Sorry Breakwater,
I was reading wrongly.
So Fiberglass is accepted for the hull and rudder and this is a good new except for the mast !
I just made a rough calculation with the Enterprise scale 1/28, the wooden hull shall not heavier then 750/800g.
For curiosity, I weighted the wooden master and is 1400g.
The two FBG shells are 280g but not joined yet.
The is plenty of matters to be analyzed if FBG is not used, although the idea to make a wooden boat is not bad eventually with veneers ribbons
Cheers
ClaudioD
Yes, Fiberglass is acceptable.
Most use laminated pine for masts, but I do believe Aluminum is permitted, which will provide some weight savings.
Additionally woven sails are required, and not Mylar. I would recommend the use of spinnaker cloth, as Dacron is very heavy and stiff.
Anyways.
Doesn’t have to be an M.
But you could make almost all of those 12s/Js into An equal length class, and they would be very closely competitive with one another. Yes, one design will reign supreme on the scaling, that is given.
But how is that any different than the full size yachts? Of the Boats built Ranger takes the cake in real life, although Svea or Lionheart might hand it a whoopin’ if they were built.
OK let’s go for 127cm long J Class and 127cm long 12Meter Class with fiberglass and aluminum Masts.
What is your choice among the ones listed ?
actual standing for 12Meter is :
- Courageous : 1
- Azzurra : 2
- Australia II : 2
- Kiwi Magic : 1 (plans ?)
- French Kiss : 1
among J-Class so far ! (my choice)
- Enterprise : 1
- Ranger :1
Cheers
ClaudioD
PS : I’m thinking to have the possibility that J Class and 12Mater may race together and having the option to use a blade with a bulb and when racing with Marblehead to replace the blade and bulb with a lead brick flush to keel see sketch.
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IMHO you just knocked out 99.5% of possible builders … with far too complex construction
Hi Alan,
who decide to make a J-Class or a 12Meter is already an experienced modeler.
It may be much less complicated then what you think.
The lead box/block is already part of the construction, and often is a removable part held in place with bolts.
In the example I imagine that the lead block is practically composed of 3 separated and bolted blocks.
Only the central part is removed/unbolted to let the fin passing trough.
The treaded rod as you already developed for the AC120 adjusting fin, is the same that control the fin height as well the central lead block
The only addition is to integrate the fin box on top.
Probably I should make another drawing to better explain the lead interchangeable game !
As you says : You can only create, what you can imagine
Cheers
ClaudioD
Claudio,
Your boats have a draft of up to about 16.5 cm. A Madcap Vintage M has a draft of 37 cm.
I do think this is a worthwhile exercise that will produce beautiful and wonderful model sailboats. I just do not think they will be competitive against Vintage M boats.
No, no, no.
It still IS a Marblehead without the drop-keel. It’s just a Traditional Marblehead.
I would never expect this hull to be remotely competitive with a MODERN Marblehead. I would expect it to be EXTREMELY competitive with a Traditional Marblehead.
The first design is a home-run. The second with the fin/bulb gets filed in the ? Category.
Atleast from a M-perspective.
Hi Scott,
here the representative side view drawing combining Madcap and Columbia for 127cm LOA.
What wrong with that ?
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ClaudioD
Perfect!
except the Columbia is a Traditional Marblehead, and is not, nor never should be a High-Flyer.
Columbia is perfectly suited to be a traditional M, without any drop-style keel modification. I would recommend option 2, without analizing the data, as the 2" keel extension will add to to model’s sailing properties. Traditional Marblehead rules will allow you to extend that style keel all the way to 304.8mm (12") however, I don’t think you want to go that far.
I will upload a photo of my High-flyer in a moment to help understand what constitutes one,
The Madcap, as drawn above is a Traditional M
This is my High-Flyer designed Marblehead. The design name is called a “Warrior II” Originally designed by S. Goodwin.
Technically speaking the only design criteria that makes the difference between a Traditional or High-Flyer Marblehead is the manner in which the rudder is hung, and it’s draft.
My boat has a spade rudder. Along with a draft less than 16" (per High-Flyer Rules) and a Non-Prothagenous keel… this model is a High-Flyer. It also carries the full 50" LWL
Now, The Madcap design carries a much different style keel, a much more “Traditional” hull form without the skeg/ballast.
But, what makes it a true Traditional is the Rudder arrangement as drawn. The rudder is integral Skeg, and the draft is less than 12"
Traditional Division boats are characterized by short waterlines, integral skeg and rudder arrangements, shallow draft, and low aspect ratio sail forms.
The Madcap is a unique design because you COULD build it as a High-Flyer if you used a Spade rudder. But, doing so of course would be handicapping the boat against full 50" LWL High-Flyer boats such as mine.
In Conclusion. All of the J or 12s could be drawn as Traditional Ms, as well as High-Flyer Ms dependent on their underwater appendages, but they will be highly competitive against boats such as the Madcap, and not highly competitive against boats such as my Warrior II
Thanks,
so if I have understood well the Columbia type (or any 12Meter / JClass side forms) should be OK if the keel shape is modified/lowered by 2 Inches as drawn for Option 1.
Not need to go as far as 12" unless proven to be necessary under strong wind conditions or because some other use it already !
Cheers
ClaudioD
Correct.
Also ensure that the Rudder arrangement remains a integral skeg and rudder, and not a spade. Any design utilizing a spade rudder will be constituted as a High-Flyer, and therefore most likely be at a LWL disadvantage.
One final note of importance is that all High-Flyer and Traditional models must have a 1" Garboard Radius turn.
This is another rule specific to the M.
Again, doesn’t have to be an M, but it would be cool since there are many hulls already competitive similar to these Js/12s
Hollow of garboards shall not be less than one inch radius and may be checked by use of a disc two inches in diameter, applied to the garboards at a convenient station.
This rule is in existance, because, well think of a Modern M with a rounded hull, and daggerboard style keel. Like I said, these hull-forms don’t warrant drop-keels. those are for Modern boats.
I wouldn’t forsee this being an issue with the 12/J style hull form at all, unless the keel is extended to a full 12" draft which would be far too much anyway. The Madcap design sails wonderfully as-is on a 222mm Draft.
Just watch John’s video!
http://www.rcsailing.net/forum1/showthread.php?6680-VM-Madcap-sailing-on-Boston-Christian-Science-pool-video
Thanks again,
this drawing represent my understanding applied to Columbia 1958 . No problems expected with gal-board.
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Do you know the Madcap displacement ?
Cheers
ClaudioD
Now that, Looks beautiful.
The Madcap Plans call for a displacement of 14.60"
However, the Madcap plans are known to be slightly inaccurate in other areas, so I personally have no verification of that. Plus the Madcap is typically hand-carved, and the actual displacement differs based on the builder’s final product.
My expectation is that the Columbia 12 will have a slightly higher displacement value at the equateable draft of 222mm, but its hard to tell for sure.
The difference being that the Madcap was a model yacht designed to be 50" long, and the Columbia is a full size yacht being scaled to fit into a different class. So, of-course it won’t be as optimized. Like we said, some designs will be better than others.
The only way this whole project will create a cream-of-the crop boat is to make a full-sized J boat, and not scale anything! And at that, the Ranger will be best.
I don’t know how you do all these drawings so fast and of such quality. Man you are good.
Additionally, the Madcap LWL is 36" per the plans. What does the Columbia LWL come out to?
Edit: Opps, I see 838mm or 33"
The other thing is, If the displacement value of Columbia at 50" comes out to be way-high in comparison to the Madcap, try scaling one of the J boats.
You might get a longer LWL out of them, and lower displacement value as the 12s have typically “fuller” underwater volume and the Js are kinda more long, deep & skinny.
But overall considering the hull-forms, the 12 Might sail better at 50" than a J at 50" due to that beamy-ness. A 50" J surely will need a keel extention.
Note that the drop keels as shown are not legal in the VM class owing to the “non prognathous” rule, included to correspond to original MYRAA rules. No part of a keel can be forward of any part above it. Long story about why that was in the original rules.
Cheers,
Earl
In regards to this, yes drop-keels are not permitted in the VM group (not class) owing to the “non prognathous” rule, included to correspond to original MYRAA rules. No part of a keel can be forward of any part above it.
You would, However be within the rules if you added a non-prognathous drop-keel, such as the one that is on my Warrior II.
But I don’t know why you would want to do that to such a beautiful traditional hull-form. It just looks dumb.
Surely you are looking for a better righting moment, but you don’t need to do that on a Traditional style hull. These boats take shorter rigs and fuller sail-plans.
The Madcap plan calls for a 58" Mainsail luff, with 784 square inches of sail (800 max permitted)
The Warrior calls for a 85" Mainsail Luff!!! With 800 sq inches of sail.
These are two completely different Marbleheads. One is a Traditional (Madcap) and the other a High-Flyer (Warrior).
I would never expect a Madcap to beat a Warrior on paper, but, of-course, it depends who’s at the helm of which in the real world.
So, resuming this is actually my understanding.
I confess my ignorance, but the word “prognathous” applied to naval design was meaningless.
I search in the dictionary “prognathous” and found reference to human jaw but also to animal heads morphology. see Sphinx
When the words are not sufficient, then I use images, my preferred language !!.
This drawing may help, is the ‘striped’ area what is so called “prognathous” ?
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For a moment I was thinking to the rare “forward” use of bulbous bow in sailing yachts, but most of the times used with big ship as tankers.
Thus:
No drop fin/bulb allowed
No “prognathous” form
Hope that an enlarged cross section to locate more lead, to favor righting moment, is permitted. (after careful check with hull volume to support it.
See sketch :
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I’m fast with drawings because I use an old version of CorelDraw 5 since 1994 and before with version 4. I don’t like dedicated 3D software since I’m faster and cleaner with CD5 !
Cheers
ClaudioD
Being member of the 12Metre Class fleet, this is the side view of Courageous 1977.
The 12Metre started using the “trimmer”.
Is that fixture allowed ?
Could make use of dedicated servo ?
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Here instead the J Class Enterprise 1930 :
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Thanks
ClaudioD