Vac-U-Tug recovery boat build

[alanr77]

Ok, with the epoxy around the stuffing tube dry, it was time to sand it all down both inside and out;

Sanded inside so the inner liner would fit properly
sandedsmooth1.jpg

I faired the outside smooth
faired2.jpg

Test fit of the stock motor and tray. I will not be using this motor but I wanted to see how it fit in the hull
stockmotormount3.jpg

This is the new motor and watercooled mount. The motor is a 28mm 950kv brushless outrunner- Turnigy 2836. The mount in the 28mm water cooled mount available here on OSE
newmotormounted.jpg

I doubt the stock tray will work but it is worth a try. I had to cut out the tray so the outruner would have room to spin
modifymount5.jpg

[alanr77]

I used a Dremel to rough cut the plastic. Filled the garage with smoke
roughcut6.jpg

Test fit of the motor mount on the cut tray
testfit7.jpg

I attached the mount with tape to hold it in place. The stock tray has the motor under the tray, so thats the way I would try the tray
tempsecure8.jpg
If you notice, the motor is mounted backwards in the mount. I did this for two reasons; the motor has the proper hole spacing on the back being that it is designed for an airplane. Second, the water cooled mount would have the water cooling at the bottom of the motor. Heat travels up, and the cooling fins built into the motor draw air through the front and push it out the back. So,the water cooling is now at the top of the motor and at the back.

Now I test fit the motor with the tray. I was unable to get a good alignment this way. I want the shaft to be a straight as possible, even at the slow speeds this motor will be turning, I want to reduce as much vibration as possible
trialalignment9.jpg

The end result of my stuffing tube install. I have to match this shaft angle to the motor shaft
shaftangle10.jpg

[alanr77]

Next I had to drill the motor coupling to match the 4mm motor shaft.
drill4mmmotorshaft11.jpg

The result of proper alignment
goodfit12.jpg

Being that the stock motor tray will not work with the brushless motor, I decided to build a new one out of 1/4" balsa sheet. The new tray will be glassed and epoxied to the inner hull liner
scratchmount13.jpg

With the new tray cut out, I test fit the motor. I wanted to ensure the motor mount adjusting screws were in the middle of their range so that I could make small adjustments after the mount was secured to the hull. Therefore it was important to get the mounting tray as close to perfect alignment as I could.
testfit13.jpg

At this point the alignment looks really good. Now I have to mark the location of the tray and the location of the motor mount on the balsa sheet
goodalignment14.jpg

[alanr77]

I simply used a marker to mark the location of the parts
markedlines15.jpg

The balsa by itself is not strong enough to handle the torque this motor will put out. So, I added cross beams going against the grain to add strength
crossbeams16.jpg

Then I added another beam of balsa to create a box
boxsupport17.jpg

Once this was dry, I rounded all the edges so that the cloth would follow the contours better
roundededge18.jpg

The cloth was cut into strips and layered on to the bottom of the new tray. cloth20.jpg

[alanr77]

I built up 3 layers of cloth. Once this has dried, I will flip it over and coat the top with clear epoxy.
3layercloth21.jpg

Now, to anyone building this boat. None of this is really needed as the kit comes very complete. If I was just building this boat, it would be done already. The stock motor and tray fit very well and the assembly is very simple. The route I decided to take pretty much changes the entire running gear of this boat. My goal is to triple the pull of the stock running gear and still have long run times. We will see.

[Make-a-Wake]

lookin good!

[alanr77]

Well I thought I was ready to start spraying the clear coat on the stand. However I have run into a small issue. The paint from the airbrush goes on so thin that whenever I start to scuff the paint with 400g, it sands right through on the corners and edges. I had to spray another coat of blue this morning. I think I will lightly scuff the main part of the stand and leave the edges alone. Hopefully this will not affect the bonding of the paint in these areas. Any suggestions from people who have used an airbrush?

[Make-a-Wake]

I wouldnt have used 400 grit, I wet sand with 1500-2000 myself then let dry in the sun, just how I do it.

[jcald2000]

I always put 2 medium coats on the corners before I do the rest of the coats, it helps.

[alanr77]

Good morning! Thanks for the tips. I am used to using painting methods that apply thicker coats so I was unprepared for what happened. I will use all the advice given. I ordered 1500 grit sandpaper and sprayed a thick coat on the edges and corners. Thanks! When the sandpaper arrives I will lightly scuff the stand and hopefully spray the first clear coat.

[alanr77]

The next step was to create a "pocket" for the motor mount side plates to sit in. Once the motor tray has been secured to the inner hull liner, and I am happy with everything regarding alignment, I will fill the pockets with epoxy and sit the motor mount into the tray.

Create a pocket for the motor mount
createpocket1.jpg

createpocket2.jpg

Next I built rails for the motor tray to sit on.
createrail3.jpg

createrail4.jpg

The rails will be attached with screws, then epoxied in place

railholes5.jpg

[alanr77]

Rails double secured to the inner hull liner

rails6.jpg

Test fit of the mount onto the motor tray

testfitmount7.jpg

Test fit the tray into the hull

testassembly8.jpg

After everything is aligned the best it can be, the hole assembly was epoxied in place. Once this dries, I will remove the motor mount and using cloth and epoxy, glass the entire assembly into the hull
epoxymount9.jpg

[alanr77]

Next I cut out the cloth strips to glass in the motor tray
clothcutout.jpg

Then using West System I wet out the cloth and attached it to the hull liner. I doubt this is going anywhere.
glassedintray.jpg

Once this dries, I will sand it all down. Ultimately, the bilge will be painted even though it may not ever been seen. I figure the paint will seal anything that was not coated in epoxy so water will not effect the balsa tray. The nice thing about this kit is that by using a hull liner, I can build everything and attach it to the liner before securing the inner liner to the outer hull. The plans call for ballast. I am unsure if this will be needed though. I am building a battery compartment that will be able to hold 2 5000mah 2s lipos. 10,000 mah should run this thing forever even with the accessories. The sheer weight of the gear and batteries may be enough.

[Make-a-Wake]

That's one purdy flex drive!

[alanr77]

After allowing everything to dry for a few days, I dry fit the motor mount to the new tray. I had to sand about 1/8" off the bottom of the OSE mount to get it to line up with the prop shaft. After carefully measuring and sanding, I was able to get the alignment right and keep the motor mount adjustment screws in the middle. This will allow me to fine tune the adjustments later in the build.

sandedmount1.jpg

I then used 5 minute epoxy to attach the motor mount to the tray.

epoxymount2.jpg

The 1500 grit sand paper worked great. I was able to scuff the boat stand and spray the first coat of clear. Thanks for the advice.