hreko

Interesting design to discuss about? www.hreko.com

 

Good looking boat and tender idea. 110 is to low for stability.

 

This boat is also compromise like any other boat. “All yachts are a convoluted set of compromises” said PAR ones. AVS of multihulls is round 85 degrees, they cannot recover from an overturned position without substantial help from aside. They still sail all over the world. 110 degrees is for hreko more than safe. Its huge float capacity, “life jacket” on the top of the mast and its RM95 of more than 1000 kgm make hreko save enough. Of course we can talk like: “What happened if your parachute does not open”
But this is another story. Most people that decide for this concept will enjoy in electric or wind, in shore and lake sailing . From my opinion, for unlimited ocean sailing one should change some design details on such boat and still retain the basic concept. If Hreko 1ooo ( 10m boat+2,2 m tender/4000 kg) has STIX value of 30,4 Hreko12oo ( 12m boat+ 2,4m tender/6500 kg) will easy get 32 points you need for A category
I am not slave of rules established by people who ‘believe in God’, fans of Colin Archer that do not realize that in his time there were no floating containers. Of course I am not scared that I will hit such thing but I will always change one boat that will sink for boat that will stay on the surface, even capsized.
To be malicious, Colin Archer design will never create high impact damage because you need speed not only mass.
Here, there is no question of Bft 11 and monster breakers, but older sailors that have respect for nature( like they always had) and have no plan to sail ‘round the world’. They did it. Now they will have one easy and comfortable boat that will not make much noise on the way to the peace.

 

Hi, some recent pictures!

 

I've always believed that placing "sponsons" in a hull was the best solution to a problem of defective hull design. Apparently I was wrong.
You really can not get the same values ​​of RMT, and other parameters of stability, with shapes that have no strange lumps?
A so asymmetrical hull can not be good for sailing the boat heeled. But I can be wrong too.

 

I also fail to see why would the sponsons be a better solution than an adequately shaped hull. If you had shaped the hull to the same width you get now with the sponsons, you'd gain the interior volume. With the sponsons you get the increased stability of a wider hull but the interior volume of a narrow one. I don't get it...

 

Daiquiri, the sponsons are part of concept! Try to think about bilge keels, about those specific low aspect bilge keels that make part of that diagonal water ballast system! Try to get out of your head centerboard keels with their moment, leg & weight. Take a look at the curves below animation http://hreko.com/concept/ . Without sponsons the boat should not have second ‘stability wave’ from about 45 degrees to 70 degrees of heeling and I need ‘that part’ of stability curve.
The ‘soft part’ of sponsons ( floats) generally assumes the role of fenders. http://www.fenderinnovations.nl/our-fenders-innovation
The same answer applies to TANSL. Try to think like this: Hreko is hybrid between multihulls that sailing against the wind normally leans up to 5 degrees, and centerboard keel monohulls that leans usually up to 30 degrees.
Hreko usually leans 15-18 degrees (with moment of almost 4000 kgm!!! that will capsize comparable conventional boat), gets luff keel out of water with good underwater profile.

 

hreko,
I do not know why you need "that part of the Stability curve". But, if you actually need it for something, it would be much better to get it as always done in shipbuilding: placing a forecastle deck or increasing the height of the bulwarks at the bow. This also has the advantage that when the boat heeling, this additional volume gets lift the bow, ie reduce the negative trimming that always occurs whenever a boat heeling. With your system, however, this increases negative trim, bow gets more into the water, which is never good.
Attached drawings of existing ship which has, also, a second relative maximum in the curve GZ. This is a totally normal boat that apparently behaves similarly to your design. And as you can see, the angle of "vanishing stability" is about 103 °, close to 110 of your boat.
I've always known designers sailboats trying to get the hull shapes that produce a water plane shape as close as possible to all heeling. From this point of view, a cylinder is the perfect hull making possible that in all heeling, the flotation area is the same. I have no knowledge to assess the importance of this idea. What is clear is that your design achieves the opposite.
I see no need for liquid ballast. As I interpret it, is useless. As there is probably something I do not understand in your reasoning, I´ll tell you what I think and you explain to me where I was wrong: You add appendages and then you fill it with water. These appendices provide additional thrust I, applied at the center of buoyancy of the appendix. When filled with water, what you do is to add a weight equal but opposite to the additional thrust, center of gravity in the center of buoyancy of the appendix. Therefore, you place two forces nearly equal but opposite, applied almost at the same point. In effect this is zero torque. Now, though, the wet surface has greatly increased and therefore the frictional resistance. No doubt I'm misinterpreting some concept.
The output of the water at the stern, all designers care so much, are totally inadequate, in my opinion. When other designers try to achieve a laminar flow along the hull, especially aft, you put there a device that makes the turbulent flow.
I guess what you want is that the boat can heeling more and more upwind. I do not think you get it with all this. Of course, while it may heeling over, the ship will be slower than any other because of all the increased resistance.
All heeling moments that can support the boat are regulated by appropriate forms and proper weight distribution. Like I said in my first post, when one do not know what to do,one put the sponsons. I do not know if a 4000 kgm heeling moment is much or little, or think it matters. What you need to do is make the boat as fast as possible in all circumstances and traditional methods have proven to be sufficient: the hull forms, positive seating, fixed ballast in the keel, oscilating daggerboard and other various methods that I, not being sailboats designer , don´t know.
I think, for the moment, that's enough. I await your clarification. Thanks in advance.

 

The fenders function of sponsons sound like secondary to me, the primary being a mean to increase the stability. If that is so, then again - why not simply shape the hull in such way to have the same beam as with the sponsons but with more interior volume?
If the hull had the section indicated with red lines, it would obtain a similar stability curve, but would gain the interior volume indicated with the yellow fill:



That's the part I am struggling to understand.

Cheers

 

TANSL, I am not naval architect and no professional sailboat designer. Another problem is that my English is not very good, I am not sure I understood what you meant to say. But I’ll do my best.

If you want to understand this design you can go to web site of that project and read the features: ‘Concept’ and ‘Hybrid stability system’ ones more to understand this concept. This concept is one attempt to get sailing monohull of 4 t displacement, with less than 0,5 m draft and RM25 more than 4 tm !

“With your system, however, this increases negative trim, bow gets more into the water, which is never good.”
If you use water ballast on HReko, typical with close hauled sailing (and why not?, water ballast is effective like canting keel) you will shift 350 kg water 3,6 m( 12 foot) transversal (and diagonally upward) to the luff side and 2,6 m( 8 foot) toward the stern! This will keep the nose of HReko out of water especially if I put some weight on the bow of the tender.

“Attached drawings of existing ship which has, also, a second relative maximum in the curve GZ. ………..”
HReko is 37 foot category sailboat with 4 t displacement, and not 46 foot and 12 t displacements!!! Do you weight 80 or 240 kg?

“From this point of view, a cylinder is the perfect hull making possible……” “I see no need for liquid ballast………”
Take a look at the hull shape of those most advanced sailing ******** http://www.vendeeglobe.org/ fully operated by one person in all weather conditions for a few months at maximal speed. They have huge water ballast. No cylinder

“I guess what you want is that the boat can heeling more and more upwind.”………
No I do not want more than 15-18 degrees, preferably no heeling at all but this is impossible with sailing monohulls.

“The output of the water at the stern, all designers care so much, are totally inadequate, in my opinion.”…….
The bottom of tender (about 2 m wide) on the aft is a smooth extension of the hull( HReko's stern). It is not perfect but also not bad if you count other advantages of such solution. It significantly extends the water line and contributes to the increase of the maximum theoretical speed about 0.5 knots

“What you need to do is make the boat as fast as possible in all circumstances and traditional methods have proven to be sufficient:”…………
But there are still some stupid people they think it can be better.

 

Dear friend, I do not know whether or not I understood the concept of your design or the 'Hybrid Stability System'. What I have clear is that you do not understand what I say, or knowledge on which I base my opinions. I think there is not a difficulty arising from the language we use, I'm not English speaker, but the lack of knowledge. So, with all love and respect, I suggest you head to a naval architect, speaking your language, and ask him to critique my comments. So avoid getting into an argument without end. Of course, I would like to know the outcome of this review.

I repeat that I deeply respect you and I believe that innovation is essential to move forward in all facets of human activity, but anything you can think of does not have to be viable or, perhaps feasible, but not improving the existing.
Sicerely

 

This increases even more my previous doubts about sponsons and the lost interior volume, which you have not addressed in your reply.

So, not only there is a smaller interior volume than it could have been with a differently thought hull shape, but part of this volume will also be used for water ballast tanks and piping. It means even less useful interior volume.

I don't know if this is intended to be a commercial product or a boat for just your personal use. In case you intend to produce this boat for the market, then IMO you might be going in the wrong direction - with all the great respect for the job you've done so far. Fact is - the interior volume is one of the most valuable characteristics of any boat. You can make it as "green", modular or else you wish, but if you don't maximize the interior volume for a given length and beam, you will have hard times in finding a market for this boat.

Your competitors will have the advantage of simpler hull forms and hence lower construction costs. So they can offer cheaper boats. I will left aside the matter of aesthetics - high doghouse covered with PV panels, and all that bow hardware definitely doesn't help there.

That's all just my opinion, of course - and honestly I feel a bit sorry to write these critics after seeing all the job you've done up to this point. Since we are talking about your money, it is your right to think it over or to just dismiss these considerations.

Cheers

 

daiquiri,

It's true but I do not want boat of 10 m long and 4,5 m wide. I do not like such hull with L/B ratio 1:2,2, and I think no extreme is good as always you lose on other side. What shape of hull should you choose with your concept? What width on the water level? The connection with tender should be problem; the whole concept should be disturbed. When you design such versatile boat you have to think about lot of things, it is not so easy.I think that you do not see the forest from the tree.

Sponsons are part of hull in the cabin section ( cc 3,2 m) so you have this space ( 4,2 m wide on the proper height) in the cabin. On the other side if you use 6 fenders it will occupy cc 300 L of most desirable space on your boat. I have this space for other things. And I do not have to tease myself with fenders every time that I go in and out harbor.

Imagine you silently sail from your busy port, through channels of Venice lagoon to the open sea. You do not have to think about fenders, you do not have to think about draft, you do not have to think about your heavy lifting keel.

Those words above I wrote yesterday as answer on your first post but I let one day rest and read ones more to prevent to unintentionally insult you.
I think you still do not see that sponsons are part of cabin space, water ballast tanks are “out” of boat shell and back of cabin( cockpit area). With your concept you have to place waterballast inside hull so you lose the space too.

"It means even less useful interior volume".

Water ballast has nothing to do with interior space (cabin space). Water from the keels goes to ballast tanks situated 'out' of hull in the last 3 aftboat meters. This space is normally not used in "normal" boats to store things. So this is also not lost space imo

 

If you fair the lines so there are no sponsons, but an even fair, the stability curve is better. However, that is the typical "skimming dish" that got banned from ocean racing because they float upside down and won't recover from a capsize. The latest loss of life was around here on the 2011 Macinac race. The boat name is "Wingnuts"

 

Hmmm, very interesting


-Two sailors died in the 2011 race when WingNuts (berthed in Saginaw, Michigan) capsized in 75 mile per hour winds. [2]

-Mark Morley, 51, the skipper of the WingNuts, and Suzanne Bickel, 41, both of Saginaw, Mich. died of head trauma suffered when the boat turned over,

-the first deaths by accident in the race's 103-year history.

If " normal " boat turn over people can not suffer from head trauma of course.