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post #5981 of 6763 Old 02-03-2014
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Re: Interesting Sailboats

Looking at those photos I don't see the chines doing anything.
That last pic shows the boat dragging quite a bit of rudder angle.
Maybe he was falling off. Maybe the boat is not well balanced.
I see lots of wetted surface. I see boats dragging their sterns.
In that first pic there is not enough chine definition to do anything but satisfy the "fashion" guys.
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post #5982 of 6763 Old 02-03-2014 Thread Starter
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Re: Interesting Sailboats

Quote:
Originally Posted by bobperry View Post
There is no question among designers that chines help a lot when you have a light, high powered boat operating off the wind where surfing or some type of borderline planing is possible. If you are sailing a boat at twice displ hull speed you need dead flat butts and a wide stern, just like a powerboat! This we know.....
As we know also that the problem is combining that motor boat hull shape with a shape that allows the boat to sail fast upwind

We also know that in what regards upwind / downwind overall better performance for a same length of boat there is not a big difference between the possible beam options and we also now that today overall faster boats are generally more beamier than some decades ago.

I believe that is due not only to lighter boats but also regarding what was learned regarding planing hulls. If the boat is too narrow it will not be able to generate the power needed to plan downwind and it will lose so much downwind that on the overall performance would not be a match.

Regards

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post #5983 of 6763 Old 02-03-2014 Thread Starter
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Re: Interesting Sailboats

Quote:
Originally Posted by bobperry View Post
Looking at those photos I don't see the chines doing anything.
That last pic shows the boat dragging quite a bit of rudder angle.
Maybe he was falling off. Maybe the boat is not well balanced.
I see lots of wetted surface. I see boats dragging their sterns.
In that first pic there is not enough chine definition to do anything but satisfy the "fashion" guys.
It seems that we see different things. On the two pictures on the water both boats, the Sun Odyssey and the Oceanis are sailing on what their chines allow. The Sun Odyssey is making force over the chine, the Oceanis close to it. The photos are there to show to you that those two boats are designed to sail upwind in a very different way.

Regarding the chine on the first picture maybe it is from the angle. In fact the chine is as well defined as in some racing boats



You give the idea (or you seem to think) that the Sun Odyssey sails badly. I don't think so. Post the polar speed of your last 46ft, the nice one that you have already posted here, and I think I can show to you that the correspondent Sun Odyssey 463 is a boat with a better sailing performance.

Regards

Paulo


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post #5984 of 6763 Old 02-03-2014
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Re: Interesting Sailboats

Paulo:
Yes. I agree that chine is well defined. But it is not working. It is 30 metric thingies above the DWL. It can't be working if it is not in the watewr. At that heel angle it only adds wetted surface.

I don't know what 46'er you are referring to. I'm not fashionable. I don't think I have anything that is applicable in this environment.

I rarely shower. I smell like my dogs, I wear woolen shirts. My hair looks funny. I own two pair of shoes. I'm not Euro.

(I do have an amazing, very expensive hi-fi system probably cost as much as your yacht)

But I sure do like exchanging ideas with you. You are an amazing reference for whatever is new in European boats.

But it is my nature to be the devil's advocate.
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post #5985 of 6763 Old 02-04-2014
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Re: Interesting Sailboats

Quote:
Originally Posted by bobperry View Post
Paulo:
Yes. I agree that chine is well defined. But it is not working. It is 30 metric thingies above the DWL. It can't be working if it is not in the watewr. At that heel angle it only adds wetted surface.
Sorry, I think you aren't right here: The chines - even if the don't touch the water - allow the flat section to be wider what makes the boat stiffer...
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post #5986 of 6763 Old 02-04-2014
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Re: Interesting Sailboats

Rob:
Imagine shaving off that chine with a big grinder. It wouldn't take much. I'm not sure you would feel the difference and I'm not sure the boat would not be faster.

For some contrast you might look at the boats in the TP 52 class and the new Ker 43. Maybe take a look at some of the newest Reichel-Pugh boats.
These boats don't use chines. In fact the current popular stern shape is pretty much the opposite to what you would get with chines. These are round the buoys racers and designed for all round boat speed. They are very different boats compared to your Mom and Pop Euro cruiser but if chines were fast for all round performance they would have them.

Please don't think I am anti chine. I have designed many chine boats. I have been trying to say all along that there is an application for chines and there are applications where chines don't help. I am not generalizing. The attitude here for some is that "Chines are better for everything". I do not agree with that.
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Last edited by bobperry; 02-04-2014 at 06:42 AM.
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post #5987 of 6763 Old 02-04-2014
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Re: Interesting Sailboats

After giving a second thought to what I posted previously and reading all your posts I think that hard chines do not contribute as prevention from heeling. For example would the hard chines on a narrow hull sailboat make it stiffer than the same hull and ballast boat without chines? I don't think so. If caught by a gust the boat will heel past the chines and the latter will create just more drag. I think we saw a similar thing on the Swedish video regarding the Jeanneau Sun Odyssey 409, where at some point it heeled to starboard past the chine. And sailing in the groove on a hard chined boat will be more a matter of perfect sail trim, which is again more likely to be archieved by professional sailors than majority of cruisers.

Regards
Rumen
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post #5988 of 6763 Old 02-04-2014 Thread Starter
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Chines

Quote:
Originally Posted by bobperry View Post
...
For some contrast you might look at the boats in the TP 52 class and the new Ker 43. Maybe take a look at some of the newest Reichel-Pugh boats.
These boats don't use chines. In fact the current popular stern shape is pretty much the opposite to what you would get with chines. These are round the buoys racers and designed for all round boat speed. ....
and that is why I say the chines are not there necessarily there to better sailing performance but to increase control. I don't believe a TP52 would be faster downwind with chines. If it was the case we would have seen some designers using them on those boats. Those boats are raced for a relatively short time with a big and expert crew and the increased control the chines would give at possibly the cost of a very small some loss of speed upwind doesn't pay off. They can control the boat even without the help of chines and the hull shape is what gives them the ability to go fast downwind on planing mode.

I agree that each case is a case and on different hulls chines are different and work at different heel angles. Regarding performance racers they are related with the best heel angle of the boat upwind, on cruisers they can be there for that, if they are performance cruisers or in the case of slower cruisers they can be there mostly to limit heel and to give a better boat control.

One of the reasons ker boats or TP 52 don't use chines is because they sail upwind with a lot of heel taking advantage of the power created by the big B/D ratio and big draft and for that they practically use all transom (that is designed for giving max hull form stability at that angle), I mean on the max heel position the transom is all sitting on the water so Chines make no sense and would only create drag.







Quote:
Originally Posted by bobperry View Post
Paulo:
Yes. I agree that chine is well defined. But it is not working.



It is 30 metric thingies above the DWL. It can't be working if it is not in the watewr. At that heel angle it only adds wetted surface.
On those beamy hulls with large transoms the waterline varies widely with heel on the transom. See, the chine is on the water and it is not needed much heel:





Quote:
Originally Posted by bobperry View Post

But I sure do like exchanging ideas with you. You are an amazing reference for whatever is new in European boats....I'm not Euro

Thanks. Regarding chines maybe you can give me some advise how these ones, on a very recent piece of American Yacht Naval architecture, work?






The Hunter 40 has much less beam and a much narrower transom than the Oceanis 41 and will sail upwind with more heel, as the photos and video can confirm but the chine is practically at waterline so any amount of heel would have it submersed. I don't get it

I saw the video and I still don't understand how it works, I mean positively in what regards performance or control. It seems to be adding drag only. I would really like you to give me a help on this, being that a non Euro boat, maybe I am missing something



Regards

Paulo


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Last edited by PCP; 02-04-2014 at 09:08 AM.
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post #5989 of 6763 Old 02-04-2014
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Re: Interesting Sailboats

Paulo:
I'm not sure. I'll take a guess:

I think the chines on that Hunter are there to help give it speed under power. They certainly will contribute to stability but they are going to dig in at modest angles of heel and that means drag like any immersed transom.

Then there is the interior volume where it can be best used, i.e. right where the berth flat height is.

I kind of like that hull shape but it is a bit odd with those" super chines".

"American naval architecture is the same as European naval architecture. Same water. Same wind. Same laws of physics. Maybe less fashion.

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Red face Re: Chines

Thanks. Regarding chines maybe you can give me some advise how these ones, on a very recent piece of American Yacht Naval architecture, work?



Regards

Paulo[/QUOTE]

May be it works for less rolling when motoring in flat seas, sails dropped.

BTW, do you happen to know what are the cines of river/canal barges, do they look similar to the ones of this Hunter?

Regards
Rumen
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