| For this trial, I have changed the ESC to an Astroflight 212D and added the factory recommended trim tabs to try and eliminate the hopping that this hull exhibited during the first trial. I also plan on trying a number of propellers to see if they affect the hopping and also to see if I can get more speed out of the hull. All test where run on 12 cells. |  |
| For the first run, I'm using the propeller the boat came with. It is marked with a "40 P" which I believe is made by Graupner. The boat runs well with it and didn't show any signs of hopping. Looks like the trim tabs fixed the problem. The boat speed is ok for sport running but it's not exceptional. I expected more from a 700/12 cell setup. The stock prop has extremely flexible blades and is also a bit chewed up from prior test. Since the hopping problem is solved, it's time to see if more speed can be had with a different prop. |  |
| The stock prop does have a bit of cavitation on startup but it's not terrible. Click on the image on the right to view a short video showing the starting cavitation and the run speed. Notice how it slows during turns. This run was made with the batteries a bit forward (but not nearly as far forward as I tried later) which causes the hull to run wet but also reduces the chance of a blow over by keeping the nose planted. |  Click on image to view 3.3 meg video |
| I had a prather 215 that I thought was similar to the 40 P, but it didn't perform very well. Starting from a dead stop, it took a long time to get going and ended up having less speed then the stocker. |  Click on image to view 3.2 meg video |
| I ended up comparing a number of props against the 40 p. First was a Graupner S 39. This prop cavitated a good bit when starting off and seemed to be slower then the stock prop. Next was a composite prop from an unknown source. It's 40mm and came close to the 40p but stilled seemed slower . Next was a Graupner S 42. This prop had less cavitation then the 40 p but seemed slower once it got going. Next was a Prather 215, it cavitated more and was slower. Finally, I found one that seemed to be a little faster. It's an Octura X642. I noticed a slight speed increase and acceptable cavitation when starting. However, the turning radius of the boat increased good bit. I thought the prop was causing it but what I didn't know it at the time was that my steering servo was on the way out. Wow all these props and I could not find one that was much faster then the stocker! I would have loved to try a Octura X440 or X442 but I didn't have one prepared. However I did have one last prop in my bag of tricks. |  |
| If you are wondering how I'm using props that use drive dogs instead of a 4mm bolt, Graupner makes a handy adapter. The adapter has a large diameter that sticks past the Octura prop hub. It should be turned down to match the prop so it doesn't drag in the water. I didn't have a lot of tools with me on this occasion so I just bolted the adapter onto the boat, put some batteries in the boat and held a small file to it while I varied the throttle. It worked well but I had to stop many times to let it cool down. |  |
| Here is my last try at changing the prop. I had a Octura 3 blade X437 prop that I never could find a use for. It looks great and I always wanted to use if but it never really performed better the a two blade prop. I'll give it a shot since nothing else I had on hand worked. |  |
| Finally, I found a prop that is a good bit faster then the stocker. The speed is decent now for a 700 sized motor. |  |
| The turning radius is pretty good although at speed it is definitely lacking. The rudder is adjusted so it has a lot of movement and there is a spin fin so I wasn't sure why the turning radius wasn't up to snuff. I later found out that the steering servo was dying. |  |
| The rooster tail looked really good at speed. |  |
| The battery placement is very far back and I managed to flip the boat a few times. Unfortunately... |  |
the self righting feature doesn't work worth a darn. The boat would sit on it's back until a good amount of water filled the hull then it would flip back over. I was able to get it back to shore after that but all of the electronics got soaked so I had to pull everything out of it to let it dry. This is frustrating because the flood tank took a lot of work to build and added unneeded weight to the hull. | 
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| After the electronics dried out for a few hours, I decided to continue testing the boat. This time I placed the batteries well forward of where I had them to try to keep the boat upright. Quite honestly, I was tired of messing with this boat and just wanted to run it without it flipping over even if it meant setting up the boat to be slow. I was very surprised by the results... |  |
| Moving the batteries changed the center of gravity so that is was just in front of the small step in the hull. The strip of tape on the bottom of the hull indicates where the COG is. This turned out to be the sweet spot, the boat picked up speed and stability. |  |
| With the new COG, the boat rides on the small step. Click on the image to the right to see what I'm talking about |  |
| You would think that the hull wouldn't be stable running like this but it was well planted in the water. |  |
| Here is the boat just after starting from a dead stop. It's just starting to ride on the small step. |  |
| Smooth and a nice rooster tail. I have to say I'm feeling better about this boat now. |  |
| Here is the boat with the batteries place toward the rear of the boat before I moved them forward. The boat spins out at the end of the video. It got much more stable after I moved the batteries forward. |  Click on image to view a 2 meg video. |
| Here is the boat with the batteries placed toward the front as discussed above. Unfortunately at this point the steering servo was just about dead so I can't demonstrate the turning ability |  Click on image to view 1.6 meg video. |
| Here is a short video showing the boat going over small waves |  Click on image to view 1.1 meg video |
| This is the last run for this trial. I was having steering problems and could only turn the boat at slow speed. It got so bad that I knew it could not be caused by the prop. It's a shame because I was really enjoying the new found speed. Eventually the steering gave out altogether and locked in a right turn. |  |
| Here is the rudder with the steering set to go straight! I used the recommended servo, an S3003 which is rated at 44oz/in torque. I'm not sure if it was a defective servo or just underpowered but I plan on replacing it with something stronger. |  |
| I wasn't able to continue with this trial since I didn't have another steering servo with me. The hull is showing promise now and should be a good sport runner. I'm surprised that the boat actually runs on the small step in the hull, I was thinking it was just a gimmick. I would like to see this boat setup with a more powerful motor to see if the hull remains stable. I wish the self righting feature worked, I'm not sure why it doesn't. I could probable add some weight to the flood chamber side to help but why should I have to? | I plan on doing at least one more trial once I replace the steering servo. Stay tuned... |
