Batwings (stabilizers)

[MurrayM]

Searching around in old posts I found this reference from Tad about 'batwings' used on commercial fishing boats on the BC coast.

Trawler Forum - View Single Post - Roll attenuation

Anybody have experience with them?

 

[MurrayM]

Bit of a quote from one boaters write-up on having them installed:

...Some favored chine keels and other additions, but the most popular one in this part of the world seemed to be the 'batwing stabilizer'. I was especially convinced by the enthusiasm shown by the owner of a fishboat who regularly goes out beyond the Queen Charlotte Islands, and who said that once the batwings were
installed, the crew stopped bothering with the flopperstoppers...

Full quote here:

T&T: Stabilizers for Trawlers

 

[AusCan]

No experience, but they do sound promising. Nothing to do once they are installed other than antifouling.

I seems they would be easier to install on a hard chined hull, in comparison to a round bilge hull, but still much simpler (easier & cheaper) than any other stabilizer system.

 

[MV Content]

Subscribed

 

[Simi 60]

A few different types here.

Stabilisers - Rogers and Lough Marine Engineering

 

[dhays]

Rebel installed some rolling checks on Rogue last spring/summer. Maybe he can give us an update on how they seemed to work out?

 

[MurrayM]

Rebel installed some rolling checks on Rogue last spring/summer. Maybe he can give us an update on how they seemed to work out?

Batwings appear to be significantly different than rolling chocks...see Tad Roberts drawing at link in first post.

 

[REAL MOUNTIE]

Starboard Batwing

Source: http://www.boatdesign.net/forums/at...s-trawler-yachts-lf1359_norse_provider_12.jpg


http://www.boatdesign.net/forums/at...trawler-yachts-lw1385_ocean_challenger_05.jpg

 

[MurrayM]

Good photo's at this link: Around the Boatyards 2014

 

[MurrayM]

From the photo's found so far, it seems any Joe Blow can cobble together a set of batwings with whatever extra materials may be lying around and little effort or thought towards design. This set looks well thought out and nobody would know they were there unless on the dry: Moody Blue

 

[CPseudonym]

Tad Roberts addressed this exact subject here at TF a few years ago. I cannot locate the thread right now to provide the hyperlink.

 

[MurrayM]

Tad Roberts addressed this exact subject here at TF a few years ago. I cannot locate the thread right now to provide the hyperlink.

Link to one such post is in post #1 of this thread...

 

[cardude01]

If doing ICW/east coast shallow water cruising it sure looks like those would be easy to tear off when running aground?

 

[CPseudonym]

Link to one such post is in post #1 of this thread...

My bad Murray, missed it on my iPhone. Failing eyes and fat fingers can be a bad combination sometimes

 

[MV Content]

I'm really keen to have these fitted on Content. We are planning to head south next year or the year after, and ultimately ship her to Europe. This would greatly improve comfort on board, and extend her range, 'cos she rolls quite a bit. Tad Roberts suggested batwings to me, and I really like the fact that they're 'always there', both underway and at anchor.

However, someone mentioned to me recently that he thought they would potentially cause issues when exposed to strong currents, and could reduce stability, presumably only in extreme situations.

I would also be interested to hear of any first-hand experiences. That said, I'll be booking my boat in for the work early in the New Year.
Eamonn

 

[MV Content]

From the photo's found so far, it seems any Joe Blow can cobble together a set of batwings with whatever extra materials may be lying around and little effort or thought towards design. This set looks well thought out and nobody would know they were there unless on the dry: Moody Blue

Murray, I guess the best solutions always look simple..... I'd certainly want some experienced input, however, before welding a bunch of pig-iron to my hull!

 

[Tad Roberts]

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.

 

[AusCan]

It seems batwings are mainly popular in Canada. The closest I've seen to batwings in Australia is the winged keel on Australia 2 back in 1983.

They appear to be a great idea. An extra plus would be the ability to dry out at low tide on a suitable beach.

 

[koliver]

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.

View attachment 59821

View attachment 59822

A good friend and frequent cruising companion has batwings on his FD 61' wooden boat. They have been trouble free for as long as I have know him. They were installed by a PO, long before he got his boat in the 80s. I don't believe he carries near the amount of zinc as show in Tad's photos.

Why all the Zincs?

 

[Rebel112r]

These taken in Blaine. Lots of zincs. . Troller that also fished offsore for Albacore.

 

[Rebel112r]

Different angle, same boat..

 

[Rebel112r]

As Dhayes said, I did have these installed. They work well, not too expensive, no downside so far.

 

[Rebel112r]

Seem to be able to get 1 pic to attach at a time. Here is a shot from stern.

 

[klee wyck]

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.

View attachment 59821

View 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.....

 

[tinped]

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.

 

[Tad Roberts]

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.

 

[MurrayM]

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.

 

[klee wyck]

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.

 

[koliver]

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.

 

[Sailor of Fortune]

Very interesting thread, never heard of these before.