Heavy sailboats are slower and

[Wayfarer1008]

This is an interesting question but its all about the design and where the weight is located.


A traditional boat like a Westsail 32 are designed off of commercial vessels with full keels, deep displacement and heavy construction. They are way slower than a modern race boat but have sea keeping abilities that make them one hell of a lot more comfortable especially if it gets rough.


An old IOR era boat can be very light but since it was built to design class rules in going to be a pig in comparison to something like a Pacific sled of the same age which was built for screaming down wind runs. Both boats if you have ever been on them are striped to the point that the head is a porto-poty Duck taped to the base of the mast with a couple coolers to carry the beer.
As much as I would like to say weight is a big deal it all depends what your trying to do. Its also important to remind people that when you go cruising you will be brining everything including the Kitchen sink with you so your not exactly wining by being light.

[avnbuff]

Funny, I wonder who actually reads the questions posted. The topic seems to get a 'life of its own'. …

I read it as a question of design... but replies go much further.. eace

Another pretty old guy interjects "yea, but you only need to get her going once!" - referring to mass I presume.

All generalizations are false, as is your current example. It depends upon conditions, and there are at least 5: ..now the design isn't at fault it is how high the wave or length of the gap...what angle the wind happens to take. The tide... current and so on.. and is the hull clean?.. REALLY GUYS, it was a simple question..

wave height
wave period
relationship of wind vectors to above
current
tide

given that hull cleanliness is not poor

[JohnAdams]

Lighter boats can be faster in the right conditions but it depends on lading, sea state, a boat's ability to look after a small crew over time, ease of sail management, ability to inspire confidence, ability to hold a desired course. If I was going to be on relatively flat water most the time with 2 friends, a lightweight hull would be great. Outside it's a bit different. Performance starts to mean different things. There's no point having a boat that can point high yet pounds so badly in 2+ metre seas you never want to go up. And a boat that surfs at 15 knots with little provocation is fabulous, too. Unless it's at night when the crew is asleep and you've gone below for a moment and put the autopilot on. Frankly, I love both types. But there are times I want different things. Also, the choice is not dichotomous. Some boats balance performance and comfort better than others.

[Mike OReilly]

My sailboat is heavy, full-keeler. She’s not slow with wind on the beam of aft. She’s not slow with wind forward unless she’s bashing into seas. She’s a displacement hull, just like most cruising sailboats. Speed is largely dictated by LWL.

So, as long as there’s sufficient wind, she gets up to around her hull speed pretty easily. Sufficient wind mostly depends on sea state, but 15 knots beam or aft will move her at hull speed.

But her motion is very sea-kindly. She doesn’t bash around easily, surf or roll much. She manages an ugly sea state safely and as comfortably as possible. She’s also easy on the helm, and on the crew’s body.

I’ve sailed lightweight designs. For flippin' around the bay, or playing around for the day, they are fine. But for long-duration cruising, I’d much rather have my heavy displacement boat.

[barnakiel]

Interestingly, the most comfortable ride we had in choppy seas on the wind was in a Farr40 which by all standards is a very light boat.


One look at her bow sections tell you the rest.


Tub owners who equal displacement with comfort should look at their sections too before claiming mine is comfortable. Unless we talk going at 2 kts to nowhere.


b.

[barnakiel]

PS I own one.


;-)
b.

[Rainbow48]

My boat, “Rainbow”, LOD 63 ft, LWL 55 ft, draft 7 ft, 2,250 sq ft working sail area, 81,000 lbs displacement. Fastest “clocked” speed to date : 11.5 kts.. Fast enough for me. Speed under sail is primarily a factor of hull form together with sail area. “Rainbow” is a traditional design and rig, and has a very easy motion at sea.

[FranklinGray]

So many generalizations here it misleading. I have a long fin keel of 8 tons but it is 6.5 feet deep and all the weight is the bottom 2 feet, not shallow. I blow by lighter boats with same waterline all the time...a whole knot faster and do so with very little effort where they are struggling at the helmet. Wind speed and sea state has a lot to do with the outcome.

[bimini blue]

The correlation between speed and stability is based on several factors on a sailboat
In the old days weight helped to offset the center of effort versus center of lateral resistance.
And the sail plans included Genoa’s up to 170%+
And the loa vs lwl were very different
As an example the boat I grew up sailing was was a Columbia 31 with a water line length of 21.9. Sail area 467. Displacement 9000 lbs speed range of 3-6 knots

My boat is a Beneteau oceanis 321 with a water line length of 30 feet sail area 500 displacement 9000 lbs speed range is 50% of wind speed heel is managed by good furling and sail control.

Mine is a 150 with 110 back up
I would also think about pointing ability
Low and slow is not a good combo

[secrabtree]

Originally Posted by Jim Cate

And an Olson 30 is a light boat and quite a lot faster. PHRF ratings: Olson 108, Pearson 174.

Your argument is not compelling.

Jim

Jim - I've read as much of this thread as I could stomach. Most seem to believe that the only things that effect speed are length, weight, wetted surface, sail area. Stuff like that. IF it were possible, which I think not, with exactly the same hull shape, mast height, sail area and shape, etc. the discussion MAY make sense. But the actual hull design DOES have a great effect. And the effect DOES vary for different wind and sea conditions. I think that the "heavier is slower, but more comfortable" is a MUCH oversimplified statement. And people that argue about that statement are more into arguing than sailing.

[wingssail]

I’ve often expressed the opinion that “heavy is not more comfortable going into waves”. Not too many people seem to be getting that message, and I guess I’m not surprised. People are stuck with their myths and talking points. But few sailors with a lot of ocean miles on more than one type of boat would agree with such a generalization.

But the point is: when waves are coming from the front a heavy, blunt, boat with weight in the ends, will “bash” more, can soar aloft and plunge on waves, and be dramatically slowed. This is not more comfortable than a boat which simply rises over each wave and keeps moving forward.
Several comments in this thread hint that the skippers of these boats know that is true:

“She’s not slow with wind forward unless she’s bashing into seas” but“15 knots beam or aft will move her at hull speed”. A boat should go hull speed in any point of sail, with less than 15 knots of wind.

I cannot emphasize too much that the most common complaint I hear when people tell me about their recent passages, “The waves were terrible, we just stopped, could hardly make two knots even with the engine…”
There are other characteristics to make a boat comfortable than sheer tonnage.

And there are so many generalizations such as, “An old IOR era boat can be very light but since it was built to design class rules in going to be a pig in comparison to something like a Pacific sled of the same age which was built for screaming down wind runs. Both boats if you have ever been on them are striped to the point that the head is a porto-poty Duck taped to the base of the mast with a couple coolers to carry the beer…” What evocative images are created in one’s mind with those words, but they don’t actually ring true. I’ve never seen a boat which matches those descriptions, and in normal sailing conditions (with winds not suitable to surfing) we have very often beaten sleds with our old IOR era boat, which, by the way, is not exactly light by today’s standards.

“And a boat that surfs at 15 knots with little provocation is fabulous, too...” Exaggeration. This is a straw horse. This is not a characteristic which applies to many boats, and few which would proposed as a cruising boat, so don't try to use this as an argument. I could just as easily say, "a boat which is stable as a bridge pontoon would never make you seasick..." ridiculas.

“I blow by lighter boats with same waterline all the time...a whole knot faster and do so with very little effort where they are struggling at the helmet…” Unlikely!

So, dear readers, stop listening to the propaganda and do more sailing. You will learn your own truth.

[Boatyarddog]

Originally Posted by mstrebe

No, this isn't how it works.

Regarding price, the price of a new boat is the cube of the waterline length in feet times about $5 ($4-$15, but generally around $5). Boats increase in price by volume, not by weight. They then depreciate along a pretty standard depreciation curve down to about $0.50 per cube where they stop until they sink.

Regarding speed, monohull sailboats are generally limited to their hull speed. That's a maximum that they might be able to surf a little beyond but that's really it. Additional power beyond the hull speed just goes into more heeling. Two boats of the same length are generally going to have the same maximum speed, regardless of their weight.

The weight affects acceleration: Light boats speed up faster in the same air. But it conversely affects deceleration: Light boats also loose momentum faster than that heavy boats.

Light boats can be faster in light air with standard sails because they can get to higher speeds with less power, but that can be matched by a heavier boat's ability to hoist a larger sail.

regarding stability or sea-kindliness, that is much more about the hull shape, keel configuration, and rudder configuration than it is about weight for the most part. A full keel that keeps a boat straight in broaching waves is also a full keel that will roll a boat when parallel to a breaking wave that a modern fin keel can more easily surf with leeway.

Racers light light because acceleration and light-air performance wins races. Cruisers like heavy because inertia dampens movement and is more sea-kindly.

Hull shape, freeboard, weight, sail Area aloft, all of these come into play in rough water.
And NO YOU DONT WANT TO EVER SURF!
Not a Ketch.
The weight and yaw, is more difficult to steer on these boats as they don't react as quickly. IMO
SV Cloud Duster

[Mike OReilly]

Originally Posted by wingssail

...“She’s not slow with wind forward unless she’s bashing into seas” but“15 knots beam or aft will move her at hull speed”. A boat should go hull speed in any point of sail, with less than 15 knots of wind.….

The “myth” we’re discussing is that heavy boats are somehow slow. The point I was making, and that you quoted, was that my boat will be doing hull speed just as well as any other displacement boat.

As for your myth, I think the answer is: It depends. In this case it depends on hull and rig design. Displacement, whether heavy or light, is part of this design. Some heavy boats are going to be less see kindly and manage seas poorly, just like some lighter designed boats. Displacement is not the only factor, but it certainly is one.

I’m not a boat designer, but I suspect that just like a 7-foot person is more likely to be a good basketball player, so too with heavier displacement boats visa vis general sea kindliness. But that’s not to say a 5’8” person can’t be as good, or better at the hoops, just like a lighter designed boat can also be sea kindly.

[Dockhead]

Originally Posted by Mike OReilly

The “myth” we’re discussing is that heavy boats are somehow slow. The point I was making, and that you quoted, was that my boat will be doing hull speed just as well as any other displacement boat.

As for your myth, I think the answer is: It depends. In this case it depends on hull and rig design. Displacement, whether heavy or light, is part of this design. Some heavy boats are going to be less see kindly and manage seas poorly, just like some lighter designed boats. Displacement is not the only factor, but it certainly is one.

I’m not a boat designer, but I suspect that just like a 7-foot person is more likely to be a good basketball player, so too with heavier displacement boats visa vis general sea kindliness. But that’s not to say a 5’8” person can’t be as good, or better at the hoops, just like a lighter designed boat can also be sea kindly.

This is all true, but just keep in mind that the heavier boat has more skin friction to overcome. If the hull form is the same, then the skin friction is proportionate to displacement, because wetted surface increases proportionately. And if the heavier boat has a longish keel, then skin friction will increase even faster and disproportionate to displacement. To be equally fast with a lighter boat, the heavier boat will need to have proportionately more sail up. That might be possible if the designer is able to increase righting moment proportionate to the sail area you need, but this is an uphill battle, needing, basically, more draft and a shorter, not longer keel.


But this type of drag is not the only one which affects our boats -- we also have wave making drag. This increases as a function of D/L and not just displacement, unlike skin friction, so when you combine all the types of drag, a heavier boat will need a disproportionately greater amount of sail up, to keep up with a lighter boat.



Because of all this, with relatively few exceptions, heavier boats really are usually slower than lighter ones. It is much easier to make a lighter boat fast, than a heavier one. This is reflected in PHRF ratings and race results -- the proof is in this pudding. If you graph those ratings to D/L you will see a very strong correlation. Very much like the 7' vs 5'8" basketball player you mention.



As to sea kindliness -- what you say is also true, but just like the case with speed -- it is much easier for the designer to make a heavier boat, more sea kindly. He can screw it up by putting a lot of weight in ends of the boat, but there is a strong correlation between weight and motion comfort, for boats of the same size.



And as was said -- all this is for boats of the same size. Make a boat bigger, and all other things being equal, it will be both faster AND more sea kindly.



So the OP is basically right, despite the true things you say in your post. "Built for speed" vs "build for comfort" -- not an absolute law of nature with no exceptions, but very high correlation in real life designs.


As one boat designer put it:


"As you know – a boat is always a compromise. Speed is always sacrificed for comfort. Fast sailing always means a considerable concession to sailing quality, seakind motion of the boat, tiring hard bounces, roughest movements in waves . . . . On the other hand, a comforting, relaxing, pleasant movement of a boat (through a V-shaped hull) can only be achieved by a higher displacement and a hull-shape which naturally cannot plane anymore: The boat will be slower. But ask yourself: Do you want to be quickly flying over the waves in a short dash or do you want to sail for days, weeks, months or even years enjoying the world´s oceans – no matter if this is done in 8-knots or 8.5 knots?"

Displacement-Length Ratio of a Yacht: Skipper´s Basics |

[RobPatterson]

There is more to it than weight. Some heavy cruisers perform well in light air. Mine is surprisingly good but not as fast as a boat designed for racing.
I have a heavy cruiser with a modified full keel and wide beam. It accelerates less than a racer. She move well in light airs but really shines when there is more wind. She can maintain 8-10-knots for days on end in trade winds while also being a comfortable (luxurious) place to live. In a gale, upwind, we can keep a lot of sail up and keep our speed near 10-knots when other boats are reefed down so in those conditions we are faster.

I have sailed in races on light boats. It can be fun and exciting but the time when the racing performance is most important is when the wind is low. That's when the heavy cruiser can't keep up.