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Old 22-11-2019, 13:55   #1
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Does anyone in Australia know a yard that can build and fit paravanes?

Pretty simple question, but searching for "paravane", and "flopper-stopper" has not found one yet. The backstory:

Seabiscuit is a lively lass in a confused sea, even if the wave heights are only in the order of a foot or two. This is largely due to her Sharpie-inspired design, which results in flat aft sections; this yields immense initial stability.

That same stability means that in any confused sea, she rolls rapidly on her longitudinal axis; this is uncomfortable and course changing has little effect on the movement.

I would like to design and fit paravanes to calm this movement down. All suggestions and leads appreciated.
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Old 22-11-2019, 14:34   #2
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

I guess one can make flopper stoppers, from scrap material, cheaply.
https://www.pbo.co.uk/practical-proj...-stopper-24531
The other option is the expensive way, like this
https://www.seakeeper.com/

Sorry do not know Oz based company
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Old 22-11-2019, 14:37   #3
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

Down the Gold Coast
Although these are only for at anchor

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Old 23-11-2019, 17:39   #4
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

Simi, thanks. I contacted these folk, and unfortunately their products are only the at-anchor models shown above. Still looking!
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Old 23-11-2019, 18:28   #5
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

Quote:
Originally Posted by Kit_L View Post
Pretty simple question, but searching for "paravane", and "flopper-stopper" has not found one yet. The backstory:

Seabiscuit is a lively lass in a confused sea, even if the wave heights are only in the order of a foot or two. This is largely due to her Sharpie-inspired design, which results in flat aft sections; this yields immense initial stability.

That same stability means that in any confused sea, she rolls rapidly on her longitudinal axis; this is uncomfortable and course changing has little effect on the movement.

I would like to design and fit paravanes to calm this movement down. All suggestions and leads appreciated.

Because the snap roll is due to flat sections, flopper stoppers are not going to work. They don't work on catamarans either. They ONLY work with more rounded sections. It is a different roll phenomenon.

At anchor the solution is better protection. Underway the solution is adjusting the angle to the waves.

Sorry for the bad news. Sharpie's are a US east coast design and this character is well known.
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Old 23-11-2019, 18:34   #6
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

Plenty of ex commercial and in current service sharpie hulled trawlers in Australia using paravanes.

This is what is commonly referred to as a sharpie hull here.
Same shape used on steelies as well.
Not a good example but you get the idea

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Old 23-11-2019, 19:32   #7
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

thinwater wrote:

Quote:
At anchor the solution is better protection. Underway the solution is adjusting the angle to the waves.
The boat is not in any way uncomfortable at anchor; it is only when underway in confused seas. Let me give you an example: on the delivery back from Brisbane, 550nm, we had two swells: easterly and southerly, roughly. They were only small (1.5m) but the intersection produced a very lively sea shape, and the movement of the boat on the longitudinal axis quick. Because we were bringing the boat home, and were 35–50nm offshore to ride the EAC, we did not try changing course.

But since then, I have experimented several times with course changing, and in seas like the ones I describe, or with a wind sea on top of a swell, the main movement is driven by the smaller sea on top of the swell, and course changes do not have a big effect.

If I can upload it, here is the sections plan, below:

As Simi mentioned, this kind of hull design is common in larger (up to 55') fishing boats here. Seabiscuit's aft sections are pretty flat though.

Anyhow, still looking. Thanks for all replies.
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Old 23-11-2019, 19:41   #8
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

Quote:
Originally Posted by Kit_L View Post
Pretty simple question, but searching for "paravane", and "flopper-stopper" has not found one yet. The backstory:

Seabiscuit is a lively lass in a confused sea, even if the wave heights are only in the order of a foot or two. This is largely due to her Sharpie-inspired design, which results in flat aft sections; this yields immense initial stability.

That same stability means that in any confused sea, she rolls rapidly on her longitudinal axis; this is uncomfortable and course changing has little effect on the movement.

I would like to design and fit paravanes to calm this movement down. All suggestions and leads appreciated.
Have a talk to these guys, they have dealt successfully with quite a few converted Sharpies over the years with the same issue....

https://rlmarine.com.au/stabilisers/
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Old 23-11-2019, 19:56   #9
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

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Have a talk to these guys, they have dealt successfully with quite a few converted Sharpies over the years with the same issue....

https://rlmarine.com.au/stabilisers/
They wont do the gallows and dragging fish type (already tried) but will do the batwing and bilge keel type.

Greggie Nielsen at Moreton Bay Boat works also does the bilge keel type in composite.


https://www.mbbw.com.au/
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Old 23-11-2019, 23:28   #10
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

Have you though about putting a mast on her- a little inertia up high will dampen the roll somewhat.
Regards Richard ( a Boden owner-builder!)
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Old 23-11-2019, 23:58   #11
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

Maybe even a mast and a small steadying sail?

Is that a useful option?
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Old 24-11-2019, 00:06   #12
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

Quote:
Originally Posted by Simi 60 View Post
They wont do the gallows and dragging fish type (already tried) but will do the batwing and bilge keel type.

Greggie Nielsen at Moreton Bay Boat works also does the bilge keel type in composite.


https://www.mbbw.com.au/
Yep thats right, on our old trawler the new owners went with the rolling chocks, worked like a dream.....
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Old 24-11-2019, 00:14   #13
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

boden36 (clearly a relation, though not yet met!) wrote:

Quote:
Have you though about putting a mast on her- a little inertia up high will dampen the roll somewhat.
I had not, but that is an interesting idea (and with a little boom) would allow me to get the dingy on the roof.

I will think on that. It's the speed of the corrections that are irritating, more to my partner then me, but 'happy wife, happy life' and it's an interesting problem.
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Old 24-11-2019, 00:23   #14
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

Steady Sails...Do they work? - Trawler Forum

Maybe it's useful info?
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Old 24-11-2019, 00:35   #15
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Re: Does anyone in Australia know a yard that can build and fit paravanes?

Pic of common commercial fishing flopper stopper used on the US West Coast. Bottom weight is 2" shafting and only goes about 1/3 the wing length. Flat steel is 1/4" plate. A decent welding shop should be able to make them from the pic, but if you contact companies making them, you might be able to buy plans.
If you're going to run with them out, rigging needs to be stout. Holes are to balance flopper to desired effect. Nose down is used in trolling to slow boat. Neutral or slightly nose up for running.
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