UL-1 Performance and Modification: A Thread Summary

[10gauge]

Selective Quotes From Threads Pertinent To The Modification And Performance of The UL-1: As of Mar 14, 2009

For someone who just bought a UL-1, like me, you may find this summary useful before launching the boat. (Footnote at beginning of paragraph).


Raptor327: M445 @ 45mph. M645 and 3/16" deeper on the strut @ 52mph. Modified 2047 and a 1/2" deep tape air dam in the tunnel @ 59mph. Same prop and air dam, 3/32" deeper on the strut @ 65.7mph/64mph. M645 @ 50's with the same air dam and strut setting.

Fluid: Air Dams - Use a strip of foam from a pool noodle, 1/2" on a side and long enough to fit across the tunnel. I Stick it down by covering it with a strip or two of 2" clear packing tape - works great. Too, it doesn't fold back at speed like the tape dams will, yet it is flexible if you hit something with it.

Darin Jordan: Water Jacket Installation. (See Sticky)

Fluid: Fixing Water Jacket:
- Remove the motor from the hull and unplug the wires and water lines.
- Shoot some WD-40 or similar lube into the inlet tube, enough to coat all the motor housing that's inside the jacket. Don't be stingy.
- Loosen the end rings no more than two turns and put a thin oil on the threads where they enter the end rings.
- Tighten the end rings by hand until tight. Make certain that the water inlets are positioned correctly.
- Wipe off any oil from the motor and jacket.
- Check for leaks by blowing into one of the inlets with the other inlet plugged. There should be no sound of air passing by the threads.
- Reinstall the motor, wiring and cooling lines.
The small rear winglets are held on with a thin strip of double sided tape. When mine arrived they were also held down with strips of regular clear tape, but I removed those. That made the winglets too easy to remove or to come off on the water. I suggest leaving the outside factory tape in place and forgetting about them.
Be sure to have the correct metric tools, esp. Allen wrenches.

Fluid: My TP5000s weigh 9 ounces each, and I have no problems getting up on plane. Brian wasn't using light weight cells at the SAWs and his never subed. I suspect that the problem most guys are having is with the strut setting. Hydros are not like monos...
The bottom of my strut came 7/8" below the hull and angled at most 1 degree down at the prop end. If you are having trouble getting on plane you can simply flatten the strut. You do not want to angle the strut any more or you'll never get on plane! A flat strut is the default setting; if the bow flies then angle it down a bit at the prop end. It won't take much. If the boat runs too hard on the water raise the strut 1/8". Several guys have e-mailed me about problems getting up on plane, and in every case a minor strut adjustment was all it took regardless of the packs used.
Different props can cause trouble getting on plane too. Screw on a lifting prop combined with too much strut angle and you'll never get on plane. If you are using a lifting prop, flatten the strut. You may even need to run the strut up a degree at the prop end. "Best" all-around prop may be an m445 or K45. It will take some additional testing to find out for certain. The x442 is pretty small - doubt it has enough blade area to load the motor enough.
BTW all strut adjustments must be done on a flat surface like a table. The hydro should rest on the sponsons and the strut. The strut angle will be between the bottom of the strut and the tabletop. Don't try to do it "by eye", it won't work.

Fluid: The stock prop has worked well with good speed and handling, but I wanted to try the Graupner K45 to see how it effected handling and speed. Knowing it would give higher speeds than the stock prop I lowered the strut to 1" with about 1 degree of down angle at the prop end. The two 2S/5000mAh TP packs put the CG 2.7" behind the sponsons; I heated them up to ~90F before running the boat.
The hydro had no problem getting on plane with the 'heavy' packs, I simply gave it full throttle and up it jumped. (Trying to ease into the throttle just makes the model submerge.) The K45 really yanked it out of the hole and top speed was attained quickly. I was running on 3/4" chop but the boat was stable as it skipped across the waves at full tilt. Low/mid-40s on rough water. The larger prop did seen to widen the turning radius a few feet versus the stock prop.
I thoroughly enjoyed the 2-3 minutes I ran the model, and the temperatures afterward were around 100F on the motor, ESC and cells.

Grimracer: the distance between the back of the strut and the front of the drive dog should be one dia of the shaft (0.187").

Fluid: Most will get plenty of speed from prop, CG changes, and minor strut adjustments.

Fluid: The boat is not nose heavy when using a more aggressive prop than the factory one. With two 2S/5000mAh TP the CG is about 2.7" behind the sponsons. My personal LSH and P Sport hulls have the CG within 1.5" or less of the sponsons to help keep the boat on the water at speed. The UL-1 has so much lifting area that I believe that we can use the heaviest cells we can fit to keep the boat on the water. Air dams and lead weights are cheaper means of preventing blow-overs. I may try 4S2P setup; TP 3300s will fit cross-wise in the hull, so I can move the CG forward with a single 4S1P pack - or use two for 4S2P and more ballast.

Fluid: Waterproofing Rcvr - Take off the receiver case and spray board with CorrosionX, then reassemble.

Properchopper/UB-Hauled: M445. The strut at zero, 2S Elite 35C 5000's - violently fast; almost too much to handle. I adjusted the strut for a little down force. One or two throttle pulls got 'er up. Added a small air dam & it was simply ripping up the water. Temps were minimal after 2-3 minute runs. No water leaks. I put a paper towel (Jay). My strut is 1 1/16 " from the bottom of the hull to the bottom of the strut & is angled down at the back @ 5 deg.

Ray: To prevent Submarining - Very common with sport hydro's that have the CG up front. Trick - blip the throttle just enough to raise the front end and let off. Once the nose drops down and starts to pop back up nail the throttle and the hydro will jump up on plain.

Tunfin Reinforcement:
-Properchopper: The area where the fin is located is just as thin as the rest of the hull and the fin bracket reinforcing plate inside the hull has a very small footprint. With the lateral leverage imparted on the fin at high cornering speeds or an unfortunate blower like mine, this is likely to be an issue. My plan to fix this on mine is to fill the hole with epoxy or resin/microballoons. Then attach the sheet aluminum reinforcing plate outside the hull, probably with 3M 5200 slow cure {it's really strong and adheres better than anything I know of}. Then mount & either tack-weld or JB the fin bracket on the plate. The bracket also will still screw into the inside-the hull-plate which will be epoxied in to fill the hole. I'd advise anyone who is going to push this boat hard make an outside-the-hull reinforcing plate like mine.
More reinforcement? I drilled a hole in the inside of the sponson; Mixed up some 30 min. epoxy thinned with alcohol & poured it in. Held the boat at various angles to let the epoxy flow all around & let it set. Small abs patch will be next. How did you attach the aluminum to the hull, JB? First I JB'd the broken piece in & let it cure overnight . Then I laid play-dough on the back of the plate, pushed in place to make an impression of the fin bracket bolt holes & drilled them out. Then scuffed up the boat & the reinforcing bracket & JB'd it in place with clamps. Let it dry overnight & then faired the bracket to the sponson surface with various abrasives. Then bolted on the fin bracket with small "spot welds" of JB to the plate to keep it strong but allow removal if needed for other fins.
-Ken Haines: Turn fin Reinforcement (see RRR Forum)
-Longballlumber: Not only do you want to increase the surface area that is bonding to the sponson transom, but you want to also tie in the sponson transom and the sponson ride pad. The intersection of the sponson transom (surface that the turn fin bracket is mounted on) and the sponson rid pad are at a 90 degree angle, you want to try and form a fillet or a chamfer in that corner that will tie the 2 surfaces together and make it much stronger.

Grimracer: Strut bushing is replaceable.

Fluid: You can build the boat to have the correct amount of lift and down force - But the amount of force changes with the speed, and a boat that has optimum aerodynamics at 40 mph probably won't have them at 65 mph. The air dam - or tunnel spoiler - or turbulator - interrupts the airflow in the tunnel, "spoiling" some of the lift produced. It adds drag of course - virtually all aerodynamic add-ons do - but the end result is higher speeds because the boat stays on the water. It is a cheap and easy mod with excellent results.

10gauge: Battery Space: 170mm (L); 28mm (H) front; 45mm (H) motor.

Darin Jordan: Race Prep Blueprint (See Sticky)

Mike Martin: Flotation/Rigidity - Remove motor; drill 3/4" hole each side of tub wall toward front; pour 4-6oz TOTAL urethane foam mix 1 side @ a time; shake toward front; reinstall motor. (Don't use spray foam). <uscomposites.com> (561) 588-1001 $30.00

Grimracer: COG at 3 to 3 1/4" back from the sponson backs. Typically, COG around center of back of turn fin. Reason my turn fin design is swept - better turning on a wider COG range. The bottom of the rudder can make lift - sharpen rudder.