Flopper stoppers

Hi all I'm thinking about fitting flopper stoppers on my boat has any one used them and what is your experience.

I have a heritage east Sundeck 40 has any one fitted them to one of these boats and if so would be great to hear where and how you fitted them.

When you use the term flopper stopper are you referring to paravanes to be used while underway or things used to prevent rolling at anchor? I was once chastised on this forum for calling paravanes Flopper Stoppers. I how ever, stand on my vast experience and say that Flopper Stopper has been used as the slang for paravanes by knowledgeable boatmen for more than forty years.

Oh wait, you said Flapper Stopper, no idea what that is.?

HopCar said:

When you use the term flopper stopper are you referring to paravanes to be used while underway or things used to prevent rolling at anchor? I was once chastised on this forum for calling paravanes Flopper Stoppers. I how ever, stand on my vast experience and say that Flopper Stopper has been used as the slang for paravanes by knowledgeable boatmen for more than forty years.

Oh wait, you said Flopper Stopper, no idea what that is.��

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Hi sorry I did mean flapper stopper. Yes it's for when we are at anchor

If I had a flapper on board, the last thing I would want to do is stop her (although my wife might throw her over just to watch her control the roll)!

I'd like to know too, since my birds don't do as good a job at anchor.

I thought I have seen something that looks like a large disc.

And i too called my paravanes flopper stoppers, as Beebe did.

I think they are paravanes on the move with delta shaped fish.
The same poles become flopper stoppers when at anchor usually with a square shaped crate with flaps that open when the boat rolls and the crate drops.
As usual with boats there is quite a variety on offer.

On Bay Pelican we use the Magnum Rock and Roll stabilizers. These are two "fish" approximately 36" x 18" when open that drop from 9' polls on each side of the boat. They are hinged so that when dropping they are closed and when being pulled up they open and act as a break on the roll.

Effectiveness has been substantial and immediate. Won't completely stop roll and can be overcome by substantial waves but are extremely useful.

Generally the term "flopper stoppers" are used for the type of stabilisers used at anchor.

These have a much larger surface area than the "birds" used with a paravane system. They are many different types of flopper stoppers, but generally they are designed to sink easily and provide resistance to any upward motion.

They can be used on paravane arms in place of the birds, or on a sailboat's boom hung out to one side, or even hung directly off each side of the hull. The further they are extended to each side on some sort of outrigger, the more effective they are.

My mate has some home built flopper stoppers on his sail boat, and they certainly reduce the rolling at anchor.

Here are a few types of flopper stoppers found on a google search.

AusCan said:

...Here are a few types of flopper stoppers found on a google search.

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I'll take a dozen of the last set please

I wonder where I would fit them and how much force on the boat they would have. Is it possible to fit them so there not in the way when not in use

Off Duty said:

I'll take a dozen of the last set please

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Doesn't TF have a dress code? Just wondering....

We have been using the Magma system on our trawler for some years in the Sea of Cortez. It works well after I made some modifications.

I lengthened the original 8' poles to 12' and this made a significant difference. The 6061 alloy aluminum poles slide inside each other for retrieving / storage.

Also, I replaced the original nylon end pieces on the poles. As the flopper down line rubbed through these end pieces during rolling of the boat, it would squeak and drove the Admiral crazy. This action also wore a groove in the nylon, down to the pole; not good. I fabricated new end pieces from aluminum and no more squeak.

I changed the fore and aft guys on the poles to braided cable with snaps on the ends to make hook up easy. When underway, we just lift the poles, remove the floppers using snap shackles on their lines, and secure the poles vertically.

Using these "roll dampeners" on our shallow draft, semi-displacement hull trawler has been well worth the cost, and made uncomfortable nights at anchor much less of a problem.

Is it possible to fit them so there not in the way when not in use

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The Seabrake drogue is advertised as being effective when used similar to the above products. It seems to stow well (folds up).

I have been on a couple of boats that have ForeSpar Flooper Stoppers. They do just as advertised. They sell the complete kits. Easy to set up and take down.

Roll Stabilizer Flopper Stopper

Donsan said:

Doesn't TF have a dress code? Just wondering....

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That is not a dress... but they sure look sweet.

HOLLYWOOD :lol:

Kukaro said:

I wonder where I would fit them and how much force on the boat they would have. Is it possible to fit them so there not in the way when not in use

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We fitted our Magnums amidship. The poles come with a boot into which the fitting on the end of the pole slides and then the pole is also secured with three lines, two horizontal and one vertical.

Krogen 42s have a double hull and we opened up the inside hull (4" hole saw) and then put a backing plate on the inside of the outer hull to fasten to the boot. This has been sufficient for years as I believe most of the strain is put on the vertical line. Vertical line is attached to a cleat I put on the underside of the upper deck, again with a backing plate.

Prime Fabrication makes a high quality flopper stopper made for heavy duty continuous use. Primefabrication.com

Here's my flopper stopper setup. It's a one-off design fabricated by the previous owner.

Despite stopping in the occasional ocean anchorage, I haven't needed to deploy them (yet).

Bay Pelican said:

On Bay Pelican we use the Magnum Rock and Roll stabilizers. These are two "fish" approximately 36" x 18" when open that drop from 9' polls on each side of the boat. They are hinged so that when dropping they are closed and when being pulled up they open and act as a break on the roll.

Effectiveness has been substantial and immediate. Won't completely stop roll and can be overcome by substantial waves but are extremely useful.

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That has been my experience with them as well. I also have had very good results with the orange cones. I just use a couple more on each side than the minimum recommend. The draw back to the cones is if you are anchored in shallow water they may hit or sit on the bottom. As the more cones you use the farther they have to hang down in the water.

After using roll reducers I think you'll findvyou don't want to anchor without them.

Donsan said:

Doesn't TF have a dress code? Just wondering....

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No silly - Only an Un-Dressed code!

Those picts may be in some OTDE thread!

Thank you all for the information. I think I may have to get some. Has anyone got a heritage east sundeck 40 they have fitted then too

Fore spar flop per stoppers

We use the Forespar flopped stoppers, depending upon the roll in the anchorage we sometimes use 1 , if needed we deploy the other. We use 8mm non stretch lines on the system. We weigh 36 tonne and 57 foot long with a 5.2 metre beam. The poles are 4.2 metres long, so we take up about 15 metres in width. The Forespar system comes as a kit , with poles, fittings for each end and connection to the vessels, it also includes the stainless hinged flopped stoppers. They work extremely well stopping probably 80 % of the roll and really slows the motion up. They are fairly easy to install. The higher the rope attachments to the vessel above the outward poles the more effective they are, giving them greater leverage.
Happy we have them as part of our kit when needed.

Cheers Chris D LIberty 2015

Using a second anchor to slew the boat into the swells frequently works and is little effort and no cost.

Liberty2015 said:

We use the Forespar flopped stoppers, depending upon the roll in the anchorage we sometimes use 1 , if needed we deploy the other. We use 8mm non stretch lines on the system. We weigh 36 tonne and 57 foot long with a 5.2 metre beam. The poles are 4.2 metres long, so we take up about 15 metres in width. The Forespar system comes as a kit , with poles, fittings for each end and connection to the vessels, it also includes the stainless hinged flopped stoppers. They work extremely well stopping probably 80 % of the roll and really slows the motion up. They are fairly easy to install. The higher the rope attachments to the vessel above the outward poles the more effective they are, giving them greater leverage.
Happy we have them as part of our kit when needed.

Cheers Chris D LIberty 2015

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I was looking at the forspar ones and was wondering did you have to put any reinforcing in where they were fitted. What sort of strain do they put on the boat where fittings are.
I am concerned that the strain maybe to much for my fiberglass flybridge.

If the underwater inspection on the new 60fter goes well I will look at doing a pre-emptive strike and make up a set.
Thinking a setup like pictured earlier,

but from 50mm ally tube.

The actual unit I was thinking of this type

as I have a selection of Aluminium Amplimesh security screens in the back shed that are marginally larger than the magma ones.
I also have several sheets of acrylic as used in kitchen splashbacks, so thinking that, the frames and some nylon but hinges will be an easy and affordable DIY arrangement.

Hey Simi 60,

An amusing follow up to my posting of my setup above-

I was told by the previous owner that he had designed and had fabricated the system himself.

Funnily enough, I found a photo of my boat's system in the real manufacturer's brochure.

Boat Stabilisers | Boat Stabilizers by Ocean Torque

They are well built and work well.

Simi 60 said:

If the underwater inspection on the new 60fter goes well I will look at doing a pre-emptive strike and make up a set.
Thinking a setup like pictured earlier,

but from 50mm ally tube.

The actual unit I was thinking of this type

as I have a selection of Aluminium Amplimesh security screens in the back shed that are marginally larger than the magma ones.
I also have several sheets of acrylic as used in kitchen splashbacks, so thinking that, the frames and some nylon but hinges will be an easy and affordable DIY arrangement.

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One of the nice things about the Magma plates is that the fold up, slip into a bag and are easy to store.

Capt.Bill11 said:

One of the nice things about the Magma plates is that the fold up, slip into a bag and are easy to store.

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One of the bad things about them is they cost close to $1000 here vs a few dollars for my DIY given I have it all laying around anyway.

As for storage, on those arms shown above its easy enough during fabrication stage to make a bracket on the arm that the flopper stopper can be stored in.

Simi 60 said:

One of the bad things about them is they cost close to $1000 here vs a few dollars for my DIY given I have it all laying around anyway.

As for storage, on those arms shown above its easy enough during fabrication stage to make a bracket on the arm that the flopper stopper can be stored in.

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They are $320. But I was talking about their style, which is easy enough for someone to knock on their own, rather than suggesting that you buy them.

As to storage, personally I think all that heavy duty permanent rigging makes a pleasure boat look rather junky. And few rigged that way seemed to be used for any real passage making away.

But as always, YMMV.

Like I said, here they are near $1000.
$798 to be exact
https://www.whitworths.com.au/main_itemdetail.asp?cat=148&item=998&intAbsolutePage=