Batwings (stabilizers)

[Gdavid]

If the paravanes pull downward on both sides, it is loading the boat to slow the rocking, just as would adding ballast.
Seems that the paravane on the descending side is just enhancing the roll?
I’d like to add ballast low in my boats keel, but it’s sealed, and I presume already weighted.
I’m trying to visualize adding a lead bulb to the keel.

The paravanes only create a downward force when pulled through the water, when the boat rocks to one side, it is reducing the tension on that cable and the paravane in turn, does not create as much force as it's mate on the opposite side. In this manner, the paravanes are an inherently stable control system that act with greater force to stabilize the vessel when it is pitching at a faster pace.

 

[Sailor of Fortune]

Batwings are interesting... There's a reason they have gained popularity over traditional flopper stoppers on the commercial fleet side at least. I have never seen a set up close,live

 

[Nomad Willy]

Think of the area involved in the bad wings and what thickness would be required for structural integrity. But the elephant in the room is weight .. a lot. Never seen bat wings on a rec boat. Just too heavy .. or small if made lighter.

I think if I were to have designed the BW they would be reversed .. as in the fluke attached a bit above mid way from the keel to the WL and the “arm” (the small part that holds the fluke in place). That would put the fluke in a position to go up and down rotating around the center of roll. This should be more efficient so they could be made smaller (or more effective) and perhaps useable on a trawler.

 

[DDW]

Steel batwings will be heavy. But there is no functional reason for them to be heavy, they just have to be strong enough not to break in normal operation (and weak enough to break if struck by something solid). If made from carbon fiber, they would be very light, in fact would probably float.

If the hull were designed from the start, I'd prefer a deep centerboard. It would do just what the batwings do, without looking like an afterthought, or being in the way of anything.

 

[Sailor of Fortune]

Think of the area involved in the bad wings and what thickness would be required for structural integrity. But the elephant in the room is weight .. a lot. Never seen bat wings on a rec boat. Just too heavy .. or small if made lighter.

I think if I were to have designed the BW they would be reversed .. as in the fluke attached a bit above mid way from the keel to the WL and the “arm” (the small part that holds the fluke in place). That would put the fluke in a position to go up and down rotating around the center of roll. This should be more efficient so they could be made smaller (or more effective) and perhaps useable on a trawler.

You probably never saw a flopper stopper setup on a rec boat until Beebe did it also... Thats the way these things seem to morph... Work/commercial boats, trial and error, refinements and them some brave soul installs on a recreational passage maker..and then goes kind of universally accepted ,at least for passage maker type boats..

 

[Nomad Willy]

S of S,
Yea like bass awkwards pilothouse windows?
But when the rec boat people develop far better anchors the anchored in tradition commercial boys just keep on w the old school stuff requiring monster ground tackle because it only has 1/5th the holding power of a modern anchor.

 

[Simi 60]

Steel batwings will be heavy. But there is no functional reason for them to be heavy, they just have to be strong enough not to break in normal operation (and weak enough to break if struck by something solid). If made from carbon fiber, they would be very light, in fact would probably float.

Weight down low is a good reason for steel.
If you look at my post above #87 there is a timber trawler with foil shaped aluminium.
Great expense, was told about 4 X more

The guys who did that variant won't do another set for timber, that was a one off for the owner of a boat building firm with lots of input and I dare say, at a guess, a waiver.

When I was considering a set for ours, knowing the cost, I considered doing a set out of cedar or Kiri core, carbon uni tows and epoxy.
I have most of the gear onboard to do it but would still need the above guys to do the hinge work and they ain't playing the game.

 

[Jeff F]

The ones I saw were all plate aluminum fins, and mostly aluminum support structures. They looked well evolved, and I didn't see a single boat rigged for paravanes on the Gaspe.

 

[normandawn1]

Heaps of bat wings in Aus. Mainly Cray fishing boats, but many recreational boats too. They work fantastically.

 

[Simi 60]

Heaps of bat wings in Aus. Mainly Cray fishing boats, but many recreational boats too. They work fantastically.

I'm guessing not the timber Cray boats?
Have only ever seen them on one timber boat with extensive input from the owner who owns a boatbuilding business.

R&L who did them said they won't do them again
Metal boats yes

 

[Labrador Coaster]

Commerical fishing vessels here in Eastern Canada/Québec are all choosing to go with the retractable “ bat wings” like those shown in Guru’s pics. Very effective, and also much easier to deploy, retract compared to paravanes out on the end of a stick..Have seen them built out of Steel, alum, and S/S. Regarding hull material, don’t see any reason why they couldn’t be installed on any hull type, as long as proper considerations are taken for proper reinforcement is done…

Final thought I think these work great when the vessel is lying abeam while fishing, but certainly would be appreciated for us pleasure folks when anchored in a “r0lly- Polly” anchorage )

 

[Jeff F]

Commerical fishing vessels here in Eastern Canada/Québec are all choosing to go with the retractable “ bat wings” like those shown in Guru’s pics. Very effective, and also much easier to deploy, retract compared to paravanes out on the end of a stick..Have seen them built out of Steel, alum, and S/S. Regarding hull material, don’t see any reason why they couldn’t be installed on any hull type, as long as proper considerations are taken for proper reinforcement is done…

Final thought I think these work great when the vessel is lying abeam while fishing, but certainly would be appreciated for us pleasure folks when anchored in a “r0lly- Polly” anchorage )

I agree that they are likely suitable for pleasure boats. The only concern I had when thinking about them for my boat is that they protrude from the side even when folded up, and so could make docking/locking a bit more challenging.

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[Labrador Coaster]

Excuse me Jeff, for the “ Guru” name, I am new to the forum.. Yes, also considered the practicality of mooring to a dock, another vessel etc. But ..the advantages seem to outweigh the negatives..

 

[Jeff F]

Heh. No offence taken... If you hang out here long enough and post regularly you too can become a Guru.

I think I remember looking at a listing for your boat Galax a couple of years ago. Steel, right? Fitting them out should be relatively easy on your boat.

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[Marco Flamingo]

As to the "pull" of paravanes, I can only describe the ones I had. I purchased them at a Fisherman's Terminal swap meet back when Seattle had a fishing fleet. They had a variety of attachment holes to "balance" the pull when travelling through the water. The idea was that they only pulled slightly when the boat was on flat water (hence the .5 knot decrease in speed). When the boat rolled, the "up side" paravane remained flat, thus providing resistance amplified by being out at the end of the rig (the moment arm). The falling vane used a fairly large counterbalance weight on its nose to dive without resistance. Once the roll reversed, the lower one would flatten out and provide resistance while the other would begin its low resistance dive. Only on really flat water would they both pull at the same time.

The amount of resistance provided was dependent on the area of the paravane (a constant), the moment arm (a constant), the angle of the paravane, and the speed of the vessel. As vessel speed increases, slight downturn of the paravane provides more resistance. Also as speed increases the paravane drops further back, also increasing the "angle of attack" and providing more resistance. A fairly small surface area can provide a lot of resistance at speed (hence chain and steel cables). At anchor? Not much, but the length of the arms helps.

As others have said, because of the amount of rigging and weight of the paravane system, there are lots of things going on. The height/weight of the system tends to slow the roll even with the paravanes and arms in. One of the studies noted above showed that at slow speeds there was no difference whether or not the vanes were deployed. Just the mass of the rigging itself slowed the frequency of the roll and made it more comfortable. But at other/higher roll amplitudes, the mass of the rigging can accentuate the roll. Deploying the paravanes not only counteracts the disadvantage of rigging aloft but has enough force to reduce the overall amplitude (without which paravanes would not be popular).

I like the traditional salty look of the paravane rigging, but if one takes a critical look, it does seem to be a Rube Goldberg system. The Lady Washington just came into my marina in Port Orchard. While it is nice to admire all that traditional rigging, modern sailboats have moved past that. It may be happening with paravanes.

 

[Labrador Coaster]

Thx Jeff, Yup, Just brought her home a few weeks ago, hull has a nice deep keel, so stabilizers are only a “Good to have”, and not high on my “To do” list..

 

[Jeff F]

Congratulations. I'm sure as you use the boat the lists will evolve.

I just looked at your location. Harrington Harbour looks very remote! I really want to travel through that area by boat some day. Do you see many long distance cruisers coming through there?

Don't be afraid to share some details about your cruising grounds and boat. I'm sure there's a receptive audience here.

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