Hi Gilbert,
In principle and on paper the 123 has nothing to do with the IOM !
Thanks Claudio, you’re right ! body clock out again :rolleyes:
Hi Claudio, I saw in post 470 that you have the shrouds fixed to top of the mast & not to same position as the forestay, why was that ? to stop head of the main falling off the wind (mast flexing above the hounds) or ?
The reason I ask is that I’m assembling a rig using profiled taped mast for square head main and the forestay is 380 mm from the top of the mast and I see there is about 5 mm sideways deflection of the mast head if I connect the shrouds at same position of the forestay and was thinking moving the shrouds higher up the mast would reduce mast head deflection.
What are your thoughts on this ?
Cheers Alan
Hi Alan,
simply because I’m use to do that since when racing with Class M.
In that way I don’t worry about lateral flexibility on top of the mast.
Meanwhile here below the last pictures of the 123 ready to go for launching once You arrive !!!
I just weighted the full boat as is and the balance mark : 4261g
Probably , not sure yet, I would like to remove some weight from the bulb up to 100g as such that the final weight will drop to 4161g
The new bulb weight will be 2820g.
The weight ratio : 2820/4161 = 67.7% compared with 63.3% of a theoretical AC120. I still have 6cm longer fin.
The hook is on the vertical position of the LCB !
Cheers
ClaudioD
PS:
I made a sort of hanging hook to pull the full boat and observe the longitudinal equilibrium - The hook is on the vertical position of the LCB ! Apparently is OK and no need for corrective actions !!
CD.
Congratulazioni!
We finally get a sense of its size, seeing it in your arms. Very impressive. And the lines are truly beautiful. It must be quite a satisfaction to get to this point after so much planification, effort, steps back, with on top the burdern of reporting to us almost daily.
It can’t possibly match your own excitement to see its debut on the water, but I guess some of us that have been following your progress since the begining will share some of it. If I could, I would gladly share the drive with Alan to be a first line witness!
If I may ask, can you take a few close-up pictures detailing all the attachment of your rigs. I mean like the clew/outhaul line, the tack/gooseneck, the turnbuckle, the mast attachments of the shroud, the attachments of the backstay and forestay (top and bottom), the masthead? This will complete the masterfull documentation of this project.
Un grand merci pour avoir partager cette passion et si généreusement transmis sans compter votre savoir et votre expérience!
Sylvain
Indeed Sylvain,
is not a small one but it is not a big one either.
For curiosity is can pass trough a rectangle of 2.44mt high and 1.23mt wide and weight 4261g.
The final ‘surprise’ is the full Rig weight of 285g against the expected 222g !
This adventure started almost 5 months and 3 weeks ago starting from a white paper and concluding with the construction of two different models by changing route from the original bowed deck to the flat deck.
My self-made outfitting are rather rudimentary ones, but sufficient to cope with the purpose.
A lot of effort shall be done to reduce the constructional weight by analyzing in detail what need to be done starting with the hull lamination and supports construction.
Not to forget that in this second model there are 2 winches, therefore some 60g can be already gained with the use of a servo arm and probably with a jib trimmer. The sheeting system will be lighter. As said previously, the bulb reduction is another possibility still maintaining a good ratio and in any case better then other existing models.
At the end of this exercise I have to abandon the idea to reach the 4050g also because I intend to introduce a movable internal ballast that could be around 200g.
As preliminary identifications for future model :
4261g - 100g from the bulb reduction = 4161g
4161g - 60g from single arm servo = 4101g
4101g - 60g from laminations & supports = 4041g
4041g + 200g from internal ballast = 4241g
So as can be seen the actual 1.2.3. weight is the same of the future model with the advantage of having the internal ballast.
The pictures below will try to show what you ask for ! Just remarking that over 700 pictures has been published with my thanks to RCSailing to have allowed it.
Of course the new drawings for the future 1.2.3.Mark II model are almost ready. See Below.
Don’t look at the paint that is not my cup of tea, next time I will go to the car body painter, as done in the past for the cost of a good servo !!!.
Cheers
ClaudioD
still some pictures :
the last ones before water !!!
Just a tip, it can be noticed that on the future model drawing, the main bulkhead, the LCB and the LCF are very close each other when the boat is standing up and when is tilted by 25°. This is what I called a well balanced hull !!!
ClaudioD
This new set of pictures is perfect. It answers all of my remaining questions. Thanks a lot!
Your 123cd4 drawing is quite a teaser. You really know how to raise our anticipation.
Sylvain
^ what he said…
love the wave peircing bow…
Sylvain
Is a teaser for me too because is another challenge to myself.
All learned lessons, could be very profitable for the next enterprise.
You may have noticed the faired bow to contrast the nose down and not only !
I was watching several filming of sailing models and almost all suffer of a pitching movement when meeting a series of wavelets.
I told myself that I need to do something !
Now the actual 123 model shall confirm the basic assumptions all related to the underwater design as : DSPL , Bulb , Fin , Rudder and the sailing performances.
Based upon that experience, I will be probably invited to make some minor changes since this hull is perfectly balanced in all aspects.
The future model (winter sport) will deal essentially with the ‘above water’ design as simply shown in the picture 123 CD4, and include a new roof design concept and 200g ballast.
Cheers
ClaudioD
Claudio,
Fantastic effort!
I love that, in the beginning you began by saying that maybe this will be the last, (and even after the restart) your here nearly at the end having never sailed the boat… now looking forward to the next project and already have it hammered out in a drawing!
Amazing! Good luck with the maiden voyage.
Jim
Thank you Jim,
the tests will bring part of the answer !
I enjoy a lot doing that, before, with the Dragon, I was playing another music !
Cheers
ClaudioD
This morning I simulated the battery consumption, so I toke a 4.8V 750mAh battery and started playing with the joysticks and sail sheeting and rudder. One full maneuver every 5 seconds that is more then what happen really.
To contrast the sails, I used an air blower, probably not very powerful but sufficient to provide some sail contrast.
I modified every 15minutes the boat position ! Funny, the butterflying position was operating almost automatically like there was a real butterfly stuff !! This tell me that the jib boom counter weight of 12g is perfect for the purpose !
The battery lasted 51 minutes , the first servo to stop was the rudder one, strange since is the less powerful of all.
To remember that servos are 3 of which 2 are winches !
ClaudioD
I couldn’t resist to see what would be like, just few pieces of foam and little sanding to get an approach to the future reversed bow !
ClaudioD
Claudio,
I believe if your bow section leads into a fairly flatter underwater mid section, there may be less tendency to bury the bows downwind. You already have the beginnings of a flatter underwater hull section, and while it might generate more surface (and drag) it might also provide a more stable platform. Having the bow tilted up slightly might cause “lift” and any large wave that break over the bow will be shed to each side and off the boat - unlike hulls with flat decks. Possibly shifting mast, sails, keel slightly aft would also help prevent any sudden pitchpole. Just my personal thoughts/theory.
Hi Dick,
I appreciate, but there are many other factors to take care.
Flatting the sections will force to increase also the rear volumes other then the wet area.
A buoyant stern will force the ‘nose down’ too.
My basic idea is to get sufficient flared bow to get reserve buoyancy ahead but also trying to avoid the hull being victim of wavelet undulations to avoid mast swings and getting sails in stall most of the time when running.
Here some working solutions, I wonder which one you will adopt ?
Considerations also imply to keep performance within a wide range of winds ! Deeper hull will be better to force breaking the waves !
My favorite is the 123-cd4
Cheers
ClaudioD
maybe the influence from the multi but would it not be better to have a slightly higher bottom end of the bow from the waterline so this reverse bow doesn’t dig too much in the little waves but still remain effective with the bigger waves ? this would change the underwater shape I suggest but might be better overall in my view, no ?
Hi
The question on the table is : how to contrast the pitching oscillations due to wavelets ?
ClaudioD
Oui … you hit a raw nevre with me, I have been thinking about this for over 12 months Claudio, and for my 2 cents worth I throw this on the table for discussion.
For us non-mathematicians, the seesaw principle simply demonstartes that in order to keep balance, the sum of the “weights” times the “distances”(to the centre) is equal but a lever can be set up with unequal weights placed at different distances from it’s balancing point.
Applied to boat, this is what I think affects pitching the most. The question I asked myself is that with all things in balance but in different positions to center how much energy is required to move one end compared to the other.
The “central balanced” weight (top illustration with one person in the centre) requires minimum energy to induce pitching.
The “end balanced” weight (middle pic with person each end of the centre) requires maximum energy to induce pitching.
The “offset balanced weight” (lower illustration) requires more energy at end where one person is seating compared to two people at the other end, to induce pitching.
Based on this simple logic I’ve started been playing around with “offseting weights” by moving bulb C.G aft & position of movable ballast (2-300 grams) more forward of the mast base in the hull, I’m slowly convincing myself that there is improvement in boat stabilty against pitching, now that could be imaginary as nothing was measured … but your welcome to shoot holes in this KISS theory 
Cheers Alan