View Full Version : 12 Metre design
Hello all,
I am interested in the bustle,both for and aft, used on the later 12 metres.
Anybody know where info could be found, photos or links would be appreciated.
Thanks, Peter.
booster
10-14-2009, 05:32 AM
Hi!
Sparkman&Stephen's Couragous had bustle both for and aft. The aft bustle was tested on earlier boats as well. The for bustle was increased to near its limits at the design Tom Blackaller sailed (Independence?): "The boat pushed water in front of it". During the tests before Fremantle Dennis Conner even tested a bulb. However, it only worked properly in flat water. The Start&Stripes that took back the Cup to the US had a compromise bustle in the bow. It slightly resembled a bulb and was nicely integrated with the gondola bow. Try to Google for sites on the subject.
Regards,
Booster
I have used Google but not much luck.
I want to know pros and cons, what works what doesn't and why.
Peter
ABoatGuy
10-15-2009, 12:45 AM
Keep in mind many of the bustles, both in 12m and IOR design were rule beaters and had little to do with pure boat speed.
I am aware of this, thanks
booster
10-15-2009, 04:23 AM
Phum!
I Googled as well, with little results. A photo of a much debated bustle you can find under "The Britton Chance portfolio" on this site. The Mariner bustle still confuses designers.
Regards,
Booster
booster
10-15-2009, 10:39 AM
Phum!
http://www.sparkmanstephens.com/yachtdesign/sailyachts/twelvemeter_designs.php
"During this period, Olin experimented with how the wetted surface of a hull could be reduced (for less drag and greater speed) without endangering the seaworthy qualities of the boat. As a result of his model testing, he concluded that "wetted surface aft was not as harmful, perhaps, as it was forward because the water by then was already going with the boat," leading to the creation of a "bustle" in the waterline of Constellation."
Regards,
Booster
Any idea what other metre classes employed bustles?
I did find one small peice by Stephen Jones that said a stern bustle was a good way of distributing displacement in a heavier displacement hull or words to that effect.
Peter
Paul Kotzebue
10-17-2009, 10:38 AM
Any idea what other metre classes employed bustles?
The six meters are more or less scaled down 12 meters and they have similar bustles. The bustle is a means of reducing the measured length by abruptly changing the hull shape just ahead of the aft girth measurement station. A bustle makes sense any time sailing length is measured between girth stations, such as the IOR and meter class rules. Those are the only racing boats that have bustles that I'm aware of.
At the end of the CCA era they employed bustles too.
Paul Kotzebue
10-17-2009, 02:26 PM
At the end of the CCA era they employed bustles too.
I know bustles started showing up on IOR boats shortly after the rule was introduced around 1970. I've also heard of pre-IOR boats being modified to incorporate a bustle to be more competitive under IOR. I'm interested to know what CCA boats were built with bustles prior to the IOR. It is conceivable the designers were anticipating the boats would be raced under the new IOR rule.
I had a 35' Lion class sloop, converted as a yawl under CCA, but it incorporated a bustle. I could only speculate the designer's logic, but it was fairly clear a tactic to beat a rule.
dskira
10-18-2009, 09:05 AM
Hello all,
I am interested in the bustle,both for and aft, used on the later 12 metres.
Anybody know where info could be found, photos or links would be appreciated.
Thanks, Peter.
My question to your post will be : why?
Cheers
Daniel
dskira
10-18-2009, 09:13 AM
I have used Google but not much luck.
I want to know pros and cons, what works what doesn't and why.
Peter
To complete my previus post why you want to know the pro and con?
What will be the use for when you have the information, meaning half will said it works, half will said it don't.
In which parameter you will want to incorporate an appendice?
Just curius.
Cheers
Daniel
Paul Kotzebue
10-18-2009, 10:47 AM
I had a 35' Lion class sloop, converted as a yawl under CCA, but it incorporated a bustle.
Is that an Arthur Robb designed Cheoy Lee Lion?
gonzo
10-18-2009, 11:00 AM
The why is to beat a rule. If you can make a boat that measures slower than it actually is, you beat the rule and win races. It doesn't mean the boat is faster, but that the rule says it is slower.
Paul B
10-18-2009, 02:14 PM
Is that an Arthur Robb designed Cheoy Lee Lion?
Like this one?
Paul Kotzebue
10-18-2009, 02:25 PM
Like this one?
That's the one I was thinking of. Designed around 1960 and looks more towards the RORC than the CCA rule. Does not have a bustle at all, which is one of the reasons it is such a nice looking boat. Wouldn't mind owning a boat like that myself.
I've had two, a 1960 copper riveted teak version and a 1968 'glass one. The 'glass version had the bustle, though the pictures from the owners group I just looked at didn't show the same thing, so it must have been a previous owner modification. It surely was very well done if that was the case. I don't remember the rudder port area on the '68, though I remember the teak one, which needed extensive bulkhead repairs. It was one of my favorite sailing boats.
Paul Kotzebue
10-18-2009, 04:02 PM
Beautiful boats.
To get back on topic, I still think the only reason for a bustle is to minimize measured length in a rating rule where length is measured between girth stations, such as the IOR and International Rule (meter classes). I am interested to know if designers such as S&S and Bill Tripp, Sr. were using bustles to optimize boats during the CCA era (pre 1970) as was implied in an earlier post.
Sailing yacht design innovations should be studied in the context of the rule they were measured under.
booster
10-18-2009, 05:32 PM
Phum and Kotzebue!
True, in the context of the rule. The 2.4mr designs can be studied at
www.24mr.se
Regards,
Booster
Dskira,
Answers to your questions.
I have freinds who design, build and sail A. Class radio controlled model yachts.
It surprises me that with all the variation in underwater profiles there is not much difference in performance.
I would like to know how bustles affect water flow and performance etc.
It can't be all cheat, there must be some science behind it.
Peter
Booster,
Thanks, I note the modded one with the Mariner type stern.
I sent a couple of emails to addresses in that site but no responce.
Peter
apex1
10-18-2009, 05:55 PM
That's the one I was thinking of.
it is such a nice looking boat. Wouldn't mind owning a boat like that myself.
Yeah it is of course! Did nobody notice that the designer was pretty drunk when he drew the rudder? That rudder does well under sail, under power you nearly have no rudder. Maneuvering with such a hole on the wrong side is a pain in tight quarters.
Paul Kotzebue
10-18-2009, 06:25 PM
Apex,
That rudder is typical of auxiliary sailing yachts built from the 1930's through the 1960's. I've sailed on many boats with that type of rudder. They did not maneuver well under power, but you went real slow in tight quarters. It was just about as easy to maneuver those boats under sail as under power. The idea was to hide the propeller behind the keel under sail. The aperture extending into the rudder allowed the propeller shaft to be removed without removing the rudder.
phum,
The reason you don't see bustles on every boat is they do not make a boat faster. They are a means of reducing the measured length under certain handicapping rules, and that's it. It can make the difference between winning and losing so it is important. The IOR bustles of the early 1970's all but disappeared by the end of the IOR era in the late 1980's. All the science and tank testing involved with the design of bustles was to optimize actual speed vs. rated speed. For a given rated length, the bustle would decrease wave making resistance at certain speeds. That's the crux of the science.
Booster,
Cool stuff on the 2.4m site. Lots of little bustles that end just forward of the aft girth measurement station.
Paul B
10-18-2009, 07:59 PM
To get back on topic, I still think the only reason for a bustle is to minimize measured length in a rating rule where length is measured between girth stations, such as the IOR and International Rule (meter classes). I am interested to know if designers such as S&S and Bill Tripp, Sr. were using bustles to optimize boats during the CCA era (pre 1970) as was implied in an earlier post.
I've never seen a bustle on any boat that was not there for a rating consideration, as you have pointed out.
For the supposed bustle on a Lion 35, if it was added as an addition to the outer skin that would be easy to spot as the visible bump on the hull would not have a corresponding void inside the hull. Back in the late 1960s/early 1970s I doubt an addition would have been done this way.
If it was integrated into the existing glass hull the surgery would have been significant. Probably the last 1/4 to 1/3 of the hull below the WL would have had to have been removed, then rebuilt over new forms. This would have required a significant portion of the interior to be removed and later rebuilt. The surgery would have left visible laminate changes on the inner skin. That's something you couldn't miss.
I can't imagine anyone spending the time and money to make that sort of a change, one that would not make the boat sail better or rate better. It makes no sense.
I can and have seen this level of "significant change", the last being a bow extension to compete in the Bermuda race as a 40' yacht with a 37'er. As to the bustle, I just can't remember that portion of the hull, internally, it was about 30 years ago now. I suspect the 'glass version of the Robb design was just a knock off, though the spec's for the two different hulls show different LWL lengths. This suggests displacement was "accommodated" in the 'glass version. If this is the case, other "modifications" could have been incorporated into the mold. My dealings with Choy Lee when I owned the 'glass version of this yacht (mid 1970's) discovered that a fire destroyed most of the records and drawings from earlier production runs. They sent what they had and were surprisingly helpful with what information was available. Of course Robb's wooden drawings were easy to get. I don't even know if Robb drew up the 'glass version or authorized the conversion.
Paul B
10-18-2009, 11:28 PM
I can and have seen this level of "significant change", the last being a bow extension to compete in the Bermuda race as a 40' yacht with a 37'er.
What boat was it that added to the bow in this way? Of course there was a surely a reason for this, such as length restriction to enter the race? Many boats have significant mods, but there is a reason. Adding a bustle to a Lion 35 has no reason.
As to the bustle, I just can't remember that portion of the hull, internally, it was about 30 years ago now. I suspect the 'glass version of the Robb design was just a knock off, though the spec's for the two different hulls show different LWL lengths.
Surely you have photos of that boat?
I imagine Cheoy Lee produced the glass mold from the same lines as the wood boats. Probably even used a wood hull to splash the mold. Regardless, I can't find any evidence of any glass hull having the bustle described.
What is it with you, do you find it necessary to call most of the forum member liars or is it that you just are one of those argumentative persons that must find fault with everything.
Just because you don't understand something, doesn't mean it doesn't exist, it just means you don't understand it.
Paul B
10-19-2009, 01:16 AM
What is it with you, do you find it necessary to call most of the forum member liars or is it that you just are one of those argumentative persons that must find fault with everything.
Sounds like someone is projecting here. Why do you have lies at the forefront of your thoughts?
I have not said anything about a lie. You claim something, and I asked if you had a photo, since my recollection and all evidence I can find on the internet don't show anything like it. If we knew things like Hull Number or registration we could look into it further to try and understand it. It would be interesting to see the modification you describe.
Ditto the question about adding to the bow of a boat. Sounds like an intersting solution to a problem.
Just because you don't understand something, doesn't mean it doesn't exist, it just means you don't understand it.
There are many things I don't understand, therefore I ask questions.
I'll leave the forum to asses rather then tolerate this type of ridiculousness anymore.
apex1
10-19-2009, 03:56 AM
Apex,
That rudder is typical of auxiliary sailing yachts built from the 1930's through the 1960's. I've sailed on many boats with that type of rudder. They did not maneuver well under power, but you went real slow in tight quarters. It was just about as easy to maneuver those boats under sail as under power. The idea was to hide the propeller behind the keel under sail. The aperture extending into the rudder allowed the propeller shaft to be removed without removing the rudder.
Well Paul, I know the reason of such design (which does´nt make it better). And I must confess I have only sailed one of such boats with that rudder outcut. That boat was a goat to maneuvre under motor. Hence my comment. And I know of several older designs with the prop well on the right side, to prevent the lack of maneuverability.
Regards
Richard
booster
10-19-2009, 07:19 AM
Well, PAR and Paul B. seems to be entering the canting-keel zone in their debate. Phum, the low cost of the 2.4mr enable you to test various bustles. The modded Mariner bustle shows great potential. Only light downwind, say 1-2 m/s seems to harm it. Probably to much water must be draged along. By increasing the mainsail (and reducing the jib) the performance is nu much better. Still the differences is small to the most common 2.4mr the Norlin mkIII. Sailing the latter boat type you can tune against identical boats which seems to be more important than optimizing the Mariner mooded bustle.
Another problem is tacking with boats having big bustles. To get the wave-pattern to develop as desired it takes longer time with such bustles. One has to remember that the 2.4mr is a small boat about 4 m long, and allmost all waves are big in comparison.
Regards,
Booster
Paul Kotzebue
10-19-2009, 05:56 PM
And I know of several older designs with the prop well on the right side, to prevent the lack of maneuverability.
What's also nice about the prop on the side is you can use a folding prop. Although a right hand prop should go on the left (port) side. My favorite full keel propeller installation is what Kettenburg did on the PCC's and K38's. The shaft poked out on centerline just aft of the rudder post. You could install a folding prop, no aperture in the keel or rudder, and you could pull the shaft.
booster
10-20-2009, 04:26 AM
Hi!
The steering of boats with bustles can be different from other boats. Who doesn't remember the reports from Fremantle. Stars&Stripes usuallay started to lee of Kokaburra. Stars&Stripes was reported to have "long legs", not pointing that high as Kokaburra but speeding. Stars&Stripes sailed "around" Kokaburra. Conner tried to keep the bow under high pressure and the steering was said to resemble that of a drunk.
Regards,
Booster
booster
10-20-2009, 10:11 AM
Hi!
Well, a good portion of bustle may be helpful, but compare the draft of Stars&Stripes at 2.96m to 2.64m of Kookaburra. This must mean that Stars&Sripe has a draft penalty under the R-rule. Perhaps this was more important than the bustle discussed previously.
Regards,
Booster
Stars&Stripes US-55
Length overall (LOA): 20.23m
Length waterline (LWL): 13.92m
Beam: 3.81m
Draft: 2.96m
Sail area: 164.70m2
Displacement: 28.180 tonnes
Mast: 25m
Kookaburra III
Length overall (LOA): 20.52m
Length waterline (LWL): 13.86m
Beam: 3.80m
Draft: 2.64m
Sail area: 162.90 m2
Displacement: 28.200 tonnes
Mast: 25m
booster
10-21-2009, 07:06 AM
36387
booster
10-22-2009, 02:43 AM
Kotzebue!
What is your analysis of Stars&Stripes US-55 vs Kookaburra III? The basic dimensions are similar but the draft. Seems that one already before the first race could tell that U-55 must be faster. Iain Murray (Kookaburra chief designer) said something about the boats looking so different that someone must have done something wrong. Later poor calibrations of measurment-devices at the tank tests was found to be the explenation.
Regards,
Booster
Paul Kotzebue
10-22-2009, 12:05 PM
Booster,
Are you sure about the draft dimension? It could be a misprint or misinformation. If S&S has a draft penalty she would have to give up length or sail area compared to Kookaburra. Yet that does not seem to be the case based on the dimensions you gave in an earlier post.
The only way to evaluate the relative characteristics of the two boats is to compare rating certificates. However, I doubt very much that S&S took a draft penalty. It is a very expensive penalty (3 x excess draft added to rating).
booster
10-23-2009, 10:37 AM
Kotzebue!
Thanks for your analysis. No, I am not sure about the draft. As you say it can be a misprint or worse, but occurs twice:
www.americascup.com/en/acclopaedia/circlinggalaxy/bateau.php?idContent=4888&idRubr=74
However, I have been told about the US-55 draft penalty about a year ago by the signature MYD on this site. But I didn't realize it was that big. I have asked MYD to comment here.
Regards,
Booster
booster
10-25-2009, 09:27 AM
Hi!
I have discussed the subject above with the signature MYD on this site. Yes, he has seen the information about draft penalty earlier. Some years ago he was in contact with someone in the design team of Stars&Stripes US-55Britton Chance, Jr., Bruce Nelson and David Pedrick. Probably it was Pedrick, MYD recalls. What came out from that contact was that US-55 was said to have no draft penalty. The boat was nothing special, but every detail was 100%.
Seems to me that it was special anyway, in having every detail 100%!
Regards,
Booster
booster
10-25-2009, 10:34 AM
Hi again!
Yes, as pointed out by Kotzebue one must have the rating certificate to see if there is a draft penelty or not. Regarding the 2.4mr in Sweden we have a site there one can study the rating certficates.
http://www.svensksegling.se/Avdforbatteknik/Matbrev/Sokgiltligtentypsmatbrev/
Perhaps there is a similar site for the 12-meter yachts?
Regards,
Booster
View Full Version : 12 Metre design