Sharrow props might be going places

[MapisM]

Of course this is what I meant…

Fairenuff, but you aren't seriously suggesting that such protection also improves efficiency, surely?

 

[Bouba]

Fairenuff, but you aren't seriously suggesting that such protection also improves efficiency, surely?

It used to be advertised as such

 

[MapisM]

Well, snake oil used to be advertised for even more interesting results...
BTW, it seems to me that the varnish detached in a few spots on the blades pressure side may well be due to a bit of cavitation induced by the cage turbulence...
Is that your boat? If you experienced first hand any performance improvement after fitting the cage, I'll swallow my hat.

 

[Bouba]

Well, snake oil used to be advertised for even more interesting results...
BTW, it seems to me that the varnish detached in a few spots on the blades pressure side may well be due to a bit of cavitation induced by the cage turbulence...
Is that your boat? If you experienced first hand any performance improvement after fitting the cage, I'll swallow my hat.

No...it’s a random picture from the Internet....it’s just something that would have saved my blushes (and blades) if I had it back in the day when I lived on the bend of an African river...

 

[billskip]

If they were any good they've have been adopted by the major manufacturers years ago. As they say, if it sounds too good to be true, it usually is.

And the military, coz we would be paying

 

[Elessar]

It used to be advertised as such

Same company made a perpetual motion machine.

 

[Bouba]

Same company made a perpetual motion machine.

A propeller protected in a cage will be more efficient than an exposed prop that’s hit a rock

 

[MapisM]

A propeller protected in a cage will be more efficient than an exposed prop that’s hit a rock

Is that what you meant when you said it used to be advertised as improving the prop efficiency?
Talk about wordsmithing...

 

[Bouba]

Is that what you meant when you said it used to be advertised as improving the prop efficiency?
Talk about wordsmithing...

No...it isn’t....but it’s still true

 

[julians]

True...the other scenario is they have invested in it...but those who are not satisfied with their current setup are the logical first customers for Sharrow..so perhaps not surprising

Yes but those people would be far better advised to buy a normal prop correctly optimised for their use than to spend thousands on a sharrow.

And if sharrows claims of increased efficiency and top speed are only possible when compared to an unoptimised normal prop then that's not really anything worth shouting about.

 

[Bouba]

Yes but those people would be far better advised to buy a normal prop correctly optimised for their use than to spend thousands on a sharrow.

And if sharrows claims of increased efficiency and top speed are only possible when compared to an unoptimised normal prop then that's not really anything worth shouting about.

That’s why it would be nice if we could get a first hand report from a forumite

 

[Portofino]

You must be joking. Those things run on cleavers, which Sharrow props aren't even remotely meant to compete with.

I think others got it ? You know “OB “ powered speed boats .Apache just sprung to mind but I did mention Yam 350 / Evenrude 400 or what ever .Every one else seemed to get the point .
Anyhow award you another bash Porto point if that’s what you like ?

 

[MapisM]

I think others got it ? You know “OB “ powered speed boats .Apache just sprung to mind but I did mention Yam 350 / Evenrude 400 or what ever .Every one else seemed to get the point .
Anyhow award you another bash Porto point if that’s what you like ?

I'd never dare guessing what anyone else understands of your posts, also because I have big enough difficulties myself, you know...

All I know is that you were referring to boats "running poker runs", and I appreciate that you've never seen any, but you can trust me if I assure you that even Mr. Gregory Sharrow himself would recommend to NOT use his props on them.
That's all I meant, nothing else.

Anyway, if you feel like I'm cumulating (in your own wording) "bash Porto points" because, as I suppose you are suggesting, I get some sort of pleasure from it (for reasons only known to yourself), doesn't it possibly cross your mind that there could be another good reason?
Like, say, the simple fact that you often post pointless and/or plain wrong comments?
Just a thought.

PS: just in case you might be thinking to ask me an example aside from poker run boats, I don't even need to look further than in this thread, because the particular boat which you described as having a "relative shallow deadrise" is actually one of those with the deepest vee in its class, almost unheard of in a 58' flybridge, unless you go back to the heyday of Italcraft and Tecnomarine.

 

[QBhoy]

Boattest.com are very upbeat about Sharrow and have published numerous articles and test...all with very satisfying results

These tests have came under serious criticism though. I’ve yet to see a test which compares it to a good quality 3 blade prop that is of a pitch that is suitable. Any I’ve seen has been up against the completely wrong pitch…with the rpm limiter quickly in play. Speed suffering seriously and Also meaning fuel efficiency is right out the window too. Still waiting for a fair comparison I’m afraid

 

[Portofino]

You must be joking. Those things run on cleavers, which Sharrow props aren't even remotely meant to compete with.

Nope not joking these Apaches are on none cleavers .^ lower pic plane old Mercury s .


The point is if the Sharrow props had an advantage these guys the poker run races would be running them and any speed boats with big petrol 350 Hp upwards OB s .

What was ” incorrect “ in my initial post .
The “ Apache “ was just an indicative example of the type of boat cigarette like American racer / poker runner .

 

[MapisM]

The point is if the Sharrow props had an advantage these guys the poker run races would be running them and any speed boats with big petrol 350 Hp upwards OB s

If you're now suggesting that in fact they don't, then I agree.
In your post #7 you said the opposite (sure go ahead start wining Sunday afternoon races), and THAT is what was incorrect.
Be patient, I did say that I struggle to understand your posts, after all.

Anyhow, just for the records, while both boats whose pics you googled are nice in their own way, poker run boats they are not by any stretch of imagination - not anymore, at least.
Not that it matters one iota, mind: save yourself the time to google for a pic of one of those vintage boats engaged in a poker run in the past millenium.
I accept beforehand that it's possible, if this makes you happy.

 

[oldgit]

Reinventing the wheel ,again ?


Picture courtesy of .
Moonraker & JCL Marine Ltd.
ISBN. 1-84280-076-0
Page 73.
Modern materials might solve the problems that occured with earlier designs but that new prop looks like its made of the some stuff and cast by the same method that was tried well over a century ago .

 

[Portofino]

If you're now suggesting that in fact they don't, then I agree.
In your post #7 you said the opposite (sure go ahead start wining Sunday afternoon races), and THAT is what was incorrect.
Be patient, I did say that I struggle to understand your posts, after all.

Anyhow, just for the records, while both boats whose pics you googled are nice in their own way, poker run boats they are not by any stretch of imagination - not anymore, at least.
Not that it matters one iota, mind: save yourself the time to google for a pic of one of those vintage boats engaged in a poker run in the past millenium.
I accept beforehand that it's possible, if this makes you happy.

“In your post #7 you said the opposite (sure go ahead start wining Sunday afternoon races), and THAT is what was incorrect.
Be patient, I did say that I struggle to understand your posts, after all.”

Ok I will put it down to lack of understanding .Your en is excellent btw , better than mine the written word .However is was a sarcastic comment , tongue in cheek kinda negative put down .My en isn’t fantastic btw Dyslexia , I struggle to get my words out .Thanks for your patience .

Works like this ,

Think of this you post a pic of yourself in some new style football boots on the beach ( beautiful Sardinia empty white sands etc ) having a kick about with a new football.

I then say / post ….this -

” Hey MapishM we will be seeing you walking out in the national team next “

You say “ THAT is what is incorrect “ ….start an argument claiming you will never reach the standards of playing for Italy .Go off on a tangent from the pic of the nice anchorage.

Of course it is not true ,( my inference you will make the team ) I know you will not play for Italy , it’s was sarcasm, a tongue in cheek comment .It s a way of saying you look rubbish , still look rubbish foot ball wise and you aren’t good enough imho to make the national team even with the new style boots

The boat pic , reminding you again Apache was just a chosen indicative example of the type of craft that might benefit.This is because before posting I googled Sharrow props , quickly skimmed a few articles.One claimed a get this “ 58% improvement of speed “ .The claimed number as others earlier explained was probably from NOT a proper like for like comparison ie a badly propped boat in the first place .
Those poker run boats have deep dearises so are more highly likely to benefit from running a % faster and the owners are motivated. They like slamming about - bolstered seats , etc The boats can take slamming built for it .

A trad 50-60 ftr FB like yours [ I choose a squadie 58 because that boat is very forum familiar ] and tried to add some realism will shake to death running the claimed 58 % benefit faster in any waves other than dead pan calm or slight sea

.By high deadrise or shallow I failed to explain I was reffering to up and over 20 degrees for high a deep V .Shallow in my book being under 20 .
Boats under say 20 are not gonna in the real world with waves feel the claimed extra speed advantage should it be there one .

I am afraid my definition of deep V i am adopting the 20 degree number as the cut off .A high dead-rise or deep V to me is over 20 .This is a well established understanding in marine / navel architecture circles .I called the Sq 58 low because it falls under this threshold .
Having said this I know possibly where the confusion originates , from marketing PR brochures .

My point was simply the majority of FB hulls could not take the alleged “ 58% increase of speed “ as they were configured for far less .

But PeteM nailed it in his post and others…..you would see them more about if they were that good .

I was just trying to figure out WHY you don’t see them , cost is in there somewhere its been mentioned by others , but it’s not the sole reason .

FWIW As far as age .Suspect with competitive sports and machines they do classes .
like this .Me on a 47 yr old trial bike ( machine ) competing in a trial yesterday.
I am in the over 60 yrs of age twin shock air cooled class .

 

[MapisM]

Very nice machine. Cota 247? And repainted, or what?
Back in the days, I can't recall to have ever seen a Montesa in anything but red colour.
Then again, I used to practice a bit of enduro, but never followed trial a lot...

PS: doh, forget my first question above. After enlarging the pic, I noticed that the answer is written under the number plate!

 

[QBhoy]

I remember trying to find a prop cage or tunnel to protect my outdrive in a river…they didn’t exist and when I thought about making one all the experts I could find said ´cavitation’ and other warnings.
A few years later…someone brought one to market ..and not only did it protect the prop but it actually increased efficiency.
So challenging accepted wisdom is no bad thing

Impossible surely