>>Can anyone help me with some problems:
>>
>>1 - A lot of water accumulates in the engine/tank department - should I enlarge the drain holes, close them, make new ones on the tub sides ?
>>2 - The rear end of the boat hopps (prop comes out of water)
>>3 - Should I make a bigger hole in the rear of the cowl to allow more air in ?
>> Any tips how to adjust the low/high speed needle since I had a lot of trouble getting the engine to run properly
Welcome to Iwaters. Here' my take on some of your questions above.
1. I run ~3/8" holes in the fuel and engine compartment. Heres a trick with drain holes.
Cut a piece of radio box tape 1.5" long. Fold over (sticky side to sticky side) the last 3/4" so you end up with a 3/4" sticky tap and 3/4" nonsticky "flap". Position the "flap" over the drain hole and the sticky side towards the front of the boat and press. The thought is to make a semi one way valve so the water cannot go from outside the boat to inside but can flow from inside to outside.
2. rear of the boat hopping is a common problem. Which prop are your using? What is the stut angle and depth, what is the angle of attack on the rear sponsons? I run 1 - 1.5 degree AOA on my rear sponsons. Strut angle is very close to flat. Strut depth (bottom of the strut) is near flush with the rear sponsons. You can reduce some slight hop by "cupping" the ears on the prop. This reduces the lift and increases the pitch (don't goo too far)
3. You want as big if a hole as you can get so you don't suck a vaccum under the cowl. If you suspect this is a problem. run the boat without a cowl and see if it the motor runs differently. If so your cowl may be too restrictive.
4. Without a flow meter its hard to tell you an easy way to adjust the low needle. Typically what I'll do is turn the low end dead rich and adjust the high end first. The motor will not idle so keep it cleaned out on the beach. O the beach, I rev the engine form between say 1/3 to 2/3 throttle to keep it cleaned out. When on the water, run Wide open on the pipe for a few laps and bring it in. If you are not getting on the pipe, you ahve a new set of debugging. (too rich, too lean, wrong prop, pipe length, sponson angle,etc)
Some excellent reading on nitro boat setup Marty Davis' page. He is on this board as well
<a href="http://www.rcboat.com/past.htm" target="_blank">http://www.rcboat.com/past.htm</a>
A few observations/questions for you.
1) what is the goal for this boat? Is it for fun at the local pond or for organized competition races? The amount of setup is vastly different between the two.
2) The vast majority or nitro boaters don't run the teflon tube in the stuffing box. This tube will get worn and cause a mess. I'd get rid of it and use a brass tubing (I think it 1/4" diameter. There is one that just fits over the flex cable, get the next size up from that one) with some light grease or gear oil. Don't use motor oil as it can cause problems with the rubber pushrod seals.
3) Is that a plastic prop? I'd recommend going with a metal prop (Octural 1445 or 1450 are good starting props) Lots of other,faster choices here too once you get it going reliably you can tune from there. Make sure you sharpen and balance them before using.
4) The fronts of you sponsons looks wide and will tend to catch air. If you find that the boat wants to fly off the water at speed, you might consider narrowing the fronts of the sponsons.
5) The plumbing in your fuel tank. Don't follow the suggestion of the tank manufacturer with the flex tubing and a counter weight sump. This is for airplanes. What I do is bend the tubing so the fuel is drawn directly from the bottom left hand corner of the tank that is closest to the motor. The fuel will sloch this way when the boat is making a right hand trun and accelerating. Bend the vent tube to the usual location or all the way to the front upper right hand corner (opposite corner from the fuel pickp). Its sometimes easier to get the tubings in the tank when the vent goes to the front corner.
6) Typically we run the water pickup built into the rudder. I'm looking at the brass tubing hanging off the back and trying to figure out if that causes drag or not since it is in the roster tail. Having the water pickup in the rudder that a whole lot cleaner and you're assured to get water to the engine.
7) What plugs are you using? Don't use too cold of a plug (Mcoy#9). K&B 1L or Mccoy MC#59 are good choices. both should be avaialble at ~$3.00 each on the net. What % nitro are your using?
There are lots more but my fingers are tired. If you have more questions, ask away. Good luck!
