Build thread: Cozy F1 T800 33" tunnel

[Dirk Jan Cozy]

Using foam cladded sponsons is something I also considered, but it has limitations regarding the sponson shape. I could also not figure out how to get the sponsons nice and straight that way? Using a foam cutter?

Here are some further build steps:

Mounting the esc below / besides the steering servo. Cooling lines attached as well.
The layout of the electronics. I put a wooden cross-brace in between the esc and lipo, as my radio box is very large and I don't want it to become a weak spot.


Designing the cowl. I will make a positive mold and laminate the actual cowl directly on top. Benefits are: easy access for laminating and easy release of the mold. No need to make a negative mold.
Drawbacks: outer surface of the cowl needs finishing, as it is not yet smooth enough for painting.
The cowl itself will be made from carbon fiber.

Start to make the mold; wooden ribs with hard foam in between. Easy to sand into shape!



The mold itself is laminated with several layers of glass cloth to give it a smooth and hard surface:

Finished with high gloss paint and ready for waxing and making the cowl!

2 layers of 200gr/m2 carbon fiber twill weave and 1 layer of 50gr/m2 glass weave for a smooth finish. I put a full glass part on 3/4th of the cowl, for rx- and gps signal reception. It will not go through carbon fiber..

And released from the mold, ready for cutting into shape!

 

[Marty Slater]

nice is the carbon an harder to work with then the glass?

 

[Dirk Jan Cozy]

The carbon is not harder to work with. The weave pattern, the weight of the weave and shape of the part to laminate determine the difficulty in my opinion.
For example, the twill weave 200gr/m2 carbon is easier to laminate over the mold than the 50gr/m2 glass cloth. Once that sticks to the part, it is difficult to get off without pulling the weave out of shape.

 

[Kez]

Very nice work Dirk. And very interesting technique for forming the cowl. Can you share how you keep the cloth on the mold without lifting while the epoxy cures?
Thanks,
k

 

[Dirk Jan Cozy]

@Kez: the cowl shape is round enough for the cloth to stick to it. Only the nose tip needed a scissor cut in the cloth for it to stick to the mold.
I use 40 minute laminating epoxy. It becomes sticky as time proceeds.

 

[Dirk Jan Cozy]

Update on the build: I made the battery tray from birch ply, laminated with glass cloth on both sides.


Painting the hull:





Result, without clear coat still:



Time for the maiden! Without the cowl, because it was not finished yet

First time in the pond:
She runs great. Of course I need to fine tune the setup still: prop height, prop angle, cog and more. But the hull runs well in its basics.
Top speed is 54mph so far, with a 443 prop. There's definitely more in it.

Here's a snapshot of a near blow over. The cog needs to move forward a little

Ans a small youtube video of the maiden run. Not great quality.. This spring I will make a better one.

 

[Wasted wages]

Nice job Dirk !!
Boy, that really has some punch when you hit the throttle!!!
That's one big advantage FE boats have over nitro boats... Instant acceleration!!

 

[David Ashcroft]

Great craftsmanship Dirk thanks for sharing the build,performs very well.

 

[Dirk Jan Cozy]

Thank you Wasted and David. The build continues:

After 4 runs, unfortunately I found a construction issue at the sponson sides. Water had come in and I had to open it.


In order to fix it well, I completely stripped the paint off and glassed the deck another time. This time I rounded the deck edges and laminated 'around the corners'. It was quite a lot of work, but the hull needs to be strong, as 60mph speeds can be reached quite easily.
Here's the stripped and re-laminated hull, with the cowl cutted and fit to the hull:

Now something that is not interesting for racing, but makes the look of the outboard that much better in my opinion: making an outboard cover.
Laminated directly on the foam core and removed the foam afterwards.

The foam core with some wooden sanding templates in the background. I kept the shape quite simple.

6 layers of 80gr/m2 glass:

Cut open and finished the bottom part. The top cover is mounted with 4 hex screws.

Painted black, added some printed decals and applied the clear coat:


The marks on the cowl are spots for applying some filler.
Now I have to wait for the temperature to rise, so I can re-paint the hull and get it on the water again!

 

[Dirk Jan Cozy]

I'm currently painting the hull. The cowl is finished.

 

[anders-e]

God looking!

 

[Kez]

Very nice work Dirk. I am thinking of making an outboard cowl as well but what I have in mind is to make a wooden plug and vacuum form. I figure it would be lighter and easier to replace should I break it. After seeing how you did yours I am now thinking of same. 80 gm/sq meter is about 2.3 Oz cloth here in the US. I may try 4 layers of 3 Oz cloth to keep it light.

The wood you used for the frames looked like balsa to me but you said it is ply. What wood species is the ply? Is it balsa ply?

Thanks, k

 

[Dirk Jan Cozy]

Thanks Kez. I think your method will work. The issue with my method is that thicker cloth will not bend around the corners. You won't have that issue with a vacuum bag around the plug with cloth.

The boat ribs are ply wood indeed. It is not specified by the diy store which wood exactly it is. It is low density wood, but not as light as balsa.

 

[Dirk Jan Cozy]

Almost done painting the hull. Some more decals on the sponsons and finish it with clear coat.

Hopefully this weekend It can be dialed in at the Lake

 

[Dirk Jan Cozy]

Yesterday I ran 2 lipo's through the Cozy F1 T800. It was the first time with 100% completed hull.

The outboard height and angle need some fine tuning still. The hull could run more freely and with more speed. Other than that I had a great time! Here are some photos and a small video.

 

[David Krienke]

Yesterday I ran 2 lipo's through the Cozy F1 T800. It was the first time with 100% completed hull.

The outboard height and angle need some fine tuning still. The hull could run more freely and with more speed. Other than that I had a great time! Here are some photos and a small video.

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Very Nice. That is a good looking boat and it seems to go real well.

 

[Marty Slater]

very nice

 

[Shane Bastick]

beautiful build and paint work to match, runs well too

 

[Dirk Jan Cozy]

Thank you fellow boaters

I'm fine tuning the setup and I gained some speed by adjusting the outboard leg with a little more positive angle and also set it a bit higher.
The T800 ran a little too loose, as can be seen in the short video. Top speed is 55mph with 443 prop, 6S and 1650kv 3674 motor.



Now, for everyone who wants to build a Cozy F1 T800, I share the plans for free. See attachments. Drawings are A1 size. It took me quite some work.. all I ask is not to use the design commercially.
It would be nice to see a T800 with a nitro engine at the back

 

[RobertDoak]

Very nice build and first run....finally a tunnel boat that looks like a F1 tunnel boat....well done...