The hull/deck joining is getting closer. Mini wedges all bonded.
Sheeting circuit ready. Waiting only the FBG pocket for battery an receiver.
Various bondings look messy and over dimensioned, I promise next I will do much better !!! uhm !
ClaudioD
123 meet the water for the first time in the bath.
Perfectly balanced !!!
Bulb CG under the LCB !
Rudder, rig, battery and receiver simulated with equivalent masses. Fin not integrated since non important for the purpose.
For easy access to the battery and Rx, I open an hatch just behind the roof.
ClaudioD
Bonding operation !
ClaudioD
PS :
During deck/hull bonding I have also prepared a couple of test samples with foam and plywood.
The pull test revealed a very good bonding, see picture 485.
The bonding process is weighting 8g only ! see 480 & 480-b
Claudio,
Congratulations!!
OK, so getting her wet in the bath isn’t quite the same as sailing but at least it does show that she floats to her lines which of course is fantastic news.
When you come to finally attach the ballast to the fin will you be placing it slightly aft to raise the bow when static?
Also, I’ve just noticed your posting times - are you feeling a little tired today?!! Anyway, as this build draws to a close from starting with a concept to conception I applaud your skills and effort (as I’m sure many more will) and definitely look forward to seeing her sailing.
Regards,
Row.
PS. Get some sleep!!
Hi Row,
I’m happy but not satisfied with my work, I shall improve for the next time. Of course all is coming out from the technical difficulty imposed by the bowed deck with an intermediated joint line. For sure, next build will be with a flat deck with possibly rounded corners !!
To day the adhesive film used to tide up hull and deck has ruined the painted surface (my mistake, since I new about) and now I’m forced to wet sanding the full model after repair of few imperfections along the joint line.
With a sketch I will show where the problem is and how to cope with next time if any courageous modeler would like to make a model of that kind unless they know the problem already !!
The LWL will be checked once in the water and, if necessary, I will force the hull to raise the bow with the bulb position or with some ballast weight at the stern if feasible.
Now wet sanding !! and repainting later.
At the same time I will take out my “sail’s bending blocs” to start the sail panels cut with templates and assembly the rig.
It is not excluded to go for the first trial by the end of the month !
I shall purchase new fbg of 80g/m² and samba wood stripes.
So that’s it for today !
Cheers
ClaudioD
PS : Here the sketch that explain some difficulties found during assembly :
The first source of dimensional modification is caused by the use of positive molds ,the hull lamination as well the deck lamination of this shape are free to modify their form during the polymerization process that generally need a week or so to be completed. Several causes may induce to deviate slightly from the original mold form, internal material stresses due to variable epoxy thickness, tissue weaving, temperature variation, relative humidity, etc.
The second source of potential dimensional variation is coming from the cutting tolerances of the negative shadows. Easy to introduce variations of 0.2/0.3mm !
The third source of dimensional variations is coming from the integration of supporting boards. If not perfectly dimensioned to the local hull width, deformations are expected. Skin thickness shall be considered !!
Summing up all above, a local mismatch between deck skin and hull skin are very probables.
The skin thickness of this type of lamination can be in the order of 0.35 / 0.40mm that is just of the same order of above constructional tolerances.
Is therefore not excluded that summing up the +/- variations some width gaps will appear between hull and deck skin .
With the use of female mold, the amount of imprecision is rather reduced.
It is therefore important when working with positive laminated hull or deck of this shape, to ensure, with momentary beams, the exact external width at each shadows position with continuous checks.
With bare eye is also possible to observe sheer curvature anomalies !
In the above drawing the various widths are marked up to the first decimal point (0.1mm).
When a dimensional figure of 171mm is given, it could be either 170.7 mm as well 171.4mm. The dimensional error tolerance can be 0.7mm , and this is enormous when two ‘walls’ of 0.4mm shall be just one above the other !!
Working care at this level is of paramount importance.
The momentary beams (my fault I did not used and the mini wedges proved to be inefficients) can be removed after integration of the supporting boards and shall be in any case avoided to 'force ’ in booth directions the skin !
With a ‘normal hull’ and flat deck, this phenomenon is not visible since it is not required to match the joint line.
Will be hardly visible a sheer-line deviation of 0.3mm along the curved deck line of 1230mm length unless for educated eyes.
" For the above reason, the next model will be made in the ‘classical’ way unless female molds will be available."
Just to remember that the actual 123 positive molds, deck and hull, where fine sanded when coupled, therefore a ‘microscopic’ variations would be copied from one to the other body. Of course being wooded made parts, may suffer from ambient conditions to.
Source of discrepancies cannot be totally avoided.
I remember once when a technical specification was providing the linear dimension of metallic part, including the very severe measurement tolerance.
The problem arose when a discrepancy was declared by the controller.
More deep investigation proved that the tolerance was more severe then thermal expansion of the metal at a given temperature !
So, to be correct, when a dimensional tolerance is specified, it should be also referred to the ambient temperature. but this was another story …
The female mold will reproduce ‘exactly’ the same form and the risk of mismatching will be rather reduced, the described above ambient and manual constructional tolerance variations may still exist but within a lesser degree !.
Of course we are producing micro metric constructions, but the model manufacturing precision shall be more carefully controlled when the hull and deck shall ‘meet together’ at the time of molding.
ClaudioD
Hi Claudio - very nice work.
Do you think you would have similar problems if you split the hull/deck vertically instead of horizontal? I built my one meter trimaran main hull that way and once I had all of my dimensions and reference points, I attached each side using balsa strip that was sanded down to deck line when done. Just a thought. I must admit setting up dimension locations was more of a challenge doing it that way - but when ready to join - both left and right sides of hulls where joints was were parallel to each other.
Regards, Dick
Hi Dick,
I tend to believe that vertical cuts are more permissive, also because working at the same curvature level : right = left.
A continuous tiny wooden wedge will help to joint the two parts. No reinforcements used at that level and one single mold is used. Often being a foam positive plug.
Lamination may occurs with two separated halves but of the same form .
With the horizontal cuts, the two parts are different in form. The mismatch error is probably coming from the use of stripes along the sheer line that are needed to offer good rigidity. The wooded stripes also offer the contact surface to carry on the bonding operation.
I have to think if it is possible to execute the same bonding approach as for the vertical cut without inducing deformations.
Gain in weight is evident since the dual stripes may be avoided.
For what concern the internal assembly, the horizontal cut offer better accessibility and this is what probably I was looking first.
Nice experience, but not ready to repeat it again !!! unless a miracle !!
cheers
ClaudioD
Time for reflection !!!
ClaudioD
Hi Claudio, the finished hull/deck construction of 465 grams equals an incrediable 11.5% of finished 4045 gram bouy weight … that is excellent result !!! I doubt many people can improve on this for size of the boat, you set the bar very high for yourself.
With hull/deck alignment challenges do you think a female moulding of hull and deck would improve alignment ?
Cheers Alan
Hi Alan,
you are a genius because your question opened my hidden mind and thanks to that, I discovered the solution for joining the hull and deck at minimum weight costs and precisely !!!
There is nevertheless a condition, the work need to be prepared in advance.
Both hull and deck masters shall be finished together to ensure a perfect matching !
The master can be assembled separately.
Before sanding and polishing is necessary to momentarily gluing/glueing the two masters via a several bits of balsa spacers as I already done with my masters.
It may be necessary once the molds ready, to joint again the deck on the hull to allow the two molds to be centered with the help of some pins.
The hull can be equipped with a fiberglass ribbon/wedge.
Once ready, the laminated deck and hull shall be isolated from the respective molds with a polyethylene film.
This operation will avoid that the two molds will stick each other when bonding the deck onto the hull.
Thank you very much Alan to switch on the lamp in my brain !!!
Cheers
ClaudioD
PS:
Forgot, there are some places where the FBG wedge cannot be positioned as a flat ribbon because of the various supporting boards unless these boards are recessed inside the hull by some 3 or 4 mm ! Any other idea ?
CD
Hi Claudio, I’m sure your lamp was always on :idea: I just helped turn-up the brightness knob.
One idea (if I understand you correctly) is to use the tips of plastic tooth pick sticks as pins embedded in the supporting boards, instead of wedges ?
Cheers Alan
Alan, I’m not sure to have understood what you mean, but this drawing explain what is the interference of a mounting board when is just flush to the sheer line.
To ensure the seal is necessary to use a strip to allow a bonding surface
The wedge can be used if the board is recessed .
Ciao
ClaudioD
Hi Claudio,
I was thinking if you bond in 3 x 3 mm balsa strip around the edges of the hull & deck while in the female moulds, then pin them (say approx 50 mm apart) so they are aligned when bonding both parts together, you would not need wedges, by supports I’m assuming your talking about bridges etc that are level with the bonding edges … if they are wide I would be inclined to pin it to opposite balsa bonding strip.
Cheers Alan
Hi Alan,
Yes I’m referring to what you call bridges and how the bridges are bonded to the hull skin.
The alignment method to be used could depend on the weight and strength !
Ribbon wedge or dual 3x3 strips, that’s the question …?
Cheers
ClaudioD
The damages caused to the painted surface by the adhesive ribbon during deck bonding revealed to be more serious then expected and the ‘repairs’ made the situation worst. Since ever I know that I should have some phobia against paints, certainly painting is not my cup of tea !!
So, armed with brush, large goblet and acetone I started removing all paints and primers layers … very dirty job !!!
Now I need to go back for wet sanding to remove residues here and there …
All that was my fault since the time I decided to paint and look what would be the result …
BTW, this exercise proved that the hull is now lighter by 67g in spite of the added stern and bow
ClaudioD
Two primer coats !
ClaudioD
Again some problems detected with fissure/cracks of the deck skin close to the round corner
Repair will adds extra weight. Not worthy to continue with this model.
Recovered the wood Master in order to add additional strips to reach the necessary height for a flat deck integration.
ClaudioD
Claudio, sorry to hear you’ve run into more problems …but to have come so far with a “development model” and still not know the possible refinements you may discover once on the water is a pity, is it not worthwhile getting what you have seaworhy for testing purposes only, then you can play with weight distribution, CLR/CE coupling etc. to know exactly what you need to do in the final model…just my 2 cents worth !
Cheers Alan
Hi Alan,
is not a problem to scrap a model that do not correspond to my requirements.
Is the first time, and probably not the last !!
Anyhow the hull is now modified with the raised sides walls by 15mm. The upper part is not exactly to what was the original 123 with bowed deck, while the immersed volume is just the same.
This evening I will cover the master with 2 x 105g/m² glass.
Now I go downtown to buy the balsa 1.5mm sheet to be used for the deck glass/balsa sandwich.
Ciao
ClaudioD
PS : just a curiosity NZL-20 and 123 side by side !
Devastating news - and you appear to be so calm about it. With all the work that’s gone into 123 it seems almost sacrilegious to scrap it. I agree with Alan that just making it waterproof/seaworthy purely for trials to establish trim/balance etc must surely be worthwhile…
If you can’t be persuaded to change your mind then I certainly admire your conviction and hope that mk2 proves to be a ‘keeper’. I guess we’ll all have to wait a little longer to see the fruit of your labours on the water & sailing.
Regards,
Row
PS. Just out of interest, can you post some close-up pictures of the fissure/cracks on the deck section of the molding?