Peace out!

[Hydro Junkie]

I think motor angle comes down to personal preference. When I built my Dumas kit boats, they had the engine mount in at better than 20* down at the rear while Brian Blazer has in the Whiplash instructions to mount it flat. I would install it at an angle that will facilitate lining up the flex cable and hiding the pipe in your application. Others may have other ideas as well.

As for the prop, I was always told to start out with the center of the prop even with the bottom of the sponson runner at its lowest point and adjust from there

 

[hgatjens]

The object is to get as straight a line as you can for the drive shaft. The exact angle is dependant on how far the mount is off bottom of the boat. On my boat I run the strut at a 1.8 degree angle.(1/`16th inch change over 2" strut length) Once the strut is set then you try and get as straight of a run with the cable to the engine mas possible.. Hopefully you can adjust the angle of the motor mount to make this as straight as possible. If you can't make it perfectly straight then allow a transition angle at then strut end of the cable. Just remember the straighter everything is the smoother the cable will turn.

On my T-3, measuring to the center of the prop shaft, I had the back of the strut 1 and1/16th" from the bottom of the boat and the front of the strut 1", .

 

[Don Ferrette]

Most of the time Harry and I are on the same page but when it comes to stuffing tubes I actually will purposely try to create a soft spaced out "S" bend to control flex cable whipping in the tube. Believe it or not there is more parasitic drag on a straight tube than the S bend because of cable whip. Years ago Rod Geraghty did a rather in depth study on parasitic drag and verified this along with other things like grease vs. oil for lubrication.

 

[hugh hargett]

Most of the time Harry and I are on the same page but when it comes to stuffing tubes I actually will purposely try to create a soft spaced out "S" bend to control flex cable whipping in the tube. Believe it or not there is more parasitic drag on a straight tube than the S bend because of cable whip. Years ago Rod Geraghty did a rather in depth study on parasitic drag and verified this along with other things like grease vs. oil for lubrication.

Randy Naylor, of BBY racing tried to teach that (s bends) to manuel on OSE but not many listened!!!!!!!! It makes perfect sense to me. Obviously Dons scales arent suffering from to much driveline drag. Don what was the final word on grease or light machine oil? Did the oil win out??????

The s bend also allows for lower motor mounting thus a lower cg from top to bottom..

 

[SayMikey]

I don't buy the s bend stuff. My scale has zero drag after running tranny fluid and caster at 50% every one has an opinion.

 

[hugh hargett]

"Zero" drag??? I wont "touch" that :lol: . I have boats with both take your pick but I do by the s-bend stuff. All i can say is Don and Randy both have very fast scales.

 

[Don Ferrette]

I don't buy the s bend stuff. My scale has zero drag after running tranny fluid and caster at 50% every one has an opinion.

Can your fingers spin it @ 20K?? Can your fingers load the cable the way the props does when it's pushing back against the cable as it tries to move the boat forward? Sorry bro, your flex shaft doesn't have zero drag on it's very best day spinning at running speed no matter what lube you're using. Here's a simple example you can do with an old flex shaft, a straight piece stuffing tube and a drill. Chuck the shaft into the drill, use a pair of curved jaw pliers or vise grips to loosely hold the tubing (so you don't distort it) up close to the drill about same distance as it would be in the boat. Hit the trigger on the drill, hold it wide open and tell us what happens, it won't take long to get your answer and that's without a prop load pushing back against it. Won't matter if you hold it straight up and down either even though that's not how it runs in the boat and your drill isn't spinning anywhere close to what that shaft does in the boat. I'll be totally honest with ya Mikey in that I didn't believe it either years ago until I proved it to myself............

 

[RobertWurster]

I like the smooth s bend to,I have not built a big scale boat but i have no choice in my sport 20 to get the engine as low as i can,I have never noticed any heat with it either,Dose it counter act cable whip not shure.I do love the scale boats tho,hope some day to build one.Keep up the good work.

 

[hugh hargett]

Robert, like NIKE - JUST DO IT!

 

[RobertWurster]

YOU FUND IT ILL BUILD IT..Hugh . Its hard enough to fund and run my 1 sport 20 right now.ive had to sell all but two boats just to play with the one..they just shut down the company i worked for .

 

[Bob Koch]

Edited for blocked membership...

 

[jwo]

Are you asking strut depth? If so, It depends on sponson depth. To measure you will need a straight edge about 3' long. With hull upside down place straight edge along the airtrap against the bottom of the hull starting at the transom. At the back of the sponsons measure the distance from the bottom of the hull to the bottom of the straight edge. This is how deep the strut center is to be. An angle of 2* is a good starting point.

 

[harvknox]

John,how do you take the depth of the rear ride pads into account if they extend below the line of the bottom of the afterplane?

Harvey

 

[Bob Koch]

Edited for blocked membership...

 

[jwo]

John,how do you take the depth of the rear ride pads into account if they extend below the line of the bottom of the afterplane?

Harvey

The Rear shoes should not be below the sponson depth. If they are, it will create lot's of handleing problems. They are only designed to help carry the hull through the turns. They should not contact the water when running straight. The prop should do all the work.

 

[Samuel Hagan JR]

John,how do you take the depth of the rear ride pads into account if they extend below the line of the bottom of the afterplane?

Harvey

The Rear shoes should not be below the sponson depth. If they are, it will create lot's of handleing problems. They are only designed to help carry the hull through the turns. They should not contact the water when running straight. The prop should do all the work.

What about strut depth to the rear pads? Should it the same depth as the rear ride pads.

 

[Duck899]

John,how do you take the depth of the rear ride pads into account if they extend below the line of the bottom of the afterplane?

Harvey

The Rear shoes should not be below the sponson depth. If they are, it will create lot's of handleing problems. They are only designed to help carry the hull through the turns. They should not contact the water when running straight. The prop should do all the work.

What about strut depth to the rear pads? Should it the same depth as the rear ride pads.

The strut depth will be deeper than the rear shoes. The top of my strut is just a bit below the rear shoes on my smokin joes. As John said, the rear shoes are only for when the rear drops in the corners (if at all) and the prop does the work in keeping the rear supported at speed with the shoes not touching the water in the straightaways.......

 

[harvknox]

Rob and John,I may have a handling problem with my gas scale though it may not show now.Here is where I am.I'm prepping the boat for finish paint.No more testing until it's finished.Testing may end up at Evansville open water before the race.Four tanks of gas thru it with the modded K-30.I don't have the right prop yet.More props on order.Engine torque held the left sponson out of the water on all straight runs.Hull is a slightly modifed ML Boat wood hull.CG 1 1/2 to 2" behind the sponson.No lead weights in boat.Boat weight less fuel 22 LBS.Canard tilted down between 10 and 15 degrees.Strut down at rear 1 or 2 degrees from tunnel surface.Strut depth below tunnel 1".We were playing with this dim.and was varied during the few tanks we ran,but I don't have records of the best setting.Afterplane depth at rear ride pads 3/4".Rear ride pad depth below afterplane 1/4",In other words 1" below tunnel at rear of boat Two mini steps across each ride pad similar to real T-6.Ride pad profile very close to real T-6 from photos except reversed.Rudder length below the tunnel is 5".That is pretty much the boat setup.

I don't think the boat speed equals a fast scale.Turns are easily made on the buoys. Boat will go straight without doing anything crazy.I have not tried to make a left turn except minor course corrections.Tail seems to drag.John,what handling problems should I be looking for?

I can certainly see the advantage of keeping the pads out of the water in the straights.less drag,more speed.I'm sure there is not enough air under the boat to hold up the rear,and I don't have the correct prop to help out.

I reasoned in my misguided logic that boats like the T-6 seeme to have shorter sponsons in relation to overall length,and would therefore use the rear ride pads to help lift the rear.I noticed that boats without ride pads seemed to have longer sponsons in relation to overall length,which would make it easier to lift the back.(modern day turbine boats)

I made the additional height on my ride pads by using a balsa spacer covered with 1/16"ply which can be easily removed if it messes up boat handling.

Anyone with helpful comments please chime in.I will probably leave the pads as is and change after the Evansville race if needed.

Harvey

 

[jwo]

Harvey, From the description, It all sounds great. What kind of speeds are you seeing? Lap times is the best way to tell. Compare it to the 1/8 scale nitro's on the same course. You might be surprized at how close they are or even faster.

The newer style hulls do tend to ride up hill. Although most of this is optical illusion. The hulls are very thick on the front half and thin towards the rear with a big wing back there.

If you can get around the course in any lane with out having to hunt for it, or with out blowing off you are headed in the right direction.

Some of the left sponson carrying can be corrected by skid fin adjustment or by trying a different style. A fin that is to large will do that. Make sure it is straight to the tunnel. At 15-17* angle. When the boat goes up the back stretch watch the spray coming off the fin. You should not see much if any.

Props and more props to get the right one for your hull. There is no cure all prop. Turn the largest diameter prop your engine will let you. A mod K30 should turn a large diameter prop fairly easy. Remeber that the larger engines like a little less RPM.use the Torque to get your speed. Get a hold of Andy Brown. Tell him what you have and set up and how the boat handles. He will give you a very close if not spot on suggestion.

The ride pads on the sponsons are just that. Ride pads. The hull is carried by air. You sponson angle of attack is important. To steep, The hull will ride up hill and blow off. To shallow it will plow and stick. A good all around AOL 2-3*. The rear shoes help get the boat out of the water. They should not support the hull when at speed.

When you test, Try taking out some of the angle in the front wing. Let more air under the boat. Ther will be a spot where you think you are going to blow over before you reach top speed. Get through it and you will see a much different atitiude of your hull and a lot more speed. Let the hull do the work it is designed to do. Fly on water.

I hope this helps and am looking forward to some video. John

 

[Samuel Hagan JR]

Should the rear ski's be the same length. My left rear ski is shorter from the transom then the right rear. I would think turning left and having a shorter left rear ski would effect cornering.