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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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Posted: 20 September 2015 at 10:56 |
Airboat !!!
This is my new airboat, Whatcha think ? All I need is a few more parts, and it will be sea worthy RIGHT ? I checked the compression "0" on all 4 cylinders. What? Plan "B" I adjusted the Lifters and bam I had compression. 125 on #1 119 on #2 120 on #3 and 129 on #4. It's a 1971 bug motor I'm thinking that will work for now. On that same subject Anyone up on there VW ID and knowledge? The # on the generator post Identifies it as a 1971 1600 cc 60 hp. motor. BUT for a carburetor I need to know if it is single or double port? I can see it is a one barrel and Single carb. Then there is some kind of thing like 3e or something What's that? Need a little help here guys I want to get a carb, coil, Distributor cap points plug wires and starter on order and see if thing will spring to life... D Edited by d4570 |
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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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engine looks like a work-horse bug engine.
Hull is?????? |
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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"Hull is?????? "
In the planning stage, I'm going to go catamaran style |
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Wing master
Administrator AKA StraightShooter Joined: 10 June 2003 Location: United States Status: Offline Points: 7481 |
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D, Your enging is a dual port. Here is a picture of a single port engine I have in my shop. Yours has the cast dual intake ports and mine has a single tube intake port. The heads are different too. I would think the difference in the carb would be where it bolts to the intake. |
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I have always considered myself to be quite the bullshitter, But ocasionally it is nice to sit back and listen to a true professional......So, Carry on.
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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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D remember. Generally, Catamaran hulls are displacement designed hulls...lots of drag; needs more horse power to plow the water, they never get up on plane.
Air boats are built on "planning" style hulls, like the jon boat or other FLAT bottom bottoms. These get up on plane fast and are low drag so higher speed. Just thoughts. |
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CB900F
Administrator Honor, Integrity Joined: 10 June 2003 Location: Eritrea Status: Offline Points: 8857 |
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D;
A couple of other considerations: Will the engine be mounted on the hull? In which case, how will you drive the prop? If it's going to be a direct drive, then the height of the engine will demand the hull be large enough to provide stability in dynamic situations. A higher center of gravity lowers stability. Water will lubricate a V-belt drive system. Chains rust. Bevel gear drives are large, heavy, and expensive. U joints are not happy with 90 degree bends. The propeller used will make a great deal of difference in the efficiency of transferring power to forward motion also. Do some research on diameter & pitch to get the desired results before buying. 900F |
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Birth certificate!? He don't need no steenkink birth certificate!!
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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I Will and I am.
Bear I'm planning on "FLAT" cat floats, Have to make them. Kinda like two 14 foot long 2 foot wide Jon boats. I have read the Prop torque Tends to tip you over with a narrow boat. I'd like to space the floats to make the boat 5 to 6 foot wide. ( I think ) From the preliminary research I have done I need to reduce the RPM to around 1500 rpm from a Hoped 3000 on the motor. You HAVE to keep the tips of the prop Sub sonic or the Howling will make your ears bleed. From what I have found a 48 or 50" 29* pitch two blade wooden prop is what could work if I can get 50 hp. out of it. I think I'll try a snowmobile clutch/ torque converter for the drive, don't know yet. I can get a drive off the puter that uses a flat cogged belt but at $1500 + just for the drive I don't know. Thanks wing I'm looking for a rebuilt carb for a 71 1600 cc VW Dual port single barrel now. I need a starter that does not hook to a bell housing too. It's going to be a multi year protect I think. Edited by d4570 |
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Wing master
Administrator AKA StraightShooter Joined: 10 June 2003 Location: United States Status: Offline Points: 7481 |
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It sounds like a fun winter project. Wing master |
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I have always considered myself to be quite the bullshitter, But ocasionally it is nice to sit back and listen to a true professional......So, Carry on.
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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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the 14x2 cat will have no more displacement than a 14x48' standard jon boat.
"Prop torque Tends to tip you over" ; as you tip a cat all the buoyance needs are transferred to a single 14x2 platform. Also, when racing cat sailboats, I can tell you the lone sponson tends to dig deep. this can twist you into a sharp undesired turn. Because of this the gunwale profile and sheer are very important so you can steer back without out flipping. With your power configuration, you will have a significant amount of vibration. plywood construction will need to be greatly re-enforced. Airboats are VERY sluggish on steering, very slow to respond to a change of direction. Importantly you are steering with an air rudder, not a hydraulic rudder. The steering is totally independent of your boat speed. Steering will depend only on your prop speed. If you get slightly unstable and reduce the prop RPM, you immediately lose steering. Tricky things these air boats. |
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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All good advice. It will be all aluminum and steel no wood. Yes I know 'bout the eleco thing and will be mindful of it. When I'm driving the jet I lose steering when the rpms drop too. Not the same I'm sure but similar. The primary use of the boat will be running in 3" or less water some times no water. It will have to navigate in deep water some times I guess I'll just have to go slow. The mud boat will only go 9 mph in deep water but in 5" it will go almost 20 mph... Ice. snow and river gravel will be the norm I think. D |
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Remember: Four boxes keep us free ,the soap box, the ballot box, the jury box, AND the cartridge box
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CB900F
Administrator Honor, Integrity Joined: 10 June 2003 Location: Eritrea Status: Offline Points: 8857 |
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D;
I wish you all the luck and good will in the world on this project. But, I'll also tell you that it sounds like the perfect project for a truly dedicated masochist! 900F |
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Birth certificate!? He don't need no steenkink birth certificate!!
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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B=brake O=out A=another T=thousand I am aware of the slippery slope thing. The boy has 3 boats one we built and I have the big jet that cost more them my house... D Edited by d4570 |
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Irish Bird Dog
.416 Rigby Too many Joined: 01 March 2009 Location: Midwest Status: Offline Points: 5511 |
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you sure are a heap of an optimist D....wish you well on
your project. guess you and boy must be pretty handy with wrenches too. Keep us informed. |
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Irish Bird Dog
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deaddog
Administrator *AKA The Flying Gun* Joined: 23 April 2004 Location: Svalbard Status: Offline Points: 991201 |
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http://www.amazon.com/Keep-Volkswagen-Alive-Step-
Step/dp/1566913101 A must have book. How to keep your Volkswagen alive. It holds your hand through everything bug related. Way better than any shop manual. As much as you have to work on the things to keep them running believe me you'll need it! No individual task or problem it that difficult it's just that things quit working properly at the most inopportune times. Notice I didn't say break, things like the valves you mentioned or the carb(s) get out of whack. The thing will still run but they are so low on power to begin with that any little thing makes them run like crap. I have a VW powered Meyers Manx dune buggy and struggle to keep it going. In fact it hasn't been on the road in several years. I owned and raced stock cars for four years so I'm not completely inept with a wrench, but that thing gets the better of me. I don't know anything about airboats but I have a fair amount of experience with air cooled engines with props. The big reason for using them is for their low end torque and ability to bolt directly to the crank. You are defeating the whole purpose of them by using a gear reduction. You'd be way better off with a liquid cooled Honda-Toyota etc than a air cooled. 2200-2500rpm is the goal. The amount of power required to pull a prop of any useful size 3000rpm is tremendous. It's the aerodynamic drag and the noise of the supersonic tips that are a waste of energy. Just pull a different pitch like you would with a boat prop. The analogy would be that you want a prop that will pull five skiers out of the water rather than have a 70mph top speed. The same engine in a car will do 4500 but pulling a prop- only half of that. The other thing is vibration. Make sure your prop is balanced and probably use some type of rubber mount. Good luck! DD Edited by deaddog |
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Endeavor to persevere.
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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BUT DD
My boat will spend way more time " trying to pull 5 people " then going 70 mph. I'm not planning an open water/deep water boat. I think I'll spend way more time on partly frozen mostly dry river bottoms and all ice on lakes then water anyway. So if I can't make it "Plane" it's not a huge deal Just has to move, the Mud Boat only goes 9 MPH in deep water but where we use it In 4" of water it will do 19, that's real fast when your racing up a ditch or creek... I have a VW motor I don't have another one of any kind. 2000 rmp, is that the prop speed ? I'm doing a LOT of research and what I'm reading is A prop 48 to 50 Inches long and a 29* pitch ??? A two bladed wooden prop is about all I'll be able to afford. A three or four blade composite with adjustable pitch would be great But at close to $2000 it is not a possibility. Everything I read ,and talk with Airboat guys say I would not have the HP to spin a direct drive prop. The ones that have a mini and VW motor recommend a reduction of 2 to 1 or 2 1/2 to 1 belt system. There again at $1500 for a drive I'm thinking I'm going to try and use a used Snowmobile belt drive with a torque converter system and try to turn as big a blade as I can. I just don't know how big that is. I have read also If a person can "Duct" the fan you can pick up a good amount of thrust with the same input. with a tad bit LESS noise from the prop. I don't know how I would do that but there again the Red neck in me is screaming " road culvert"...Take an appropriate sized peace of plastic culvert And ducting it with that some how.???? All In the planning stages still. First I need a carb, starter and some ignition stuff and make the motor "Run". How about a boat? I'll need one of them too.... Edited by d4570 |
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CB900F
Administrator Honor, Integrity Joined: 10 June 2003 Location: Eritrea Status: Offline Points: 8857 |
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D;
I'm willing to bet that in the long run, you'll wish you'd found one of those amphibious 6-wheel ATV kinda things. The noise factor alone will probably run off waterfowl for at least a half mile in any direction from an airboat. I also get the feeling (shiver!) that you're gonna learn more about wind chill than you ever wanted to know. 900F |
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Birth certificate!? He don't need no steenkink birth certificate!!
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d4570
.416 Rigby Joined: 27 January 2004 Location: United States Status: Offline Points: 9403 |
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Wind chill !
You have not had "Wind Chill" till you have run the Missouri river In the pitch dark In a loaded mud boat, Standing . When it's -5*.... I'll bet I could have a wind shield in the front of my air boat. We have one on the snowmobile / 4 wheeler sled that I HAVE to ride in ...As far as noise It will jus let them know to get there affairs in order, death is coming! |
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BEAR
Administrator Joined: 07 September 2013 Location: Appalachian Mtn Status: Offline Points: 13734 |
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CB900F
Administrator Honor, Integrity Joined: 10 June 2003 Location: Eritrea Status: Offline Points: 8857 |
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D;
On the wind chill, I beg to differ. I come from the (as far as I'm concerned)wind capitol of the U.S. Once upon a time, not nearly long enough ago, I was out in -138 degrees fahrenheit wind chill. That was on Casper Mountain when the bottom fell out of the thermometer and the wind came up. WAY UP. We had to get people off the mountain before it literally killed them, and it damn near killed me. 900F |
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Birth certificate!? He don't need no steenkink birth certificate!!
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deaddog
Administrator *AKA The Flying Gun* Joined: 23 April 2004 Location: Svalbard Status: Offline Points: 991201 |
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D, I think you may have misunderstood? I agree you need a flatter pitch
prop to pull quicker. The prop rpm is the same as the engine. The prop tips are moving at a faster speed but they are still doing the same rpm as the slower moving crank. They have farther to go in the same period of time. DD |
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Endeavor to persevere.
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