super fin - long post

[cpubud]

Re: super fin - long post

the new stainless steel fin bolted on and ready to try-out

 

[cpubud]

Re: super fin - long post

This weekends test was a bust had a weld break on the bottom cross brace. will reweld and test again.before it broke the boat was acting great, jumped up on plane, low speed steering was great with no bow wonder and fantastic handling.

 

[MRS]

Re: super fin - long post

If you got your trim tabs working right you would not have to worry about the other stuff,,,

 

[pduquette]

Re: super fin - long post

Yeah , but some were born to to tinker ; and have the toys to play with.....I'll watch and learn on his dime peter

 

[MRS]

Re: super fin - long post

Yeah , but some were born to to tinker ; and have the toys to play with.....I'll watch and learn on his dime peter

That is so true but if you can do it with less it will work way better. I have invented the wheel soooo many times and all it did was cost me more money and ruined more things till I bought what was already made. But you are right on you got to thinker if that is what you got to do....

 

[scoutabout]

Re: super fin - long post

Nice work!

 

[Mark42]

Re: super fin - long post

I would think that that putting a round tube around a round spinning propeller would be more efficient at directing the water stream from the propeller where its wanted rather than putting a square box in front of a round spinning blade trying to redirect water that is moving in a spiral.

If your going to experiment, try the tube idea and see if it works better.

I see a lot of energy being wasted when the spiral of water created by the prop is striking the flat sides of the box.

I'm not an engineer, but I pretend to be one on the internet.

 

[45Auto]

Re: super fin - long post

I would think that that putting a round tube around a round spinning propeller would be more efficient at directing the water stream from the propeller where its wanted rather than putting a square box in front of a round spinning blade trying to redirect water that is moving in a spiral.

Google "Kort Nozzle".

I see a lot of energy being wasted when the spiral of water created by the prop is striking the flat sides of the box.

If you want to make it really efficient, jump on plane, handle great at low speed, etc, etc, put a second prop turning in the opposite direction directly behind the existing prop to take advantage of the energy in that spiral of water .....

From "Propellor" on Wilipedia:

Contra-rotating propellers offer increased efficiency by capturing the energy lost in the tangential velocities imparted to the fluid by the forward propeller (known as "propeller swirl"). The flow field behind the aft propeller of a contra-rotating set has very little "swirl", and this reduction in energy loss is seen as an increased efficiency of the aft propeller.

 

[security6]

Re: super fin - long post

If you got your trim tabs working right you would not have to worry about the other stuff,,,

The OP says his device helps with low speed steering. I know trim tabs help with a lot of stuff, but I didn't think low speed steering was one of them.

 

[superbenk]

Re: super fin - long post

The OP says his device helps with low speed steering. I know trim tabs help with a lot of stuff, but I didn't think low speed steering was one of them.

Maybe he meant low speed wander that's inherent in smaller V-hulls? That was one of the main reasons I got my Smart Tabs & they made a *world* of difference. Boat tracks much straighter now & requires very little input on my part to remain straight.

 

[CharlieB]

Re: super fin - long post

Any airplane pilots in here?

They should be familiar with 'speed brakes', in essence, trim tabs.

Think about it, ANYTHING like a big 'ol flat plate dragging in the water causing 'drag' deflecting the water in order to change the 'attitude' of the craft, is taking a toll on efficiency, speed, and raising fuel consumption.

Trim tabs are like the common cold, you treat the symptoms, but you are not curing the underlying problem.

While the 'Dual-prop' concept IS a great improvement by reducing lost thrust in the 'swirl' of water coming of the prop, it is NOT a total cure for the lost thrust cause by the 'slip' of water off the outer edges of the blades.

An enclosed prop in a 'nozzle' is proving a lot of promise, I soon expect to see a Dual-prop with 'nozzles' on each prop, now THAT would be a much more efficient drive.

 

[superbenk]

Re: super fin - long post

Any airplane pilots in here?

They should be familiar with 'speed brakes', in essence, trim tabs.

Think about it, ANYTHING like a big 'ol flat plate dragging in the water causing 'drag' deflecting the water in order to change the 'attitude' of the craft, is taking a toll on efficiency, speed, and raising fuel consumption.

Trim tabs are like the common cold, you treat the symptoms, but you are not curing the underlying problem.

Is that exactly true? The tabs divert the flow of water downward thus providing additional lift to the back of the hull getting more of it out of the water thus reducing drag. I won't argue that there's better solutions, but I don't think you're really dragging the plate through the water the way you describe it.

As for the plane analogy, I'd think that the air-brake would work in combination with down-turned flaps to compensate for the additional drag across the top of the plane such that the flaps would produce drag along the bottom of the plane at the same time thus causing the whole plane to slow.

On the other hand, perhaps I have it all wrong and you're right.

 

[superbenk]

Re: super fin - long post

An enclosed prop in a 'nozzle' is proving a lot of promise, I soon expect to see a Dual-prop with 'nozzles' on each prop, now THAT would be a much more efficient drive.

Sounds like jet propulsion... hrmmm

 

[cpubud]

Re: super fin - long post

first of all the boat has trim tabs ,bennit hydraulic 8x12 tabs that work properly . I can get the boat on plane using the trim tabs it just takes longe r .the boat suffers from low speed bow wonder under about 4 mph again typical of this style boat , in no wake zones any faster and it creates a wake more than I am comfortable with around others with my version installed I am able to jump on plane with out having to adjust trim tabs in adout half the time, all but stops the low speed bow wonder again tipical of this style boat , I am also able to run at 5 to 6 mph and have very minimal wake. this product im trying is available to the public for a cost of around $160 for a single rudder to $200 for a dual rudder. And it has not effected my wot mph other than giving me 1 1/2 more or rpm at all . You can call it what you want . take all the jabs at me you want no one is saying you have to run it . im just sharing what im doing and the results im getting .

 

[superpop]

Re: super fin - long post

I would be curious to see the device and particularly how the sides behave at WOT. I would guess they are doing all kinds of crazy movements as that prop puts out a lot of thrust at WOT and I doubt that your contraption will hold up to this kind of force for any period of time. You are trying to redirect a lot of thrust with two rather thin, lightly supported pieces of flat stainless. I am not surprised that a weld broke already. Sorry to sound like a downer but I think your design is flawed.

 

[MRS]

Re: super fin - long post

Not throwing jabs at you but only one more thing about tabs. The tabs you have are really to small for your boat what you have would work good for up to 20ft. and not to heavy. Any how if you are happy your results that is all that matters, good luck and I do want to see your final results.....

 

[CharlieB]

Re: super fin - long post

Forget all the nay-sayers and keep on doin what you're doin.

You are improving the performance and efficiency of your drive and are handling any problems or faults as you find them.

That's progress thru trial and error, far better than any textbook could ever hope to achieve.

Good Luck with your sea trials, and keep posting your results,

A lot of these guys are jealous because they either haven't thought of it, or do not have the means to do it.

Congratulations!

 

[cpubud]

Re: super fin - long post

The weld breaking was my fault . I ground to much of the weld away when I was grinding the edges to round off the corner . was not a design flaw just stupidity on my part . one weld broke at the bottom cross brace not a big deal.

 

[Mark42]

Re: super fin - long post

I would think that that putting a round tube around a round spinning propeller would be more efficient at directing the water stream from the propeller where its wanted rather than putting a square box in front of a round spinning blade trying to redirect water that is moving in a spiral.

If your going to experiment, try the tube idea and see if it works better.

I see a lot of energy being wasted when the spiral of water created by the prop is striking the flat sides of the box.

I'm not an engineer, but I pretend to be one on the internet.

Google "Kort Nozzle".

I R a genius and don't even know it!

 

[Mark42]

Re: super fin - long post

Good Luck with your sea trials, and keep posting your results,

A lot of these guys are jealous because they either haven't thought of it, or do not have the means to do it.

Congratulations!

You could not be more wrong. The problem is they don't have the means to think of it!