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Old 08-01-2009, 15:36   #61
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Some people aren't comfortable unless they are going faster than the next guy.

Speed vs. comfort? Kind of like which is preferred, blondes vs. brunettes.

My experience is that blondes are faster.

* * *

The real unexamined question here is what is comfort on an ocean passage?
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Old 08-01-2009, 15:48   #62
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Sorry for the High Jack ...I will start a different thread..my answere may have already been given though...you cant.
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Old 08-01-2009, 16:20   #63
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And, they've pretty much moved to window shade sailing other then the main which is dead simple also.
What they've done is make putting out max sail area as easy as possible.

Which dovetails perfectly with Beth's point in her book that light airs is the biggest speed differentiator.
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Old 08-01-2009, 16:20   #64
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....
Speed vs. comfort? Kind of like which is preferred, blondes vs. brunettes.

My experience is that blondes are faster.

* * *

The real unexamined question here is what is comfort on an ocean passage?
I have experience with both. 2nd time around I went with blond. So far, so good.

It is levels of discomfort. Something like banging your head against the wall. It feels great when you stop.

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Old 08-01-2009, 16:40   #65
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Lots of good info, which of course drifted a little as expected. At this time I'm going to try to pull it back to my starting question I asked below. Maybe try to thing of it as whether on a passage the overall speed would have been better or do wish the rise was a little smoother (say 5 foot seas, 15-20 knots wind).

"Not counting extremes and given that light air is more common than heavy air; what is the group preference between the boat design that is faster with a rockyer ride (but probably only a lot of difference at seas beyound full reefing points), or the boat with "comfort" soft movement but slower (all the time but still going to be rough beyound the same fully reefed point)? In this I am asking about cruising boats overall and not race designs."
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Old 08-01-2009, 16:51   #66
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Don,
I would take issue on how the issue has been framed. You seem to imply that soft movement and speed are mutually exclusive for any given LWL. i disagree.

Light is considered fast because light accelerates well, which is important in a racing context. Acceleration is not important in a cruising context.

Surfing is also important in the racing context, and light boats surf sooner and longer. Again, surfing is not that important to most short handed sailors on a long passage.

Not all heavy boats with soft motion are slugs. Once you get outside the racing context, long distance speed is more a function of SA/D than displacement. It's not really an either/or choice. The boat industry would like you to think it is, because boats are roughly sold by the pound and heavy boats cost more.

To be sure, there are heavy boats that are slow. But not all. So it's not an either/or choice.
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Old 08-01-2009, 16:58   #67
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This is why the Hood comment resonated with me. Ted Hood was proponent of moderate-to-heavy boats with adequate SA/D.

Key phrase is 'adequate SA/D.' That's where the action lies.

It's much easier to pile on SA/D with a light boat than a heavy boat. But that doesn't mean it can't be done on a heavy boat too.

So, I'm a advocate of comfort and speed. Not racing speed. Adequate cruising speed, which is largely a function of SA/D.
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Old 08-01-2009, 17:40   #68
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Don,

A final comment and then I'll stop monopolizing the thread: As soon as you put light airs into the equation (as you must), underwater surface area figures into speed. Full keel is a no-no.

So, I like moderate-to-heavy displacement, healthy SA/D ratio (preferably 17 or 18, but will settle for 16), moderate-to-deep draft, and a fin keel.

About rudders I'm agnostic, so long as they are big enough and well built.
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Old 08-01-2009, 18:44   #69
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Well there you have it.

A couple final notes from me. Comfort is a function of weight and waterline. Speed is a function of of waterline and SA/D. In light air downwind you need to bump the SA/D number and keep pressure (ie sail the polar and build app.) In a breeze and upwind this is not so important. Weight does not hurt you in light air because all boats are limited to LWL, they cannot plain.

We are about 19 upwind not sure downwind with the assy.

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Don,

A final comment and then I'll stop monopolizing the thread: As soon as you put light airs into the equation (as you must), underwater surface area figures into speed. Full keel is a no-no.

So, I like moderate-to-heavy displacement, healthy SA/D ratio (preferably 17 or 18, but will settle for 16), moderate-to-deep draft, and a fin keel.

About rudders I'm agnostic, so long as they are big enough and well built.
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Old 08-01-2009, 19:01   #70
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Quote:
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....... Comfort is a function of weight and waterline.
And perception. Different types of motion affect people differently.
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....Weight does not hurt you in light air because all boats are limited to LWL, they cannot plain.....
I don't understand how you come to this conclusion. If you took your boat and a sistership, put an extra 3,000 pounds of gear on sistership and then took off on a long, light air crossing, who would get their first?

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Old 08-01-2009, 20:38   #71
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Well, the light boat will be stopped by every wavelet and ripple, while the overloaded boat will sail more flat and have more carry. There is a point where the slight increase in wetted surface area will be the greater issue in near-calms, but likely both boats will be motoring by that point.
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Old 08-01-2009, 21:12   #72
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You can go to a long, high prismatic coefficient, lightweight multihull. This flattens out the problems of chop, is pretty slippery and has a very high SA/D
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Old 08-01-2009, 22:29   #73
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With respect to the comments being made regarding light wind performance there may be some relevance of those to the mundane production, etc cruising boats that I think perhaps many are familiar with and which are generally all slow (even the "faster" ones), but a fast cruising boat will be close to or at hull speed even in around 7-8 knots of wind so light wind performance is always high.

Two points -

SA/D ratio only predominates when residuary resistance from wave making is small (ie at very low Froude numbers when resistance from wetted surface predominates) but as Froude number increases ie as one increases speed towards hull speed, then residuary resistance from wave making predominates. Wavemaking resistance for a hull is roughly proportional to displacement, so for two hulls, identical apart from displacement, the lighter hull will have a higher speed.

Also the displacement speed of the lighter boat will be faster than the heavier displacement boat because the heavier boat's wavemaking resistance increases at a much faster rate than that for a lighter hull as displacement speed is approached (the lighter boat can reach higher Froude numbers). This higher resistance resulting in a lower displacement speed cannot be beaten by adding sail area.

Putting those two matters together the light fast cruising sail boats that I am familiar with will reach close to their hull speed even in light winds and so wavemaking is the most important as far as resistance is concerned. The same but heavier boat will still be at speeds much lower than hull speed in those same light winds. Even if the heavier boat then puts on more sail than the lighter boat so that it too reaches displacement speed (but it is difficult to get a heavy boat to hull speed in light airs regardless) then it will still be slower by nature of it being burdened with a slower displacement speed.

Wavemaking resistance is typically of order of 35% of total resistance so any increase in it through higher displacement is significant eg two boats of same lines but one 25% heavier than the other, the heavier one will have nearly 10% extra TOTAL resistance to overcome. So in other than flat calms the lighter displacement boat will be faster but will never be slower even in calms all else being equal.

It is therefore for good reason that the modern fast cruising sail boats are built both strong and light, typically using foam sandwich, kevlar and carbon but I know of older but strong light displacement timber/glass composite cruising boats that will pretty much be on displacement speed in even 7-8 knots of wind. I don't know any designers with a reputation for designing these fast cruising boats that work on the principle that one makes a fast (as opposed to mundane speed) cruising boat by going for other than light displacement and then making up for heavy displacement by cramming on sail area.

I know Hiracer will vehemently disagree with me again on all that as he has often claimed in other threads that displacement can be made up for by piling on more sail area. But as he has told me in another thread that he does not think Froude numbers are important in sail boat design (which is the same thing as saying that wavemaking resistance is not important ) I personally would not take much notice.

Comment has been made that these light fast boats are of necessity uncomfortable and indeed in small boats they can be due to higher accelerations. But those accelerations can be controlled by good modern design and also by increasing waterline length as length most always adds comfort for a given sea state. So many of these fast boats are in the 50 foot plus WL length range if intended for independant ocean cruising (and WL length for these boats is typically within inches of being the same as the length over deck, and LOA being dependant on the length of the prod for carrying line furling gennakers).

I think one issue is that many are likely not familiar with the light, comfortable fast cruising yachts that are increasingly around. There have certainly been many built here, most now for export and those often custom design/builds for very experienced owners.

Of course, not everyone wants speed.
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Old 09-01-2009, 07:15   #74
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How then do you explain racing boats using water ballast even in light air? Why do they flood leeward or forward tanks in light wind conditions?

I've seen too many heavy boats crush it's lighter brethren on the race course in light air flat water to buy into the lighter is better in light wind argument. The only time the lighter boat shows a clear advantage is when the breeze is on and the heavy boat is digging a hole and the light boat is surfing. But how many cruisers sail boats that can get up and get it when the breeze is on? Not many guys out there cruising an M32 in the Caribbean.

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I don't understand how you come to this conclusion. If you took your boat and a sistership, put an extra 3,000 pounds of gear on sistership and then took off on a long, light air crossing, who would get their first?

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Old 09-01-2009, 07:16   #75
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But I've yet to see a multi that isn't sticky in the light stuff.

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You can go to a long, high prismatic coefficient, lightweight multihull. This flattens out the problems of chop, is pretty slippery and has a very high SA/D
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