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Old May 23, 2010, 03:53 PM
"I Am The Animal!" in training
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Winston-Salem, NC
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Build Log
scratchbuilt 31cc ryobi - deep vee - my first boat

hey yall. i have a lot of experience with rc planes, and a little bit with rc cars, but none with boats. my father and i got a new weedwacker a while ago, and this week we decided to build a boat to put the old weedwacker's engine into! its really starting to shape up! (we dont have any plans or anything - just some general dimmensions, and pictures - were pulling it all out of thin air, and making it up as we go along. haha) its 52" long. by 18" wide

let me know what yall think so far. im gonna have a ton of questions later on about things like the rudder set-up, and the prop.

thanks yall!
Helifryer
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Old May 23, 2010, 05:52 PM
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Looks like a good'un. One issue you may find with such a large amount of deadrise at the back is stability, I reckon it'll rock from side to side a lot.
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Old May 31, 2010, 09:44 AM
"I Am The Animal!" in training
helifryer's Avatar
Winston-Salem, NC
Joined Sep 2008
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more progress... the hull is all built now. we sealed (sort of...) the seams from the inside with some adhesive caulk. if nothing else, it should at least provide some structural integrity - its not really going to help much with waterproofing tho.

next step is to rough sand the outside, and then start filling holes/gaps/cracks with bondo. we dont really know what we r doing...but itll work. hahaha

after that, i think we will fine sand it all, and get the shape correct, and either paint it then finish it with 30 min. epoxy, or finish it with epoxy, and then paint it..... not really sure which comes first.... lol. im gonna have to do some more research.

Heli
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Old May 31, 2010, 10:25 PM
"I Am The Animal!" in training
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Winston-Salem, NC
Joined Sep 2008
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ok. so the glue/adhesive/caulk stuff still needs another day or two to set up to the point where we can sand it w/o gumming up the sand paper. so today (dads day off ) we stipped down the powerplant - ryobi 31cc weedwacker engine.

we took the whole thing apert, and cleaned everything out - all shiny-like.
we removed unnecessary parts, and moddified a few others and put it all back together for a test run.

it fired right up! there seems to be a small issue with the tuning i think, because it will only run if its half choked. wont run if the choke is off all the way. (might also have something to do with the fact that we didnt have any kind of exhaust/muffler/pipe on it at all tho. - i know o inkw - not a good idea. - we didnt run it for long or hard at all. )

things i need to get a hold of from the LHS: - a prop or two to try out, some sort of exhuast header/pipe and some new fuel line. ive got a bunch of questions for the guys up there anyway :P haha

im excited! now that ive heard the engine run - its looking like this is really going to work
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Old Jun 01, 2010, 10:15 AM
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Cauking it was a waste of time. You should have fiberglassed the outside. The Ryobi engines are crap for speed. You need a motor with a clutch to stop it or it will just keep going. Put the stock mufler on. It's a waste of time looking for a aftermarket exhaust kits. Making your own will reduce the hp you allready have. Wood adds weight to the boat. Running hardware kits are expensive at Your local hobby store.
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Old Jun 01, 2010, 10:39 AM
"I Am The Animal!" in training
helifryer's Avatar
Winston-Salem, NC
Joined Sep 2008
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woah dude... how about a little constructive criticism huh?

first off - i know that the ryobi engine isnt the same as an rc engine built for speed. - we are just doing this for fun - father son project - if it float, and works, then great! - I.E. im not about to go out and spend a bunch of money on it - so far we havent spent a dime.

second - this engine has a clutch. no worries there.

third - the caulking was just to make it stronger - not to seal it. the wood that we bent in on the sides/bottom of the hull was under a lot of stress as it was, and might have pulled out some nails if we didnt re-enforce it with the glue.

and last - the hull is going to be completely sealed shut so that if i should ever have an accident - like rolling it - the engine wont get wet. so we need a way to get the exhaust out of the hull. so it only makes sense to fashion some sort of pipe. that way
we will be (hopefully) increasing power, and routing the exhaust out of the hull all at once.

im headed up to the LHS in a few minutes here - im gonna ask all about it.

Heli
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Old Jun 01, 2010, 03:36 PM
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I have never run a clutch in any of my IC boats, and I never, ever, ever will do.

Don't seal the hull, you need as much airflow into it as you can possibly get. Drying an engine is a case of taking the plug out and turning it over with throttle open and your hand over the carb air inlet until water gets replaced with fuel. You'll know when it has because you'll smell it one your hands.

Making your own tuned pipe, that has the right volume, design and length from the centre of the engine will hopefully increase the engine power by up to a third when on pipe.
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Old Jun 01, 2010, 07:22 PM
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Helifryer My father and i just got done building a Ryobe powered RC Yacht . What we learned is if you enclose the engine inside the boat '' like we did '' It WILL over heat on the first run . Its gonna be like Shake and Bake . You wont be able to get enough air flow to keep it cool. The exhaust you can make your self . I made my header out of a 90 degree Steal Hydraulic Fitting the rest was Copper right out to the Stearn. Your gonna need a MIG welder and the copper you just solder. Our boat is not a Race boat its built to be dependable and low Maintenance . The clutch will work just Fine. You will be needing a Pulse type Fuel pump to pump water to cool the exhaust also you will need to get the cylinder water cooled . That will cost about 50 Bucks to have someone install a water cooled Sleeve . You will also need to Tap a fitting into the crank case to operate the water pump aka fuel pump. The pump I'm running has Three outlets, one to exhaust and the other to Cylinder and one not in use . If i you need any pictures or help please ask . I posted three pictures of our boat before the water cooled cylinder Mod.
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Old Jun 01, 2010, 07:42 PM
"I Am The Animal!" in training
helifryer's Avatar
Winston-Salem, NC
Joined Sep 2008
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winkman

wow! thats very impressive!

ok.. so i talked to my dad about it - we wont be closing the engine up. lol nothing is set in stone yet anyway. i just hadnt thought it all the way through yet.

im thinking about just buying a simple ryobi conversion muffler like this one, and justr letting the 2 pipes go straight up and out the top of the boat! - simple, effective, and would look pretty beastly. http://wackerengines.com/Ryobi.htm

can you please explain, and post some pictures of how you guys set up, and mounted the prop, and shaft? we are pretty confused here.... could you recommend a prop? i wanna go fast. itll probly end up being a submerged drive, but im considering doing the extra work to try and set up a surface drive.

thanks!
Heli
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Old Jun 01, 2010, 09:24 PM
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You should have a square drive on the crankshaft end, use the cable that came with the unit and find a way to hook to the prop your local hobby shop should have something you can use, every thing wont be free but you can do it very cheep.
Dave
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Old Jun 01, 2010, 09:45 PM
"I Am The Animal!" in training
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Winston-Salem, NC
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haha. thanks. i dont mind spending a little $ here annd there. lol i know there will be parts i have to buy. im just trying to keep the budget tight.
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Old Jun 02, 2010, 05:59 AM
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I hate to jump forums but this is right up your alley.

http://www.rcuniverse.com/forum/m_9772360/tm.htm
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Old Jun 02, 2010, 08:32 AM
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Quote:
Originally Posted by andyn22 View Post
I have never run a clutch in any of my IC boats, and I never, ever, ever will do.

Don't seal the hull, you need as much airflow into it as you can possibly get. Drying an engine is a case of taking the plug out and turning it over with throttle open and your hand over the carb air inlet until water gets replaced with fuel. You'll know when it has because you'll smell it one your hands.

Making your own tuned pipe, that has the right volume, design and length from the centre of the engine will hopefully increase the engine power by up to a third when on pipe.
I see you like wrecking your driveline. A motor with a clutch will allow a boat to completly stop in the water and make it easier to bring your boat in. I guess you like it to just keep on going by. You need to completly seal the boat otherwise you will be sinking faster than you need. Maybe you should think about getting a submarine. Water adds weight when racing.
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Old Jun 02, 2010, 11:14 AM
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Erm thanks mate, but I've been in this game for years.

Clutches sacrifice about 10mph from your top speed, and are just another thing to go wrong. I don't need the abilty to stop out in the water, I can drive. I've also only broken one flexi in the last year of running, and that was due to a dry shaft. When I want to bring my boat in, I cut the engine about 10 feet out and it'll glide to the bank pretty quick.

I run an autobailer in the back of my boats, and my multi's just have two 1/4" tubes running through the underside of the radio box. When tuning a boat, you want to run it with the top off anyway. Have a look at most American circuit boats, quite a lot of them don't even have hatches over the top.
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Old Jun 02, 2010, 08:09 PM
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I think you guys are missing what he's trying to accomplish here . It's just a fun boat that he will not be racing and does not want to spend much money on . A fun boat to me = Dependability and Low maintenance . The only thing i see him having a problem with is trying to Stuff everything in the Hull . Ohh one more thing , The Prop Strut on our Boat was also custom made out of aluminum with added Bushings , Ferrule and Stub Shaft from Warehouse hobbies . We also used the fuel tank and flex shaft from the Weed Whacker too.
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