Tuesday, October 10, 2017

Try, try again

With things not looking good, it was time to spend a bit more money. First, a new prop - something in red this time because red things go faster. Also, slightly smaller than the old propeller and without the hasty scissor modifications.

While I was at it, the rudder support box has been opened up properly both at the back and sides. Much neater, no longer will it work as a parachute. I've also shortened the rudder as there's no need for it to be lower than the bottom of the prop and I reckoned it might be increasing drag. Yes, I am a bit desperate.

Next, some weight loss. The C-cell battery pack has been replaced with an AA-cell one which weighs half as much. Moving it to the front of the battery box moves the centre of gravity forward too.

Back at the lake, does any of this make a difference?

Not really. The boat moves but once underway, the prop is still thrashing around in a void created by the hull. Hang on to it and with plenty of water, the thing really pulls. Let go and it's a bit rubbish.

Once thing, I've never, ever seen one of these kits made up. I'm beginning to understand why. 


Anonymous said...

Just as a "way out there" idea ... is the rudder too large or too close to the prop and breaking up the water flow from the prop, or is the rudder shaft large enough that it's the same thing? What happens if you try running it without the rudder?

Daryl said...

Perhaps something like this might work as the box at the end might be acting as a water break by digging into the water despite cutting holes in it

Phil Parker said...

I think the drive isn't right for this boat. Daryl's photo shows a device that I suspect would work but if I'm going to modify the boat that much I have other, more attractive ideas.

The problem seems to be that as the boat moves forward, the hull leaves a hole in the water in which the prop sits. My plan now is to take all the running gear out and move the prop to under the boat so it has some water to work in.

Then I want to re-build the rudder, but the prop first. If the hull ends up broken when I take the shaft out, then I have another kit this motor and stuff can go into...