Heavy vs Light Displacement

[barnakiel]

Originally Posted by S&S

How about a heavy and fast boat? Not being facetious but, at least with non-planeing boats, we're generally talking single digit speeds- and that mostly based on waterline length.

Contradictory. Unless you define 'heavy' as a heavy hull with lotta sail. But this is not the standard understanding of heavy. Heavy has a lot of disp and relatively little sail.

Then, heavy boat will have some features that will not let her plane (meaning - she is slow) and seriously limit the hull's ability to achieve the upper limits of hull's speed - so she will be fast, but only in a blow. But the blow is not very common - most sailing I have done has been in 10-15 knots. Meaning - the lighter boat can be faster under the same canvas - less strain on the crew, more miles covered, easier driving.

But I am biased because I have a "heavy" boat and a racing background.

b.

[S&S]

Originally Posted by barnakiel

Contradictory. Unless you define 'heavy' as a heavy hull with lotta sail. But this is not the standard understanding of heavy. Heavy has a lot of disp and relatively little sail.


b.

That's ours- heavy hull, lot of SA.

No, but I see your point. I equate "heavy" with displacement. Put enough SA on it it'll go. I don't agree with your idea of "standard understanding"- all the boatbuilders and naval architects I've talked to relate "heavy" with displacement only. YMMV

[barnakiel]

A heavy (a lot od displacement per waterplane) one with a lot of sail may go surprisingly fast.

To me the big surprise was an Ohlson 38 - definitely not a sleigh but under that specific skipper she was faster (ocean passages) than two fellow sailing Amels (Maramu). And an Amel is (?) 54'.

I believe that such a (heavy but fast) boat can be seen as the happy small/medium cruiser's compromise. But there aren't many around.

b.

[Joli]

Pretty funny stuff.

So in this years Carib 1500 the Valiant 42 finished at the same time as the J 44 which finished at the same time as the PDQ 44 which finished at the same time as the Catana 431.

Anyone see a pattern? They are all 40 some foot, they all sailed a broad reach on port tack in moderate breezes and they all averaged about 8 knots. (heavy mono, light mono, multi with 900 sq ft of sail, multi with 1300 sq ft of sail).

Similar waterline, sailing in a sea state, sailed by cruisers conservatively, with cruising gear. Pick what you want, they're all gonna average about the same passage times.

[sneuman]

Originally Posted by Joli

Pretty funny stuff.

So in this years Carib 1500 the Valiant 42 finished at the same time as the J 44 which finished at the same time as the PDQ 44 which finished at the same time as the Catana 431.

Anyone see a pattern? They are all 40 some foot, they all sailed a broad reach on port tack in moderate breezes and they all averaged about 8 knots. (heavy mono, light mono, multi with 900 sq ft of sail, multi with 1300 sq ft of sail).

Similar waterline, sailing in a sea state, sailed by cruisers conservatively, with cruising gear. Pick what you want, they're all gonna average about the same passage times.

Well, there you go!

[sneuman]

Further to Joli -- and the cats did fine, but not spectacularly so ... even on their best point of sail. I've labeled them as cruiser, racer, catamaran:

C: Etheos (Valiant 42): 11-10 8:53:01
R: Sapphire (Jeanneau 54DS): 11-10 08:57:50
CR: Karina (Tayana 55): 11-10 09:00:51
CR: Billy Ruffian (Van de Stadt 47): 11-10 9:20:57
CAT: Cat-Ion (PDQ 44): 11-10 9:24:29
R: Shazam (J/130): 11-10 12:56:23
CR: Habits of Health (Moody 54): 11-10 13:01:53
R: Namaste (Jeanneau 54DS): 11-10 13:02:11
CR: Ocean Pearl (Amel 53): 11-10 13:11:54
CAT: Meridien V (Catana 431): 11-10 13:12:07
CR: Andante (Island Packet 380): 11-10 16:55:29

CR: Summer Love (Amel SM 53): 11-11 16:56:14
CR: Pelekan (Island Packet 485): 11-11 16:58:56
R: Seven Strong (Hylas 51): 11-11 16:58:57
C: Kalista (Cabo Rico 45): 11-11 17:00:26
CR: Kia Orana (Hallberg Rassy 39): 11-11 17:04:14
R: Oceane 5 (Ovni 43): 11-11 17:04:15
R: Romany Life (Hylas 54): 11-11 17:04:32
CR: Lucky Bird (Moody 425): 11-11 17:08:26
CR: It's Only Money (Hylas 49): 11-11 17:09:04
CR: North Star (Tayana 52): 11-11 17:11:53
C: Discovery (Bowman 57): 11-11 17:18:22
CR: Brown-Eyed Girl (Amel 53): 11-11 17:23:46


C: Ohana (Custom Cutter 45): 11-12 08:19:33
R: Shay La Mer (Beneteau 43): 11-12 09:09:33
R: Ceol Mor (J/42): 11-12 17:15:02

CR: Moonlight Fantasy (Nauticat 43 PH): 11-18 9:06:01

[sneuman]

Here are the results from the Rally Class:

1 Antonina Cherubini Schooner Vince Archetto
2 Clover III Swan 56 Neal Finnegan
3 Joy For All Farr 50 Gil & Joy Smith
4 Fado Fado Leopard 46 Cat Denis McCarthy
5 Special Delivery Taswell AS 58 Bill & Diana Quinlan
6 Nana Maria Tayana 58 Mark & Janel Seier
7 Zafu 444 J 44 CR Mike Scott
8 Sapphire Jeanneau 54DS Bill & Linda Knowles

9 Dancing in the Dark Island Packet 485 David Heaphy

Once again, the Cat does Ok, but doesn't beat out the monohulls and a heavy cruiser and a racer-cruiser take 1st and 2nd.

What are we seeing here? I think we're seeing that when boats are loaded and crewed for cruising, the odds even out for heavier displacement boats and monohulls.

[Paul Elliott]

Are these Rally results actual time, or corrected time? Not that I care, but my boat is definitely on the heavy side, and in the Pacific cup we really appreciate our rating -- if we were scored on elapsed time only, we would have finished much worse than we did. On the other hand, if the conditions are just right we can run away from the smaller boats, due to our waterline. If the conditions let the lighter boats start surfing they leave us in the dust/wake. If the wind dies, the light racers zoom on by.

It all depends on conditions and point of sail.

[sneuman]

wrong year, in any case, and probably handcapped results besides. ignore my previous.

[bobfnbw]

If your talking about racing only, I think there is no doubt that the long water line, ultralight displacement boat is hands down the winner, unless the skipper and crew are inexpirenced on that boat.
But if your talking general cruising, a good boat, sailed well, will get there. Maybe not first, but I don't think even a heavy weight boat will come in to far last.
I remember when a westsnail 32 came in first on a pacific run a few decades ago, proving that even a very heavy boat sailed well can do well. And of course who can forget the perfect storm. Boat rode out the storm even without human assistance. Light displacement boat would probably not survive something like that... but then who knows.
Me I am ok with my heavyer displacement boat. Sails well in most air. In light I go slow. Its ok.

Bob

[roger.waite]

Originally Posted by sneuman

Further to Joli ... :

C: Etheos (Valiant 42): 11-10 8:53:01
CR: Karina (Tayana 55): 11-10 09:00:51
CR: Billy Ruffian (Van de Stadt 47): 11-10 9:20:57
R: Shazam (J/130): 11-10 12:56:23
CR: Habits of Health (Moody 54): 11-10 13:01:53
R: Namaste (Jeanneau 54DS): 11-10 13:02:11

CR: Andante (Island Packet 380): 11-10 16:55:29
CR: Summer Love (Amel SM 53): 11-11 16:56:14
CR: Pelekan (Island Packet 485): 11-11 16:58:56

IMHO it is wrong to interpret the data as proof that heavy, medium & light yachts travel at similar speeds. (Which may be true for some boats, in some conditions, and sailed by 'race' crews with little interest in times.)

The same results also tell us that 'length doesn't matter' (42' outsails many 50+'), and IP 38 outsails IP 48. So we must also reject the hypothesis that speed is a function of waterline length?

Yeah, right. I don't know what, but something else is going on here. As said already, are these elapsed or corrected times?

[Joli]

Hello Roger,

Those are elapsed times. What we don't know is how hard the boats are pushed, how much crew is on each boat, and routing. Between race trim and cruise trim we can have very different elapsed times for our boat. That is not to say one way is right or wrong as a methodolgy to sail.

We do know a Valiant 42 and a J 130 are substantially different boats but none the less they finished at about the same time. Then throw the multi's into the mix and the picture truly becomes blurry.

I guess I'll continue to fall back on: "it's all about waterline" generalities. Similar waterline boats sail at similar speeds but there can be outliers.

Originally Posted by roger.waite

IMHO it is wrong to interpret the data as proof that heavy, medium & light yachts travel at similar speeds. (Which may be true for some boats, in some conditions, and sailed by 'race' crews with little interest in times.)

The same results also tell us that 'length doesn't matter' (42' outsails many 50+'), and IP 38 outsails IP 48. So we must also reject the hypothesis that speed is a function of waterline length?

Yeah, right. I don't know what, but something else is going on here. As said already, are these elapsed or corrected times?

[Bloodhound]

Originally Posted by bobfnbw

If your talking about racing only, I think there is no doubt that the long water line, ultralight displacement boat is hands down the winner, unless the skipper and crew are inexpirenced on that boat.
But if your talking general cruising, a good boat, sailed well, will get there. Maybe not first, but I don't think even a heavy weight boat will come in to far last.
I remember when a westsnail 32 came in first on a pacific run a few decades ago, proving that even a very heavy boat sailed well can do well. And of course who can forget the perfect storm. Boat rode out the storm even without human assistance. Light displacement boat would probably not survive something like that... but then who knows.
Me I am ok with my heavyer displacement boat. Sails well in most air. In light I go slow. Its ok.

Bob

Interestingly, the boat of the Perfect Storm was also a Westsail 32, called Satori, now sailing out of the Kemah, Texas area. Hmmmm... strange, that.

[sneuman]

I wasn't trying to suggest that it "proves" anything. I just thought the data was interesting.

What it mighht mean, however, is that few, if any, single-handed crews sail their lighter displacement racers to their potential day in and day out. If they did, we might expect to see that reflected in a set of data such as these. But, alas, we do not.

So, the perceived performance advantage to have cruising in a light displacement racer or a catamaran, might be significantly narrowed in "real world" situations.

Just maybe

[bobfnbw]

Originally Posted by Bloodhound

Interestingly, the boat of the Perfect Storm was also a Westsail 32, called Satori, now sailing out of the Kemah, Texas area. Hmmmm... strange, that.

Yes, I know. Not strange. But I didn't know Satori was now based out of Kemah.
Thanks for that info.

Originally Posted by ,

the perceived performance advantage to have cruising in a light displacement racer or a catamaran, might be significantly narrowed in "real world" situations.

Just maybe

I believe its a yes, not a maybe. As you say, its not that the boats are that much different in profiles, cause they are, its that I believe that 1) its how they are sailed, and 2) its "the real world" where things happen.
Now take a ULD sled and of course its going to smoke anything out there... till the rig brakes mid ocean or the keel bulb falls off and watch that Heavy displacement boat just sail on by.
Unless of course the crew on the heavier boat is sick, is drunk, or just likes to take is slow at night etc...

Again, to each his own.
I'll take a heavier boat with a good SA/D ratio.
Some will go light.
Some wont know the difference.

Bob