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Sailors have known for centuries that a deep centerboard or daggerboard will reduce rolling, so not really a new concept.

The other technology to compare the bat wings to is rolling chocks, which were discussed in another thread at one point.

If I had to guess, the important variable would be the surface area of the device (wing, fin, or chock) multiplied by the distance from the center of effort to the roll center (or similar) of the vessel. So fins = small area, long moment, chocks = big area, short moment, and bat wings in the middle.

The rolling chocks are not retractable, but also not susceptible to damage. Also likely the cheapest of the three. Possibly the least effective?
 
The trick is to have automatically water-pressure self-adjusting, flexible sides to the keel. Self functioning, it activated similar to airfoils' air-pressure mechanical-adjustment on airplane wing... but rather, in a vertical position. My dad and I worked on this, with prototypes, for years. We built and thoroughly sea tested it. He patented it in 1971. Worked very well... however, dad was not a marketer at all... and, I was too busy in late teens/early 20's to take up on trying to sell it to boat builders or marine equipment manufacturers... so it "went dead in the water" so to say. LOL

BTW - Dad flew Spitfire and other planes in WWII. That's how he got his mind straight-on fluid [air] dynamics. He also worked with Wernher von Braun's crew for Grumman Aircraft; while designing the landing gear for first L.E.M. While in middle school I'd go to dinner-meetings at Grumman to listen to Wernher von Braun speak.
 
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If I had to guess, the important variable would be the surface area of the device (wing, fin, or chock) multiplied by the distance from the center of effort to the roll center (or similar) of the vessel. So fins = small area, long moment, chocks = big area, short moment, and bat wings in the middle.
There is another very large component. The reason batwings and to some extent rolling chocks work is the roll. A symmetric airfoil in aligned flow makes no lift. However if you try to move it across the flow, it makes lift, and the faster you move it across the flow the higher the lift (up until stall). This is because the local flow as seen from the airfoil is now coming from angled from one side.

On batwings, this movement across the flow is created by the rolling motion of the boat. The longer the wings, the faster this motion is (being further from the roll center), and the higher the lift. So long foils like batwings, or a long daggerboard, benefit doubly from length: more leverage, and more lift with the same roll, with the highest lift coming at the point of most leverage. Effectiveness goes up proportional to the length squared. You can see why batwings, having several times the span of rolling chocks, would be much more effective.
 
Here's the Canadian document comparing paravane performance with "hinged fin roll-damping systems" (batwing stabilisers). The paper notes that there is a trend among these fishers to transition from paravanes to the hinged fins. Performance is similar, but the hinged fin type are easier to handle and safer. Having built a paravane system on our last boat and having cruised with them, next time I'd go with batwings. I saw a system on a vessel that had hydraulic lowering and lifting controls, too; looked great.
 

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One thing that is understated in the study, though mentioned, is that some or maybe a lot of the roll reduction in the paravane setup was from the booms alone, due to their increase in roll moment of inertia and reduction in stability. This roll reduction was noted when the booms were deployed, but without the fish in the water.
 
I don't know if this has been posted before, but it works for me. Excellent builder and you can get it ice prepared(heavier aluminum).
I'm not sure exactly what type of hull it is.
I can see that in the Pacific NW.


https://bestevaer.com/yachts/motor/models/53-m-y

It is a semi displacement hull and the range is limited compared to other boats. The 53MY would be great for cruising the coast, canals and rivers.

Later,
Dan
 
One thing that is understated in the study, though mentioned, is that some or maybe a lot of the roll reduction in the paravane setup was from the booms alone, due to their increase in roll moment of inertia and reduction in stability. This roll reduction was noted when the booms were deployed, but without the fish in the water.


This is noticeable in our boat exactly as described. We get, at a guess, maybe a 10% reduction in roll by just deploying the stabilizer poles, and before putting the fish in the water.:thumb:
If we're anticipating rougher seas, we like to deploy the poles, then if needed, both fish can be deployed in about two minutes.
 
It is a semi displacement hull and the range is limited compared to other boats. The 53MY would be great for cruising the coast, canals and rivers.

Later,
Dan

The video is interesting because it lists 2 engines of 110 ea and speeds of 8-12 knts, yet it sure looks like it's moving a lot faster than that.
 
Around June a very interesting boat will come on the market, at least that is what the current owners are saying at this moment.
They have a Youtube channel, bought a 56' Ocean Alexander a little over a year ago to fulfill their dream: doing the American Loop.

It is a couple with 2 young kids, they just completed the loop, now want to go to the Bahama's and then they need to sell the boat. Why ? Because the kids want to see their friends again and don't want to be on the water anymore.
If you want to see what the boat looks like you can see this video on Youtube. I have no idea what the price will be, but the boat looks immaculate.
 
The video is interesting because it lists 2 engines of 110 ea and speeds of 8-12 knts, yet it sure looks like it's moving a lot faster than that.

If you download the specs, there's options for much larger twins. That is why I was wondering about the hull design. I was thinking planing hull possibly.
The specs are very interesting if you have the time.

L
 
The video is interesting because it lists 2 engines of 110 ea and speeds of 8-12 knts, yet it sure looks like it's moving a lot faster than that.

Agreed - That the fastest 12 knots I recall seeing!
 
Around June a very interesting boat will come on the market, at least that is what the current owners are saying at this moment.
They have a Youtube channel, bought a 56' Ocean Alexander a little over a year ago to fulfill their dream: doing the American Loop.

It is a couple with 2 young kids, they just completed the loop, now want to go to the Bahama's and then they need to sell the boat. Why ? Because the kids want to see their friends again and don't want to be on the water anymore.
If you want to see what the boat looks like you can see this video on Youtube. I have no idea what the price will be, but the boat looks immaculate.

Very nicely outfitted and cared for 56' OA. I looked up same model/year OA on google. It has twin 700 hp. diesels. Wonder what the planing cruise speed is and at that speed what the nmpg is? If you figure WLL of a 56'er being 53' +/-... then 9.75 is calced hull speed. So, about 9 knots is probably the most efficient.
 
The trick is to have automatically water-pressure self-adjusting, flexible sides to the keel. Self functioning, it activated similar to airfoils' air-pressure mechanical-adjustment on airplane wing... but rather, in a vertical position. My dad and I worked on this, with prototypes, for years. We built and thoroughly sea tested it. He patented it in 1971. Worked very well... however, dad was not a marketer at all... and, I was too busy in late teens/early 20's to take up on trying to sell it to boat builders or marine equipment manufacturers... so it "went dead in the water" so to say. LOL

BTW - Dad flew Spitfire and other planes in WWII. That's how he got his mind straight-on fluid [air] dynamics. He also worked with Wernher von Braun's crew for Grumman Aircraft; while designing the landing gear for first L.E.M. While in middle school I'd go to dinner-meetings at Grumman to listen to Wernher von Braun speak.


That had to have been an amazing table to sit at.
 
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This boat may have been discussed here. Looks like an amazing build and I have always found the Seatons very eye appealing. Needs updating, note the TVs, upholstery in pilothouse etc. I like the black hull paint to help with the "beard"? Is that why it is black there? Perhaps that is reinforcement for bow or just ascetics?

A couple of key takeaways from the description:

VOYAGER is a massive (100+ ton) 67’ fiberglass/aluminum trawler whose design and engineering budget alone exceeded $600,000 when built.


BUILDERS NOTES

Hull is solid fiberglass ranging up to 2 ¾” thick below water lineSuperstructure is cored fiberglass up to boat deck

Hull has 15 integral in fuel, water and holding tanks with same layup schedule as hull.

This effectively provides a double hull over 85% of the wetted surface.

Pilothouse, flying bridge, mast and electronics arch are marine grade aluminum.

Entire vessel is heavily insulated thermally as well as acoustically, utilizing balsa core, isolation and vibration dampers, rigid fiberglass, aluminum foil bubble blankets, high density urethane and lead sheeting.

Hull has molded in protective pockets for keel cooler’s.

Rudder is three part segmented, articulated molded hard rubber barn door type.

Large heavily built swim platform serves as boarding station for tenders.

Vessel comes with a large spare parts inventory, commensurate with a yacht that is designed to be self-sufficient for 6 months at a time.

Tool inventory is adequate to breakdown main engine

Documentation of as built wiring is extensive. Each wire is labeled and listed in manual with description of points of service and length of wire.

 

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This boat may have been discussed here. Looks like an amazing build and I have always found the Seatons very eye appealing. Needs updating, note the TVs, upholstery in pilothouse etc. I like the black hull paint to help with the "beard"? Is that why it is black there? Perhaps that is reinforcement for bow or just ascetics?

A couple of key takeaways from the description:

VOYAGER is a massive (100+ ton) 67’ fiberglass/aluminum trawler whose design and engineering budget alone exceeded $600,000 when built.


BUILDERS NOTES

Hull is solid fiberglass ranging up to 2 ¾” thick below water lineSuperstructure is cored fiberglass up to boat deck

Hull has 15 integral in fuel, water and holding tanks with same layup schedule as hull.

This effectively provides a double hull over 85% of the wetted surface.

Pilothouse, flying bridge, mast and electronics arch are marine grade aluminum.

Entire vessel is heavily insulated thermally as well as acoustically, utilizing balsa core, isolation and vibration dampers, rigid fiberglass, aluminum foil bubble blankets, high density urethane and lead sheeting.

Hull has molded in protective pockets for keel cooler’s.

Rudder is three part segmented, articulated molded hard rubber barn door type.

Large heavily built swim platform serves as boarding station for tenders.

Vessel comes with a large spare parts inventory, commensurate with a yacht that is designed to be self-sufficient for 6 months at a time.

Tool inventory is adequate to breakdown main engine

Documentation of as built wiring is extensive. Each wire is labeled and listed in manual with description of points of service and length of wire.


Very Nice... Thanks! - However, ER looked a bit cramped at video end. Also, never showed look/view off bridge toward bow. I'm sure that is an exhilarating sight. I adore piloting on the FB!
 
"ER looked a bit cramped at video end" yes and that's probably because the it has saddle fuel tanks in the ER. Something I would like to avoid in a future new-build.

I know we've discussed the need for fiddles on trawlers in other threads, but I really like these short fiddles. They would keep small items like spoons and salt shakers from sliding off, but mostly in controlling spilled water/liquids from dripping onto the sole.
 

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"ER looked a bit cramped at video end" yes and that's probably because the it has saddle fuel tanks in the ER. Something I would like to avoid in a future new-build.

I know we've discussed the need for fiddles on trawlers in other threads, but I really like these short fiddles. They would keep small items like spoons and salt shakers from sliding off, but mostly in controlling spilled water/liquids from dripping onto the sole.

I noted this in the write up, says they have 15 integral tanks effectively making a double bottom.

"Hull has 15 integral in fuel, water and holding tanks with same layup schedule as hull."

And the salon picture is totally different than the video, updated perhaps? And from the flybridge I assumed they are a McDonalds franchisee.

I forgot to post the link.

https://www.yachtworld.com/yacht/1990-seaton-expedition-motor-yacht-4909852/
 

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That is good looking cruiser.

ER looks nice... not sure of room to manage working on engine outer sides.

Seems 200 gal water tank [water maker maybe - didn't notice one listed] and 100 gal black tank could be a bit bigger. Wonder the range at 10 or 16 knots with 1600 gal fuel?
 
Boat will need some TLC on the exterior I have had the painting at vanish bid but I am looking to sell rather than take on that project, I am just not using the boat as much as it should be.

Proofreading is dead, too.
 
He speaka da goodly Englees like da Nigeria princes

Go ahead and send him $40k - what could possibly go wrong???
 

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