in the lines. Use a boathook to lift the bottom of the bag into the boat and tip the water out.