Heavy sailboats are slower and

[charliehows]

c'mon you guys, the OP has invested years of thought into his question, at least you could give him a decent answer; compare a sailboat of approx 15 tonnes, perhaps a ketch in fibreglass with a 100hp diesel vs a sleek aluminium and carbon fibre vessel with a 2000hp turbo jet, the latter will attain greater speeds if it is sufficiently equipped with aluminium sails laid horizontally to encourage lift and control. There could be a differential of 500 mph at times. But the latter vessel could also cost considerably more than the former and may not have a comfy place to sleep.
It's really a little bit complicated.

[Scaramanga F25]

Simply, no!

[Althebass]

Originally Posted by picklesandjesse

Some well designed and equipped heavy boats can be faster in light and variable conditions as once they get going they tend to keep going for longer and can catch the next bit of breeze ahead while lighter boats tend to stop. Can be quite embarrassing to the lighter more modern boats.

we love to do this when racing against modern lightweights in our Nicholson 32! 7 tonnes with 3 tonnes of lead in the keel

[thinwater]

Why don't we all just agree there is no point in comparing apples with hand grenades and move on to another thread....


I'm glad we didn't spread out into multihulls. It would have gotten even weirder, since there are arguments both ways on that too.

[hamburking]

I think the OP has oversimplified.

For example, a "heavier" boat can have more sail area, which really helps in light winds.

And a "lighter" boat may be too tender to go out at all in big seas or big winds. It can also lack the power to punch into big seas/winds when going upwind.

And of course the most important thing in sailing....the sailor. A good sailor can make any boat go. And a poor sailor can make any boat slow.

I owned a "heavy" 1972 Pearson 30. And it was quite fast.

Every boat is a compromise. Every boat has its own strengths and features. And for every "rule" there is an exception.

[nortonscove]

Originally Posted by agpilot88

Question:


This is the way I understand it. The heavier the boat, the more stable and slower it is and the lighter the boat the quickler and less stable it is?


Correct?


Of course take into consideration of the draft and the shape of the hull. Seems like price and weight corresponse with each other.


Lee

Probably not as simple as that but true in some instances. Older boats tend to heel more and in less wind. They usually need higher wind speeds to get up and go. But my boat falls between the most modern and the full keel types and offers a great compromise. Modest heel and steady in most sea states.

[oleman]

All USN war ships are capable of running in excessive of 30 KTs, the NUKE powered ones can do it indefinitely. The fossil burners can not keep up because they have to stop to refuel every couple of days. They are certainly displacement hulls so with enough power available any hull can go at any speed.

[zengirl]

Originally Posted by CSY Man

No, not correct.

Would be nice if you explained to him why he isn't correct, rather than just spitting out "No, not correct"

[wingssail]

Originally Posted by oleman

All USN war ships are capable of running in excessive of 30 KTs, the NUKE powered ones can do it indefinitely. The fossil burners can not keep up because they have to stop to refuel every couple of days. They are certainly displacement hulls so with enough power available any hull can go at any speed.

1.3 * (SQRT LWL)

If you make it longer (aircraft carriers) that formula still holds.

If it is underwater (submarine) some other formular might apply

A planning hull is not subject to this formula

[Jim Cate]

I owned a "heavy" 1972 Pearson 30. And it was quite fast.

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

[hpeer]

Originally Posted by agpilot88

Question:


This is the way I understand it. The heavier the boat, the more stable and slower it is and the lighter the boat the quickler and less stable it is?


Correct?


Of course take into consideration of the draft and the shape of the hull. Seems like price and weight corresponse with each other.


Lee

With your condition of draft and hull shape then - correct-ish. Even with identical hull shapes a heavy boat makes a bigger hole in the water and presents more resistance to movement. And that displacement means it has more momentum, it will be react more slowly to any force in any direction.


As to price and weight I also think you are thinking asking the correct lines. We often compare boats by looking at LOD (Length On Deck) but I've often thought displacement or $/lb make more sense.

At a boat show were 2 brand new boats, same length, boat B was nearly twice the cost of boat A. While they had superficially similar specs. Boat B also had nearly twice the displacement of boat A. A quick look at the anchor roller will illuminate the difference; one was thick plate welded and heavily bolted into place while the other was thin bent plate with small attachments. The $/lb were not that far off.

[ohdrinkboy]

one of my favorite quotes from a naval architect. "weight in an of itself does nothing good for a boat." You have to look at the entire of the design. a jon boat and a sunfish may weigh the same, but are totally different.

[NormanMartin]

A topic designers have chased an answer to for centuries... maybe longer. Ted Hood designed and built some very fast ocean racers that were very heavy and successful. Things such as wetted surface area and sail area are factors.

A great video on the subject is here:

https://www.youtube.com/watch?v=PDn6Bhq-msw&t=2131s

The speaker Bill Crealock is very articulate and the 58 minute video goes by quickly.

Books: Offshore Yachts by John Rousmanier, Sailboat Kinetics by Danny Greene and Seaworthiness by Marchaj will inform you wisely.

Keep well.

[waterman46]

Originally Posted by picklesandjesse

Some well designed and equipped heavy boats can be faster in light and variable conditions as once they get going they tend to keep going for longer and can catch the next bit of breeze ahead while lighter boats tend to stop. Can be quite embarrassing to the lighter more modern boats.

Such an occurence will be rare, and random. The usual case is that since the lighter boat accelerates faster, it can take advantage of brief puffs of wind that will leave a heavier boat just stalled.

[David M]

The larger a vessel, the lower the rate of change for pitch, roll, and yaw as measured in degrees. For example, a J-24 compared to a ship. There can be exceptions for vessels closer in size.

Lighter does not necessarily mean the stability curve is less favorable. Passenger ships have a very low metacentric height giving them a less favorable stability curve but a much better ride for the passengers. They roll at a slower rate. More stability, a higher metacentric height, provides more stability at the expense of comfort.

Stability has to do with how the center of buoyancy moves with respect to the center of gravity. As a vessel inclines, the center of buoyancy moves creating a righting arm with respect to the center of gravity. Gravity pulls down and buoyancy pushes up, tending to bring the vessel back towards level. The distance times the force between the two is the moment arm that rights the boat. When the center of buoyancy goes back under the center of gravity, the vessel is level. Yes, under, in most all cases.

Different vessels have different shaped stability curves.

Boats really are a compromise of many different things making for no such thing as an ideal boat.