Flopper-Stoppers - Anti Roll Devices. Do They Really Work?

[Old Bumbulum]

I'm asking those who have tried them - do they work?
If so, which design and how rigged?

I'm sure thread creep may turn this into a theoretical dicussion - but first can we please listen to those who have actually used these things?

 

[Motor_Sailor]

Yes we fitted them to our new build trawler yachts. Pretty much set up as detailed in the Beebe and Leishman cruising under power books.

Their use and short comings were pretty much as in the literature. They work very well, but are big, highly loaded things that require a lot of work to rig, set and recover. So good for long trips, pretty much useless for anything less.

 

[Graham376]

I have two sets (port and stbd) of the plastic ones which were only a help in non tidal waters. Although weighted, with any tide running they were swept astern and hardly worked. Still in store room somewhere as I gave up using them.

 

[PlankWalker]

Yes they work, plywood triangle with lines to each corner and weight to one corner.
but personally I would sooner anchor somewhere else.

 

[Star-Lord]

I found mine impossible to stow because it was so big so I left it lying around a yard somewhere.

 

[James_Calvert]

In Alderney once I filled an old plastic box with stones and slung it from the spinnaker pole so it would just lift out of the sea with the upward roll.

Worked brilliantly. But a faff to set up.

I think doing something similar with a tender might work, if its fixings were strong enough. Without the outboard on...

 

[Salty John]

I experimented with various systems using the dinghy and buckets but none were very effective and all a faff to set up. (I'm assuming you're talking about devices at anchor, not under way). In situations where the wind and swell were from different directions and the boat lay to the wind, taking the swell on the beam, the best system I found was taking a line from a sheet winch up to the anchor chain, then running out the chain to bring the lead point aft, so the bow turned towards the swell. This bridle system was very effective on a couple of occasions in the Bahamas where the combination of low lying land and fringing reefs means you get the swell entering the anchorage from a different direction to the wind.

 

[RupertW]

In Alderney once I filled an old plastic box with stones and slung it from the spinnaker pole so it would just lift out of the sea with the upward roll.

Worked brilliantly. But a faff to set up.

I think doing something similar with a tender might work, if its fixings were strong enough. Without the outboard on...

Oh that’s an interesting idea - we have the tender in the water and it has a hoisting strap permanently fitted so easy to try with main boom first. As long as it’s not lifted and slapped down again and again

 

[RupertW]

I experimented with various systems using the dinghy and buckets but none were very effective and all a faff to set up. (I'm assuming you're talking about devices at anchor, not under way). In situations where the wind and swell were from different directions and the boat lay to the wind, taking the swell on the beam, the best system I found was taking a line from a sheet winch up to the anchor chain, then running out the chain to bring the lead point aft, so the bow turned towards the swell. This bridle system was very effective on a couple of occasions in the Bahamas where the combination of low lying land and fringing reefs means you get the swell entering the anchorage from a different direction to the wind.

I’ve used that a few times - and tend to have the anchor angle offset anyway by the bridle as that cuts down on yawing about.

 

[Poey50]

I'm asking those who have tried them - do they work?
If so, which design and how rigged?

I'm sure thread creep may turn this into a theoretical dicussion - but first can we please listen to those who have actually used these things?

I made one for our 32 footer. It is the largest equilateral triangle I could make from a 1 metre square piece of 6mm aluminium sheet. One corner has a dive weight attached. The corners are rounded and the edges covered with a plastic moulded edging strip to protect the GRP. I deploy it from the end of the fully extended spinnaker pole. It always helps in damping the roll; not eliminating it but preventing that kind of progressive rolling that spills stuff from lockers. The last time we used it I was less happy with it but then found that one of the three rope legs had got snagged and it was not deployed horizontally in the water. All in all, a very useful bit of kit.

 

[Tim Good]

Made one from a large piece of triangular plywood with a diving weight at the end. Worked well but when I have chance I’ll get a thick piece of GRP and make a better one.

As said, it doesn’t eliminate the rolling but makes it tolerable by preventing it getting to a point where things are flying around.

 

[Elessar]

Yes we fitted them to our new build trawler yachts. Pretty much set up as detailed in the Beebe and Leishman cruising under power books.

Their use and short comings were pretty much as in the literature. They work very well, but are big, highly loaded things that require a lot of work to rig, set and recover. So good for long trips, pretty much useless for anything less.

Having used one on a large trawler yacht I’d completely agree with every word you said.
The effectiveness I found to be almost unbelievably good.
It had a long boom and a very heavy stainless paddle, hinged in the middle to allow it to sink quickly, 2 key factors I think.

 

[RichardS]

The best flopper-stopper is a second hull.

There are disadvantages though.

Richard

 

[vyv_cox]

Having used one on a large trawler yacht I’d completely agree with every word you said.
The effectiveness I found to be almost unbelievably good.
It had a long boom and a very heavy stainless paddle, hinged in the middle to allow it to sink quickly, 2 key factors I think.

I think this is the key factor. The angle of roll is inevitably dependent upon the amplitude of the flopper stopper. So a very large triangle may be largely ineffective until all of it is being raised. Hinging it halves the amplitude and clearly is beneficial. The ultimate solution is a device somewhat like a Venetian blind, with each strip hinged along its long edge. A USA company makes one like this, link here FlopStopper.com Unfortunately they do not show it in action but a man I know who has one reports that it works very well.

 

[Iliade]

Nah, bilge keels and a good tidal range are the best flopper stoppers :0)

I have tried a range of bucket on a string variety of stoppers and they were never big enough to make a real difference.

 

[Mikedefieslife]

I've used a drouge as one on my Snowgoose. It kind of works in slowing the action down, but really my boom is too short, and I don't think a fully extended spinnaker pole would be strong enough.

 

[Elessar]

I've used a drouge as one on my Snowgoose. It kind of works in slowing the action down, but really my boom is too short, and I don't think a fully extended spinnaker pole would be strong enough.

The load on the spinnaker pole is compression only. The vertical load is taken on a halyard. Fore and aft loads are taken on 2 additional lines probably taken to cleats.
If it’s strong enough to be a spinnaker pole it’s strong enough to be a flopper stopper pole.

 

[Muddy32]

The best flopper-stopper is a second hull.

There are disadvantages though.

Richard

+1 or should it be 2 or 3?

Mind you I still use a bridle to face the swell/waves and stop yawing around.

 

[geem]

We dont need a flopper stopper as we roll less than just about any monohull we see BUT, there are times, very occationally when we get a small wave spaced a long way apart that hits our natural frequency perfectly and we start a long slow roll. This is when we hoist our mizzen sail. Its fully battened and lose footed so we can set it bar tight. It doesn't flap and it does stop the roll incredibly well. It makes the difference between a carp nights sleep and bliss

 

[PhilipH]

We have a large triangular piece of epoxyied marine ply weighted with 10mm chain on all three edges but one edge doubled chain to create an imbalance. It is quite heavy and sinks quickly and the weight helps on the upward roll. It hangs from the end of the spinnaker pole via a block. Does it "work"? Depends what you mean. It does not stop rolling but it does reduce it. We have a very large anchor locker which is its home when not in use.