Building a hull around an engine
 

Does anyone have any idea how big of a hull I will need to build for a 30 cc Homelite engine? I plan on using a large pusher prop and don't want to find the finished project under or over powered. I have a couple airboat plans but they are to be used with airplane engines.

RE: Building a hull around an engine
 

A good starting point would be around 40"x20"

RE: Building a hull around an engine
 

Any recomendations on the pusher prop? Size and composition? I was thinking a triple blade made of anything but wood.

RE: Building a hull around an engine
 

I would say you would be swinging a 16"-18" prop.
Once you get the boat built you may want to experiment with the prop size.

RE: Building a hull around an engine
 

Would you recomend a single or duel rudder? what about the electronics?

RE: Building a hull around an engine
 

I use a single rudder on my boats and have good steering response.
A single rudder is a little easier to set up than a dual, saving you some build time. Both set-ups work well for rc's.

You'll definitely need a 1/4 scale servo for the rudder. A standard servo should work well for the throttle.

RE: Building a hull around an engine
 

The single rudder design is something I hadn't thought much about but the build time is definately something to consider. What would you recommend for a radio? Have you seen that pusher of haljmac's? That's kind of what I am after, something traditional for a first build. :D

RE: Building a hull around an engine
 

I prefer Futaba radios.
If your on a budget, the Futaba Attack SR is a good radio for the buck. I believe $54.99 from Tower. That is the standard radio I put on my boats, unless the client prefers another radio.

I'm very familiar with Hal and his work, we talk all the time. He's a excellent builder with some great experience.

RE: Building a hull around an engine
 

Hey, thanks for all the info, you've been a big help! Guess I have all the info needed to get started. Yeah, Hal lives just a couple hours south west of me, he has some great videos huh? I not only admire Hal's work, but yours also. Have you built many pusher style airboats? How long have you been in to airboats? I sure am glad there are pros like you and Hal out there to give newbies like me advice.

RE: Building a hull around an engine
 

Mastertchris,

Glad to be of any assistance! Glad to help out whenever I can, and share what I know.

I have yet to build a pusher. I'm more of a puller man. I've seen a friend build a 46LA pusher and it performed terrible....barely ran dry. He turned the motor around on the same boat and it out performed the pusher.
Each style prop (pusher/puller) has its pro's and con's.

How long have I been building.....I built my first airboat about 15 years ago, then got out of rc's for a while. I got back into them about 4-5 years ago. And been building steadily for about 3. Alot of my experience comes from the full scale boats. Been around them all my life, I live on a 750 sq. mile lake here in south Florida. I know several guys that build custom boats for a living and several guys that drag race full size boats professionally. One friend's father has held the world record for 4 cylinder aircraft for 6 yrs.
He was clocked at 64 mph in 150' on a dry run. The unlimited class hits 120-130 mph.

Thanks for the compliment. [8D]

You can find some more good info here.
http://rcairboats.net/v-web/bulletin/bb/index.php

RE: Building a hull around an engine
 

Wow that's a big lake! Hope you faired well with all the hurricanes that have hit Florida this season. Hey there is one more question I have. What is the best way to fasten the plywood together with and how do I go over it with the fiberglass?

RE: Building a hull around an engine
 

been out for a while. Thanks for the comps. When I'm building I tack glue the parts with CA, then run a beed of 30min epoxy at all the joints and seams, then seal with epoxy inside and out. Depending the wood you are useing, with the aircraft quality birch, fiber glass helps a lot but can be left off. if you are using lite ply or door skins I would put 2-4oz cloth, with the epoxy.
Inside of my hulls at the points where high stress takes place I use some 2 oz cloth to help hold it together.
40" X 20" is a good size, make the sides between 2-1/2" and 3" high

RE: Building a hull around an engine
 

Glad to see you back Hal. Always good to hear from you!

On my builds...
The motor stand base pieces are tacked together with brades then wood screws in appropriate areas.
To attach the base (which is recessed in the hull), I laminate it to the foam with epoxy.
Then glass over with 5 oz. cloth on the bottom and sides with 2 oz. on the top.

RE: Building a hull around an engine
 

Your the man Hal! You just answered my next question about how high the sides should be, I am cutting them out tonight. I am very curious about that cage you used on that airboat of yours, did you make it yourself? I sure would like something like that on mine! What's it made of?

RE: Building a hull around an engine
 

I think I am going to combine both of your suggestions to attatch the plywood together with brads, and epoxy, not sure about the screws yet. what is CA glue?

RE: Building a hull around an engine
 

CA glue is cyanoacrylate or super glue.

RE: Building a hull around an engine
 

Thanks Randall, I decided upon Gorilla glue instead and along with the brads and screws this thing is never coming apart! I stayed up late last night cutting everything out and did a mock setup, looking good so far. Today I am sanding everything down so I am moving right along....:D