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Old 12-01-2017, 11:26   #61
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pirate Re: Your opinion of classic VS Modern Boat Design

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Originally Posted by Polux View Post
Quoting what an old solo cruising sailor said to a friend of mine when he asked him if sailing solo a fast small Dragonfly was not too much: "Well, I can always go slower but you can't go faster"
Good one..
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Old 12-01-2017, 12:19   #62
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Re: Your opinion of classic VS Modern Boat Design

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I am coming to the conclusion that the new modern so-called "Pizza" style boats are really designed for space and comfort. And designing them after the new mono racing boats for the reason to go faster under average cruising conditions is only marginally more efficient. .....What I am impressed with is how stable and smooth the new boats sail, at least in the videos I saw in mostly protected waters without ocean swell.
Quite a contradiction here. You say that they sail marginally better and are impressed with the smoothness they sail and then you say that they are designed only for interior space and comfort?

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Yes they do sail somewhat faster in certain conditions and when not loaded down, but I cannot imagine a hull designed for planing a very good sailing shape if loaded down very much.
All the videos of these new designs I have seen sailing, are either new models with nothing in them in protected seas, or ultra-light boats that are not applicable to cruising like the one shown in the earlier posts.
Those hulls, I mean the ones of mass market sailboats based on the shape of open boats, are not designed to plane. They are based but they are not the same. What they take from the hulls of the solo racers is the ability to control easily roll downwind, to sail with less heel, to provide an overall bigger stability (increasing hull form stability). All this has as consequence a smaller effort on the autopilot that works better on this type of boats.

Regarding performance the more stable ride downwind, with less roll, translates itself not only by a bigger safety but also by a bigger speed since as you are more in control you can push more the boat.

Close upwind there is not advantage in performance even if well designed the disadvantages can be minimal and are by far overwhelmed by the added comfort and safety of sailing upwind with little heeling.

On a bean reach the added form stability results on a superior stiffness that translates itself on the possibility of sailing more area that more than compensates in speed some eventual small superior drag and therefore they are faster.

since you never saw a movie of one of those boats offshore here is one, during a Transat a Dufour 500:

Here another on a RM 10.50 a small, performance voyage boat:

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Originally Posted by SV Windrush II View Post
I would think if the hull cannot get up on plane, then its best to design it to move through the water with the least amount resistance. ...
Yes if it is a racing boat that does not need any "help" from the chines to the crew to be fully in control of the boat and that's why most pure racing boats designed for a full crew don't have chines or if they have, they have them so high that only at very big heeling angles they will enter in action. Off course racing boats will still be beamy and with all the beam pulled back, for superior hull stability, but that has nothing to do with chines.

The chines from crewed racers are completely different from the chines of solo racing boats or cruising boats. The last ones are there for helping to control the boat because solo or with a small non expert crew it is impossible to take advantage of the small gain that would happen without chines. Quite the contrary, solo or with a small crew it is possible to sail faster a boat with the help of chines helping boat control and that's why they exist on all solo racers and on many cruising boats.

On VOR crewed boats, made for sailing in open ocean and many times on very adverse conditions, even if they are crewed, the type of extensive sailing makes the small drag introduced by chines (somewhat compensated with a bit more stiffness) compensatory regarding boat control and speed at long term. So even in some race boats control chines can have an advantage on overall performance.
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Therefore I believe fast cruisers are best designed for semi-displacement, so you have some lifting effect but still mostly in the water because of the load, at the same time creates more of a cushion ride when pounding into the wind, or getting hit from a breaking wave astern.
So unless they can get the cruising Pizza boats up on plane, I don't think we will see a huge difference in speed. and the challenge is I believe a boat needs to be going at-least 12 knots to start planning, even faster depending on load.
...
Yes, I agree there. Unless they are performance cruisers like for instance this one:

Regarding mass performance main market cruisers, as you say, the diference is not big even if some, depending how old is the boat you are talking about.

Certainly the comfort of sailing the boat with less effort, with less heel, rolling much less , having the boat less affected by load, having a considerably better control under autopilot and besides all that to have a bigger cockpit and a bigger interior space are much more important than a gain of 0,5 or 1k and that's why these boats are designed the way they are, to make them better cruising boats.
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Old 12-01-2017, 15:32   #63
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Re: Your opinion of classic VS Modern Boat Design

I think they are bigger cruising boats,might be better but might not be, depends on the boat. Often a bit on the slow side downwind in light airs. Yes on a beam reach the wide beam does allow them to carry more sail which is a plus but most of them are not very close winded but life's a compromise, can't have it all. Certainly you have to take your hat off to the designers as they have designed cruising boats that by volume are much larger than their contemporaries and are very close or in some cases faster. Quality is ok for the intended purposes and they certainly seem to meet or exceed what their customers are looking for. Lots of choice these days.
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Old 12-01-2017, 16:07   #64
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Re: Your opinion of classic VS Modern Boat Design

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Originally Posted by Polux View Post
Quite a contradiction here. You say that they sail marginally better and are impressed with the smoothness they sail and then you say that they are designed only for interior space and comfort
What I ment was, the designers are more concerted about stability and space, than trying to Go fast. Although like I said and I think we all agree that they are somewhat faster and yes easier to sail.
I have to admit, sure would be nice not to be thrown around so much on the boat in heavy weather.
That's enough for me to want to purchase a modern cruiser over older designs, thus the reason why I want to upgrade. And of course my wife likes them!
I was just expecting a little more speed than what I am seeing out of them is all
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Old 12-01-2017, 16:08   #65
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Re: Your opinion of classic VS Modern Boat Design

Quote:
Originally Posted by Polux View Post
Quoting what an old solo cruising sailor said to a friend of mine when he asked him if sailing solo a fast small Dragonfly was not too much: "Well, I can always go slower but you can't go faster"
Yes, but I think a key question for a cruiser would be.....
Which type of design would be more comfortable, if forced to go slower (or even hove to) because of heavy weather?
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Old 12-01-2017, 16:24   #66
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Re: Your opinion of classic VS Modern Boat Design

[QUOTE=SV Windrush II;2302073]What I ment was, the designers are more concerted about stability and space, than trying to Go fast. Although like I said and I think we all agree that they are somewhat faster and yes easier to sail.
I have to admit, sure would be nice not to be thrown around so much on the boat in heavy weather.
That's enough for me to want to purchase a modern cruiser over older designs, thus the reason why I want to upgrade. And of course my wife likes them!
I was just expecting a little more speed than what I am seeing out of them is all

I think you can get quite a bit more performance but it's going to cost you a little more than one of the high production builders products. There are some pretty cool performers out there these days and some of them can really boggy. Wish I was in your place, shopping for something new, pretty exciting.
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Old 12-01-2017, 16:51   #67
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Re: Your opinion of classic VS Modern Boat Design

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Originally Posted by SV Windrush II View Post
What I ment was, the designers are more concerted about stability and space, than trying to Go fast. Although like I said and I think we all agree that they are somewhat faster and yes easier to sail.
I have to admit, sure would be nice not to be thrown around so much on the boat in heavy weather.
That's enough for me to want to purchase a modern cruiser over older designs, thus the reason why I want to upgrade. And of course my wife likes them!
I was just expecting a little more speed than what I am seeing out of them is all
There are two radically different types of boats you are grouping together. The Bene/hunter/Catalina group are still draggy displacement boats just with wide transoms. They may be marginally faster in some conditions, but they really aren't a game changer. Just wider versions of what went before.

Then there are fast cruisers like Pogo, RM, etc. these boats are much faster than traditional boats, go to weather very well, and thanks to the wide beam typicallly sail very flat. The downside is when you are really hard on the wind they have to carry a good amount of heel to lift the windward side or they stay stuck to the water with lots of wetted surface.

They may look similar, and superficially are somewhat alike, but the underbody is radically different.
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Old 12-01-2017, 16:54   #68
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Re: Your opinion of classic VS Modern Boat Design

Thanks for the videos Polux, I haven't seen these and it gives me a better idea how they ride, especially the one with the Dufour 500. Looks like they are taking a beating. About the same conditions I had for 7 days crossing the Pacific. Needless to say, I was very happy to enter the harbor in Hawaii after that one
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Old 12-01-2017, 17:58   #69
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Re: Your opinion of classic VS Modern Boat Design

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Originally Posted by SV Windrush II View Post
What I ment was, the designers are more concerted about stability and space, than trying to Go fast. Although like I said and I think we all agree that they are somewhat faster and yes easier to sail.
I have to admit, sure would be nice not to be thrown around so much on the boat in heavy weather.
That's enough for me to want to purchase a modern cruiser over older designs, thus the reason why I want to upgrade. And of course my wife likes them!
I was just expecting a little more speed than what I am seeing out of them is all
Depend what they are designing and for whom. If you want to go faster have a performance cruiser. Not all are the same. some are designed to be fast on the trade winds and those are planing boats, most of them are less radical and have just a bit less interior space than mass production main market boats but are faster in all conditions.

On the trade winds they are faster but where the difference is really very big is in what regards sailing upwind and with weak wind. With 10k wind, were most boats are starting to do a decent speed these ones are going already near hull speed. In the end on most conditions they are much faster.

There are several brands and options regarding both types. Speed is always expensive but some of these boats are not much more expensive....others are.

They sell much less than main market boats because what most cruisers want is a decent sailing boat, as easy to sail as possible, as less expensive as possible and with the biggest possible interior space. That is what mass main market boats are about. Main market luxury ones are about the same but with a better quality interior, some are better built others not so much.

Giving this priorities it is amazing that they sail better than older ones
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Old 12-01-2017, 18:22   #70
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Re: Your opinion of classic VS Modern Boat Design

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Yes, but I think a key question for a cruiser would be.....
Which type of design would be more comfortable, if forced to go slower (or even hove to) because of heavy weather?
Tabarly that had experience with both said it was the lighter boats but he was really comparing them with full keel boats not medium modern fin keel boats.

The general consensus is that modern boats even if able to heave to prefer to be kept sailing even if slowly. Personally I don't have much experience on extreme conditions and I have been only once on a F10 (and that was enough) but what I found out is that i could keep the boat sailing upwind, with very little sail being almost stopped in what regards GPS (doing 1k or so) but moving faster through the water, even at slow speed.

I did not put the boat heaving too and somehow I did not thought it was the best: the waves were huge and very steep, sometimes breaking over. I felt like the forward motion contributed for a better boat dynamic stability.

Anyway I don't think that would be the relevant question, I mean what is more comfortable on extreme conditions, but if it is safe, giving the rarity of those situations on the latitudes and seasons most cruisers cruise.

If the boat is safe on those conditions it is much more logical to chose a boat by the way it sails in 99% of the conditions and not on 1% of the conditions. and in what regards comfort opinions vary regarding what type of movement they find more comfortable and also in what regards comfort versus sailing pleasure or speed.
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Old 12-01-2017, 18:38   #71
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Re: Your opinion of classic VS Modern Boat Design

I agree Polux, it would be better to keep a light displacement boat sailing slowly in heavy weather.

However, I am wondering what is the priority with a couple and maybe some children onboard in Storm conditions.

My experience is that while not comfortable, heavy displacement vessels resist breaking seas with a softer, slower motion, than a lighter one.

I cannot argue with your 99% Point.
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Old 12-01-2017, 19:07   #72
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Re: Your opinion of classic VS Modern Boat Design

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I agree Polux, it would be better to keep a light displacement boat sailing slowly in heavy weather.

However, I am wondering what is the priority with a couple and maybe some children onboard in Storm conditions.

My experience is that while not comfortable, heavy displacement vessels resist breaking seas with a softer, slower motion, than a lighter one.

I cannot argue with your 99% Point.
I would say that it depends on the couple

Regarding resisting better to breaking seas with a softer slowing motion it is a mixed blessing.

True that it is better for comfort but worst for safety in what regards dynamic stability: If the boat moves and slides when it is hit by a breaking wave he is dissipating a substantial part of the energy of the wave on that movement while if the boat does not move much more energy will be transformed on a rotational movement. That is specially true when yachts have a substantial keel area as the heavier ones use to have.

Not really a problem for boats the size of the one you have on the avatar but for most yachts that matters.
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Old 12-01-2017, 19:38   #73
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Re: Your opinion of classic VS Modern Boat Design

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I would say that it depends on the couple

Regarding resisting better to breaking seas with a softer slowing motion it is a mixed blessing.

True that it is better for comfort but worst for safety in what regards dynamic stability: If the boat moves and slides when it is hit by a breaking wave he is dissipating a substantial part of the energy of the wave on that movement while if the boat does not move much more energy will be transformed on a rotational movement. That is specially true when yachts have a substantial keel area as the heavier ones use to have.

Not really a problem for boats the size of the one you have on the avatar but for most yachts that matters.
So my experience with my full keel heavy displacement boat is when rolling over a larger wave sailing down wind, it will heel to one side and then immediately heel to the other and back again, usually swinging 3-4 times before leveling out just in time to get hit by the next wave. Basicaly the momentum of all that lead in the keep and the narrow beam turns the boat into a swinging pendulum.
If almost straight downwind, I cannot use my autopilot at this point because it will not keep the boat heading straight enough to keep from jibing.
I'm sure all boats have some level of this problem but mine seams to be excessive. So I end up sailing closer a broad reach and tacking so the boat will stay on a even tack downwind.

Here is a video of me sailing to Hawaii on calmer conditions but still heeling considerably

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Old 12-01-2017, 19:47   #74
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Re: Your opinion of classic VS Modern Boat Design

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True that it is better for comfort but worst for safety in what regards dynamic stability: If the boat moves and slides when it is hit by a breaking wave he is dissipating a substantial part of the energy of the wave on that movement while if the boat does not move much more energy will be transformed on a rotational movement. That is specially true when yachts have a substantial keel area as the heavier ones use to have.

Not really a problem for boats the size of the one you have on the avatar but for most yachts that matters.
Not sure I agree on the dynamic stability benefit of side shifting

If when hit by a cross sea and the yacht slides into a trough, the kinetic energy of the leeward fall would more likely cause the Lee deck to bury in and dig (I think that is called the 'point of intraflection' in stability calculations.) You see those calculations in cross curve stability and is similar to free surface effect in reducing stability

Obviously we need to compare with the same size and somehow test with the same seas, but as I discovered many years ago when tank testing for a flooding tender recovery system....You Cannot Scale Inertia, in these scaled tests.
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Old 12-01-2017, 20:20   #75
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Re: Your opinion of classic VS Modern Boat Design

All monos roll going DDW in the trades, some just roll more. Some of the real beamy boats could do more than their share of rolling downwind. A typical scenario was the boat would roll, because the wide rear stern had way more floatation than the bow the boat would want to turn as it rolled. The vane or pilot would correct of course but as the boat heeled in the roll the top of the rudder would ventilate removing a lot of lift from the rudder and requiring more rudder and on and on. The newer designs with twin rudders has really improved this as at least one rudder is fully underwater. Rolling also depends on speed so the faster you can go the less roll you'll get. The older narrow full keeled boats were born rollers and it was their manners that coined the phrase "rolling down the trades" These boats would accelerate the rolls, first roll not bad, second rolls further, third etc until the cycle stopped but it would only be for a short time before it started again. Twin headsails seemed to add more rolling even though it was much easier for the autopilot or vane to have the sails pulling the hull. Hoisting the main double reefed and sheetfed hard amidships was a common technique to stop the roll from accelerating, the boat would still roll but it would reduce the cycles and severity of the roll. The big issue with full keel boats and barn door rudders was that the boats were directionally very stable with a rudder that was not very effective (when compared to a modern spade) so waves move boats around, all of them but the barn door rudders were not as effect on getting the boat back on course so that didn't help. In the right conditions many of those old full keel boats would sail all day and hardly need much rudder . So in my opinion if you take a real beamy boat out into bigger seas and sail downwind don't expect it to sail flat, not going to happen but with its modern foils it will hold a good course and in most cases the pilot will handle it just fine. For a short handled couple in storm conditions you can slowly for reach in a modern boat but they do not hove to...the long keeled boats will usually hove to very well. If the waves start to break hoving to is no longer a good option and it's time to run off which in most cases depending on the wind and seas will require active duty on the helm (steering the boat) If short handed it's unlikely you'll be able to keep this up for too long and it's time for a passive approach which there are different options for but the Series Drogue is a pretty good one.
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