Hull Vane

By that theory, wouldn't you also then have to say no stabilizers, but design a hull that is good enough without them?

Guess to me the attachment for different conditions doesn't sound bad.

Sure, a gyro for zero to 20 knots and interceptors for higher speeds. Nothing that can tangle outside the hull would feel safer to me...

I am 100 % with AMG. A gyro stabilizer plus intercepter is THE perfect solution for a fast boat up to about 100 ft LOA (Have not seen any bigger jet with inceptors). You are not driving around with your handbrake pulled either. So why having a planning boot with fins. The first Mangusta 165 quad KAMEWA jet is completely gyro stabilized, for example.

For displacement boats, the bigger gyros (customized in size and performance) are comming and the simple hydraulic fin stabilizer for slow boats will be a thing of the past, with those new high effectice, less drag devices like the Magnus effect stabs, the varialble profile / swept angle and flapped-slatted stabs and the new 2-axsis stabilizers, which are far more efective when in use and give far less restistance, when not in use. And the electrical stabs are comming. Things like electrical power steering (for boats) are on the drawing board too.

The big boys will live for many years to come with their large retractable high aspect ratio fins but things like rudder-roll stabilisation is getting more common obove the 20 Kts regime.

From reading the papers of P. Oosaamen and listening to a man
on the SMM trade fair in Hamburg (must have been Innomare ), the hull vane must be an interesting feature. But from my knowledge base and present point of view, I would like to some kind of retract her, if not in use.

Evolution goes on, even in boating.

A bit of a reversal, but like a convertible's top on a nice sunny day;

yet, up during inclement weather.

Mercedes-Benz SLK280 Retractable Hardtop - YouTube


Or, perhaps a US of A lead-sled example.

1957 Ford Fairlane Convertible Retractable Hardtop - YouTube

That sounds like a real educated answer, OP .

Hi,

The hull vane is not a "fix for poor design" as trim wedges can be on some hulls. It's an appendage to recover forward thrust out of the water movement created by the ship (unavoidable for any ship) and to reduce the (stern) wave produced by the ship (like a bulbous bow does with the bow wave), by creating a low-pressure zone just aft of the stern. The 55 m vessel on which we seatrialed in July (and achieved 10% reduction at 12 knots up to 15% reduction at 21 knots) was already a very good hull design without the Hull Vane.

Due to its location aft of all the running gear, we don't expect the Hull Vane to be a "garbage collector". The stabilizer fins, rudders and propellers are much more prone to this. And due to its relatively high location (about 1-1.5 m below the waterline), it will be easier to remove anything if it would snag. As there are no moving parts on the Hull Vane, mechanical damage is also unlikely. We like to keep it simple, as there are high forces involved.

HTM09 - thanks for dropping by!

Bruno

I am sure, that the hull vane is an very elaborate and well designed piece of equipment. Dr. Peter van Oosanen is a great naval architect and scientist. The only thing, I was talking about, was the possibility of retracting the hull vane completely out of the water, i.e. behind the ship, if not needed or wanted, for whatever reason.

Such a reduction in fuel consumption, if proven, could make the difference of live and die for a commercial ship in the future. It will be a concideration for a newbuild, for sure.

I personally believe, utilizing the full benefit of this hull vane, the whole rear lower part of the hull has to be optimized for this hydronamical device. As other "gimmicks", like split rudder with costa bulb and flap or assymetrical prop fairings have been introduced to the shipping world, the interaction / interferences of all those gadgets has to be thoroughly tested.

During my university time, we were developing a new glider in our aerodynamic course. We had a great designed fuselage and a well proven wing but as we found out during the wind tunnel testing, the complete glider was a lousy bird at slow speeds. Reason was, the poorly designed wing / fuselage joint (fairing) created a huge amount of interference drag during high angles of attack. And we had no personal computers, no 3D FEM CAD, only little HP handheld programmable calculators (Fortran !) and one big IBM mainframe with punch cards for the whole university !!!!

Will say, we will need to do some tank testing besides a lot of FD computer "games". As you can see on the picture below, this is a complicated matter and the calculations have to be done for each hull individually.

http://www.youtube.com/watch?feature=player_embedded&v=4Npm5FXnOLE

But I am open minded, we will see.

P.S. Innomare, I did like the tank testing model in your booth at the SMM being used as a bar. That would be something for my office .

My opinion is that it will do as advertised... and reduce fuel consumption and increase speed... and it seems a reasonable refit or add-on during construction to existing hull forms.

The film that was previously posted here does a good explanation... reposted for refer.

Hull Vane - Fuel Saving Foils - YouTube

From the film there are three areas it improves...
1. The effect of the hull squatting or properly trim. This reduces both form and wake drag.
2. It straightens flow off the stern... this reduces wake and some form drag.
3. It reduces the tough and stern wave following the boat... this reduces wake drag.

I believe it likely also counter acts the effect of shaft angle some... also I believe it would work best with a bulb type bow.

It seems that likely it would be very much less effective on a sail boat type hull or one with the old fashioned what we call canoe stern.

Water is a viscous material and the effects of wake are not to be taken as nothing so it is my opinion a great idea. Now certainly some of the effect would be changed with pod type drives where the propulsion angle is parallel to the direction of travel... the question there is would it help more or less? However, on most modern motor yachts I believe it would be worthwhile investment. The question of tangles I think is not significant but it was a real issue could be eliminated with one center strut and some back sweep to the the wings. That will take time in the field of use to find out. It seems easily fit to existing boats and even easily removable or made deployable but I suspect it works best when mounted right at or just forward of the aft end of the hull shape rather than behind. It should be successful. I suspect the best marketing success would be with owners and directed toward them. The problem I see in marketing is evident many times on this forum those that operate the yachts then to be highly conservative and closed to other than the tried and true so professional advice might be prejudiced toward new things particularly hull and underwater appendages.

It will be very interesting if we get any feedback and information as to the Hull Vane works for them in a real situation. Theory and test tanks are one thing, but the real test is about to come. Hopefully it will be everything hoped for.

I am pretty sure, the hull vane will work as advertised on this yacht. The underwaterbody of this so called "High Speed Displacement Hull" and the hull vane were designed and tested to work in combination. A typical yacht will not have any dramatic load changes, associated with large variations in draft and trim. As long as the hull and the airfoil are kept clean and undamaged, they will most likely work as advertised.

IMHO, the predicted savings, in fuel consumption and/or lower propulsion power required, of 33 %, sound pretty optimistic. But even savings in the range of about 20 % would be sensationell. Hats off to Dr. Oosanen, if the daily use of this yacht will proof his calculations.

But transfering this numbers directly into the commercial world, might be a little hasty judgment. I personally do not believe, that a fixed hull vane (fixed in angle of incidence and draft (in relation to the water level) and in height above the prop axis) will cover the different conditions of a cargo vessel or large passenger vessel / ferry as far as loading conditions are concerned. The draft of commercial vessels can vary tremendously and therefore change the flowpattern around the hull and the wake completely. Plus commercial vessels are not kept as clean as yachts below the waterline. Growth can turn the savings into a different story.

Will say, for a commercial vessel with varying cargo load and draft, the hull vane most likely has to be adjustable, both in AoI and depth.

To answer a few of the questions above:

1. one of the first full scale applications was on a sailing yacht for the America's cup in 2003. Reduction of 8% at 10 knots was achieved, as well as the ability to reach closer to the wind. Unfortunately, the rules committee did not permit the use of it. Current high performance yachts (America's Cup and Volvo Ocean Race) sail too fast for the hull vane, but large cruising yachts, of which several are under construction at the moment, could be good candidates.

2. the 33% figure for MY Alive is for the combination of the FDHF (Fast Displacement Hull Form) and the Hull Vane. The Hull Vane will account for 20-23% of the reduction (depending of the speed). We will not be able to test the yacht without Hull Vane (as we did on a 55 m supply vessel in July), so for comparison we have to rely on the CFD work and model testing which was carried out. Also, these numbers are exceptional because the boat sails at the most advantageous Froude numbers. For suitable commercial ships, it's more in the range from 5 to 15%, which is still very significant.

3. to work properly, the vertical position of the hull vane should be at a specific distance below the transom (independent of the water level). If the ship is very light loaded and the Hull Vane is near or above the water, the effect will of course be lost.

4. fouling of the hull will influence the frictional resistance (though not very much the flow pattern), while the Hull Vane can only influence the wave-making resistance. Actually, the Hull Vane will reduce the load on the propeller(s) and therefore can compensate some of the added frictional resistance due to fouling. But cleaning your hull is easier than installing a Hull Vane, so why not start with that?

5. HTM09 - thanks you liked our bar! If you buy some Hull Vanes for your container vessels, I'll see if I can throw it in the deal
I attached a pic for those who are wondering what we're talking about.

Innomare I had not heard of this could you tell us more or have a picture/drawing of what this was like?

Lets say you had a sail yacht for example using yacht somewhere between a Swan 90 (29M) and the Frers Unfurled (34M) about where would this be located in general... about where the rudder is or aft of that location... would it be a single vertical fin with wings off it... about how far below the surface... if one were to build one of the new DSS type boats of Hugh Welbourn where there was less heal would it work better... ??? Just wondering for now but call me interested...

Maybe slow brain cells and not recalling correctly; But did one of the Atlantic Challengers use a hull vane?

I seem to remember something... like but I don't think it was a hull vane exactly.

Finally found an old image. Yep, dead brain cells.
Those were horseshoe rudders/nozzles. Maybe I was remembering the arch.
Oh well, Thx for the comeback Karo.
,rc

That U rudder deal never went anywhere... heavens I have thought about a ring shaped rudder for a long time...

Here is a Swan 90 (picture of Red Sula off a brokerage site). This is typical of modern performance sail boat underbodies. What you were talking about had a U shaped rudder deal rather than the twin fins. Now sail boats lean and the twin rudder allows larger effect off the leeward rudder as the other becomes pretty close to horizontal with little effect. This is what intrigues me is how the Hull vane works on sail boats and the tilt! And, where it might be located.

See with Welbourn's sliding horizontal fin just after of the mast step it that might make the hull vane work better on a sail boat. When Innomare mentioned that they considered sail boat options it rather surprised me for two reasons... problem of heel and second the fact the sail boat hull are darn efficient... though he mentions 8% gain which is much less than 20-30% on motor boats. I would imagine it would be mounted after of the rudders and on a single center vertical support. If it was like a canting keel it might be pretty good. The problem I see with that is Frers about 10 years ago did the pretty exotic "Only Now" boat with a canting keel and forward vertical fin and really never did anything. A standard boat like Unfurled or Moonbird both near same length etc would eat it up. Volvo racers used canting keels to effect but I really think Welbourn's idea is better solution. Canting keels are hugely hard to sail and you lose a lot to side slip without rudders and a forward fin to make up.

But I see with Welbourn's concept and if the vane could be integrated into the rudders for mounting might be something. The problem is the ratings systems might eat up you gains... as they are designed to even the playing field... and make it who you sail the boat (poorly with me on the wheel... but I am good a trimming) but something to think about. It's like Unfurled and Moonbird both came on the market... and the newest performance Fitzroy 37.5m Escapade is now for sale too (new owner/builder I think got in over his head and lots of problems finishing up as Fitzroy closed)... it makes you think. Of course acquiring a know successful existing boat... if you don't do well then everybody says your a poor sailor and its your fault you nearly finished in the max time limit.

Page 8, section 4.4

http://www.oossanen.nl/beheer/wp-co...s_cup_yachts_-_recent_design_developments.pdf

Thanks... great article and defines much on sail boat design. I am surprised and thinking on not by that the hull vane works better at angles of heel... that helps understand it much better.

Basically, it is simply hull form optimized whether that form is tilted or not does not matter. As modern sail boats have straighter shapes on the sides than the bottom it all makes perfect sense... with the bottom at an angle of heel it still cleans up the flow off that portion but at angle of heel the water slipstream off the straighter sides interferes with the angular slipstream off the bottom shape... increasing drag at the stern end so the hull vane straightening that out makes the boat overall have less shape induced drag due to the lessening of the interference of the side and bottom slipstreams creating drag force. This means I was wrong in my initial assessment... it certainly proves the kinetic theory of slipstream shape induced flow bending affecting drag and lift characteristics... which in the hull vane translates into drag and forward bias lift or propulsive force. Very good, Excellent!

So heel with the hull vane is not a bad thing but good... as it lessens drag overall.

Hi, the Hull Vane on Defi Areva was shaped differently. The foil was a rounded profile in section view (to follow the curvature of the hull). It was mounted on two struts, like most of the Hull Vanes.
It was located behind the rudder, but as on motorships, the location of the Hull Vane and its angle are very critical. This requires either an extensive model testing program or a CFD study. Place it wrong and you only create a source of drag.

The Défi Areva dates from before the potential of CFD (Computational Fluid Dynamics) was fully unleashed. I think we would be able to optimize it better nowadays (with CFD), but as I said, current racing yachts sail at higher Froude numbers and the Hull Vane may not be suitable at all for them (contrary to large cruising yachts).
You can see the tip of the Hull Vane piercing the water surface in the photo attached (sorry for the low resolution).