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wrd4
08-05-2011, 11:28 PM
To all who have much more knowledge than me. I am a boater from the 70"s and back then I had some very fast boats with gas engines. I have recently gotten back into boating because I never got over how much fun I had back then.

My question concerns my purchase of a used Aquacraft UL-1 Superior boat. The boat was very clean out of the box. I had a after-market metal propeller (Aquacraft L40 x 57 AQUB9760). The drive strut was also tilted way down towards the positive. The turn fin and the rudder were sharpened and I felt that maybe someone before me knew what they were doing.

I pulled out the shaft and re-lubed it and then checked the propeller for balance. It was horribly out of balance so I began to feel that maybe the person who owned this boat before me just wanted to get rid of it. I decided to put it back to specs.

I balanced the prop and lubed the shaft and put the strut back to neutral. I also added a airdam as per instructions on the OSE blogs and sanded the bottom of the sponsons. My airdam was 1 3/4" back from the front crossover and 3/8" deep. I was now ready for my first run.

When I put the UL-1 in the water and gave it some throttle, it just submarined. I decided to remove the airdam and then try again. It still submarined a bit but by putting more throttle to it, it finally popped up but not with much speed. Then, boom, it came up on step and flew acorss the pond like a raped-ape. Upon throttling down though, it went right back into drag mode.
I decided to put the strut up as far as I could move it. This time it didn't submarine but it just stayed in drag mode until it finally came up on step. When it's on-step, it's a monster.

My dilema. I didn't have the original prop so that may be of some significance. I also didn't run the UL-1 at its very positive strut setting. Years ago, we used to glue on some extra bottom thickness to the sponsons but I don't think that's necessary today.

Any help would be greatly appreciated. I have owned and competed with some very fast boats but that was years ago when fuel was the only option. I think it's the prop---am I right?

Bill 602-692-8783/cell kiteflier4682/Skype wrd4682@cox.net:wink:

Fluid
08-06-2011, 12:01 AM
Even with the stock prop the UL-1 will submarine off the beach if you are too gentle with the throttle. Usually giving it full throttle until it pops up works well. But if the strut is too deep or has too much down angle at the prop end it can be very difficult to get on step. A lifting prop like the one you used can make the problem worse, but it can be worked around. The air dam is just to help keep the hydro from blowing off at top speed.

Each UL-1 setup will be a little different due to battery weight, etc. but try the bottom of the strut 7/8" below the bottom and dead flat. Set the boat on a flat table to set the strut depth and angle. This is a good place to start, running the strut too deep upsets the aoa of the boat and spills too much air causing side-to-side rocking. We have one UL-1 in the club which is ballistic, it runs flat and very fast. You do not slow a hydro down much or it falls off step and drags badly. That will damage your motor, ESC and battery by heating them up. Run the hydro like it's supposed to be run - full throttle most of the time. Extensive part throttle running is bad for the ESC. Welcome to the FE side! We have watts.


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detox
08-06-2011, 08:34 PM
The Aquacraft L40 x 57 AQUB9760 is a difficult prop to sharpen and balance, but prop works verygood if done correctly. The most simple prop to use with the UL-1 is probably the Octura x442. It is lots easier to sharpen and setup.

My strut was set 1 1/8" deep and a little positive (tilted downward slightly) with both props. Speeds were 49-50mph in perfect smooth water conditions. The lipos I used were two Hyperion 2s 5000mah packs (4s1p). UL-1 is a little unstable in race conditions (slightly choppy water) so drive carefully. Be sure to read and understand your manual.


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