prop shrouds

[gonzo]

Waterwar: if you have an old OMC outboard and are talking about joining the big dogs in speeds, you must be delusional. The boat is a crapper too. You want speed, you need new technology and lots of money. I can sell it to you, but show the money first. BS is plentiful and free.

 

[Submarine Tom]

"Talk's cheap 'till you get the bill."

-Tom

 

[waterwar]

Thank you for the advice

Waterwar, the topic is a good one and has been ongoing one over the years, it's an interesting topic and worth some new input The problem i think was in your excitement to create debate you took the wrong approach by using the tool of confrontentation to create debate instead of querry. We're probably all guilty of this at some point in our life, it's usually a sign of higher levels of tetosterone thus the question on your age.Good for you if your levels are high but bad for you if you want meaningful debate. Thats why old guys mellow and become more patient and wise. So me thinks if it's not too late you could re tone your post and a transfer of info could possibly occur. Geo.

A yacht is not defined by the vessel but by the care and love of her owner.

'Vows made in stormy waters are forgotten in calm ones.'

I appreciate your sage advice I want to thank all who have given so much of their time to share knowledge on a very complex problem
The advancements in the last fifty years in marine propulsion are impressive.
I want to thank everyone for sharing here.
Putting all those ideas on a subject such as you all have shown willingness to do..
In particular, l I want to thank the various engineers who shared their knowledge on the complex subject freely.

If you look at the old threads the subject was dismissed go to another beach

we need to advance this application; to find one that does work reasonably well
I mean no endorsement of any one product unless it works does the prop guard live up? what could be made different?

thanks
stewart

 

[gonzo]

A propeller resistant manatee?

 

[waterwar]

I have a little advice too about boat ownership its like a woman you can't wait to get until you do then you look forward to another..

 

[waterwar]

I think there's room for them and you too gonzo personal differences aside

 

[Jeremy Harris]

we need to advance this application; to find one that does work reasonably well
I mean no endorsement of any one product unless it works does the prop guard live up? what could be made different?

thanks
stewart

You can't defy the laws of physics, I'm afraid. There's no way to remove the extra drag that the duct produces, and as the power needed to overcome drag is proportional to the cube of speed it only gets worse the faster you go.

You can explore ways to improve on the efficiency of the best ducted props/pump jets around by careful design of duct and blade shape, but that still won't make them operate at high speed without high losses too.

These things first came about on outboards as propguards, to protect people or marine life from being injured by exposed props. They do that job well and some marketeers have extolled the increased low speed thrust enhancement as a selling point. As has been said before, if you want more low speed thrust they work OK, if you want higher speed they don't. Technology isn't going to change this basic principle, much as you might want it to.

Jeremy

 

[waterwar]

Waterwar: if you have an old OMC outboard and are talking about joining the big dogs in speeds, you must be delusional. The boat is a crapper too. You want speed, you need new technology and lots of money. I can sell it to you, but show the money first. BS is plentiful and free.

I am a fish farmer and like to collect some times I use a trailer-able boat and its freshwater lakes and swamps here my friend not the deep briny deep
jeez

 

[waterwar]

You can't defy the laws of physics, I'm afraid. There's no way to remove the extra drag that the duct produces, and as the power needed to overcome drag is proportional to the cube of speed it only gets worse the faster you go.

You can explore ways to improve on the efficiency of the best ducted props/pump jets around by careful design of duct and blade shape, but that still won't make them operate at high speed without high losses too.

These things first came about on outboards as propguards, to protect people or marine life from being injured by exposed props. They do that job well and some marketeers have extolled the increased low speed thrust enhancement as a selling point. As has been said before, if you want more low speed thrust they work OK, if you want higher speed they don't. Technology isn't going to change this basic principle, much as you might want it to.

Jeremy

thank you Jeremy'
the maker of the 'prop guard has his dad for his nozzle contribution

but i guess wishing it does work doesn't make it so

thanks
stew

 

[waterwar]

When I was young we used to attach a pitchfork on an outboard and go up the rapids of the South fork of the shenandoah river in the Blue ridge mountains and fish for trout and shoot carp with arrows.
Wasn't pretty and great loss of speed.

so the claims made by Mr. shultz are false? just cause thinking of am going to put one on my ole crate and i will feedback I can pull a skier now guess we'll see..

 

[gonzo]

It is really hard to understand what you write. If you took more care with the grammar, it would help.

 

[waterwar]

gonzo all kidding aside I am seeking the real experts

 

[gonzo]

In what?

 

[waterwar]

Mr Shultz claims that his product gives a boost, because it's intakes and outtakes size
vary. What does that do? Could that happen? Does it really give the small boost he claims to cancel drag effect cause a venturi effect ?

http://www.propguardmarine.com/test.html


http://www.propguardmarine.com/index.html

I just want to hear thrust increase vs drag discussion to be scientific not chatteric

 

[TeddyDiver]

I just want to hear thrust increase vs drag discussion to be scientific not chatteric

You should have said that some pages earlier IMHO