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Old 01-03-2007, 19:57   #1
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Light vs Heavy boats

I've been lurking here for some time, learning about sailing. I think I'm doing pretty good seeing how I've never sailed before. So I think I have a good question for my first post:

I'm wondering about boat weight vs speed. Its my understanding that waterline length and hull design make up "hull speed". Its also my understanding that hull speed is pretty much a cap for a boats speed. If this is so then why do people talk about light vessels being faster than heavy vessels. Can't you just put a larger rig on a heavy boat of equal length and get the same speed?

Thanks for the feedback.

~Brett
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Old 01-03-2007, 19:59   #2
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And that is usually what they do do. Take a look at the thread directly below on "ocean going". We are dicussing this very topic right now.
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Old 01-03-2007, 20:03   #3
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Actually that's where the question came from, but the thread was all but answering my question

~Brett
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Old 01-03-2007, 20:09   #4
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Light boats (with a correct hull shape) can break free of their hull spead and plane. A displacement boat will not. A light boat sailing at displacement speeds will accelerate quicker on a puff or out of a tack.
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Old 01-03-2007, 20:26   #5
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Quote:
Originally Posted by bmanley
Can't you just put a larger rig on a heavy boat of equal length and get the same speed?
If the weathers blowing hard enough, then yes the bigger rig will get the boat up to hull speed. You will require bigger sails, heavy rigging, etc. etc to get there. On a typical cruising boat that has a Mom and Pop crew, those big heavy sails having to be carried in blowing conditions can be tough and tiring. Alight weight-boat can carry much less sail and still sail faster

Paul L
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Old 01-03-2007, 20:28   #6
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Racing ferro cement...

When I was sailing my first boat, a 32' 7tonne ferro cement yacht I thought, because the designer had designed it as a half tonne yacht under the RORC rule that it maybe had a chance as a racing boat.

Well I met up with this fellow who had been in the navy as an officer and we decided to enter one of the CYC races.

We went out and it was blowing a gale.

This bloke had us doing everything right. We made a good start and changed sails and tacked like men possessed.

We got to the end of the course and the finish boat had gone home.

They listed us as finishing though.
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Old 01-03-2007, 21:14   #7
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Lighter boats accelerate better than heavy boats .... accelerating back to speed after being slowed by a wave(s), accelerating out of a tack, etc. Lighter boats are more 'easily' driven, needing smaller sails, etc.
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Old 01-03-2007, 21:24   #8
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And for inshore racing, Richh's point about acceleration is even more important. The top two boats can spend six hours on the water and finish 15 seconds apart. Since both will make many tacks, and a lighter boat will come back up to speed faster on each one...save one second twenty times, and you've built the lead that wins the race.

A warped persective about speed and time, huh? Shavings seconds off something that moves slower than the average bicycle.<G>
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Old 02-03-2007, 12:08   #9
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And Hellosailor brings up another point. The ease of Tacking. I just don't bother. I motor for 3hrs till I get into an area where I can set the sails and go. Tacking a big boat up the sounds is just plain exhausting and frustrating. I pass Small trailer sailers and such having a blast tacking up and down the sounds. I sometimes think, I must get me one of them someday, so I can just spend a spare afternoon doing some sailing. Any sailing in my big boat requires a weekend.
HOWEVER, I am very happy with the situaion, because going out for a weekend is exactly what I want to do. So I enjoy the boat I have. So once again, it is personal in choice. Like all boats, it depends on the person and what they want in life. No boat is wrong and no boat is right.
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Old 02-03-2007, 12:09   #10
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Heavy Boats

Are more comfortable in the rough and quieter. They do require heavy rigging and more sail area, usually by putting up more sails like on a Ketch, Yawl, Clipper or Cutter.

In light air they are slow as snails, which makes windy days more desirable. That's one reason they're not seen much on the inland waters, except motoring. They do make good liveaboards and are slightly more expensive to maintain. They are more common for offshore because of their comfort in heavy seas.

Their hull shape is usually a full keel or a cut-back full keel. Sometimes a fin keel with bulb and skeg mounted rudder. Their bows and transoms are less likely to have much positive buoyancy. Perpetual motion gets them thru the waves and are wetter boats (sea spray) depending on the freeboard.

Most boats are designed for particular usage. The light is more for racing. The medium is more for coastal cruising. And the heavy is more for offshore. The problem being when you take one out of its particular realm then it becomes less desirable.

Picking the boat that most fits your needs (safely) and dealing with the other realms, when necessary, is what makes the happy boat owner......................._/)
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Old 02-03-2007, 12:34   #11
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Hmm,

Conventional wisdom would tell you that a sailboat is locked in at hull speed, but that is not true. A well designed racer or excellent performance cruiser will jump out of the water & "plane" or surf, typically on a downwind run. That is often where the weight is such a factor and you will see racers pulling everything they can out of their boat. A friend of mine has a performance cruiser, 41' (cannot remember the wl), but he seriously exceeds hull downwind.

For many of us liveaboard/cruisers, weight becomes much less of a factor - well, except we have a bunch of it!! A heavy boat is typical for most passagemakers, but light boats (typically racers) will run the pond too. But as I said before in the other thread, a heavy boat does not neccesarily mean it is a slug, a light boat not neccessarily fast. But it is a good generality. How do you define heavy? How do you define light? Would you consider a Swan or an X heavy? A Hunter light? A Valiant heavy? What is a performance cruiser? A passage maker?

Ahh, forget all this talk and as a newbie, just think what was said by delmarrey.

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Old 02-03-2007, 12:45   #12
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Argh, Wheels, that's just because you're driving Kubla Khan's Pleasure Palace not a real boat.<G>

Thousand gallons of water, thousand gallons of waste, you know, pretty soon all that weight adds up and slows down the tacks, too.<G>
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Old 02-03-2007, 12:53   #13
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Quote:
For many of us liveaboard/cruisers, weight becomes much less of a factor - well, except we have a bunch of it!!
Pretty much. The requirements for a Crusier is it has to be large enough to hold all the stuff. That makes it at least heavy displacement though of course the weight on the scale culd be a lot more or less.

It's fine to talk about round the world racers where they bring as little as possible but those same boats loaded down with all the comforts of a cruisng family won't perform all that well as a Crusier.

I think the topic is somewhat pointless as posed. "Heavy vs Light" makes little sense. I can knock off almost 1000 pounds on our boat if I drain all the tanks. I don't think I'll be attempting any long trips that way though. With a loaded boat you can't exceed hull speed though the theoretical speed may not be the actual hull speed.
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Old 02-03-2007, 12:57   #14
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Quote:
Originally Posted by Cruisingdad
But it is a good generality. How do you define heavy? How do you define light? Would you consider a Swan or an X heavy? A Hunter light? A Valiant heavy? What is a performance cruiser? A passage maker?

- CD
That's relative, and there are no lines drawn to seperate them. It is in sea conditions that will tell ya. Medium for one maybe light for another. If one has been spoiled on the big yachts, they're all light after that. ..................................._/)
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Old 02-03-2007, 13:22   #15
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Well, let me just tell any of you really intersted on cruising and living aboard: RAISE YOUR WATERLINE!! Once, twice... whatever it takes. WHen the wife moves in with the pots and pans, well, you get the picture! HAHA!

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