I have alot of Ideas and I need help.

[larrysmash]

Hello,

I will get right to it, I plan on builting a wooden boat. I have been designing it off and on for over a year now. Its kinda like a tug boat model. Anyways where im having trouble is I came up with the idea to put the motor in the front of the boat and run the prop hydraulically, I know a fare bit about hydraulics but I would like to know if this has been done, and what the problems are or would be. And other thing is I was wondering about running a jet drive motor. It seems like thats what every one is going to, I would like to know the pros and cons of the that before I make any decisions. Oh by the way the boat is going to be 22' long 8' wide I really dont know the weight but I would say close to 2000 lbs. Im not looking for speed this is a cuising boat. Any ideas or suggestions would be appreciated.

Thanks Larry.

[Thunderhead19]

Jet units are generally used in shallow or debris filled waters because there's nothing hanging under the boat to get snapped off. Jet units do have high performance applications too. Again, this is because there is no appendage and therefore reduced drag. For a nice sunday cruiser that you don't plan on going more than twenty knots. It is far better to go with a propellor and shaft. There's nothing fundamentally wrong with using hydraulic systems to transfer power to the prop shaft from the motor, and in fact it is done quite a bit, particularly with bow/stern thrusters. You're probably quite familiar with the mechanical issues of the hydraulic system such as cooling, efficiency loss, etc... But the other issue is that small boats are sensitive to putting weight up fwd. If you don't watch your weights and buoyancy distribution, your boat will be pointing it's nose down. Most small boats have gobs of buoyancy aft of midships, and that usually means that the stern is a good place for motors, tankage, gear and whatnot. It's a good little engineering project for someone who likes to tinker though. If you know what you're doing with hydraulics, and you've paid attention to all the needs of the boat structurally, hydrostatically, etc.. be my guest. It'll work. But,if you have never built hydraulic systems that transmit over a hundred horsepower before, you'll find it is amazingly easy to kill someone.

[larrysmash]

Thunderhead19,

Thanks for the reply, I do plan on using a prop with a shaft but I was looking for some insight on the idea.
Ok as for the hydraulics, I have built many hydraulic systems and I understand the concept of them. And I know I can make it work the only problem I can see will be heat. I think I'm going to have trouble there. And like you mentioned about the motor in the front it may tip the boat noise first. I plan on building a flat bottom haul, I know this will be more stable than a v bottom but I don't know if it will affect the buoyancy shape. I'm thinking about a little 25-30 hp diesel. weight is really minimal but again I don't really know how it will affect the shape, what is your thoughts.

Larry

[waveless]

There are some designers only can tell you the knowlogy that their master taught them.

[PAR]

One of the biggest reasons the drive system is located in the rear is for protection. On a hydraulic driven shaft, the engine/pump assembly can be where the weight is most beneficial. Also on planning and semi planning craft the forward third of the bottom is quite important in the dynamic relationship it has with the water's surface while it produces lift. Generally it's best not to cut this area up with devices hanging down from the bottom. On displacement speed vessels, this location for a drive system will effect the water flow around the hull, adding considerable turbulence where you don't want it. The prop wash, directly under the midship areas of the hull will cause it to sink farther then a drive in a more conventional location, requiring more power and fuel consumption for the same speeds.

Basically speaking, it best to stick with previously engineered concepts, that have a reasonable chance for success. Venturing out onto the design limb and hoping for the best, without a complete understanding of the principles, theories, formulas and engineering necessary to developed new concepts, can be a cruel learning curve sometimes. This isn't to say you shouldn't think out of the box, you should. This is one of the few way new things get envisioned.

You may want to look up some of the companies that produce hydraulic systems for boats and check out the way they handled heat and other issues sure to come up on your adventure.

[waveless]

Thousands years, the shape of the boats are looks like the same, the only improvement is the power. There are no mysteries that less wave generate the less energy waste. The hydrokinetics is a tool to analysis the movement of the water, try to reduce the turbulence and wave. The design of the waveless boat is base the on principle hydrokinetics, the duct under boat is the special design to reduce the turbulence of the water, because the force is blocked in the duct, the water will be quiet immediately and become the force to push the boat forward. This knowledge you can learn from waterpower station.

I am not the designer, but I know that huge bubbles out of the rear that’s the energy to be wasted. I also know the big wave generated the big energy is wasted.

My design not adventure or hoping for the best, the boat like a black box, if no energy leaked, the input of energy will become the force of forward.

[mackid068]

My 2 cents:

a little 25-30 hp diesel: yes, but you could go smaller if you'd like (10 hp even, but you'd be really slow)

try fiberglass, perhaps?

[masrapido]

larry, I'd agree with above voice of reason: do not place the engine forward (it's to heavy, will tip the boat and make you look funny in front of your friends, to say it nicely), and stick with familiar concepts, unless you have naval architecture knowledge. Water is very soft and nimble medium. Weight distribution is of extreme importance on supertankers, more so for small nutshells like the ones we play around with.