Flopper stoppers

kierasdady said:

Hoping I'm not too late to throw in my 2 cents.

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Incredibly helpful post - thanks. Would love to see pics of your setup.

I’ve been trying to sort out how to rig up poles. Our SoCal anchorages are rolly! I don’t think I can do 1/2 beam (13.5’ beam and no mast) but thinking of a pole run off the rub rail and then a line up to the flybridge cap rail or thereabouts.

Looking at those "out of stock" magmas it makes me wonder why you couldn't make your own version of the same either from s/s or 3 mm ally plate.

Would take all of an hour to cut and fold a pair in any half decent sheet metal shop
TIG or bolt on some piano hinge
Would like to think no more than a couple of hundred for the pair.

Seeing as some are contemplating using them on bigger boats than recommended, easy to scale them up in size a bit.

Review of the Magma Flopper Stopper.

https://setsail.com/magma-flopper-stopper-test/

My Flopper Stoppers are identical to the yellow ones in the Dashew article (they worked well for him, but based on thr test, will replace old with the Magma plates). The yellow ones work well on my boat but unfortunately are no longer made. I've considered a similar design could be inexpensively made DIY with a heavy plastic diaphragm and industrial wire mesh or expanded metal similar to these products used for safety railings and security cages;

https://www.easternmetal.com/m/standard_extrusions_and_sheet_products-aluminum_woven-wire-mesh.html

Peter

Simi 60 said:

Looking at those "out of stock" magmas it makes me wonder why you couldn't make your own version of the same either from s/s or 3 mm ally plate.

Would take all of an hour to cut and fold a pair in any half decent sheet metal shop
TIG or bolt on some piano hinge
Would like to think no more than a couple of hundred for the pair.

Seeing as some are contemplating using them on bigger boats than recommended, easy to scale them up in size a bit.

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If you've got the tools and skills to do it, yes, you could absolutely make a set yourself (or one of the other valved plate designs). The off the shelf ones are the easy button, not so much the cheap option.

Insequent said:

My location is virtually midship, exactly the same location as my Naiad's. The latter are OK anywhere in the middle third of the boat, so they told me when installing. Yours might be better located but I think I'll be fine.

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You have both naiad and flipper stoppers ? Why ? Cheers just signed contract to buy an older 44 defever in Spain with naiad , wondering if I should add something else also

Zkaliman said:

You have both naiad and flipper stoppers ? Why ? Cheers just signed contract to buy an older 44 defever in Spain with naiad , wondering if I should add something else also

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"Flopper stoppers" is a term used for relatively lightweight outrigger poles used for stabilizing at anchor. Some regions are prone to open roadstead anchorages and can be rolly. Since Naiads are useless at anchor, you might consider flopper stoppers if your cruising grounds include rolly anchorages.

Paravanes are much beefier outrigger construction (compared to flopper stoppers) and stabilize the boat underway. The forces are much greater and consequently, the paravane structure is much heavier. Paravanes can also be used at anchor, though the "fish" used when running are usually replaced with some sort of plate with a diaphragm that allows the plate to sink easily but provides resistance on the upstroke. It would be unusual though not unheard of for a boat to have both paravanes and Naiads.

Peter

Our Paravanes work pretty well to reduce roll while at anchor as well, but as Peter noted above, they aren't supposed to be as effective as the box flopper stoppers. A never used set came with the boat . . . . and they are still never used!
Underway, our paravanes ROCK! Well, actually, they REDUCE the rocking . . . . Used them yesterday crossing the Straights between US and Canada when we had beam seas.

Zkaliman said:

You have both naiad and flipper stoppers ? Why ? Cheers just signed contract to buy an older 44 defever in Spain with naiad , wondering if I should add something else also

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mvweebles said:

"Flopper stoppers" is a term used for relatively lightweight outrigger poles used for stabilizing at anchor. Some regions are prone to open roadstead anchorages and can be rolly. Since Naiads are useless at anchor, you might consider flopper stoppers if your cruising grounds include rolly anchorages.

Paravanes are much beefier outrigger construction (compared to flopper stoppers) and stabilize the boat underway. The forces are much greater and consequently, the paravane structure is much heavier. Paravanes can also be used at anchor, though the "fish" used when running are usually replaced with some sort of plate with a diaphragm that allows the plate to sink easily but provides resistance on the upstroke. It would be unusual though not unheard of for a boat to have both paravanes and Naiads.

Peter

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Peter nailed it. My Naiads switch off (centred) below a speed of 4 kn.

I should also mention that while my boat has a pair of flopper stoppers, many users only install one, not two. My hunch is you get 75%-80% of the benefit from one, the second provides some assistance.

While Seakeeper gyros can be used at-anchor, if the owner prefers to limit generator time, flopper stoppers make a lot of sense.

As I write, my flopper stoppers are being replaced. I designed a "knuckle" that attaches the inboard end to the side of the flybridge bonnet. In boat-buck terms, fairly reasonable (about $3k all-in including rigging). But has involved some time on my part. Just depends on how badly you want/need stabilization at anchor. A Defever 44 is pretty tall. I wouldn't be surprised if the inhabitants would experience quality of life issues with any roll in an anchorage.

Peter

Simi 60 said:

Looking at those "out of stock" magmas it makes me wonder why you couldn't make your own version of the same either from s/s or 3 mm ally plate.

Would take all of an hour to cut and fold a pair in any half decent sheet metal shop
TIG or bolt on some piano hinge
Would like to think no more than a couple of hundred for the pair.

Seeing as some are contemplating using them on bigger boats than recommended, easy to scale them up in size a bit.

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Revisiting this
Stainless plate has gone up drastically in price, in fact, all metals have
Be looking at near $1000 just in material for magma style for our size

Got onto a guy in Brisbane to make our arms in Aluminium and have them now
Now waiting on the bits for in the water.
Will likely be this style done using old aluminium security screen and ally box section frame

The arms mounted
Using nylon double braid for ropes as shock absorber
Add splicing double braid to my new skills.

I like it!

Simi 60 said:

Revisiting this
Stainless plate has gone up drastically in price, in fact, all metals have
Be looking at near $1000 just in material for magma style for our size

Got onto a guy in Brisbane to make our arms in Aluminium and have them now
Now waiting on the bits for in the water.
Will likely be this style done using old aluminium security screen and ally box section frame

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Whitworths called me a couple of weeks ago. They finally had the Magma Rock'n'Roll come into stock. They are A$535 each.

About 6 months ago I had some lookalikes made up. Cost was $A300 for a pair, made from 1.5mm 316 SS (same as Magma). Plus some additional $ for some eye nuts, bridle and hinges. They work a treat.

Not long after installing I added a warning notice in red next to the engine start buttons as a reminder to retract them BEFORE raising anchor and cruising away. No need to ask why I decided that was a good idea......

Insequent said:

Not long after installing I added a warning notice in red next to the engine start buttons as a reminder to retract them BEFORE raising anchor and cruising away. No need to ask why I decided that was a good idea......

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Hah! Yes, I've had the same experience myself... "boy, she's sluggish this morning..."

Insequent said:

Whitworths called me a couple of weeks ago. They finally had the Magma Rock'n'Roll come into stock. They are A$535 each.

About 6 months ago I had some lookalikes made up. Cost was $A300 for a pair, made from 1.5mm 316 SS (same as Magma). Plus some additional $ for some eye nuts, bridle and hinges. They work a treat.

Not long after installing I added a warning notice in red next to the engine start buttons as a reminder to retract them BEFORE raising anchor and cruising away. No need to ask why I decided that was a good idea......

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Who made those for you Brian?
Will try them myself if I may
Was told ours would need to be 3mm which seemed a tad heavy

Simi 60 said:

Who made those for you Brian?
Will try them myself if I may
Was told ours would need to be 3mm which seemed a tad heavy

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I'll send a PM

Insequent said:

I'll send a PM

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And thanks

Roll fins

Has anyone tried roll fins? Thinking about trying them on my commercial boat. Sarted in Canada but catching on in the US.

Jaep said:

Has anyone tried roll fins? Thinking about trying them on my commercial boat. Sarted in Canada but catching on in the US.

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Interesting concept. Thanks for sharing that.

Jaep said:

Has anyone tried roll fins? Thinking about trying them on my commercial boat. Sarted in Canada but catching on in the US.

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Popular on steel, work a treat.
Use search on here for batwing stabilizers

Jaep said:

Has anyone tried roll fins? Thinking about trying them on my commercial boat. Sarted in Canada but catching on in the US.

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Hard to work out when the study was done, but sometime in the 2010-2015 period it seems. No doubt they are relatively cheap. It would have been better to see comparison with active fins included although I realise a lot of fishing boats would consider them too expensive.

Of course they are for stabilisation underway, whereas I started this thread specifically for stabilisation at anchor. Best to search for other stabiliser threads if you want something for when underway rather than cause thread drift here. No biggie, but I'd appreciate it ....

So my improved Magma type flopper stoppers arrived yesterday
Bigger boat than magma recommended so scaled it up in size
Used 3mm 316 stainless plate
1/2 links of s/s chain welded on for attachments
Large robust 316 hinges welded on
And spent a few hours splicing the 6mm blue dyneema ropes.

The rope attaching it to the arms and arms to roof is double braid nylon, learned a new skill splicing that lot as well.

Looking forward to report on testing them out.

Friday night looks suitable .........

mvweebles said:

Review of the Magma Flopper Stopper.

https://setsail.com/magma-flopper-stopper-test/

My Flopper Stoppers are identical to the yellow ones in the Dashew article (they worked well for him, but based on thr test, will replace old with the Magma plates). The yellow ones work well on my boat but unfortunately are no longer made. I've considered a similar design could be inexpensively made DIY with a heavy plastic diaphragm and industrial wire mesh or expanded metal similar to these products used for safety railings and security cages;

https://www.easternmetal.com/m/standard_extrusions_and_sheet_products-aluminum_woven-wire-mesh.html

Peter

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Ok, I have two of the yellow ones that the plastic is worn out, cracked and broken. I finally found a good replacement but probably not the best. It is 3/16" (2.8mm) LDPE sheet. Measuring some of the old material it seems the same only it is 1.5mm Or 0.052" thick. I have installed the 3/16 and will see how it goes. I'm on the lookout for thinner but I can't find it yet. If anyone does, please let me know. Also, as I mentioned in an earlier post the previous son of the manufacturer said the best material was rubber infused fabric. I just came up with a possibility. Old offset printing blankets. They are rubber over fabric. I'm going to check with a local printer and I know he'll give me one to try.

Simi 60 said:

So my improved Magma type flopper stoppers arrived yesterday
Bigger boat than magma recommended so scaled it up in size
Used 3mm 316 stainless plate
1/2 links of s/s chain welded on for attachments
Large robust 316 hinges welded on
And spent a few hours splicing the 6mm blue dyneema ropes.

The rope attaching it to the arms and arms to roof is double braid nylon, learned a new skill splicing that lot as well.

Click to expand...

I was in the work shop the other day and saw those being fabricated. Didn't realise they were for you otherwise I would have written on them.
Waiting to hear how they go.
My magmas on Tidahapah were good once I added bit of extra weight.

Tidahapah said:

I was in the work shop the other day and saw those being fabricated. Didn't realise they were for you otherwise I would have written on them.
Waiting to hear how they go.

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Attachment point at roof is my concern

Every 400mm there is a 75 X 75 laminated deck beam running full width sticking out 550mm from cabin side

I chose the one on a bulkhead and also about 600 mm from a supporting upright

Drilled a 25 mm hole through the beam about 50mm from outer end, filled with epoxy glue, drilled it back out and screwed in a 12mm stainless eyebolt with backing plate.

Hoping the nylon double braid will stretch enough to take any shock loads out.

My magmas on Tidahapah were good once I added bit of extra weight.

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These have got no shortage of weight.
Hoping I can get them out just using the trip line

Used them yesterday as we got a good roll up on the incoming tide against 35 knots of wind.

Pretty sure the flappy things stayed where they were and the boat still rolled but pretty sure it had slowed considerably

10mm nylon double braid has an impressive amount of stretch, I could sit in the lounge and see the tips of the arms drop a good foot and then as she rolled the other way they'd Bungy back up

Loads to the roof didn't seem to be anything to worry about so I pulled the flaps up and tied in a slightly shorter dyneema rope from roof to arm and tried again.

Rope from arm to flaps is still 10mm nylon double braid so there will be some stretch / shock absorbtion there.

Unfortunately by that stage the swell was dropping so a fair accesment can't be given yet

In a few days time well be at Peel island with ferry wash every half hour - until then...

Simi 60 said:

Used them yesterday as we got a good roll up on the incoming tide against 35 knots of wind.

Pretty sure the flappy things stayed where they were and the boat still rolled but pretty sure it had slowed considerably

10mm nylon double braid has an impressive amount of stretch, I could sit in the lounge and see the tips of the arms drop a good foot and then as she rolled the other way they'd Bungy back up

Loads to the roof didn't seem to be anything to worry about so I pulled the flaps up and tied in a slightly shorter dyneema rope from roof to arm and tried again.

Rope from arm to flaps is still 10mm nylon double braid so there will be some stretch / shock absorbtion there.

Unfortunately by that stage the swell was dropping so a fair accesment can't be given yet

In a few days time well be at Peel island with ferry wash every half hour - until then...

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It’s my guess that the line stretch is working against you. On the fishing boats we always used steel cable. If the line is allowed to stretch, the roll is allowed to build momentum, and the flopper is delayed.

Bmarler said:

It’s my guess that the line stretch is working against you. On the fishing boats we always used steel cable. If the line is allowed to stretch, the roll is allowed to build momentum, and the flopper is delayed.

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This may well be the case. I'm using 8mm dyneema for the load lines. I'm still in the early phase of assessing them, but an effect I've noticed is outlined below.

I'm often anchored in the northern part of Moreton Bay which is traversed by ships entering the Port of Brisbane. Mostly the ships travel at 11-15 kn in the Bay with Pilots on board to meet pre-arranged times for meeting tugs or the line handling crews at their berths. But occasionally they are running late or in a hurry for some reason and barrel past my anchorage at 20 kn or so. At those times the waves from their wakes can generate enough roll in my boat to have stuff sliding across bench tops. And you know what happens - the first wave starts the roll and then more often than not the subsequent waves are in phase and exaggerate the roll. So the 3rd, 4th and 5th wave-rolls are annoying.

Since I've been using the magna-style flopper stoppers what seems to happen is the the roll amplitude is reduced a bit. I cant quantify how much but the water on the surface above the rising flopper starts to "boil" so there is clearly a decent amount of force being imparted. More importantly I suspect is that the roll period is being increased a bit. The longer roll period is enough that the 3rd and successive wave-rolls are getting more out of phase from the first couple, and the boat settles quite quickly. No more stuff sliding across the bench.

the water on the surface above the rising flopper starts to "boil" so there is clearly a decent amount of force being imparted.

Having had a bit of experience with making and employing flopper stoppers my thoughts are -
1. Your flopper is too shallow in the water.
Or much more likely...
2. Your flopper has insufficient surface area to be effective.