When I joined this forum, I mentionned I was interested to build the Nzl-20 based on the plan of Claudio and on the thread shared feeded by Claudio and Alan. I started several weeks ago but encounter several problems that make that I had a very few news to publish. Nowaday, I 've finished the positive mould in wood and have several photo to illustrate this story.
First of all thank you Claudio for sharing your experience and plan with the VRC lovers. Thanks also to all the people publishing very interresting messages and sharing experience on this forum. It helps me a lot.
After getting the plan of the Nzl-20 from Claudio, I directly make my first mistake when printing them I didn’t deactivate the resizing option in Acrobat, meaning they were not at the right scale. Hopefully I saw it before sawing the shadows and Claudio indicate me my mistake.
I prepare the mounting board, verify the printing and cut the paper.
After having printed the shadows, I wanted to saw them on wood. I had a very old Dremel 576-5 saw using small blades of 7,6 cm, but unfortunatelly there is no blade anymore. Enfin, I found some blades but in the US … what would cost me almost the same price than a new one. So I search a new one and choose for a Proxxon DS-460 that I bought via internet at SMDV in Germany. I recommand this site as this is the best price I found, delivery within one week, no surprise.
I made a comparison of the jig saws in an excel sheet for those who are interrested.
It took me one week to receive my jig saw, so I could start sawing the shadows and mounting them on the board. I controllded the alignment with an elestic as I don’t have a laser pointer as Alan used for his building. In the meanwhile I ordered Balsa wood at Weymuller, but it was out of order so I needed to wait 3 more weeks to be delivered
Hi Frederic,
this is the most pleasant time for a modeler.
You start already to appreciate the form of what will be soon.
It look like a Gothic style construction !!!
Of course I’m very pleased to see it, please keep all informed about your progress !
Cheers
ClaudioD
Finally, after three looooooong weeks, I receive the samba and balsa and started the planking. I tried to imitate the way of working of Claudio and Alan … but it’s not easy when building a hull for the first time! Fixing the samba plank was pretty straight forward, but the balsa plank was much more difficult.
Nevertheless, it’s so exciting when the volume of the hull begin to take form even if this is only the mould for the hull But it gives a good idea of the beautifull line and shape of the boat.
Hi Frederic,
I’m probably wrong but the picture 5 from left give the impression that there is a knee.
In my design I removed to give better fluidity in the water. See below
Also I recall your attention, to avoid construction problems at the bow, from shadow ‘0’ to the bow is a bloc of balsa shaped once the full coverage is done !
Cheers
Claudio
I got to think about the bow and stern of the boat. I now understand why Claudio put a plank in oblique along the curving part of the hull. I found a pretty way to plank the nose but made a bad choice for the stern … So I started bottom-up and had to go top-down and finish in the middle of the hull. I also had to cut some plank to adjust the joining (see picture 41 and 42).
Also, the balsa I baught was not the most hard one, so I broke a peace during the building needing a fix.
You’re really impressive ! You can not only manage two or three projects in parallel, but you can also follow projects of other people and point out what’s wrong
So, you’re right and you’re right. There is a knee and it bring me some contructing difficulties. I was not so confortable to shape a bloc of balsa as you did. That’s the reason why I inspired myself of the option taken by Alan.
I had some difficulties to plank the bow and the stern. I understand now why you put a plank in oblique following the curving part of the shadow With exception with your (obious and correct) remark, I succeed to plank the bow correctly. But I made a wrong choice for the stern. I begun to plank the hull bottom-up what was more easy for the bow until I came in trouble with the stern. Then, I switch planking top-down what was more ease for the stern and finish the planking in the middle of the curve. By doing this, I also had to cut some fixed plank to adjust them as shown on picture 41 and 42.
Unfortunatelly, by looking from loan there are a lot of imperfections that I had to fix by sanding and to fill with mastic.
Even after a first correction, I had several imperfections to fix with a second, and third layer of mastic
In order to finalize the finishing work, I detach the hull from the mounting board and cut some upper part of the shadows that I will not need for the polymerization
I agree, this is not the perfect work compare to the result made by Claudio, but I only want to build a boat for having fun and not making race. So, I don’t have to stick to a jauge. I also agree, with the remark of Claudio and the knee is not intended in the original plan not in the original boat
On the other hand, the knee is above the line of water, so there should be no incidence on the boat performance.
What would you advice:
– I can let it like this
– I can try to correct the line with mastic and sanding to try to reach the line shown on Claudio’s picture
– I can cut the nose and rebuild it with a cloc of balsa
I’m preparing the hull for lamination. I varnish the inside with polyurethane varnish to reinforce the planking and will coat the outside with a primer later today.
This will be my first experience in lamination and I have some questions .
[ul]
[li]Are there some references I can read before starting this and avoid some stupid trouble ?
[/li][li]Otherwise, I’m thinking about using 3 layers (2 x 105 gr/m² + 1 x 85 gr/m²) of twill type fiber glass + expoxy resin to build the hull. Does this looks good ?
[/li][li]Is the carbon fiber absolutely necessary for the fin and the rudder ? I’m hesitating to use it and was thinking about plywood and fiber glass but don’t know which size to use.
[/li][/ul]
I’m looking forward to read some recommandation or references.
I wish you a pleasant journey,
Frédéric.
Sorry Frederic I was absent and I did not read your last posts.
First, you have to options : live the bow as it is with the knee or just cut it away and replace it with a balsa bloc to recover the entrance lines. Personally I will cut it.
For the lamination Is not clear what do you intend. Is this the lamination of the wooden plug, and in this case 2 layers of 85g/m² are good, or is the lamination for the hull ?
If it is for the hull lamination, then 3 layers of 105g/m² are more then sufficient.
My next hull could use 1 layer of 105g/m² and 2 of 85g/m². 50% resin - 50% tissue and covering with layers one after the other -wet on wet !
Don’t forget the Wax for the first hull lamination, at least 5 to 6 coats according to manufacturer instructions
Please pay attention to direct lamination on the plug covered with primer only !
The primer, if of polyurethane type, may be incompatible with wax and epoxy resin. I would recommend first to make a sample trial to verify that it will not stick.
Carbon layers are providing the fin strength - 3 layers of 165G/m² are the minimum necessary to get a rigid fin, at least one layer should be laminated at 45°. The Fin weight should come out around 150-160g.
For the rudder you may use only glass. The rudder weight should be around 35/40g.
Cheers
Claudio
My question was about the hull lamination. I’ll do as you suggest, one layer 105 gr/m² first and then 2 layers 85 gr/m². I’ll buy the material next week and hope the weather will be better because it’s very cold for the moment in Belgium, around the 17°c :shake: I will laminate on packing tape as shown in your threads. So I understood there is no real need for wax but it could help to avoid any problem of sticking.
For the fin, I’ll go for carbon lamination … if I never try, I’ll never know
The joys of using epoxy - 17c and it’s not really warm enough…
Just for your information, the basic WEST epoxy (with a fast hardener) can allegedly be used in temperatures as low as 5c. I’m not sure I’d be inclined to rely on a full polymerisation at such a low temp, but at 17c it’s definitely ok - we used to use it a lot for repairs / restoration on full size yachts in temps regularly as low as 10c. For model hull lamination you could always let it partially polymerise at 17c for the first 24hrs (so that it’s not dripping!) then put it in polythene bags and put it in a warmer area than a workshop for a few days to let the chemistry continue doing its thing. Even better, leave it somewhere warm for a week and it will completely cure.
Hi Frédéric, great to see your build log here yes your right, using packing tape to cover your plug, you don’t need to use wax of any other type of release as the “plastic” does not stick to epoxies.
Just an observation, when finished planking it is always good idea to coat inside of the plug with epoxy before any sanding (not after) to make the plug sturdy & avoid any possible sanding pressure hollows between the frames.
When you prime the hull, it is good opportunity to check the final hull shape & smoothness again and re-apply minor fairing for final corrections, if needed.
Thanks a lot for your advising and encouraging messages. It’s a real pleasure to have a community I can rely on to build my project.
I’m taking good notice of your remarks and I think the next hull will be better.
I’ve corrected the noze (the bow) to stick back to the original design of Claudio and have a smooth line without knee.
I’ve also order the material to laminate the hull, the fin and the the rudder.
I’ll be off for the 2 coming weeks and than have 2 complete weeks to progress with the boot.
Meanwhile, the weather is getting better 27°C …
I’ll keep you posted as of my return.
Best whishes,
Frédéric.
I didn’t deactivate the resizing option in Acrobat, meaning they were not at the right scale. Hopefully I saw it before sawing the shadows and Claudio indicate me my mistake.
.
yes your right, using packing tape to cover your plug, you don’t need to use wax of any other type of release as the “plastic” does not stick to epoxies.