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Old 26 May 2013, 04:29   #11
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Quote:
Originally Posted by J@mes View Post
Well I think WOT is 6k rpm from memory with just me in the boat = 39mph.

Also from memory with my dad in the boat (+ 85kg) the top speed is 35mph and I think the WOT is slightly less, maybe 5800 rpm.

James
Hi

2 v quick points

1: you are right to ask advice as many people throw money a things like props expecting a huge difference and unless its a few sizes the change will be minimal and as stated before bad bang for buck. There are also different types of props and other things you can do to help performance that would be cheaper in most circumstances.

2: you imply that these figures are a good guess and not 100% and hence the first thing I would do is check these. If i have miss read then v sorry.

Dave
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Old 26 May 2013, 12:10   #12
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Originally Posted by Locozodiac View Post
If already achieving 6K at wot with you alone, personally would stay there, it's normal that with more weight rpm will be slightly decreased. The top speed difference between standard delivered prop and next adyacent pitch is minimal, not cost effective.

Is 39 MPH not enough for you ? More top speed, lessens better hole shot and viceverse. Placing a 15" prop will decrease rpm by 200-300 rpm. Probably will benefit achieving better hole shot with slight top speed than with 13"

Happy Boating
My hole shot is very good at the moment and I don't mind sacrificing a bit of it for a little bit more top speed. Is 39 mph enough, well you know how it is, boys and there toys lol, yes I would like a little more if possible by simply changing the prop, but don't want to spend a lot of money on it as tbh I don't think its really worth the bang for buck!


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Originally Posted by spartacus View Post
If you were local - you could borrow my 15 pitch propeller, on the understanding if you damage it you replace it with a nice shiny stainless steel one!

Any Ribnet members near you - you could swap propellers with?
I would love to be able to try someone else's prop, but my problem is my boat is in Spain, though I am next over in 3 weeks time. Don't want to lend me your prop do you?! lol


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Originally Posted by clydeoutboards View Post
Hi

2 v quick points

1: you are right to ask advice as many people throw money a things like props expecting a huge difference and unless its a few sizes the change will be minimal and as stated before bad bang for buck. There are also different types of props and other things you can do to help performance that would be cheaper in most circumstances.

2: you imply that these figures are a good guess and not 100% and hence the first thing I would do is check these. If i have miss read then v sorry.

Dave
What other cheaper things could I do to help my top speed? I don't carry unnecessary weight in the boat so its not like I can make it lighter.

You have read correctly, I cannot say 100% WOT is 6000 rpm with just me in the boat, I need to double check when I next get a chance!
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Old 26 May 2013, 14:07   #13
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Well we have customers who have been on diets to waxing the hull, changing the ballence of the boat etc. Its not for me but hay if thats your thing then go for it.

You have a great set up so first I would check the numbers and take it from there.

Dave
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Old 27 May 2013, 13:54   #14
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Some issues not clear :

You are curently running a 13" factory delivered prop, right ? Is rev limiter kicking in at 6150 with same prop ? If so, will need to go 2 pitches up to 15" so engines lowers it's max rpm achieved and works safely around 5500 rpm, which is the middle numbers between min 5150-max 5850 stated factory parameters.

Personally don't like to go boating alone with an engine with rev limiter kicking in constantly when giving juice and playing near max throttle, if placing a 14" pitch prop will be around 5850 rpm which are much better numbers than over reving.

As this is not exact rocket science playing with prop pitches under trial and error is a must do. Try to find a good Spanish Samaritan that can lend you a 14" to test at wot.

Happy Boating
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Old 27 May 2013, 18:25   #15
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Originally Posted by clydeoutboards View Post
Well we have customers who have been on diets to waxing the hull, changing the ballence of the boat etc. Its not for me but hay if thats your thing then go for it.

You have a great set up so first I would check the numbers and take it from there.

Dave
Well I will definitely check when next out there, but I'm pretty sure its close to bang on 6000rpm WOT with just me in the boat and 5800rpm with me and my dad. I don't think I'm more than 100 rpm out tbh. But either way I think it would be safe putting a 15" prop on because it will lower the WOT rpm to within the correct rpm range, 5150 - 5850, I really don't think (hope lol) that my memory of it is that far out!

Quote:
Originally Posted by Locozodiac View Post
Some issues not clear :

You are curently running a 13" factory delivered prop, right ? Is rev limiter kicking in at 6150 with same prop ? If so, will need to go 2 pitches up to 15" so engines lowers it's max rpm achieved and works safely around 5500 rpm, which is the middle numbers between min 5150-max 5850 stated factory parameters.

Personally don't like to go boating alone with an engine with rev limiter kicking in constantly when giving juice and playing near max throttle, if placing a 14" pitch prop will be around 5850 rpm which are much better numbers than over reving.

As this is not exact rocket science playing with prop pitches under trial and error is a must do. Try to find a good Spanish Samaritan that can lend you a 14" to test at wot.

Happy Boating
Yes factory 11.1 x 13 prop is currently on. I have never heard the rev limiter, I assume you would hear it like in a car?! Also the ECU has not logged any over revving fault codes (I checked for fault codes when I last put my boat away), though that's assuming it would log a code for over revving?!

Yeah if I don't bite the bullet and buy a 15" prop before I go out there then I will definately try and find someone with a 15" prop to try, but tbh I think I will struggle to find someone!

Lastly, If I was to buy a new 11 x 15 prop, do you think I should get an OEM Tohatsu one, or something else like a Solas one? From the few pictures I have seen online, dare I say they look very similar, maybe even Solas produces the OEM Tohatsu props?! Any ideas? Also can you recommend a cheap place online to buy a new prop? Thanks.
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Old 27 May 2013, 18:25   #16
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Whoops double post, please delete.
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Old 27 May 2013, 18:54   #17
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Solas costs bit less than original, as long the size and pitch are correct not an issue. As an example boating solo with a light rib and factory delivered prop my horse achieves full 5800 rpm, that's max 5800 factory stated.

Preffer to be on top max rpm, when boating with 1- 2 more mates max rpm will decrease accordingly, but will remain inside safe working readings at wot. So a prop pitch that will give near or max rpm at wot with will be good to consider.

If not mistaken, TLDI engines don't show a code when rev limiter kicks in, just faulty engine codes.

Happy Boating
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Old 27 May 2013, 20:15   #18
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Ok thanks for that. When the rev limiter kicks in, does the engine make a noise like in car? I certainly haven't heard any similar or unusual noises, actually come to think about it I have, I think from memory on the very odd occasion at WOT I have heard a very high pitched noise, but I was pretty sure the noise was coming from the front of the boat!!! As stupid as it sounds it never worried me as it wasn't a bad sounding noise, but I assumed it was the pressure release valve from one of the air chambers at the front of the boat making the noise due to the fact the boat was going fast and skimming the water, maybe putting extra pressure on the tubes? I don't know, think I have just made myself look stupid?!! lol
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Old 29 May 2013, 18:32   #19
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James i have a tohatsu 50 on a small rib and get almost identical performance to you with the standard prop . I tried a stainless prop just one pitch more and it did give a bit more top end with no load in the boat . However add a bit of load or pull a ringo or skier and its was slower dropped too many revs and used more fuel cruising .

I have gone back to the standard prop
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Old 29 May 2013, 19:18   #20
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Originally Posted by ian parkes View Post
James i have a tohatsu 50 on a small rib and get almost identical performance to you with the standard prop . I tried a stainless prop just one pitch more and it did give a bit more top end with no load in the boat . However add a bit of load or pull a ringo or skier and its was slower dropped too many revs and used more fuel cruising .

I have gone back to the standard prop
Hi Ian, thanks for the input, that's very interesting to hear!

Sounds like we have a similar set up going by your username info, your rib is 4.3m and mine is 4.2m.

Out of interest how much more top end did you get with no load using a stainless 14 prop? 2, 3 mph extra?

If I was to get an 11 x 15 (alloy) prop I was planning to simply pop the standard 11.1 x 13 prop back on for days when using my rib for tubing/skiing! That was assuming I needed to, which seems the case from your experience! Though even still I hardly use the ring or ski nowadays, and it wont take long to change the prop if needs be I guess.

Hmm you have made me think now, I think maybe I should wait until I can next actually use my rib (3 weeks time!) and then double check my WOT rpm with just me and also +1 person. If I am correct and its slightly too high at 6000rpm with just me (the recommended WOT range is 5150 -5850rpm) then I will be very tempted to go up to an 11 x 15 prop to lower my WOT rpm slightly. As we know all boats are different, maybe mine is slightly lighter or something and will react differently? Who knows!

Out of interest what did you do with your stainless prop? lol

Cheers,
James.
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