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I have been seeing a number of sailboats with hard chines. What are the advantages or disadvantages of hard chines?
I can see where longitudinal strength may be increased but what about sailing characteristics. It would seem to make the boat stiffer but I'd love to hear from someone who knows a little about design.
 

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Have you been following the 'Interesting Sailboats' thread? Plenty of discussion on all the 'new' designs, many of which have varying degrees of the chine approach.

Must be something to them, the chines are working their way forward recently.. but for me it's hard to imagine that the vestigial 'chine' that you see on some Jeanneaus, e.g., would make much of a difference.. Paulo (PCP) will disagree with me on this..l. ;)

However, chines don't seem to be fading.. at the same time you see designs like those by Ker, and the Sydney line, that seem to go the opposite way with narrower WLB aft and strong topsides flare in the aft quarter sections - a very different look.
 

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One of None
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Hard chines are a plus on shallow draft boats if I'm m not mistaken.
 

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Hard chines like the good 'ol Thunderbird obviously put reserve bouyancy into the water when immersed.. and some of the more pronounced chines seen on some of the latest boats are more along those lines and then some with the pronounced beam aft and the 'wedge' shape.. The newer Hunters are more 'T Birdy' than the Jeanneaus, esp when seen out of the water.

Like wing keels, plumb stems, 'wave piercing' bows etc, in some cases one has to ask 'fad or function'?....;)

I'd love to hear BP's take on comparing, say, the chines on the Jeanneau 379 vs the RM boats and some other more extreme European designs.
 

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Have you been following the 'Interesting Sailboats' thread? Plenty of discussion on all the 'new' designs, many of which have varying degrees of the chine approach.

Must be something to them, the chines are working their way forward recently.. but for me it's hard to imagine that the vestigial 'chine' that you see on some Jeanneaus, e.g., would make much of a difference.. Paulo (PCP) will disagree with me on this..l. ;)

...
Of course:D ....and there are things that are objective, not a matter of opinion: The chines on the Jeanneau are not vestigial. Are as marked as in some racing sailing boats.





I believe that on the Jeanneau they don't have to do mostly with speed but with making sailing easier maintaining the boat upwind in a grove at the more efficient heeling angle and making downwind sailing easier, limiting roll.

They are also used by Benetau and several other brands, in fact I should have said, other designers. Jeanneau are designed by Marc Lombard, many other designers use them, principally the ones that also design solo racing boats were the chines were developed as a way to make the sailing more easy for the solo sailor and that way increasing performance.



Regards

Paulo
 

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Super Fuzzy Moderator
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Fast mentions the Thunderbird ..... I have always been under the impression that hard chines as per the TBird were simply to make it easier and cheaper for the home builder. Our old VDS34 was multi chine in steel. Other VDS34s in cold moulded timber or glass were round bilge.

Still and all I'm guessing the OP was talking about the chines apparent on more modern designs such as the Jeanneau Paulo posted rather than antiques like the TBird or VDS34.
 

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Fast mentions the Thunderbird ..... I have always been under the impression that hard chines as per the TBird were simply to make it easier and cheaper for the home builder. Our old VDS34 was multi chine in steel. Other VDS34s in cold moulded timber or glass were round bilge.

Still and all I'm guessing the OP was talking about the chines apparent on more modern designs such as the Jeanneau Paulo posted rather than antiques like the TBird or VDS34.
I think you're right (twice!! in one post! :p)

Interestingly the other day I saw a new H40 out on the hard and my first thought was 'big Tbird'...
 

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grumpy old man
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Do not generalize about chines.
Do not assume they are doing the same thing on different boats.
The chines on a lightweight flyer and not there for the same reason they are on a Bentaeu mom and pop boat.

On some boats chines are for performance.
On other boats chines are for volume and have almost zero effect on performance. They look trendy and fool some people.
On some boats chines are as effective as a spoiler on the trunk lid of an old Toyota.
 

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I think you're right (twice!! in one post! :p)

Interestingly the other day I saw a new H40 out on the hard and my first thought was 'big Tbird'...
Our first "real" boat was a 1957 era home built T-Bird 26 (I still have the complete set of her plans) on which we had to add a 500# lead "shoe" to make her suitable for sailing on SF Bay. Once she heeled down to her chine she just refused to go any farther and went like a scalded cat. For all intents and purposes, the first nearly "ULDB". Great boats. Designed by Ben Seaborne for the Western Wood Products Association at the end of WWII in the WWPA's effort to find applications for plywood. We sailed that boat all over heck's half acre relying on a "bucket" head, Primus stove (for cooking), oil lamps for light/heat, and scratchy old WWII surplus wool Army blankets for berthing. Several of our friends from those daze that haven't yet died still have their boats. The famous old TransPac flyer "Ragtime" was naught but an up-sized T-Bird.

FWIW...
 

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Do not generalize about chines.
Do not assume they are doing the same thing on different boats.
The chines on a lightweight flyer and not there for the same reason they are on a Bentaeu mom and pop boat.

On some boats chines are for performance.
On other boats chines are for volume and have almost zero effect on performance. They look trendy and fool some people.
On some boats chines are as effective as a spoiler on the trunk lid of an old Toyota.
Yes, that's what I have said except than on a Beneteau I don't believe they are there for nothing. They are there for controlling heeling and maintain the boat sailing at low heeling angles. They are also there to make downwind sailing easier diminishing roll and I am not talking specifically about the boat that I posted (that has a very good performance downwind with lots of wind) but about less sportive and comfortable boats like the luxurious Sense series (heavy too):



Regards

Paulo
 

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grumpy old man
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The chines on the boat in your pic are there for volume. Look at the way that corner is digging in at the transom; That is textbook SLOW! That boat would be faster without that chine. They can get the stability they need with the right keel. That chine is all show and volume. Of course it "helps" stability. Any extra volume outboard aft will help stability. But that photo is the perfect example of a chine slowing a boat down. Heavy boats don't need chines.
 

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This do, Bob?

 

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grumpy old man
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Perfecto Faster!

Look how that stern is not digging in. Look how the water is streaming straight off the run
and leaving the transom edge free and clear. This boat is performing like a high powered powerboat. It's planing with the power from it's huge rig driving a light hull with minimal rocker and chines. Chines help keep the buttocks flat.

Your mom and pop cruising boat doesn't perform like this. It's too heavy, has too much rocker and too small a rig.

If you wanted a very efficient 40' powerboat that maybe used a 35 hp diesel you would be operating in the same or similar performance realm as a mom and pop sail boat. I tank tested two hulls for such a high efficient powerboat. The client wanted to operate at 12 to 16 knots. Unfortunately that was well above the displacement hull speed of 8.26 knots. I designed two hull and two models were built, $9,000 USD per model. One model had a round bilge and the other had chines. My client spent over $50,000 on tank testing.

At displacement speeds the round bilge model behaved beautifully. But above 10 knots things began to go wrong. By 14 knots the stern had sunk, the boat squatted and threw up a huge wake. The chine model worked OK at low speed but not as well as the round bilge model. More drag and more resistance at low speed was the peroblem. But once we got above 14 knots the chine hull was immensely more efficient. It just took a lot of horsepower. 16 knots was easy. We eventually got that hull to 20 knots.

If you asked for a 40' power boat and you would be satisfied with hull speed, 8.5 knots, the best shape might be a double ender, the exact polar opposite shape to a chined hull. This is where most mom and pop boats operate, i.e. at or below displacement hull speed.

I reviewed three new, modern European models last month for SAILING Two had chines. The boat without a chine was in almost every way a similar boat to the other two, just no chines. The no chine boat was designed by the Farr office. I am inclined to think they got it right.
 

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The chines on the boat in your pic are there for volume. Look at the way that corner is digging in at the transom; That is textbook SLOW! That boat would be faster without that chine. They can get the stability they need with the right keel. That chine is all show and volume. Of course it "helps" stability. Any extra volume outboard aft will help stability. But that photo is the perfect example of a chine slowing a boat down. Heavy boats don't need chines.
Bob, not in this case, I mean volume. That boat has nothing except storage on the aft part of the boat (no aft cabins). The extra small volume would serve no purpose. The chines are there to limit heeling. That (and other similar boats) are designed to sail with very low heeling angles. The wives like that. Also to make very easy and safe downwind sailing. I agree that the the chines are not there for speed but even so that boat surprised many, include me by having a good sailing performance.


Regards

Paulo
 

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grumpy old man
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Pauol:
Yes, volume aft will increase stability every time. Sometimes a stiffer boat is a faster boat. But I look at that rooster tail fountain of water shooting up from that tranbsom and to me that does not look like the shape of speed.

I agree with you, everyone likes a stiff boat.
 

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Pauol:
Yes, volume aft will increase stability every time. Sometimes a stiffer boat is a faster boat. But I look at that rooster tail fountain of water shooting up from that tranbsom and to me that does not look like the shape of speed.

I agree with you, everyone likes a stiff boat.
Bob, regarding speed I am agreeing with you since the beginning. On the Sense 46 the chines are not there for speed but for control: to allow max stability at a relatively low angle of heel. When that rooster tail starts to grow up, then it is time to reef the boat even if for one used to sail in more normal boats it seems that the heel angle is rather small. For comfort reasons they wanted a boat that heeled less than more traditional boats while sailing so that chine increases stability at a rather small angle of heel and if someone insist in going over it, than what he would get is more drag and a bigger rooster tail, not more speed.

Those series designed by Berret Racoupeau represented a revolution in cruising yacht design. The idea was to mingle the advantages of a multihull in what regards interior space and sailing with little heel with the seaworthiness of a monohull, using for that the shape of boats developed for solo racing. The fist boat of the series, 4 years ago was this one:


I, like most at first, thought that the boats would have a great interior but that would sail badly, specially upwind and in light winds. Well, I was wrong and it was very funny to see that the several boat testers from whom I read the reviews were as astonished as me. Off course the boat is not a performance boat but it sails well for a cruiser of that weight allowing sailing with very little heel and a huge interior as well as a huge cockpit living space as well as a big storage space (all the space normally used by the aft cabins is storage).

Regarding chines and speed I think that many times they are used more than for absolute speed for speed with control. On an offshore boat meant to go for days at speed, if that speed is not easily controlled in the end the boat loses in performance because it is impossible to sail the boat for all that time at 100% driving it always at the tip of the fingers with all crew working to drive it.

Look at this very interesting picture of a Jason Ker hull:



See those chines, like the ones we see on some racing boats? well they do not exist on that hull since that is a mold, the hull is the interior and it has no chines but follow the same line. The boat is designed to sail on the same angles of heel but on a very slightly rounded surface. It will be slower? I don't think so but certainly it will be more difficult with the boat more lose and needing adjustments at all time.

For a boat designed to go at speed for several days with a solo pilot that extra speed can be of no use because he cannot be all times at the wheel and the autopilot while not be able to cope with the very precise adjustments needed to have it always under control (not the mention the precise adjustments that come from the movable ballast that is the crew weight and the permanent sail adjustment).

So in the end in what regards performance, absolute speed is not everything and sometimes easy controlled speed is more efficient in what regards racing than absolute speed. It is not by chance that the chines in what regards an improvement for performance started and were developed on solo racing boats, precisely the ones where easiness of sailing can be an advantage even over absolute speed.

Experience showed that in what regards Open 60's the more powerful boats were not the fastest (they could not manage all that power) and after a race to power, nowadays the fastest boats are not the more powerful ones (those belong to a previous generation) but the ones that offer the best compromise between power, drag and easiness of sailing (power management).

Bottom point, all this has nothing to do with the sense (where those chines have not do with a better sail performance) but only with the pleasure to exchange views with you;)

Regards

Paulo
 

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grumpy old man
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Paulo:
When I was doing those last three reviews I went on line and read a sailing report for one of the boats published by an English magazine. They claimed that the boat was fine until about 15 degrees of heel. Then the chine was immersed and they had a hard time past that point keeping the boat from rounding up. I think that can be a problem with any boat with an ultra wide stern. I've seen it myself.

I was wondering what you thought of this. Do you think it is more of a problem consitant with this type of beamy, chined hull when pushed hard?
 

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Paulo:
When I was doing those last three reviews I went on line and read a sailing report for one of the boats published by an English magazine. They claimed that the boat was fine until about 15 degrees of heel. Then the chine was immersed and they had a hard time past that point keeping the boat from rounding up. I think that can be a problem with any boat with an ultra wide stern. I've seen it myself.

I was wondering what you thought of this. Do you think it is more of a problem consitant with this type of beamy, chined hull when pushed hard?
Only an ass would try to sail a boat like the Sense series with over 15º degrees of heel.

The boat was designed to sail with less heel and it opposes violently to more heel, screaming for a reef. The boat would not go faster and will only be doing more drag. However I read many test sails about this type of beamy cruisers designed to heel very little and never heard about the boat have a tendency to round up, quite the contrary: The boat is slower with more heel, more drag but will only round up if someone is forcing the boat to insane angles of heel. Much more than what the boat is conceived to sail with. What sail test are you referring too?

Here are some. I read a lot more but they are not availabe online:

BW magazine:

We rolled out the mainsail and then the 105 percent jib so we could tack our way seaward in the narrow channel. The 55 handled well as we threw her through tack after tack. The boat has twin wheels and twin rudders, so even when heeled slightly the rudders bite the water firmly. ... The 55 tacked inside 90 degrees and the small headsail was a snap to trim.

In the building breeze, the 55 tended to translate wind pressure into forward motion more than into heeling angle. The boat has 16 feet, four inches of beam, which gives the hull a lot of initial stability. With a very broad transom, that stability is enhanced, while the hull has been given extra volume aft to accommodate the large cockpit and storage lockers.

The 55, like her little Sense sisters, likes to be sailed very upright. The hulls have chines in the after sections and you don't want to heel the boat beyond the chines. ..

We close-reached out into the open waters of the Florida Straits at a very pleasant 7 knots and then cracked off a bit more so we could watch the speedo climb past 8. With the twin rudders, the 55 steered like she was on rails and held her line very nicely-easy on both the helmsman and the autopilot.

.. Easing sheets even more, we ran up the channel toward the bright lights of Miami with the genoa and main pulling us along at a good clip. Under sail, the Sense 55 has an easy motion, a good turn of speed in all wind angles, and is set up well for a couple to manage all sheets and control lines.


and then there is this strange one from cruising world magazine even if they seem to be motoring the boat:

"By the time I'd run below and donned my foul-weather gear, gusts hit, and all 55 feet and 40,000 pounds of boat lurched onto its side. Wayne, on the wheel, eventually brought the boat back nearly into the wind, and with the throttle opened wide, managed to maintain headway-barely-and steerage. Steep waves soon engulfed us as 50 knots plus of sustained wind ripped the tops from the waves. Lightning crashed all around us in a grizzly show that lasted well over an hour. Tethered as I was to the sturdy stainless-steel handrail running the length of the cockpit, and somewhat protected by the dodger, my first impressions of the Sense as a party boat quickly vanished. "Great boat for a blow," I concluded."

Beneteau Sense 55 Sailboat Review | Cruising World

The Sense 46 has a shallow bottom, a creased chine in her topsides aft, and a beam that is carried right to her transom, giving her an immense amount of form stability. ....

The Sense 46 is shown here sailing slightly overpowered. Her lines call for her to sail with only a 10-to-12-degree heeling angle. It might take sailors used to conventional sailboats time to get used to this comfortable heeling angle -- just watch the speedo! Note that the mainsheet runs through two blocks on the arch. This is a major innovation of the Sense series and makes boat handling easier and safer.

Low Heel Angle. Going along with her hull shape and broad beam (14'6"/4.43 m) is the fact that she is designed to sail with only a 10-to-12-degree angle of heel. Heeling her more just slows her down and makes her uncomfortable for family and friends. This is the "genius" aspect of the Sense 46 -- keeping her comfortable means she is sailing on her lines and going as fast as she can...


Beneteau*Sense 46 (2013-)*2013* Reviews,performance,compare,price,warranty, specs,Reports,Specifications Layout, video | BoatTEST.com

Sense 46: "I was surprised at how easily the big boat topped 6 knots in a 10-knot breeze, at which point the wide beam aft and hull chine seemed to lock the boat in place to minimize heeling. The advantage of having twin rudders became very clear as the breeze continued to build and the windward rudder started to lift out of the water. Steering remained smooth and easy throughout, and the boat resisted broaching even when clearly overpowered."

Sail Magazine

Beneteau Sense 46 | Sail Magazine

There are a lot more in French and German but all say pretty the same.

Regarding heeling and the type of boats based on Open hull forms not all are the same and if the type of chines and hull design that is used of mass market cruisers like the Sense are designed to prevent heeling at very low heeling angles the same doe not happen in a boat like the Pogo whose hull is designed to sail with a lot less heel than a narrow performance cruiser like a Luffe but with a lot more than a Sense, I mean close upwind, allowing its considerable ballast ratio and ballast at the end of an almost 3 m keel to produce RM to join to the one provided by the hull form.

The boat is designed to go comfortably fast upwind with this heel angle (bigger than on the sense):



but can be pushed upwind like this:



The boat will be faster, but not much, however if you are racing... you will go for it. But that's just close upwind. with a bigger angle the boat will not take so much heel. I have sailed on that type of boat going fast with a lot of heel and I have to say that is really odd, being on top of the mountain looking down at a big fall if you don't hold tight:D. Not necessary anyway if the point is cruising, even fast.

Regards

Paulo
 
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