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Old 01-08-2017, 10:02 AM   #1
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Anchor flopper stopper - replacement lines

Boat CHB34, flopper stopper rig installed by previous owner. Rig works great at anchor. Existing line is 3/8" 3 braid nylon and there is significant stretch when the boat rolls.

Can I replace all line with 3/8" double braid poly (sheet line)? Or, should I maintain some nylon in specific locations to reduce shock load on the mast?

What is the ideal pole angle? How much load should be on the fore / after lines vs top of the mast?

Thanks
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Old 01-08-2017, 10:35 AM   #2
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I guess my thought would be if it's working fine why change it? Or do you want to try the rig underway and that's why you are thinking about changing it up?
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Old 01-08-2017, 10:50 AM   #3
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My guess is the "significant stretch" is still allowing for quite a bit of roll, and he's wondering if lines with less stretch will transfer too much load to his mast and/or attachment points.

Maybe you could change it incrementally, and monitor/modify things over time?
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Old 01-08-2017, 10:56 AM   #4
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I guess my thought would be if it's working fine why change it? Or do you want to try the rig underway and that's why you are thinking about changing it up?
For use at anchor only.

The existing 3braid is noisy as it rolls through the blocks. Initially I purchased 300' of sheet line (poly) for the boom, which I'm using to lift a 110lb dog, previous line was same nylon 3 braid, which binds in blocks and stretches too much when lifting the dog or outboard.

Observing how much stretch is in the flopper rig when the boat rolls, it appears as though I can reduce roll a bit more by using a line that stretches less?

I'm thinking, swap out lines incrementally and observe.
1. Replace nylon line connecting flopper to pole with poly.
2. Replace nylon foreguy and afterguy with poly.
3. Maintain nylon on the lift lines (to top of mast) to reduce shock load on the mast?

Which reduces roll more, stiff poles or stretchy poles?
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Old 01-08-2017, 10:59 AM   #5
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My guess is the "significant stretch" is still allowing for quite a bit of roll, and he's wondering if lines with less stretch will transfer too much load to his mast and/or attachment points.
Yes, exactly.

thank you.
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Old 01-08-2017, 11:21 AM   #6
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The loads on your mast are significant and are asymmetrical - a heavy pull on one side and then it goes slack while a heavy load is applied on the other side. I would first investigate the condition of the guying that is supporting the mast. Also check the roof-top support, check that it's not damaging the cabin structure as that is where the loading is going. If it is bearing up under this kind of loading I would change out the lines to nylon double-braid, which still has some stretch and will avoid some of the shock-loading to your rigging. I would not use polyester in this case. I would also closely examine where the poles are attached to your gunwales too... your system is NOT designed for use while running. I am not an engineer but look where that heavy anti-rolling load is going, try and visualize the force vectors, that will help your inspection. The mast side-to-side; vertically through the cabin roof (or wherever it's mounted); the pull on the guys; the push on the gunwales; the fittings on the pole-ends.

That's all I can think of, based on the design of my flipper-stoppers with their dedicated bracing, copious welds plus their use of chain, wire cables and double-braid.
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Old 01-08-2017, 11:35 AM   #7
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Is it possible that the flopper stoppers are too big for the boat? The line stretch loading and unloading may be causing more roll, snapping back like a rubber band.
You didn't show a picture of the flopper stopper that's in the water, but possibly adding some spacers to not allow them to fully close would help.
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Old 01-08-2017, 11:40 AM   #8
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Quote:
Originally Posted by MurrayM View Post
My guess is the "significant stretch" is still allowing for quite a bit of roll, and he's wondering if lines with less stretch will transfer too much load to his mast and/or attachment points.

Maybe you could change it incrementally, and monitor/modify things over time?

Ahh I savvy now. I'm fairly obtuse.
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Old 01-08-2017, 11:49 AM   #9
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My guess is everything should be as rigid as possible...as in amsteel or equivalent, wire and or chain. Poles as stiff as can be made.


If you don't find a solution...one of the easiest is to just hoist the dingy off to one side and lift it partially out of the water. Works well on many boats...but not as good as dedicated flopper stoppers
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Old 01-08-2017, 12:04 PM   #10
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My guess is everything should be as rigid as possible...as in amsteel or equivalent, wire and or chain. Poles as stiff as can be made.

I was thinking that I would be looking at Amsteel or wire for all the supports of the mast and poles, then use a line with some stretch for the fish.
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Old 01-08-2017, 12:20 PM   #11
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I was thinking that I would be looking at Amsteel or wire for all the supports of the mast and poles, then use a line with some stretch for the fish.
+1^. The only thing I would add is to also fasten the pole downward so that it can't come back up toward the mast on a roll, do not rely solely on the weight of the flopper stopper to do that.
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Old 01-08-2017, 12:22 PM   #12
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I was thinking that I would be looking at Amsteel or wire for all the supports of the mast and poles, then use a line with some stretch for the fish.
I'd use Spectra or Amstel, etc. for every thing.
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Old 01-08-2017, 01:00 PM   #13
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I was thinking that I would be looking at Amsteel or wire for all the supports of the mast and poles, then use a line with some stretch for the fish.
At anchor we use the paravanes. Each fish is about 300 sq". With the exception of 8' of 3 strand nylon, inline to the fish, all the rigging is wire rope.
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Old 01-08-2017, 01:06 PM   #14
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Here's Forespar's kit. In their literature, they talk about five vinyl coated support cables. Sounds like there's not much stretch there.

Roll Stabilizer / Flopper Stopper
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Old 01-08-2017, 01:15 PM   #15
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I'd use Spectra or Amstel, etc. for every thing.


Cant imagine having stretch where it's not needed.

Never saw any on commercial paravane rigs doing essentially the same task.
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Old 01-08-2017, 01:35 PM   #16
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Here's Forespar's kit. In their literature, they talk about five vinyl coated support cables. Sounds like there's not much stretch there.

Roll Stabilizer / Flopper Stopper

If it was me I would go with non-coated wire or dyneema. Vinyl coated wire can hide corrosion.
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Old 01-08-2017, 02:31 PM   #17
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I'd agree with changing to spectra or dyneema. It would be like removing the rubber bands in the system. Just make sure your anchor points are secure.


The angle looks good. It seems close to equal above & below the outrigger.
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Old 01-08-2017, 04:18 PM   #18
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Is your mast wood? You haven't described the structure that supports all this. The pictures are not sharp enough to tell. Now, some of the shock loads are being absorbed by the elastic line. If you use wire or Amsteel, the shock loads will be transferred directly to the structure. Before you go to Amsteel, look carefully at the structure. Think worst case scenario, like a sudden boat swell or a storm that hammers away at you all night. If you only have typical thin stainless wire to support your mast I would say you are at significant risk of structural failure.
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Old 01-08-2017, 06:51 PM   #19
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Old 01-08-2017, 07:17 PM   #20
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Mast compression isn't just for sailboats, and doesn't need big loads either...grrrrr
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