tried to build a light weight tub... and failed :(

[bzubee]

David Hall almost had to leave half of a lightweight hydro in the lake luckily his run was getting videoed and Rod was able to pin point exactly where the hull went in the water by playing the video on a big screen tv . Modern Technology helped out with that one.

 

[TomMoorehouse]

speaking of saving driveline weight.... with the center ski, do we need to use a brass tube? how about aluminum with teflon liner? (would that be lighter?). or maybe just teflon with a few balsa supports??? any ideas?

 

[TomMoorehouse]

could you heat and bend a heavy wall teflon tube? would that be lighter? 1/4" id?? http://www.mcmaster.com/ part number 8547K11

 

[misshydro]

speaking of saving driveline weight.... with the center ski, do we need to use a brass tube? how about aluminum with teflon liner? (would that be lighter?). or maybe just teflon with a few balsa supports??? any ideas?

teflon linners??.. I dont run any teflon linners. Some threads I'd read guys melting them on there race boats=freezeup= broken cables or damage there engines. I'm surprise you didnt say carbonfibler tube? or running a smaller flex cables like Glen is using on the.12 or trying 125 or 130/ 1/8. On .21's 150 thats what I running with no proublems. I think 3/16 cable is alittle over kill for a.21.. I can see on the.45+.. and what about smaller or lighter boom tubes/rods? the.12 JAE 1/4 is alittle on the heavy side. If we want to talk cazy talk what about making the rudder and turn fin out of carbonfiber??? let runs alum props or carbonfiber props?? HOW LIGHT TO YOU WANT TO BE?? ENOUGHT WHERE THE BOAT AINT WORTH A POOO IN THE WATER?? You need some weight to keep that boat planted in the water without it blowing over easly on you..

 

[TomMoorehouse]

I've run teflon liners for many years without problems. Only time I had a failure was with a plain brass tube.

 

[Ted buckley]

speaking of saving driveline weight.... with the center ski, do we need to use a brass tube? how about aluminum with teflon liner? (would that be lighter?). or maybe just teflon with a few balsa supports??? any ideas?

teflon linners??.. I dont run any teflon linners. Some threads I'd read guys melting them on there race boats=freezeup= broken cables or damage there engines. I'm surprise you didnt say carbonfibler tube? or running a smaller flex cables like Glen is using on the.12 or trying 125 or 130/ 1/8. On .21's 150 thats what I running with no proublems. I think 3/16 cable is alittle over kill for a.21.. I can see on the.45+.. and what about smaller or lighter boom tubes/rods? the.12 JAE 1/4 is alittle on the heavy side. If we want to talk cazy talk what about making the rudder and turn fin out of carbonfiber??? let runs alum props or carbonfiber props?? HOW LIGHT TO YOU WANT TO BE?? ENOUGHT WHERE THE BOAT AINT WORTH A POOO IN THE WATER?? You need some weight to keep that boat planted in the water without it blowing over easly on you..

I happen to agree with you on this - somewhat, Nessa.. However; I don't think we should cease trying to achieve "Light Vs. Heavy" due to blowing over.. Part of being light means a change in Aerodynamics to make the hull stick to the water(Also Set-up). I think Glenn is displaying this in his New Hull. Good job Glenn!! Also, I never had a problem - either running Teflon.. I'd rather not use it though.. I'm going to an Oiler in my .21.

 

[moparbarn]

another advantage of building light, is if you do need to add weight, it can be added where it does the most good. not where the build dictates it will end up.

 

[Ted buckley]

another advantage of building light, is if you do need to add weight, it can be added where it does the most good. not where the build dictates it will end up.

Good point!! When I used to dabble in Electrics - they always said: "If your gonna add weight - always do it in the form of Energy" I don't know how it would be applied to Nitro though, due to we don't want fuel-tanks all over our boats. :lol:

 

[LarryConrad]

I'm not sure if it's even possible to build and outrigger hull that is too light, but on hulls that ride on a cushion of air such as an outboard tunnel hull as the lifting force of the trapped air starts to exceed the mass of the boat It becomes harder and harder to keep them on the water..

 

[Charles Perdue]

speaking of saving driveline weight.... with the center ski, do we need to use a brass tube? how about aluminum with teflon liner? (would that be lighter?). or maybe just teflon with a few balsa supports??? any ideas?

teflon linners??.. I dont run any teflon linners. Some threads I'd read guys melting them on there race boats=freezeup= broken cables or damage there engines. I'm surprise you didnt say carbonfibler tube? or running a smaller flex cables like Glen is using on the.12 or trying 125 or 130/ 1/8. On .21's 150 thats what I running with no proublems. I think 3/16 cable is alittle over kill for a.21.. I can see on the.45+.. and what about smaller or lighter boom tubes/rods? the.12 JAE 1/4 is alittle on the heavy side. If we want to talk cazy talk what about making the rudder and turn fin out of carbonfiber??? let runs alum props or carbonfiber props?? HOW LIGHT TO YOU WANT TO BE?? ENOUGHT WHERE THE BOAT AINT WORTH A POOO IN THE WATER?? You need some weight to keep that boat planted in the water without it blowing over easly on you..

OK, HERE GOES.....One of the problems with drive lines (binding up/ getting hot/ wadding up the teflon liner, ect) is the very often repeated AND WRONG setup of spacing the drive dog too far away from the strut to make up for the drive cable getting shorter caused by supposedly CABLE WINDUP. When the boat is running, this pushes the cable forward causing it to press against the stuffing tube on the OUTSIDE OF THE RADIUS of the curve in the stuffing tube and the engine.

To accurately measure the amount of cable shortening, the same amount of torque has to be applied to the cable as when the boat is operating at maximum speed. This is done by holding the flywheel, twisting the stub shaft with an inch pound torque wrench. Figuring the actual amount of torque that the engine is putting out at its peak power is simple.

The formula for calculating this amount of torque is: Torque in inch pounds-force = Horsepower X 63025 divided by the Engine RPM. Say a 21 engine is putting out 3 HP at 30,000 RPM, the amount of torque that is twisting the drive cable is 6.31 inch pounds.

A 45 engine at 5 hp at 30,000 RPMs has 10.51 inch pounds. A bigger engine at say 8 HP at 30,000 RPM has 16.81 inch pounds of torque. NOT THAT MUCH, huh.

If the drive dog is slightly touching the thrust washer, between the drive dog and the strut, at the cables maximum amout of wind up, this will keep the cable from thrusting as hard against the outside radius of the stuffing tube, making a freer running drive line, allowing the boat to run faster and also eliminating problems.

Have Fun,

Charles

 

[misshydro]

speaking of saving driveline weight.... with the center ski, do we need to use a brass tube? how about aluminum with teflon liner? (would that be lighter?). or maybe just teflon with a few balsa supports??? any ideas?

teflon linners??.. I dont run any teflon linners. Some threads I'd read guys melting them on there race boats=freezeup= broken cables or damage there engines. I'm surprise you didnt say carbonfibler tube? or running a smaller flex cables like Glen is using on the.12 or trying 125 or 130/ 1/8. On .21's 150 thats what I running with no proublems. I think 3/16 cable is alittle over kill for a.21.. I can see on the.45+.. and what about smaller or lighter boom tubes/rods? the.12 JAE 1/4 is alittle on the heavy side. If we want to talk cazy talk what about making the rudder and turn fin out of carbonfiber??? let runs alum props or carbonfiber props?? HOW LIGHT TO YOU WANT TO BE?? ENOUGHT WHERE THE BOAT AINT WORTH A POOO IN THE WATER?? You need some weight to keep that boat planted in the water without it blowing over easly on you..

OK, HERE GOES.....One of the problems with drive lines (binding up/ getting hot/ wadding up the teflon liner, ect) is the very often repeated AND WRONG setup of spacing the drive dog too far away from the strut to make up for the drive cable getting shorter caused by supposedly CABLE WINDUP. When the boat is running, this pushes the cable forward causing it to press against the stuffing tube on the OUTSIDE OF THE RADIUS of the curve in the stuffing tube and the engine.

To accurately measure the amount of cable shortening, the same amount of torque has to be applied to the cable as when the boat is operating at maximum speed. This is done by holding the flywheel, twisting the stub shaft with an inch pound torque wrench. Figuring the actual amount of torque that the engine is putting out at its peak power is simple.

The formula for calculating this amount of torque is: Torque in inch pounds-force = Horsepower X 63025 divided by the Engine RPM. Say a 21 engine is putting out 3 HP at 30,000 RPM, the amount of torque that is twisting the drive cable is 6.31 inch pounds.

A 45 engine at 5 hp at 30,000 RPMs has 10.51 inch pounds. A bigger engine at say 8 HP at 30,000 RPM has 16.81 inch pounds of torque. NOT THAT MUCH, huh.

If the drive dog is slightly touching the thrust washer, between the drive dog and the strut, at the cables maximum amout of wind up, this will keep the cable from thrusting as hard against the outside radius of the stuffing tube, making a freer running drive line, allowing the boat to run faster and also eliminating problems.

Have Fun,

Charles

still dont trust teflon linners.. I leave 3/16 space between prop dog and brass bushing that upagaist the strut. never had proublems with my brass tubes.. I grease mine every two runs..

 

[Charles Perdue]

speaking of saving driveline weight.... with the center ski, do we need to use a brass tube? how about aluminum with teflon liner? (would that be lighter?). or maybe just teflon with a few balsa supports??? any ideas?

teflon linners??.. I dont run any teflon linners. Some threads I'd read guys melting them on there race boats=freezeup= broken cables or damage there engines. I'm surprise you didnt say carbonfibler tube? or running a smaller flex cables like Glen is using on the.12 or trying 125 or 130/ 1/8. On .21's 150 thats what I running with no proublems. I think 3/16 cable is alittle over kill for a.21.. I can see on the.45+.. and what about smaller or lighter boom tubes/rods? the.12 JAE 1/4 is alittle on the heavy side. If we want to talk cazy talk what about making the rudder and turn fin out of carbonfiber??? let runs alum props or carbonfiber props?? HOW LIGHT TO YOU WANT TO BE?? ENOUGHT WHERE THE BOAT AINT WORTH A POOO IN THE WATER?? You need some weight to keep that boat planted in the water without it blowing over easly on you..

OK, HERE GOES.....One of the problems with drive lines (binding up/ getting hot/ wadding up the teflon liner, ect) is the very often repeated AND WRONG setup of spacing the drive dog too far away from the strut to make up for the drive cable getting shorter caused by supposedly CABLE WINDUP. When the boat is running, this pushes the cable forward causing it to press against the stuffing tube on the OUTSIDE OF THE RADIUS of the curve in the stuffing tube and the engine.

To accurately measure the amount of cable shortening, the same amount of torque has to be applied to the cable as when the boat is operating at maximum speed. This is done by holding the flywheel, twisting the stub shaft with an inch pound torque wrench. Figuring the actual amount of torque that the engine is putting out at its peak power is simple.

The formula for calculating this amount of torque is: Torque in inch pounds-force = Horsepower X 63025 divided by the Engine RPM. Say a 21 engine is putting out 3 HP at 30,000 RPM, the amount of torque that is twisting the drive cable is 6.31 inch pounds.

A 45 engine at 5 hp at 30,000 RPMs has 10.51 inch pounds. A bigger engine at say 8 HP at 30,000 RPM has 16.81 inch pounds of torque. NOT THAT MUCH, huh.

If the drive dog is slightly touching the thrust washer, between the drive dog and the strut, at the cables maximum amout of wind up, this will keep the cable from thrusting as hard against the outside radius of the stuffing tube, making a freer running drive line, allowing the boat to run faster and also eliminating problems.

Have Fun,

Charles

that upagaist the strut.I leave 3/16 space between prop dog and brass bushing still dont trust teflon linners.. never had proublems with my brass tubes.. I grease mine every two runs..

 

[TomMoorehouse]

Hey Charles, I don't think you need to write on the chalk board any more

 

[Charles Perdue]

Hey Charles, I don't think you need to write on the chalk board any more

 

[Tim_Duggan]

OK, HERE GOES.....One of the problems with drive lines (binding up/ getting hot/ wadding up the teflon liner, ect) is the very often repeated AND WRONG setup of spacing the drive dog too far away from the strut to make up for the drive cable getting shorter caused by supposedly CABLE WINDUP. When the boat is running, this pushes the cable forward causing it to press against the stuffing tube on the OUTSIDE OF THE RADIUS of the curve in the stuffing tube and the engine.

To accurately measure the amount of cable shortening, the same amount of torque has to be applied to the cable as when the boat is operating at maximum speed. This is done by holding the flywheel, twisting the stub shaft with an inch pound torque wrench. Figuring the actual amount of torque that the engine is putting out at its peak power is simple.

The formula for calculating this amount of torque is: Torque in inch pounds-force = Horsepower X 63025 divided by the Engine RPM. Say a 21 engine is putting out 3 HP at 30,000 RPM, the amount of torque that is twisting the drive cable is 6.31 inch pounds.

A 45 engine at 5 hp at 30,000 RPMs has 10.51 inch pounds. A bigger engine at say 8 HP at 30,000 RPM has 16.81 inch pounds of torque. NOT THAT MUCH, huh.

If the drive dog is slightly touching the thrust washer, between the drive dog and the strut, at the cables maximum amout of wind up, this will keep the cable from thrusting as hard against the outside radius of the stuffing tube, making a freer running drive line, allowing the boat to run faster and also eliminating problems.

Have Fun,

Charles

Great post Charles - thank you. It really made sense to me and I'll be adjusting my non- square drive flex set-up's accordingly.

Tim.

 

[Rick Doane]

speaking of saving driveline weight.... with the center ski, do we need to use a brass tube? how about aluminum with teflon liner? (would that be lighter?). or maybe just teflon with a few balsa supports??? any ideas?

teflon linners??.. I dont run any teflon linners. Some threads I'd read guys melting them on there race boats=freezeup= broken cables or damage there engines. I'm surprise you didnt say carbonfibler tube? or running a smaller flex cables like Glen is using on the.12 or trying 125 or 130/ 1/8. On .21's 150 thats what I running with no proublems. I think 3/16 cable is alittle over kill for a.21.. I can see on the.45+.. and what about smaller or lighter boom tubes/rods? the.12 JAE 1/4 is alittle on the heavy side. If we want to talk cazy talk what about making the rudder and turn fin out of carbonfiber??? let runs alum props or carbonfiber props?? HOW LIGHT TO YOU WANT TO BE?? ENOUGHT WHERE THE BOAT AINT WORTH A POOO IN THE WATER?? You need some weight to keep that boat planted in the water without it blowing over easly on you..

OK, HERE GOES.....One of the problems with drive lines (binding up/ getting hot/ wadding up the teflon liner, ect) is the very often repeated AND WRONG setup of spacing the drive dog too far away from the strut to make up for the drive cable getting shorter caused by supposedly CABLE WINDUP. When the boat is running, this pushes the cable forward causing it to press against the stuffing tube on the OUTSIDE OF THE RADIUS of the curve in the stuffing tube and the engine.

To accurately measure the amount of cable shortening, the same amount of torque has to be applied to the cable as when the boat is operating at maximum speed. This is done by holding the flywheel, twisting the stub shaft with an inch pound torque wrench. Figuring the actual amount of torque that the engine is putting out at its peak power is simple.

The formula for calculating this amount of torque is: Torque in inch pounds-force = Horsepower X 63025 divided by the Engine RPM. Say a 21 engine is putting out 3 HP at 30,000 RPM, the amount of torque that is twisting the drive cable is 6.31 inch pounds.

A 45 engine at 5 hp at 30,000 RPMs has 10.51 inch pounds. A bigger engine at say 8 HP at 30,000 RPM has 16.81 inch pounds of torque. NOT THAT MUCH, huh.

If the drive dog is slightly touching the thrust washer, between the drive dog and the strut, at the cables maximum amout of wind up, this will keep the cable from thrusting as hard against the outside radius of the stuffing tube, making a freer running drive line, allowing the boat to run faster and also eliminating problems.

Have Fun,

Charles

Good post Charles.

Rick

 

[DON MAHER]

Or just run a sq. drive

Don

 

[Charles Perdue]

OR, better yet.......a wire drive.

 

[Charles Perdue]

speaking of saving driveline weight.... with the center ski, do we need to use a brass tube? how about aluminum with teflon liner? (would that be lighter?). or maybe just teflon with a few balsa supports??? any ideas?

teflon linners??.. I dont run any teflon linners. Some threads I'd read guys melting them on there race boats=freezeup= broken cables or damage there engines. I'm surprise you didnt say carbonfibler tube? or running a smaller flex cables like Glen is using on the.12 or trying 125 or 130/ 1/8. On .21's 150 thats what I running with no proublems. I think 3/16 cable is alittle over kill for a.21.. I can see on the.45+.. and what about smaller or lighter boom tubes/rods? the.12 JAE 1/4 is alittle on the heavy side. If we want to talk cazy talk what about making the rudder and turn fin out of carbonfiber??? let runs alum props or carbonfiber props?? HOW LIGHT TO YOU WANT TO BE?? ENOUGHT WHERE THE BOAT AINT WORTH A POOO IN THE WATER?? You need some weight to keep that boat planted in the water without it blowing over easly on you..

OK, HERE GOES.....One of the problems with drive lines (binding up/ getting hot/ wadding up the teflon liner, ect) is the very often repeated AND WRONG setup of spacing the drive dog too far away from the strut to make up for the drive cable getting shorter caused by supposedly CABLE WINDUP. When the boat is running, this pushes the cable forward causing it to press against the stuffing tube on the OUTSIDE OF THE RADIUS of the curve in the stuffing tube and the engine.

To accurately measure the amount of cable shortening, the same amount of torque has to be applied to the cable as when the boat is operating at maximum speed. This is done by holding the flywheel, twisting the stub shaft with an inch pound torque wrench. Figuring the actual amount of torque that the engine is putting out at its peak power is simple.

The formula for calculating this amount of torque is: Torque in inch pounds-force = Horsepower X 63025 divided by the Engine RPM. Say a 21 engine is putting out 3 HP at 30,000 RPM, the amount of torque that is twisting the drive cable is 6.31 inch pounds.

A 45 engine at 5 hp at 30,000 RPMs has 10.51 inch pounds. A bigger engine at say 8 HP at 30,000 RPM has 16.81 inch pounds of torque. NOT THAT MUCH, huh.

If the drive dog is slightly touching the thrust washer, between the drive dog and the strut, at the cables maximum amout of wind up, this will keep the cable from thrusting as hard against the outside radius of the stuffing tube, making a freer running drive line, allowing the boat to run faster and also eliminating problems.

Have Fun,

Charles

Good post Charles.

Rick

Thanks guys for the compliments. I really love this hobby and when I do not understand something about it, I keep searching and studing the area in question until I can understand it. I enjoy this part of the hobby and sharing what I have learned very much also.

As you may have noticed in some of my other post, I enjoy the lighter side of life, joking, picking on people and so on. Must of the people that know me are completely aware of this. A lot of times we take things so seriously that we cannot enjoy ourselves and our lives.

Thanks Again,

Charles

 

[TomMoorehouse]

New tub in similar state of construction....120kg! That's better. 1/8 light ply tub sides.1.5" high tub sides. 2" wide inside width.1/32 ply top and bottom.