mwohlenhaus

I had some materials leftover from another project and decided to get started on an RC boat build. Never been into the world of boating before. I do have limited experience building/repairing RC planes. So here is what I have so far.
1. A desire to build an RC Boat from a pile of wood
2. plans downloaded for the Prowler from here http://www.john-tom.com/RCPowerBoats/RCPowerBoat.html
3. 3/16 Luaun plywood, 1/8 doorskin (reclaimed), 1/4" Plywood
4. 22 cc John Deere 200C weed trimmer motor, more about that later
5. 2 standard sized servos, radio, receiver. I know this is not all inclusive of the electronics needed, just don't have the UBEC yet
6. a few pictures of the process so far (to be attached later)

I printed out the plans on my home printer and taped the pages together. I glued the taped and cutout templates onto their respective pieces of wood. Cut the pieces out a little proud of the lines. Sanded the edges down to the lines. The frame fits together very nicely. The long pieces of door skin for the decking need a little touch-up sanding to get them to fit together. and I haven't cut out the 2nd half of the bottom yet.

I was toying with the idea of scaling the model down to a 42-44" due to my available motor only being 22 cc. I decided to leave it as is due to having no knowledge of how to resize in a PDF. If this proves to be too under powered I will look for a larger weedeater motor. In the future I may go to a liquid cooled marine engine but not for now.

So now the questions start.
1. is epoxy the best glue to use for the parts?
2. I have been looking for rudder/drive setups and have seen the dual rudder with struts, have not noticed these on many boats. Are there any inherent issues with this type of setup. Have also seen single rudder directly behind the strut and like that too. I am not a huge fan of the looks of having the rudder offset on the transom.
3. I am currently unsure on how to run the stuffing tube but will research this further.
4. will the standard sized servo have enough torque to run the rudder?


I am open to any suggestions/comments regarding anything. As stated above I need to keep researching things as I go, but just some primary questions to continue going.

mistycreekboats

My Feedback: (1)

Reading through the Zipp manual for a Easy V may help your build and answer a few of your questions, will also give you a chronological build order.

http://zippkits.com/~zippkits/evman.pdf

dwr9

Definitely use epoxy. I used a Zippkits stinger drive on mine. I would not use dual rudders or rudder behind the prop. There is a small text file and build pics included with the plans. I hope you have reviewed them. Those are my plans, I designed the boat. Have fun and please post pics of the build. We all love pics. Doug

mwohlenhaus

I must thank you Doug for allowing new comers that want to give building a boat a try without alot of money invested initially. I did review the pics and the written instructions. If setup properly will the smaller motor have the power to get it on plane? I am not looking for racing, just cruising.

Hydro Junkie

It should, if you build it light. The issue will be the RPM capabilities of the engine. Weedeater engines are not made to run fast so getting sufficient power could be an issue
One thing I would warn you about is the problems involved with using doorskin in a boat. Doorskin is inherently brittle. Since it isn't made to handle a load, it can and will crack or splinter. It is also very porous so it will take some serious work to seal it against water. If it's not sealed, it will absorb water, adding weight and ruining the wood.

dwr9

I've built all my boats using doorskins with no problem. You do have to seal the boat well inside and out with epoxy. I would guess that motor would get you to the high 30's to low 40's with the right setup.Doug

mwohlenhaus

here are a few of the progress

dwr9

Lookin good so far. Doug

mwohlenhaus

some more updates

dwr9

Nice job. Keep the pics coming. Doug

mwohlenhaus

So far I have the bottom skin glued to the frame. Working on gluing the strips between the frame to help hold sides on currently. Am soaking the front pieces in water overnight to soften them up to make the bend. Have rubber mounts for motor and a 1/4 scale Hitec HS 755 HB servo for steering. Am planning on ordering the Zippkits basic hardware combo for mono hulls, and the stub shaft combo for running hardware. Will need to figure out what prop to use at some point as well.

One question that is coming to light as I get further into the project is that of fuel tank placement. I see several fuel tanks towards the front of the hull. Do you figure motor placement based on full tank of fuel or average it out at half full?

Another question regarding motor placement and stuffing tube; Is the ideal method of running stuffing tube to bend by the motor and then run parallel to the hull out the back, or make an even more gradual bend so it becomes parallel right before exiting transom? In looking at the easy vee instructions it appears that it is parallel for the majority of the run with the bend being right away but not sure if I am seeing that correctly, or if it is a gradual bend.

All in all everything is going well (albeit a bit slow due to limited time to work on it). Once again any and all comments/questions/concerns are welcome!

crapshooter

you should place motor and all gear into the hull and balance from there. normally the balance c.o.g. is approx 1/3 rd of the length of hull measured from the stern ,. balance should be done with an empty fuel tank. as for shaft log set up you should always have a gradual bend so theres no drag in the tube to shaft. so have a straight section of the tube log from the transom flat on the hull floor and start your bend about 4 inches down from the top end, this should give a nice gradual bend . heat up the tube log first and let it cool before bending as this will make it very easy to bend the brass tube by hand.

mwohlenhaus

Thanks for the advice.

Are stuffing tubes something that need to be replaced if kept in grease/oil? Do I need to make it removable or can I just epoxy it in place? I have seen both ways, but did not clearly understand how to make the tube removable and still secure.

crapshooter

i use the thicker wall brass tubing for my shafts and they don,t wear out atall. keep the shaft greased or oiled up . if the tube is inside the hull running surface drive propulsion you don,t need a sleeve so the shaft can be removed, its only if you have the shaft under the hull like the hydros have that its a good idea to have the sleeve so the shaft tube can be removed if it every got hit and bent underneath the hull. the sleeve for shaft tube should be the next size inside diameter up from the main shaft tube to slide into, just like a car radio telescopic antenna. also you can buy shaft supports that go between both engine rails and the center fits over the shaft tube and held with a grub screw or clamp , this will stop the shaft tube from turning if you decide to use the sleeve method.

dwr9

With the engine you're planning on using I would set the center of gravity at about 28 to 30%. 1/3 of the distance from the stern(33%) would be good with a mod Zenoah. Yup, a gradual bend in the stuffing tube is best and I just epoxy them in. I use thin wall tubing and have never worn one out. You don't need to soak the strips of wood, I just put cuts about halfway thru the strips about every 1/2 inch or so and it'll bend fine. Remember when putting the strips in because of the angle between the bottom and sides they must project beyond the edge of the bottom so you can sand them back flush with the sides. See the attached pictures. Doug

mwohlenhaus

I just bent the pieces around the front of the hull and have them clamped and drying. Will glue them on when dry, but didn't think of the slits in it. that would be much quicker.

crapshooter

if its not hard to bend the wood by hand you only need to use some C.A. Glue and finish with a thin bead of epoxy along the edge. this comes from the old r/c model aircraft building days where alot of timber stringers were used in the constuction of the fuselage.

mwohlenhaus

Any recommendations on a prop? So far using the weed trimmer motor @ 22cc and stock. Not a lot of power but it is what i have for now. I also noticed that with the motor I have the fan shrouding is not symmetrical. The right side is bigger around than the left (as viewed from the PTO side). If I mount the motor as low as it can go in the chassis it will hit the rail on the right side. Is it an acceptable practice to offset the motor a bit in an effort to not have to raise it up in the hull. Talking at most 1/4". It will still need to come up a bit as well, but not as much as clearing the rail would take. I will get some photos of what I am talking about if it is unclear.

dwr9

I usually offset my prop 1/4" to the right. If I interpret your post correctly you need to offset the motor to the left side of the boat. How much of of the stringer would you have to cut away to keep the motor centered? Doug

mwohlenhaus

Here's a few more pics of progress so far. DWR9, as far as I can tell I will need to cut 1/2" down to clear the right side rails. If it needs more I will reinforce the rail. The pic of the finger is from when I was cutting the engine mounts out on my bandsaw. saw 1-finger 0. Thank goodness I didn't have a wood blade on it. the motor mounts are done. Right now I am waiting for the radio box area to cure. I am using the area from the 1st bulkhead to about halfway to the transom. I am using the full depth of the area so if I do have to repair the stuffing tube or modify it I don't have to try to tear the radio box out. Another reason is I need the depth for the big servo, I couldn't figure out how to mount the servo on it's side and be able to get to the servo screws easily. I have the Zippkits mono hull basic hardware combo stinger/rudder kit and the 1/4" stub shaft set on the way. Everything is coming along nicely, not quickly though but I think it's good for only doing 1/2 hour here a couple hours there.

mwohlenhaus

As far as the motor goes I need to remount the coil, get a carb kit and install it, modify the muffler, and figure out where the fuel tank will go and plumb it. As far as the muffler goes I am not sure if I am going to run it straight up or plumb it out the rear. I am thinking that due to the lack of power I will save the weight and run it up. After the radio box is done I am going to fill in the splash rails on the underside of the hull, then will be ready to get the radio gear and hardware mounted. My goal is to have test and tune done by mid-July when we go on vacation so I can take with to the lake.

dwr9

Keep up the good work. Doug

crapshooter

you need to make up stronger engine mounts than those you have now. looks like 1/16 inch aluminium used, go to atleast 1/8 inch plus do not use rivets, bolts with nylock nuts only. otherwise all going well.

mwohlenhaus

Update on progress. I got the radio compartment sides installed and am looking at the stuffing tube construction/installation, more on the installation as construction is easy enough. According to the Easy V manual they ran it 1/2" on center up from bottom of the hull is this standard? The manual did reference the 1/2" for a zen. I built new mounts out of 1/8 angle and bent it instead of fastening pieces on. As far as the assymetrical fan shroud hitting the sides I will be able to touch the side rail with a sander and get it to clearance the motor. Am going to call zippkits and see what they suggest for a prop unless someone has a suggestion on here.

mwohlenhaus

one more question regarding stuffing tubes, I have heard of where the stuffing tube protruded from the transom 1/4-1/2", was sleeved and then o-ringed to seal the stinger and the normally exposed flex shaft. Is this something that is an acceptable option or just overkill?