wolfmodels2004

Hi guys, just had boat out for first runs and so far im quite happy apart from the steering, it seems very very slow to respond, and the faster i go the longer it takes to respond, turning circle of about 20 metres and thats at 1/4 throttle ! i increased to half throttle and the thing hardly wants to turn at all, i have to slow down to make turns. The rudders right now are set to 20 degrees either side. rudder sizes are 1.5 inch wide x 6 long and a decent amount of rudder in the water as can be seen from the photos. they are made from 2mm alloy sheet, could this be flexing too much under the load from waterflow? when i apply full rudder and ease up on throttle water is getting thrown and churned up by the rudder rather than turning. The radio is set to only apply 50% throttle right now till i get used to the model and check for problems etc, the boat just starts to get up on plane. I cant help thinking the rudders would be much more efficiant and make less drag if they were behind the prop ? im totally stumped as to what to do next

jdoug

2mm? I'd bet they are flexing. How much does your boat weigh total - 20lbs? If they aren't flexing - Do you have a 1/4 scale or at least a high torque servo for the steering. It is a must have.

wolfmodels2004

The boat weighs about 11Kg, according to digital bathroom scales. A high torque servo is fitted, 152 oz torque hi-tec.

Captain Ramius

This is the first question I ask when this comes up,

Are your batteries at full charge?

That pushrod looks small, how big in diameter is it?

2mm is thin , most gas boats run a rudder that is 5-6mm thick at the back

Ron Olson

My Feedback: (1)

I don't know what that thing is hanging off the strut behind the prop but that could be a partial, if not the cause of the problem. At about any speed, that can affect the flow of the water coming off the prop working more like a fixed rudder. Remove it and I think that your steering will really improve.

wolfmodels2004

Yep batteries were at full charge, the pushrod is 3.5mm diameter. The part on the strut behind the prop was a scrap piece i fitted in place to ease my worry about seeing my brand new prop sink to the bottom of the lake, but i agree Ron i think that is the problem, the boat acts like its trying to turn but its being stopped and that piece totally skipped my mind as i kept assuming for some reason it would be out of the water as the boat runs but now i see that it isnt. i will remove some metal from it and make it like a thin strip a few mm wide, or is there any better ways to prevent the prop coming loose ? the ferrule will prevent it coming from the strut but only if the tiny set screws and loctite hold it ! Also i think i should construct some 1/4 thick rudders instead to stop the flexing, just thinking how to get the taper on each side of the blade without having to file for 17 hours.. hand held angle grinder maybe a small jig to hold the blades at an angle or somthing while grinding ?? Thanks !!

vsop

Yea, those rudders look like they are made from tin foil.. I would double or triple the thickness of them.

jdoug

wolfmodels - I don't think you need to worry about loosing your prop if you got everything tight and you used loctite (removable of course) on everything you could. Just check everything after 5 minutes of running - still tight?

As for your rudders - I wouldn't think you would have go more than 1/8" thick on the back of the blade the thickest part. If you use 6061 T6 aluminum - they won't flex unless you hit something while running. This stuff is made specifically for structural integrity. It's strong.

I agree with Ron - lose that "prop saver" It is acting like a fin and not letting you turn. Clear the way for flying water and try it as is - Your rudders might work just as they are.

Ron Olson

My Feedback: (1)

With my props, I use a piece of fuel tubing between the prop and prop nut. I can use a small piece of large fuel line on my 3/16" drives but you'll need something a little larger for your 1/4" shaft. The piece of tubing does 3 things, first it works as a lock washer. Secondly, in case the prop nut should ever come off (which it shouldn't with the tubing in there), it will help to keep the prop on. Thirdly, it will work like a mini shock absorber in case you hit some debris in the water. A small slice of Tygon might do the job.