Gator RC AirBoat Forum

[hmcnett]

Click able pictures bottom of this post.

Building a 24” X 14” X 2” flat bottom, puller style, airboat. The above drawing is of the finished top and side view. This is the basic style of hull, that adding improvements will not be all that hard to do. Some building knowledge is necessary. You will need, 1/8” plywood for the framework and 1/16” plywood for the skin. I recommend using model grade plywood. Lite ply can be used, it is easy to work with, when it comes to bending the rake. “Lite ply is not made for strength” 30 minute epoxy works best to hold the parts in place, with using thin and thick CA to tack all of the parts together.

First you will need to cut out all of the frames. Using 1/8” plywood.
2 frames that run the length of the hull, that will placed 4” apart from one another.



Next cut out the transom, using 1/8” plywood.


Cut out the rear radio box bulk head using 1/8” plywood.


Cut out the front radio box bulk head using 1/8” plywood.

It is important that all cuts are straight, other wise you will have trouble during the build.
Cut out the deck bulk head using 1/8” plywood.

Now that you have all of the frame work cut out, inspect and check that all of the parts slide together.

Cut out 2 doublers for the engine stand, using 1/8” plywood.


Next cut out the bottom sheet, using 1/16” plywood, 1/8” plywood can be used, it will be harder to bend, and will be heaver. 1/8” plywood would make a stronger bottom. Layout lines to mark where the frames will be placed.


Place the frames on the bottom and CA tack into place, taking your time bending the rake into place. Bending the rake is not a easy job.

Next cut out 2 strips of plywood, and using the build you have now trace the lines for the side cut outs.


You should have a cut on the bottom for the rake, that is curving up. A cut on the front deck, top of side, that is curving down, and also top of the side from the deck bulk head to the transom, you should have a line to trim. This part I normally leave in place, it helps to keep the water out of the hull, and IMO looks better. The broken lines show something like the cuts will be.
CA all the frames, bottom sheet and the sides into place. Laminate the doublers onto the insides of the engine stand. Apply epoxy to all of the joints and let dry. Now your ready to install the deck. The easy way of doing this is to glue plywood onto the frames leaving the sides larger than the hull. Don’t forget to cut the opening for the radio box first. Trim the excess around the hull.
For the top of the engine stand laminate 3 layers of 1/8” plywood, cut that to fit between the legs. Using screws and epoxy to hold it in place. (Pre-drill holes for screws)
Using the 30 minute epoxy seal the outside of the hull, making sure that the joints have enough to hold them together.

You can add runners on the bottom, this will help to stop some of the sliding in fast turns. A grass rake on the deck will help to stop water, from coming over the deck, when crossing over something or just entering the water. Good luck on your build.

[hmcnett]

I have put a lot of work into making this set of plans, please do not abuse them.
If your not a member yet, would you take the time and register.
Help others or ask others to help, your input is needed. Thank you

[model_mann]

could i see a pic of this boat hull completed, (after being built) so that ill have a general idea of what it will look like when i m done

[hmcnett]

It will be just about the same as the 46 hull that is posted in airboats nitro/gas forum. except that this is a puller setup and it does not have the drop style deck floor.

[model_mann]

ok thanks but ive still got a few questions,

1st. in what order do the bulk heads go,

2nd. the transome piece has a shape like this cut out of it \______/, what is this for, do i cut seperate pieces to form this shape in the hull/deck, if so these pieces would intersect the verticle pieces \|___|/ did i measure wrong? or did you purposely make it like this, and does this v shape run from the back of the boat to the next bulk head.

3rd. when im ready to put the bottom top and sides on the frame work, do i put the top or bottom on first, or vice versa, cause i cant figure out how to put the sides on and have them the right size,

4th. will an enya. 19 be able to push this hull around, it seems as if its going to be pretty light, if so, how do i mount my engine to it, would i have to cut out a place in the top of the pylons to put the engine or do you have a different method you could clue me in on.

5th. where does the gas tank go, is it to be set into the hull or does it go up by the engine.

sorry if there are 2 many questions, i just want to make shure that im putting this hull togeather right, i have little money (im 17 and only work sat and sun, getting 7.50 an hour) so i want to make shure im not waysting money doing something wrong, if you would help me i would greatly appretiate it.

thanks ty weber

[RS 38-40]

I made up a set of templates from your plans and also noticed the angle cut in the transom didn't match the pylon frame . Maybe that should be left solid so the deck will lay flat around the pylon . On the reference hull the pylon is ahead of the transom and it has a drop deck .

[hmcnett]

question 1.starting from the transome, working towaards the bow. Transome, BH3, BH2 and the first bulh head is not numbered.
2. \______/ the parts of this shape are the bulk heads, they run across the hull from side to side. the bulk heads have notches cut out in them to match the notches in the longitude frames.The transome does not have any notches, is to be install after the other frame work has been inner locked to one another. All of the bulk heads must be placed in the correct order, so that the shape of the hull will work out. If they are not placed in the correct order, your boat will not fit together. After all of the frames are together, it will make the shape of the hull.
3. After you have the frame work connected together(do not glue anything yet) Lay out the bottom sheet, to mark where the framesare to set. Spot glue(with thin CA) the frames and the bottom sheet. Working from the transome foward. Rolling the bow into place will take some work, take your time, if you try to work it to fast, you will take a chance on twisting the hull. Next install the sides. Now you want to epoxy everything into place, seal all of the seems, and run at least a beed along the sides where all the parts meet another part. Now you are ready for the deck.
4. the .19 should move it around and it should work very well, in the water or snow and ice. The drawing do not have the top of the engine stand. Just add a piece of 1/4" plywood onto it. Use CA to hold it together, and add in at least 4 servo screws then epoxy over all of it. Cut out the slot to set your engine, drill engine mount and mount your engine.

[hmcnett]

5. the fuel tank, I recomend making a shelf to support it behind the engine, or if your engine has what it takes to get the fuel up to the engine then install it inside of the hull. This part is up to you, on where you want to install it. I had to leave a little something for you to design....lol
6. The engine stand has 2 tabs on each leg, they are to mount hinges to attach the rudder. Just add in strips of plywood along the sides to support the deck. The deck will have to be cut out to wrap around the legs, after you get to the point of installing the deck, you should be able to see how to cut the deck to fit around the legs. The deck at the transom willhave to be made in 3 parts, since it drops down for the airflow. If you do not want it to drop, just cut the transom straight across.

[model_mann]

ok thanks, now when you talk about the airflow/ the droped part below near the transome, do you recomend keeping it there, what is it for, does it help in preformance.

thank you for the help

[hmcnett]

Its for more than just the air flow. There will be times when you'll get water over the deck, with the dropped section below the prop, you will have less chance of extra water contacting the prop, causeing the prop to break or even over load the engine causing it to die. Then you will be left with trying to get your boat back to shore.

[Unusual RC]

Thanks for the plan. Really a very nice initiative

I am planning to build this model using a .25 engine I have spare. Before I start building I set-up the model in 3D CAD.

Here are some screenshots taken from the original model:






It seems that the 3rd top width dimension is wrong? I have adjusted it in my plan. Is this right?

[hmcnett]

Not sure dim. your talking about, 1' 1-1/8" ? If this is the one your talking about, it is correct. You can make adjustments if you want, from the drawings you have here they look really good. Thank you for posting them, now every one will know just what the boat will look like.

[Unusual RC]

Sorry, I found out that I made a mistake converting the dimensions from imperial to metric. I did that by hand, rather let the CAD software do it

Anyway, the width of the bulkheads from the stern to the bow in metric are in my model:

stern bulkhead: 350mm
2nd bulkhead: 360mm
3rd bulkhead: 355mm (here I made a mistake calculating)
4th bulkhead: 330mm

This gives in CAD a nice looking hull, as you can see on the pictures above.

[Unusual RC]

I am also doubting to make the hull out of foam. A colleague of mine is very skilled in cutting foam wings for his airplanes.

I can make the templates out of this 3D model. The turn chines can be either wood, or PS thermoplastic sheeting, glued with epoxy.

I will keep you all informed about the progress.

[Goose Chaser]

Perhaps I should know better than to ask this, but I am extremely new to this, so please bear with me.

Mr. McNett, when cutting the wood for this Airboat, did you use a Band Saw or a Scroll saw. Which do you feel does a better job at cutting 1/8", 1/16" or 1/32" plywood wood?

What type of blade did you use for the machine used for this task?

What types of applications are either of these two cutting tools best suited for?

Do you have any special preferences?

Thank you for this forum and for your help. Have a great day!