What in tarnation?

[Northern Spy]

Too bad that's a whale.

Don't be silly. You can't catch a dead pet whale with a Island Gypsy 32.

 

[FlyWright]

I'm guessing it is to reduce pitching in a head sea.

Pretty sure this is the Island Gypsy 32 we discussed years ago.

Edit: yup, it is.

We have a winner!!!! Thanks for the great detective work, NS!!

I saw this on Facebook a couple days ago and suggested the guy post it here for an answer. You guys are an amazing source of great info.

 

[Northern Spy]

We have a winner!!!! Thanks for the great detective work, NS!!

I saw this on Facebook a couple days ago and suggested the guy post it here for an answer. You guys are an amazing source of great info.

Funny thing is though, I can't find the original TF thread in which we discussed it, but I do remember it.

EDIT. Here it is: https://www.trawlerforum.com/forums/s3/hull-modifications-see-believe-9946.html

 

[skyhawk]

The guy got tired of sticking his tongue out to everyone he approached, so now he doesn't have to.....

 

[timb7734]

Post did not mention length of vessel. Pretty well known that bulbous bows do not improve vessel performance much below 60 feet waterline.

 

[Trimjb]

Forward looking sonar dome.

 

[ronobrien]

It's the Capt's quarters when he pisses off the Admiral.

 

[Birdman]

It actually adds a bit of bow lift to the displacement hull, kind of like the hydrofoils on the racing sailboats. Instead of the bow dunking under small swells and chop which increases friction and slows it down, it raises it up over the chop a bit.

 

[ProMaritime]

This does not look like a bulbous bow. It appears to be flat and looks more like a platypus' bill. Undoubtedly it will force the bow down when meeting the seas head on or its for those who have never been pitch-polled when screaming down the face of a wave directly behind you. OMG, get out the cutting torch.

 

[Birdman]

A well known marine architect/engineer/designer, told me it will create lift.

 

[PNW Drifter]

What happens when male enhancement pills are dropped into the fuel tank.

 

[ProMaritime]

I have over 15,000 hrs. in heavy multi-engine jet airplanes as well as 60 years experience running boats of all types. Please explain to me how a flat plate will create lift.

 

[Northern Spy]

I have over 15,000 hrs. in heavy multi-engine jet airplanes as well as 60 years experience running boats of all types. Please explain to me how a flat plate will create lift.

Angle of attack. Turns out the whole concept of lift has lots to do with angle of attack as well as shape. Don't need a foil shape. Any kid who studied aerodynamics with their hand out of the window can attest to this. How does my perfectly flat plate steel rudder turn my boat? Foils are more efficient, of course, but there aren't many foiled rudders out there on non-commercial boats.

My guess is that it was put on after the sponson like appendages adding buoyancy upset the pitch underway by making it ride bow down.

Not saying it is necessarily effective or efficient, but I'm sure that is the idea.

 

[backinblue]

Most it creates is dockside conversation

 

[Birdman]

I have over 15,000 hrs. in heavy multi-engine jet airplanes as well as 60 years experience running boats of all types. Please explain to me how a flat plate will create lift.

I'm not an engineer, but he explained the angle is facing upward much like a hydrofoil. Creates low pressure under it, creating lift. I've also been running boats for 50 years, and have Air Force, Pan Am, and Delta airlines in the blood for 40 years! But none of those help with this.

 

[backinblue]

The last thing I need is bow lift. My trim tabs fight it for all they are worth.

 

[skyhawk]

Newton's 3rd law
Not too long ago I watched an interesting vid on youtube, some aerospace engineer lecturing on lift....
is it Bernoulli's pressure delta
or
newton's force/reaction from the deflected air mass

took some digging but found it....
https://youtu.be/QKCK4lJLQHU

In school and as a private pilot I've always been taught Bernouli
but as an engineer, some 'pleasure' reading I did a long time ago had me convinced it was more about the deflected air mass
I've forgotten most of what was said.... but as I recall I found his presentation interesting. Maybe I'll watch it again....

 

[ProMaritime]

The initial lift developed by an airplane's wings on takeoff and climb at relatively low air speed (250 knots below 10,000ft.) is a function of Bernoulli's Principle, low pressure on top of the wing, high pressure below it. At high altitude at speeds approaching the speed of sound an airplane's lift is developed by angle of attack since the air behaves more like an incompressible fluid like water. If you strap enough power on to a full-displacement hull you can make it plane.
I think your rudder for the most part actually redirects propeller thrust (with a little help from Bernoulli) to turn a power boat. With a boat under sail the rudder is more like a water borne application of Bernoulli, high water pressure on one side, low on the other. I think you would need very high boat speed to attribute directional control solely to the rudder's angle of attack and that rudder would have to be a very small one.

 

[skipperguy]

Now bolb

It’s based on a bow configuration referred to as a bow bulb. I have seen one small cabin cruiser from Europe that was built with something like this but it was cylindrical with a dull point on the front. This one appears somewhat flat. Many working vessels have a feature like this.

 

[Northern Spy]

The initial lift developed by an airplane's wings on takeoff and climb at relatively low air speed (250 knots below 10,000ft.) is a function of Bernoulli's Principle, low pressure on top of the wing, high pressure below it. At high altitude at speeds approaching the speed of sound an airplane's lift is developed by angle of attack since the air behaves more like an incompressible fluid like water. If you strap enough power on to a full-displacement hull you can make it plane.
I think your rudder for the most part actually redirects propeller thrust (with a little help from Bernoulli) to turn a power boat. With a boat under sail the rudder is more like a water borne application of Bernoulli, high water pressure on one side, low on the other. I think you would need very high boat speed to attribute directional control solely to the rudder's angle of attack and that rudder would have to be a very small one.

I'll stick with "we don't really know (yet)".

Pretty decent article here:

https://www.scientificamerican.com/article/no-one-can-explain-why-planes-stay-in-the-air/

I too was taught the bernoulli principle as the reason for flight. I also remember that my 8th grade science teacher couldn't explain why planes can fly inverted at an air show. Poor guy. Years later, watching a Yak 55 perform was pretty mind-blowing.

 

[phillippeterson]

What keeps a surfboard up? Or a skimboard? It's not Bernoulli. It's the deflection of the mass of water.

 

[jlhegland]

What in tarnation

I believe it’s a cavitation plate for an external bow thruster.

 

[Juggerknot]

What the heck is this about?
View attachment 119141

View attachment 119142

It's a breakwater to eliminate hull slap for those sleeping in the v berth while at anchor...That can be annoying as crap!

 

[ben2go]

Watch "Cruising Sea Venture" on youtube. They did a bulbous bow on their Cheoy Lee and it made a big difference in their boat.

 

[NCheaven]

Clearly a puzzle. Some awful guesses:
1. Knowing that platypus' are venomous, such a platypus-looking bow appendage would frighten away manatees, and other creatures that might otherwise be injured by the boat.
2. Forward mounted sonar for treasure searching, with less engine noise and other clutter. (Aren't there some airplanes with pointy radar noses for hurricane duty like that?)
3. Anchor cleaning station.
4. Trawler adaptation for bonefishing enthusiast.
5. Hang Ten platform for winning all Guinness World Record Hang Ten endurance categories.
6. Envying deep Vees that "slice through the waves", he found a way to do that (horizontally) with a trawler.
7. Photo shopped pic to see what TF crazy explanations would arise..... Do we get prizes?

 

[ronobrien]

I'm not an engineer, but he explained the angle is facing upward much like a hydrofoil. Creates low pressure under it, creating lift. I've also been running boats for 50 years, and have Air Force, Pan Am, and Delta airlines in the blood for 40 years! But none of those help with this.

Wouldn't low pressure UNDER it create downward force?

 

[Birdman]

Wouldn't low pressure UNDER it create downward force?

No, the water below it would "push up", to try to equalize the pressure. But the "deflection of mass" theory mentioned above is more of what was explained to me is going on here. As mentioned, like a surfboard....

 

[HTurner]

I would love to see what this boat does in 6' seas. I think someone read too much on the internet.

 

[ronobrien]

No, the water below it would "push up", to try to equalize the pressure. But the "deflection of mass" theory mentioned above is more of what was explained to me is going on here. As mentioned, like a surfboard....

You may be correct in practice, but I was quoting the post that suggested a "low pressure under" the foil. Bernoulli's law is that movement of a medium (air or water) over a surface at high speed creates a low pressure area and thus, lift. So if the "low pressure" is under the foil, that would create a downward lift. But as I said it may be that your analysis is correct. I was only referring to the direct quote.

 

[phillippeterson]

I have over 15,000 hrs. in heavy multi-engine jet airplanes as well as 60 years experience running boats of all types. Please explain to me how a flat plate will create lift.

See experiments in lift by Sir George Cayley in 1792 that shows he had an understanding of lift from a flat plate.