Strut Questions

[rcboatlover]

I finaly got my running hardware today and have a few questions. The boat is a 31" Dumas Sk Daddal and I bought some Speedmaster hardware for it. The plan called for a fixed strut under the boat, but I went with an adjustable one on the back. The question I have is how far into the water is should be? If I mount it as low as I can, the prop will only be 1 1/8" from the bottom of the hull. Is this enough?

Also if I use a Teflon liner, how far should I leave it exposed under the hull? It's going to be run through a brass tube starting from the engine and threw the hull. Should I stop the brass there? Or shoud it run all the way to the strut. I diden't want to use teflon, but the brass tubing doesn't fit into the strut, and I don't think it would be easy to adjust the strut if brass tubing was used all the way to it.

Please tell me what you do!

Thanks for the help!

Dale P.

 

[EatMyShortsRacing]

What sort of shaft setup are you using? If you are using a ferrule then the brass tubing should go to about 1/2" from the tip of the ferrule. The teflon liner should end where the brass tubing ends. If you are using the flexdrive with the stub shaft attached then the brass tube should go into the strut so it supports the cable all the way. This means a teflon liner is probably out. If your brass tubing does not fit into the strut then you need smaller tubing. if the brass tube you are talking about is already mounted in the boat you can use the next sizes down to get the tubing to the diameter you need (like a telescope theory)

EMS Racing Twins R Us

 

[rcboatlover]

I think I'm going to go with a flexdrive with the stub shaft attached. I don't realy want to use Teflon, but the strut nose won't fit the size tube I need. The shaft is .187, and the tubing I need for it is too big to fit in the strut nose. I would drill out the nose, but there isn't much material there. The only thing I can think of it to change shaft size to .150, but the strut bearing is set up for the .187 .

So if I use a furrule I don't have to support the shaft, but if I use a stub shaft I have to? It makes sence to support the shaft, but if you don't have to with the furruel why should you have to with the stub shaft?

Also how do you adjust the strut with the brass tubing going all the way to the strut? Do you just allow the tube to bend alittle when moving it?

Thanks for the help!!!

I realy want to install it this weekend and need to know the best way.

Dale P.

 

[Flyin Rat Sass]

Years ago,in a far away place....Ok,wait, let Me start over.Years ago I built a couple of these boats and after trying a lot of things ended up with the prop 3/4 submerged,semi sub-surface.out of all the adjustments I made ,strut depth,strut angle(2%-4%up )the most important thing was the hull shape.from the transom forward there should be a slight gentle convex curve.this gives a lot more control to the trim plates.if the hull is flat(or God forbid has a hook)You will have only two settings--#1 trim tabs down - too wet won't plane.#2 tabs up - massive wheelies till it goes over or you let off the throttle.back then I was building the 36 inch sk-daddle,now I'm building another 36 inch sk-daddle plus scratch building a fiberglass 42 inch flatbottom dragboat that is shaped more like todays modern hulls.You will be able to adjust the strut with the tubing slightly bending with it.The reason for ferrule or supporting the tube is the lube in the strut wuold be quickly washed away from the water pressure,then there's the issue of the disturbance of the flow of water just before the prop.

 

[Flyin Rat Sass]

Oh yea,here's a pic of the boat and the plug(nearing completion)for the fiberglass boat.

View attachment 1055

 

[EatMyShortsRacing]

Well if you have the tubing going into the strut you leave a little play so the tube doesnt go right in. A little bending of the tube will give you the right angles.

EMS Racing Sticky tape works too

 

[rcboatlover]

Sounds good guys!

I will have to see what I can do with the flex shaft, stuffing tube, and strut bearing size. I should be able to find a combination that woks out right with out having to use the Teflon liner.

Flying Rat,

Your boats look nice! You must have a thing for the SK Daddal! I took a look at the bottom of mine and it's flat. It has a small crown from the keel to the sides, but not from the transom to the front. I have my hull built and only needs the running gear installed, how do you suggest I fix this?

Dale P.

 

[Flyin Rat Sass]

i would use some 15 or 20 min epoxy(if you want you can dig some pigment from the bottom of the bottle ect to color it...test first) it only needs to be 1/16 of an inch maybe less srtetching forward 6 to 8 inches or if your paint/epoxy is thick enough just sand the 'rocker' into it,then give it a light coat of epoxy.

And yes I'm fully into this type of boat.The're tricky to setup,then at their best can get unpredictable,doing all the crazy stuff the full size flatbottom dragboats do.the challenge of fine tuning is why I chose to go the route less traveled with the flats.

 

[rcboatlover]

My boat is a wood hull. Guess I will have to build up some epoxy with micro balloons and sand away!

Thanks for the help! I will post picts when it's done!

 

[Guest_guest]

You're first message said the plans were for under the mono but you put the strut in back. The # for strut lenght is 10% of the lenght of boat. I have a El Lobo 2 and for a long time could not get it to plane till one day i said to **** with it and made the strut lenght including the rear of prop at 2 1/2" with rudder blade even with drive dog and now with a 1.6 prop cut down to 26mm and she's a mover. Ok, here's something for you to read and is called Mono-mania on web site www.fastelectrics.com. Go to setups where they have a list and is written by John Finch and copy it and is the best info you will ever get.

 

[strut questions]

I just read some more on you're strut ; for a .187 which is 3/16" you need teflon which is 3/16" also and teflon will go into strut nose 1/4" cause flex stub will go in 1 1/4". Ok , when you put the strut in , have it go to the right a little to get away from torque roll and have strut parallel with the keel and maybe 1 deg. up ( positive ) and have alignment from endbell or motor stem in a straight line so as not to rob you of power.

 

[Hap Mulvany]

I race flat bottom cracker box and use surface drive tube through the transom to the strut.

 

[Flyin Rat Sass]

Hey Hap

Do You run those cracker boxes with a little bit of curve in the hull like I was tryin to describe earlier in this thread?

 

[strut questions]

Once you get the correct teflon and have run it thru the stuffing tube, you can have a space between the stuffing tube ( brass ) and the strut for adjustment but make sure you insert the correct teflon into strut 1/4" and to be honest the stuffing tube can and could use brass piece that goes up and into bottom of boat after you solder tube and upright piece. Ok, when the upright piece goes thru keel, put a slit pin or roll pin, whatever you want to call it and epoxy it. A nail would work too which will support and atabilize the tube and you still can adjust the strut without moving stuffing tube and you won't have leaks either. As of right now i'm working on a c-box with sub drive and straight shaft and am trying to follow Mark Plasek's setup. My goal is to have a c-box with surface drive but have not found one boater who has gone that route till now, There are a lot of ?'s like cg, motor place and placement of rudder and thats it. The rest would be placement accordingly to cg. Have a good day and have fun, thanks for reading!!

 

[Guest_guest]

Hap Mulvany; how are chances of getting you're specs on the surface drive c-box. I don't race cause there is nobody in this size of city who has electric boats, gas only. If i had you're e-mail or you had mine, it would not pass out from me. I have no idea exactly where everything goes. I just have lots of fast fun with my boats. I hope i don't step on toes, cause life is too short and when you're retired you really know it is short. Have a good day!