Budget Wild Thing

[stablgr]

Hopefully the attached drawing will give you a better idea of how it works.

The flooding tube is sealed at the transom and the stuffing tube sealed at the opposite end with an epoxy plug. This way the end of the stuffing tube that exits the hull is 'free' to flex up and down allowing a little easier adjustment of the strur height (and angle).

I "borrowed" the idea from a couple of monos that Darin Jordan posted on the site. Seemed like a great idea to me.

[sailr]

I love that big tube but won't the epoxy plug crack if you move the stuffing tube too much? Would a silicone plug work better and then the motor end of the stuffing tube supported more solidly? Just a thought.

[stablgr]

Good point sailr. I guess another option would be to stop the stuffing tube short of the strut and only run the teflon tube into it.

[stablgr]

After a rather long and unplanned break from making any progress I'm determined to get this finished and on the water this summer.

I need to buy a new servo and have no idea what size/torque rating I'm going to need to operate the rudder. Any feedback would be great.

Thanks

[CornelP]

For that size, any type of standard servo would do the job. I usually prefer to get one with a bit more torque, around 8kg, metal gears, digital.

[stablgr]

Short update.

Flooding shaft and stuffing tube finalised and motor mount tacked in place. All nicely lined up and spinning freely. Had a few problems trying to cut the flex cable and finally went and bought myself a Dremel. Boy I wish I bought it when I started this little project. It's an amazing little tool!

I think I've settled on a paint scheme (after consulting with, and getting approval from the project director - my son) and have sprayed a couple of coats of primer onto the many layers of yacht varnish.

[stablgr]

A little more paint added...

[CornelP]

Looks perfect!! You should add a Top Gear logo...

http://commons.wikimedia.org/wiki/File:Top_gear_toybota_2.jpg

http://www.topgear.com/UK/videos/amphibious-1

[jstolz]

Any suggestions on the best glus to use for laminating the sheets of ply?

The best glue for laminating sheets of of ply is West Systems epoxy. It is espensive stuff, but it really works great. Once the boat is done, you can seal the finished boat with West Systems.

[stablgr]

It's been a long time coming but it finally hit the water today.

I was dreading what might or might not happen when I let it loose in our local neighbourhood lake (well more of a big man made puddle with a couple of fountains in it really). I had float tested it in the bath at home to make sure no water made its way inside and was a little concerned that the top of the stern was right at the water line. Maybe putting two 3S 5000mAh Lipos in there wasn't such a good idea after all, but it was designed for run time, not outright speed. I left it there for a good 15 minutes and after removing the canopy all seemed well. So it was off the the puddle with my son in tow.

My first fear was that it would loose radio signal and go off on its own merry way into the concrete sides of the lake, so we did a range check over the length of the lake and all was good.

Everything was checked, double checked and probably triple checked..... what the hell, in it went, it was now or never. I knew the lake wasn't too deep so if the worst came to the worst I could always wade in and salvage it from the bottom if need be (remember the fountains I mentioned earlier.... hold that thought). Well, what a pleasant surprise, a quick squeeze of the throttle and it was up on the plane and away. Not super fast but certainly quicker than I had hoped for considering the weight of the damn thing. Turning to the right was sharper and tighter than to the left, but I guess that makes sense given the location of the rudder. So then it was over to the test pilot of the day, my 10-yr old son. I think the big smile on his face and the comment "that's sick dad" was a sign of approval.

I think I need to either look at the water cooling to improve it's efficiency or maybe use a different prop. The batteries were quite warm but you could comfortably hold them. However the motor and ESC were a little hotter. Too hot to hold on to for more than a few seconds at the end of the run.

After the first set were drained my son's smile faded a little, only to return when I produced a second set of batteries. We let the motor and ESC cool for about 20 mins then got it back on the water. The aforementioned smile returned and he was soon zipping up and down the lake again, with the odd figure of eight here and there. Then, remember the fountains? Yup, you guessed it, full throttle straight over it followed by an impressive barrel roll to land fairly and squarely..... the wrong way up!

I really didn't fancy wading into the puddle as the water doesn't look that inviting. Luckily there was a bit of a breeze blowing, so based on the fact that it was floating upside down quite well we let the wind do it's work and waited for it at the far end of the lake. About 30 minutes later it arrived and after opening it up, although there was a little water in there it really wasn't much at all. The hull was untouched and the only damage was to the rudder and the control rod. The rudder shear pin broke, but that was about all.

All in all I'm really pleased with how it all went. Only down side is that I forgot to take my camera. Maybe next weekend I'll get it back on the water and gets some video ..... assuming my son remembers to steer clear of the fountain!

Next project has already started. A 30" F1 Tunnel Hull. But I think I may be challenged to get two sets of 3S 5000mAh Lipos in there.