P1 Puma RIB racing-scratch building

[Dim L]

Update #16: the molds for the cowl and the outboard cover are ready for painting.

This time I ll go by the book in order to release the cowl as smooth as possible (waiting patiently the resign to cure, use warm water for releasing etc).
One question for the experts. How long should I wait after applying the PVA to start laminating? The manufacturer says 20 minutes, is that enough or should I wait more to be sure?

 

[Dirk Jan]

Nice work Dim! Sanding and filling is always time consuming, and not the most fun part for most. But it pays in the end! I recognize the spot marks method as well [emoji6]

Regarding PVA, waiting longer will not be harmful at least. I waited a few hours for the cowl of my tunnel.
Looking forward to the result!

 

[Dim L]

Thanks Jan.

I recognize the spot marks method as well

Haha learning by the experts, actually it gives you a guidance where to apply the putty.
Patience is the key for laminating...

 

[Dim L]

The molds are ready for waxing... I also applied a layer of shinny clear coat...

 

[Tamiya1970]

Wow nice work,really envy to try laminating my selve .
But I am still a bit nervous to try[emoji28].
But you only learn by trail and error I guess.
Looks good so far Dimm.

 

[Dim L]

Thanks a lot Alex ...
To be honest I have failed each and every time I have tried laminating...
I mean the releasing is far from good, the cowl sticks to the mold, the mold has spots from the epoxy resign and then I sand the cowl like crazy to make it smooth...
So yes it's trial and error and for the time being I am still on the error side...
This time I decided to be very patient... Let's see...

 

[Dim L]

Update #17: After hours of sanding I laminated the bottom of the hull... Fingers crossed the spray rails have not gathered so much air...

Overall I am satisfied with the shape of the hull. The tubes are also well shaped.
Now, I am curious about its performance in the water and the overall stability of the hull...
Meanwhile, I am also waxing the molds...

 

[Dirk Jan]

Nice progress! Did you laminate the bottom of the hull with 1 piece of laminate? I think it is almost impossible to do in 1 piece with the stringers on? Because the laminate pulls itself loose from one stringer, if you press it to the next stringer.
I'm curious how you did it!

The molds look very smooth already. What kind of fiber are you going to use for the cowl and hatch? Carbon / glass and how many layers?
Many questions I read and watch your project with much interest [emoji106]

 

[Dim L]

Thanks Jan.
Yes this is one piece with only one cut at the bow.

laminate pulls itself loose from one stringer, if you press it to the next stringer.

You are absolutely right, this is what actually happened.
So I decided to use extra amount of epoxy resign (more than usually necessary) and I laminated the stringers moving the paint brush along them in one direction.
The stringer was always among the paint brush hair (I mean I did not laminate the one side of the stringer and then the other) with a rich anount of resign so as to be able to fill any empty space between the stinger and the bottom of the hull.
When I reached the tubes I tried not to pull the fiber with the paint brush and create air bubbles at the stringers. A rich amount of epoxy was also very helpful here since the paint brush slided easily on the fiber without pulling it.
I don't know if there are no bubbles at all, but as far as I can see the lamination seems quite smooth.
Well, regarding the cowl, one layer of 180 gr carbon and one layer of fiberglass 110 gr. I think this would be enough judging from the Cozy cowl.
Now for the outboard cover 2 layers of 110 gr fiberglass for the two half pieces and then when the pieces would be glued together another 1 or two layers of 110 gr fiberglass. I think carbon is almost impossible to bend given the shape of the outboard.
No worries Jan, It is a pleasure to discuss with you and the other guys here.

 

[Dim L]

Update #18: Fixing the bubbles and laminating the molds.
Although my technique worked for the most of the hull I did not avoid bubbles completely.
Nonetheless, I came up with a simple solution that worked fine and I am very happy for this. I just injected epoxy resign with a syringe...

I let the pva film rest all night and then i laminated... The cowl seems very smooth.

I would like to have some naked carbon areas on my cowl. What do you think, will light sanding and then spraying clear coat work?
Now, I will let the resign cure for 3 days and then I will go for the tricky part... releasing..

 

[Dirk Jan]

The carbon laminate came out really neat, good job [emoji108].
Curious about the release and final products!

I think a light sanding and clear coat will definitely work.
By the way, what kind of clear coat do you use?

 

[Dim L]

Indeed it came out good.
I use a standard acrylic clear spray. E.g. see the link below https://www.service.european-aeroso...ormatic/aerosols-putty/painting/ipg-1240.html
Do you use a different type of clear coat?

 

[Dirk Jan]

The link shows a 2k clear coat. I use Motip clear varnish, but I would like to use 2k sometime, as I think it is more durable and has more gloss.

 

[Dim L]

Update #19: Painting the outboard leg.
Since the laminated parts and the hull are resting, I grabbed the opportunity to paint the lower part of the outboard.
It's the first time I paint aluminum and I am curious whether the paint will be durable.
First I use epoxy primer, then spray putty and sanding with 400 grit sandpaper. I repeat this circle 2 times. Then epoxy primer and 4 layers of color.
Below I share with you some photos...

Epoxy primer

Spray putty

Sanding with 400 grit sandpaer

And the final result...

P. S. Jan my glossy clear coat is 1K (see below)

I have a non glossy (santine) clear coat which is 2k and I am planning to use it on the tubes. In 1/1 ribs the tubes are inherently non glossy because of their construction material (hypalon neoprene).

 

[Unusual RC]

Wow, looks almost like you bought it from TFL or MHZ!
Well done!

 

[Dirk Jan]

Thanks for the info on the paint Dim. And indeed, your outboard looks very smooth! It would be really nice to compare it to the TFL mini, with same setup.

 

[Dim L]

Thank you Michael for your kind words .
I am glad you like it but I have to say that there are some imperfections...

 

[Dim L]

Thanks for the info on the paint Dim. And indeed, your outboard looks very smooth! It would be really nice to compare it to the TFL mini, with same setup.

This is a good idea Jan! You mean same motor + hull and compare e.g. top speed ?
I guess weight and friction would play a role. I will see if I can adjust the sss motor to the tfl.

 

[Dirk Jan]

Yes and also run time and durability would be nice to know. Although the last one would require intensive side by side testing..

I guess with the reduced flex shaft angle, your goal is to reduce friction, and therefore increase efficiency, right?

 

[Dim L]

I guess with the reduced flex shaft angle, your goal is to reduce friction, and therefore increase efficiency, right?

Exactly! This is why I have also used ball bearings at the end of the shaft to reduce friction even more compared to the teflon bushings. We ll see in practice if it works.

I also had in mind the durability of the flex shaft in high rpm. I think that less angle translates to longer life span for these shafts.

Overall, I tried to improve what I considered as drawbacks in the the TFL outboard.

Bytheway, do you have any problems with the flex shaft in the big outboard of the cosy t800. With the 6s it works at high rpm.