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Just done 20 hours on new Merc 115 CT ProXS

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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 09 Oct 2019 at 10:19am
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Titanium
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Be interesting to see what an 18" prop does, I tried one on mine, top speed was lower by a couple of knots, and fuel economy was crap
 Just trying stuff...well hit in miss.
 Some good data (as described ion many other posts how to..) on a prop that is ball park. will give you the prop you actually require, or turn out to be the current prop.

 There are 2 main factors in propping for a paining hull.. Pitch and Slip (grip)The grip must be sorted calculated before messing with pitch.

 Just dumping a "18" on without knowing slip numbers could very well end up like driving with a baddly slipping clutch in a car...yet the 18" pitch could be the correct pitch for that rig


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Post Options Post Options   Likes (2) Likes(2)   Quote Bigfishbob Quote  Post ReplyReply Direct Link To This Post Posted: 09 Oct 2019 at 1:18pm
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Originally posted by Steps Steps wrote:

Be interesting to see what an 18" prop does, I tried one on mine, top speed was lower by a couple of knots, and fuel economy was crap
 Just trying stuff...well hit in miss.
 Some good data (as described ion many other posts how to..) on a prop that is ball park. will give you the prop you actually require, or turn out to be the current prop.

 There are 2 main factors in propping for a paining hull.. Pitch and Slip (grip)The grip must be sorted calculated before messing with pitch.

 Just dumping a "18" on without knowing slip numbers could very well end up like driving with a baddly slipping clutch in a car...yet the 18" pitch could be the correct pitch for that rig



Yes that's right but you could have asked if that's what I did or have I actually calculated Slip @500 rev increments which is what i did, for both and other options. just because somebody presents a high level summary of what they found, doesn't mean they didn't do the analysis. 
www.waikatosportfishing.co.nz
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 09 Oct 2019 at 5:49pm
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Titanium
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Didnt ask as its usual it hasnt been done, or in most cases ppl are not familiar with the formulas.
 But point taken
 Out of interest what where the data numbers?
 What where the slip numbers at 4000 and WoT?
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Post Options Post Options   Likes (0) Likes(0)   Quote Bigfishbob Quote  Post ReplyReply Direct Link To This Post Posted: 09 Oct 2019 at 6:03pm
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for the 16" pitch enertia18knots, Slip18% at 4000rpm, 23knots, slip 7.6% at 4500rpm and 33.8 knots slip 2.24% at 6250 which was close enough to WOT for my liking. 

Can't find the analysis I did for the 18" but remember I got 31knots at 6100 revs with it.  That worked out at 2.01% slip, but like I said that prop was really susceptible to load, and slip increased alot through the mid range with extra weight on board. The 16" doesn't notice any difference. 

I also have numbers for a 15p Rev 4 , 4 blader, but they were horrible, max speed 30 knots with 7% slip. Mid range was very similar to the Enertia 16" but boat handled differently with more porpoising that was more difficult to tame. The Enertia Props have much more Stern lift despite their higher rake, so my boat runs flatter as a result.
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2019 at 9:11am
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If around a 5.5m hull with cabin then 18% is a little on the high side.. would be looking more to 13/15% at 4000.
 More diameter would be the way to go rather than pitch.
 Going pitch is why you found the results not suitable.

 Little strange to have a high 4000 and a low WoT thu..rather low. This is why approx 500 increments are taken to pick out inconstancy in the data taken.

When round numbers in data are taken there is usually inconsistencies due to being time consuming, run out of flat water and lot adjustment to get them.
 Easy/ best way is trim little down, set to say, just under 3500, trim up. then take actual rpms /speed  eg 3550 X speed.
 Then set to just under 4K re trim ....

 Gong to 4 blade, espec little below optimum power usually helps but in some cases it also changes the engine height requirement, espec if height already on or very close to optimum with a good 3 blade.

The Enertia Props have much more Stern lift despite their higher rake, so my boat runs flatter as a result.

 yep that rake works real good espec can be taken advantage of if the power to weight is is down, say min )

What is your rig?



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Post Options Post Options   Likes (0) Likes(0)   Quote Bigfishbob Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2019 at 11:57am
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Extreme 605, all the data I have done is in 500 rev increments. You can see that the boat is not fully planing at 4000 revs, but the slip drops significantly at 4500 revs.
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 11 Oct 2019 at 9:24am
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Titanium
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Extreme 605 18% slip at cruise (4000 is the general norm for plain on well powered powered boat)  thats right in the ball park, yet not on the plain????
Even a min powered boat should be up on the plane at around the 3K mark...
Looking back thru my data  thats around a 1800kg ( the cab hull) gross weight on water with 3 to 4 guys ave 85kg each plus gear.
 Got a note : "max hp rating 150" 1800kg well powered 200 hp.
 140 hp At the prop is well (min, nice, well, over) powered for a 1200/1300kg boat gross weight on water and 150 over.
Keep in mind 4S have another approx 15% over and above what the label says.. and reduces a little as the rpm reduce thru the power/ rpm curve but still above the equiveint 2S

 What is the engine?

EDIT:
 Going to throw this in here, and its not a plug at ANYONE.
 I get approached in forms PMS and email to recommend re powers and propping.
 This often takes couple months because of gaps between trips and suitable water to get data.
usually have 2 or 3 on the go at once.. currently 3.

What I do HATE is when a boat is min and under powered... one props to the power ON the boat and the end use of the boat.
 NOTHING fixes a min or under powered boat, yet it is I who have to pass on that to the person which to them is very upsetting for them. And their reaction can be rather varied.

 I cant change what a sales man on a yard says to make a sale, nor can I change what specs a manufacture recons is right for a boat. 
Most manufactures NOW their min is little under powered and their max rarely meets the well powered... but gets close...some are good.


 

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Post Options Post Options   Likes (0) Likes(0)   Quote Rozboon Quote  Post ReplyReply Direct Link To This Post Posted: 11 Oct 2019 at 11:59pm
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Originally posted by Steps Steps wrote:

 I cant change what a sales man on a yard says to make a sale, nor can I change what specs a manufacture recons is right for a boat. 
Most manufactures NOW their min is little under powered and their max rarely meets the well powered... but gets close...some are good.

You heard it here first folks, Steps knows better than the manufacturers themselves Wink I could go into it more but anyone that occasionally fact-checks the guru here might find things whiff a little bit.

And Joker, I've asked it about 5 times already and you always seem to miss it, but did you pay retail, or close to it, for your motor, or did you receive a sponsorship, pro-form-deal, or other type of hook-up on it? Transparency is important, and I reckon if you got hooked up on your motor you owe it the people you're telling how great it is to tell them that you got a deal. Google "astroturfing" some time.
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Post Options Post Options   Likes (0) Likes(0)   Quote JustAnotherSpearo Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2019 at 6:15am
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Originally posted by Rozboon Rozboon wrote:




And Joker, I've asked it about 5 times already and you always seem to miss it, but did you pay retail, or close to it, for your motor, or did you receive a sponsorship, pro-form-deal, or other type of hook-up on it? Transparency is important, and I reckon if you got hooked up on your motor you owe it the people you're telling how great it is to tell them that you got a deal. Google "astroturfing" some time.


Who cares?? I got my dad a great deal at the boat show. End of the day Joker has provided his experiences and how he finds the 115 CT ProXS and im sure we all greatly appreciate his honest feedback.

On another note Joker I noticed you had some snacks and drinks onboard hidden away. Was this sponsored by New World or Pak n Save??? Did you pay retail for them or get them on a discount. Please reply 2 me.
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Post Options Post Options   Likes (0) Likes(0)   Quote Rozboon Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2019 at 11:20am
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What I'm getting at is that the "honesty" of feedback is always going to be coloured by getting free ****.
</div><h1>Bug Squishing...
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Post Options Post Options   Likes (0) Likes(0)   Quote MacSkipper Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2019 at 12:42pm
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Originally posted by Rozboon Rozboon wrote:

What I'm getting at is that the "honesty" of feedback is always going to be coloured by getting free ****.
It's a fair question but you should only ask once?  I would expect if some relationship with supplier it should be declared.  Don't expect a detailed answer just a yes or no? 
Good fishing trip nothing breaks, great trip catch fish.
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Post Options Post Options   Likes (0) Likes(0)   Quote Legacy Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2019 at 12:53pm
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Originally posted by Rozboon Rozboon wrote:

What I'm getting at is that the "honesty" of feedback is always going to be coloured by getting free ****.


I take Jokers views on Fc boats and his motor with a grain of salt . I don’t know his experience of other similar sized boats and the hours spent on them or how many new motors he’s bought over the years so it’s hard to know what he’s comparing then too .
Obviously he loves his last couple of rigs .
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Post Options Post Options   Likes (0) Likes(0)   Quote Rozboon Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2019 at 1:44pm
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Originally posted by MacSkipper MacSkipper wrote:

Originally posted by Rozboon Rozboon wrote:

What I'm getting at is that the "honesty" of feedback is always going to be coloured by getting free ****.
It's a fair question but you should only ask once?  I would expect if some relationship with supplier it should be declared.  Don't expect a detailed answer just a yes or no? 



Absolutely. I've only asked it repeatedly because every time I do it doesn't get answered. Leads one to speculate that if it was a simple yes or no I woulda got it by now? As you say, if there's a relationship with a supplier it should be declared.
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2019 at 7:36pm
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Ohh Roz trolling again..
 this has come up before.
 its about me not if Im actually right or wrong, not actual data or basis  other than
Steps knows better than the manufacturers themselves Wink
Most manufactures do spec max power well..
 but Roz missed that part right.. has a mission only sees what he wants and tries to twist to suit.


 Anyway moving on no need to waste time on this BS.
 back to original subject comparing numbers.

 My numbers way back where high... though being over powered I do cruise faster.. cause it is there...
but still where high.
 Found out way a couple hrs ago..
 I had swapped out the prop for a 19" alloy last feb to see what was like out off the west coast..
Then had the open heart thing .. and totally forgot about it.
 Going over the boat checking  before bar trip tomorrow morning check prop pin and nut , noticed the 19" still on.
 Now back to the 21"  ...
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Post Options Post Options   Likes (0) Likes(0)   Quote Rozboon Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2019 at 8:22pm
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Originally posted by Steps Steps wrote:

Ohh Roz trolling again..
 this has come up before.
 its about me not if Im actually right or wrong, not actual data or basis  other than
Steps knows better than the manufacturers themselves [IMG]https://www.fishing.net.nz/forum/smileys/smiley2.gif" alt="Wink" title="Wink[/IMG]
Most manufactures do spec max power well..
 but Roz missed that part right.. has a mission only sees what he wants and tries to twist to suit.



Ok, data or basis then. You've repeatedly claimed that 4 stroke manufacturers consistently underrate their motors by 15% or so. Got any evidence to back that up?

Also...

Originally posted by Steps Steps wrote:


Most manufactures NOW their min is little under powered and their max rarely meets the well powered... but gets close...some are good.


Originally posted by Steps Steps wrote:


Most manufactures do spec max power well..


How on earth does this tally? Their max rarely meets well powered, but most spec max power well? Which is it?

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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 14 Oct 2019 at 8:17am
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Like i have said you have trolled for a while..
In doing so you will find in older posts threads the reason why.
Also Im not going to publish copy write data sheets, that if you wish to do your own research (will have to pay for most of it thu) you may come across
 As I said you tend to skim thru posts and just see what you want..

How on earth does this tally? Their max rarely meets well powered, but most spec max power well? Which is it?

Well here is a example..twisting to suit your perception Different manufactures rate their boat different..if thats a revelation..there is no regulation as to how they should.. just like how to advertise boat weights, even boat hull lengths.. fews back many where closer to min power for max. Seems market and manufacturing practices have change that for  many.. but not all..

There is a tactic in debate, to answer a question with a question... which you have just done... rather than answer the question
I will repeat.. I you think Im wrong, then actually say so and give solid reasons for that.. not opinion or perception.
I have been wrong about stuff before, been called out and reasons given, Dont have a problem with that at all.

If going to call someone out , call them out on data , facts , substances... not red herrings, sarcasm or insults , inferred or other wise as troll do.

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Post Options Post Options   Likes (0) Likes(0)   Quote Rozboon Quote  Post ReplyReply Direct Link To This Post Posted: 14 Oct 2019 at 9:58am
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Well, as the person making the claim, the onus is on you to prove that you're not talking out your bottom if asked for further information.

But we'll set that aside. Just for you, with cited evidence:

You are incorrect about modern 4-stroke outboards making considerably more power than advertised. The EPA testing data for outboards is available online here:

It's bloody horrible to read, but let's take the example of the Yamaha 350hp.
Measured maximum output was 261kw. Just a pinch under 355hp, or about 1.4% over the rated power.

Do you have a source that contradicts this?

It's not "trolling" if someone is talking bollocks and you point it out. Many people consider you to be a bit of a "guru" on here; you owe it to them not to state things as fact if they're either untrue or extremely dated information that is no longer the case; many people will take it at face value.
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 14 Oct 2019 at 10:56am
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Now go back as find out how that data was collected , by who etc.
Its not exactly independent..
 Then go find actual on the water power /rpm graphs.
Then figure out how the modern 4S marketing guys have 'overcome' that they have lower poer bottom end and how that was over come..
 Then there is the legal action  re claims of 4S over 4S in ....
you believe every 'official' number thrown at you regardless?? total faith in beurocrates, marketing guys and politians stats right?  or that just selective at face value?

Many people consider you to be a bit of a "guru" on here;

 
Maybe dunno , never really considered that... seems to be important to you thu.
On the other hand my PMs emails run into pages.. people who contact privately, then we spend several months sometimes (available time weather windows etc).
And why privately?
Because the same old little handful of trolls come along and high jack with no substance or data.
Just sarcasm and resentment...
 Shame really because so many of the results just dont get published... and the thread gets destroyed.

PS if you happened to get the opportunity to crunch data 2 to 3 times a week at least for a few yrs on end, you would end up with a considerable data base...and from that would those be able to see significant patterns in power to weight ratios of trailer boats, different hulls, motors  brands etc.

To even consider that an engine labeled X at Y speed on a given hull.. then replace with Z engine X and it moves the same hull at Z speed and they have the same power curve defied basic physics and disbelief.
And if Official numbers dont match...then the basic physics must be wrong in your books..

One of many classic examples of under rating engine power is back in the late 60s , early 70s with American ( and few other countries , "official' hp ratings of muscle cars to get around legislation and insurance premiums.
 lets not forget the VW numbers.. that where also official EPA numbers, for a while.

Well you have destroyed another thread for someone..
 put ppl into private communications to finish off...
 Well done, again.
Maybe we should count up the number of threads one day... and number ppl gone private..



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Post Options Post Options   Likes (4) Likes(4)   Quote Grasshoppa Quote  Post ReplyReply Direct Link To This Post Posted: 14 Oct 2019 at 5:05pm
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Steps while you have some useful input on some things you often get your back up after waffling sh|t about various things you are often out of your depth in and accuse people of trollingor "dumping" on you, yet your happy to chip away at others?
With your apparent extensive knowledge and expertise i dont know why you dont open your own dealership, the rest of the industry would collapse before you
My personal opinion is the majority of people dont know any better and while i think Guru might be a bit far, you do talk a good story so the uninitiated can be excused for thinking this way.  You have a good understanding of calculating a starting point for propping but outside of that, some of your opinions are frightening

Opinions are like ar$eholeS, everyone has one, and the above is one ive formed over time (not necessarily relating to this particular thread)Smile

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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 7:58am
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GP If find your post informative more than anything..
 No you dont post up on a regular basis non substantiated comments...
you do talk a good story so the uninitiated can be excused for thinking this way.
 The story is more  that rather than a simple statement I put in the background and reasoning why..If ppl know that then they can evaluate situations , understand symptoms themselves.

 If some of my opinions of which are prefixed with "I think" or "maybe" (which very often is skimmed over) are "frightening" then It should be pointed out and why. And in many cases has been without issue.
 Would you like to post up. or
 privately some of the "frightening" stuff and why?
 I ask this with genuine sincerity



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