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Old 12-23-2016, 04:06 PM   #21
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Different angle, same boat..
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Old 12-23-2016, 04:21 PM   #22
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As Dhayes said, I did have these installed. They work well, not too expensive, no downside so far.
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Old 12-23-2016, 04:25 PM   #23
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Seem to be able to get 1 pic to attach at a time. Here is a shot from stern.
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Old 12-23-2016, 06:17 PM   #24
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Here's a couple of cleaner bat wing installations. These are big and heavy, 5/8" or 3/4" steel plate so well over 1000 pounds of additional ballast down low. They are not going to reduce stability.

These show the shortest possible support leg, which minimises drag compared with the type (On Poplar III) where the leg carries up above waterline.

Attachment 59821

Attachment 59822


This is a very attractive concept largely based on its simplicity.

However, I am struggling a little based on my own limitations to imagine 70% dampening with the physics of this having never seen a set in real life or seen them in action.
Is the horizontal axis of the wing plumb to the horizon? If so, is the dampening affected solely by the vertical displacement of water over the horizontal surface of the wings as the boat starts to roll? Or, is there a slight forward downward angle to the wing that exerts downward force due to the direction of travel and squats the whole hull?
Interesting concept for sure especially given the two hulls that I have and the potential ease of installation on these hulls. Thru bolting is mentioned but I wonder how much force is involved here and if a large area of attachment to the 6mm steel plate of my hulls would suffice. Someone referenced an installer in Vancouver. Design there also and any specifics for contact information? That is my neighborhood.

Always something to consider spending money on.....
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Old 12-23-2016, 06:33 PM   #25
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What would be involved with installing these on a fiberglass boat, as to backing? It would appear that a pretty large area would have to be reinforced. I would think that the kind of reinforcing required would probably only work on the initial buildout of the hull. Otherwise, fuel tanks, and other outward bound equipment would most likely have to be removed to gain access.
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Old 12-23-2016, 06:59 PM   #26
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This is a very attractive concept largely based on its simplicity.

However, I am struggling a little based on my own limitations to imagine 70% dampening with the physics of this having never seen a set in real life or seen them in action.
Is the horizontal axis of the wing plumb to the horizon? If so, is the dampening affected solely by the vertical displacement of water over the horizontal surface of the wings as the boat starts to roll? Or, is there a slight forward downward angle to the wing that exerts downward force due to the direction of travel and squats the whole hull?
Interesting concept for sure especially given the two hulls that I have and the potential ease of installation on these hulls. Thru bolting is mentioned but I wonder how much force is involved here and if a large area of attachment to the 6mm steel plate of my hulls would suffice. Someone referenced an installer in Vancouver. Design there also and any specifics for contact information? That is my neighborhood.

Always something to consider spending money on.....
If you look at the pictures I think you can see that the "wing" is approximately parallel to the keel. If anything this results in them being tipped up at the forward end when the boat is at rest, due to keel drag. But at sea the boat will be bobbing up and down, so sometimes they are tilted up, and sometimes tilted down. These are typically on >8 knot boats and generally fishermen report little or no increase in fuel consumption. There's going to be a bit, the surface drag has increased for sure, but frontal area is tiny. The batwings will slow heave a bit, as well as really reduce rolling because there's lots more flat surface to drag through the water (on the upward swinging side), and push through the water(on the downward swinging side).

Most say it's like having the paravanes out, without putting the paravanes out.

For fabrication and installation most shipyards in BC will know what to do. Chris Earl at Gronlund Boatworks in Richmond will do a good job. 604-244-7402.
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Old 12-23-2016, 09:25 PM   #27
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I really like the zero deployment/retrieval issues and minimal fussiness/maintenance of these bat wing stabilizers, but unfortunately, the only way to get Badger out of the water here in Kitimat is with a trailer that has hydraulic pads. Don't think the pads can lift Badger high enough for the bat wings to clear the trailers frame. Nearest marina with a travel lift is hundreds of miles away, so that's not really an option.
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Old 12-23-2016, 10:17 PM   #28
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Quote:
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If you look at the pictures I think you can see that the "wing" is approximately parallel to the keel. If anything this results in them being tipped up at the forward end when the boat is at rest, due to keel drag. But at sea the boat will be bobbing up and down, so sometimes they are tilted up, and sometimes tilted down. These are typically on >8 knot boats and generally fishermen report little or no increase in fuel consumption. There's going to be a bit, the surface drag has increased for sure, but frontal area is tiny. The batwings will slow heave a bit, as well as really reduce rolling because there's lots more flat surface to drag through the water (on the upward swinging side), and push through the water(on the downward swinging side).

Most say it's like having the paravanes out, without putting the paravanes out.

For fabrication and installation most shipyards in BC will know what to do. Chris Earl at Gronlund Boatworks in Richmond will do a good job. 604-244-7402.

Thanks for that. It is as it appears then in that the roll reducing force is the lifting of the water on the top surface of one wing and the pressing of the water on the bottom surface of the other wing.
Strange that such a relatively small surface can offset that much of the roll momentum of such a large mass as the boat itself.

Very cool.
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Old 12-24-2016, 05:17 AM   #29
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The size of the batwing is always going to be many times the size of any paravane fish for a given boat. As they are positioned much closer to the centre of roll, for each square foot of area they are less effective by close to the same ratio as their size difference would suggest.
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Old 12-24-2016, 08:43 AM   #30
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Very interesting thread, never heard of these before.
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Old 12-24-2016, 03:33 PM   #31
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Very interesting thread, never heard of these before.
I've seen them on many boats, mostly commercial such as trollers, but a number of pleasure boats. They are not common amongst the pleasure boats though.

There was an article in , I think Pacific Yachting, recently about the addition of a set of the long hard chine mounted types on a PT38. It was two or three months ago and they were successful, to the owner. Installed by a Coombs , B.C. yard, I think Independent Shipyards.
I don't have the mags. with me so I cannot look it up.
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Old 12-25-2016, 03:23 AM   #32
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As Dhayes said, I did have these installed. They work well, not too expensive, no downside so far.

Thanks for those pictures, they help a lot. Now that you have had them on for a while now, was the amount of roll reduction noticeable and under what conditions? Anymore idea how much, if any, affect they have had on speed?

For a SD hull like ours, I would guess that the roll chocks would be more effective than batwings but that is just an ignorant guess.
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Old 12-26-2016, 01:39 AM   #33
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May be
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Old 12-26-2016, 07:13 PM   #34
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Going slow in that thing would be a real drag..
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Old 12-26-2016, 08:04 PM   #35
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Going slow in that thing would be a real drag..
Articulate those things and you could rename it "Tiktaalik" and park it on your lawn
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Old 12-26-2016, 11:19 PM   #36
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Just guessing but I'm pretty sure that would be a hydrofoil.

Is it correct to assume the "batfish" are roughly that same size as the "fish" on para-vanes?

If so I imagine it would be at least as effective underway or anchored.
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Old 12-27-2016, 12:21 AM   #37
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Thanks for that. It is as it appears then in that the roll reducing force is the lifting of the water on the top surface of one wing and the pressing of the water on the bottom surface of the other wing.
Strange that such a relatively small surface can offset that much of the roll momentum of such a large mass as the boat itself.

Very cool.
One thing that was common to the several different batwing designs was the presence of holes in the horizontal surface. I believe this has a purpose other than to lighten the steel plate. When the vessel is rolling, some of the water going over the horizontal surface has to go through those cutouts, creating a lot of drag. I believe this drag is the predominant force in reducing the roll, as opposed to the water flowing over and around the batwing. Along the same lines, I had rolling chocks (bilge keels) fitted to a 93' steel, aft wheelhouse fishing boat, similar style as both your boats. I had holes cut out of the rolling chock allowing water to drag through while the boat was rolling, thus increasing their effectiveness.
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Old 12-27-2016, 12:58 AM   #38
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I'm always looking for fresh ideas to stabilize my vessel, but at least with coastal cruisers in the Eastern US, such a design would be a trade off of reduced roll for Crab pot vulnerability. Still a nice idea though, especially if it works at anchor.
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Old 12-27-2016, 06:53 PM   #39
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I'm always looking for fresh ideas to stabilize my vessel, but at least with coastal cruisers in the Eastern US, such a design would be a trade off of reduced roll for Crab pot vulnerability. Still a nice idea though, especially if it works at anchor.

I keep thinking that since I seem to ground my boat in the ICW fairly often, bad things could happen with these bat wings. Seems like they could bend, or possibly even pull away from the hull and hole the boat?
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Old 12-27-2016, 07:10 PM   #40
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I don't see them as a huge issue on the Atlantic or Gulf ICW.

As far as grounding, most of the types of grounding for me a a bazillion others...you are just sliding up on mud or a sandbar if you have a keel they are bolted to.

Now backing off may be harder, but damage would only concern me if they weren't installed well or catching one on a rock somehow.

As far as crab pots, better them than my shaft....a sharp serated edge might eliminate that..,and way too many pots in the channel too....
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