Hi Row,
I understand your point of view, but the decision was not only triggered by the fissures but also by the weight increase that I could not managed to reduce to an acceptable level.
If the model is “too” heavy the performances will be jeopardized and this is what it is most important from my point of view.
The fact that I will loose a couples of weeks is not so dramatic if the results are there !
When I discovered the fissure the painted hull including the servo winch was 782g
Because the adhesive damages I was obliged to remove all paints white and red and the weight dropped to 713g
Now after repair of one large fissure and one small at the opposite side and with the primer and white paint coat, the weight is raised again to 754g, while the red paint is still missing
The painting for this model is actually calculated and measured to be about 70g and this shall be consistently included in the budget since is an important issue.
Here in attachment the damages and the repair results.
The model is not definitely rejected, at the contrary it will be used as a sailing partner in order to evaluate the impact of weight vs performances.
Master laminated, tomorrow primer and wet sanding.
Meanwhile I should start preparing the deck plastic foils for the deck glass/balsa sandwich lamination.
ClaudioD
Hi Claudio, as my grand mother said (sorry I only know it in French) faire et refaire c’est toujours apprendre ! and it seems to fit here but still - it is a pity - though I like your idea of 2 boats to compare the proto. Good idea.
On the repair did you just slide a band of glass fibre and epoxy it into place ?
Setting up the New deck sandwich construction ! Glass tissue and 2mm polystyrene foam.
The deck is slightly bowed and the sandwich is pressed between two plastic sheets.
According to my calculations the deck shall weight less then 70g :
Deck surface 15.40dm²
2 layers of 80g/m² = 0.8g/dm² x 2 x 2 for resin = 3.2g/dm²
3.2g/dm² x 15.40 = 49.28g
4.28 + 18.75g foam = 68.03g
ClaudioD
PS:
The foam absorbed more resin than expected, hope the final weight will not suffer too much !!!
I decided at the last minute to remove the wooden bar under the plastic sheets and therefore abandoning the bowed deck idea.
This was a wrong approach, since the bowed deck change radius as function of the beam.
A special mock up should be used for that purpose.
The deck will be really flat unless will be possible to bent it with some mini shadows once on the hull !
2nd primer coat on the Master - outside is raining cats & dogs !!
CD
As a matter of fact I was surprised by the amount of resin ‘absorbed’ by the roughness of the foam slices cut with a band saw.
Today I got the confirmation of my doubts : 142g !!! for the deck laminated sandwich.
After roof and cockpit floor cuts, the weight will drop to 95g but for me, at the moment, is still too much !
Only one remedy, a new simple lamination with 2 x 105g/m² + 1 x 80g/m² aiming again to 70g for the deck.
Probably 2 x 105g/m² was sufficient.
your perseverance and attitude have helped me try new things…So keep it up… I need the inspiration…Another delta rig on the way…
Oh and if you decide to put the model in the trash can, let me know. I’ll send you some money for shipping and we can add to the garbage can in my shop here in the USA I
Hi Marc,
is not really a big problem, at least I tried and found out that my building method was not OK.
As said above, with the use of the molds, the work will be perfect.
Now my main goal is to make it one with a flat deck for simplicity and in particular to prove that it is feasible within 4050g including the use of an RMG 280.
It is not excluded to use also two separate winches for Main and Jib, I’m working on …
Don’t worry the ‘scrap model’ will be used for trial with the second under construction.
Happy to knows that you are busy with another Delta Rig and would like to know what are your comments about the first one
New deck lamination just cut out + start of new roof construction while the hull is resting for 72 hours after 3 coats of primer .
ClaudioD
PS : Hull master wet sanding completed. Picture taken when hull still wet ! This method may show any tiny defects if any under finger touch !
After drying, wax will be applied.
As it is can be used for female mold build.
Micro defects detected after wax coating and back light ! These defects will not disturb the direct hull lamination.
Wet sanding to be carried out for female mold.
ClaudioD
Claudio, I have been reading and following your Onetwotwo article since I found it about a month and a half ago. Let me begin by saying that your 122 design is one of the most beautiful designs I have ever seen. It is so beautiful that I just had to have one. I downloaded your drawings and had it scaled to 650cm, the RG65 class model yacht. My model came out very well. I am currently waiting for a carbon keel and keel box. I can keep you updated, if you wish. I wanted to ask you if you designed the hull using the Admiral Turner method of building a “balanced” hull. (https://dl.dropbox.com/u/2751363/TurnerPaper.pdf).A big THANK YOU for the design. I look forward to following your build article to its completion. Thanks again, FlaRGsailor
Hi FlaRGsailor ,
I hope that the RG65 version will sail well.
It is not always the case when reducing the scale of another model. The 123 it is very demanding in term of weight budget and displacement.
One recent example is the scraped first model that do not correspond to my weight budget.
The 123 when transformed in an RG65 should have a displacement of 735/750g at the buoy in order to perform well.
Honestly the paper you refers is discussing the same matter as in others books, the principle of a well balanced hull are well none since it was of paramount importance when the free sailing design boat was in use.
Today with the RC control this aspect is rather ignored, not by me anyhow.
Hi, FlaRGsailor,
you are right, that the 123 is a really nice design and it would be worth to scale it down to the RG65 format - but ending up with a displacement of about 750g most probably you will not get a well performing RG. Our experience here in Germany is, that the weight of a RG65 should be around 1000g. A lower limit seems to be at about 850/900g. Lighter boat perform well only in very light winds. All experiments with boats with a smaller displacement done here failed more or less. Weight has to be saved mainly in the keel bulb and the boats need very long fins to get the necessary righting moment.
Although a lot of of M-boat designs have been adopted in the last years resulting in very well performing boats, all designs have been modified in a way that they meet a displacement of about 950g.
My own design (No.3) is originally based on the Prime Number. The lines have been modified to have a design displacement of 950g (in addition to some other modifications). In lightwind conditions the boat performes well with a keel bulb of 550g, resulting in an overall weight of 850g, in a breeze I go up to 650g and sometimes a bigger receiver battery, resulting in a total displacement of around 980g. With this increased weight, the boat performes much better. The displacement of the original lines would have have been about 750g.
I am eager to learn from your experience - unfortunately I have not the space at home to build (&store) a full size 123…
Finally had a chance to check on progress since my last post - all I can say is you really don’t hang about!!
Many thanks for posting the fissure/crack pictures. From your initial descriptions I really couldn’t understand why you were considering scrapping the hull. Well, as the saying goes, ‘a picture says a thousand words…’. I now appreciate your decision - I guess it’s a matter of semantics - I had no idea of the extent of the damage and as the purpose of the build is to get the displacement down to 4050g I fully understand the need to start again.
With the work done on the plug, where you have minor surface anomolies, would a high-build primer be sufficient to correct them or will you be using/have you used a filler/knifing stopper to correct them? Regarding the new deck, while a flat deck offers simplicity of construction, would it also require additional support (deck beams) compared to a radiused deck? Although the radiused deck would have a marginally higher material content, owing to it’s ‘monocoque’ type form I’d have thought it would need fewer deck beams thus being lighter overall. Perhaps my thinking is a little too simplistic (wouldn’t be the first time!!) and the potential weight savings just aren’t there at this size…
Last question (honest!) What is that ‘plastic’ material that you used as a base in the foam sandwich deck experiment & does epoxy stick to it? (OK, so that’s 2 questions really!)
Very impressed with the rate you work at, I’m getting itchy fingers to get back to my ‘Enterprise’ - been kept busy lately building a OO gauge train layout for son’s birthday - so hopefully I’ll be making some progress soon…
Hi Row,
nice to hear that soon you will be able to start some lab work on your Enterprise.
The sandwich was just glass and foam cut in 2mm slices, see pictures in previous posts.
About the deck : generally is just like an umbrella to avoid wet inside and no matter about strength.
Here I will probably use a couples of balsa beams.
The bowed deck is not abandoned since, with the help of Alan, I understood that coupling will be easy and lighter with the female molds. See previous sketches.
Now I want to go into the water as soon as I can and the female molds will be done later if the expected results are OK.
I’m happy with my primer, is rather thick and respond well to wet sanding. It may happen later to use the white paint undercoat before female mold construction if any.
Actually the deck plain sheet is down to 82g, some further reduction expected later
Today I will start the new Hull lamination on the plug with 3 x 80g/m² instead of 3 x 105g/m² as before
Cheers
ClaudioD
congrats on your interesting project :)!!! I see you have some specific tape to use as peel ply, what stuff is it? Do you think a poliester fabric will serve the same purpose???
Hi Lukasz
Peel ply, as I knows, is a sort of woven Dacron that do not adhere to the epoxy laminate. You may read this : http://www.ptm-w.com/index.asp?pgid=204.
Myself I remove it about one hour later from the time of application and serve to absorb the excess of epoxy resin from the laminated glass.
Cheers
ClaudioD
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