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GEB

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Posts: 2,175
Reply with quote  #16 
Hi jazzavac,
For what it's worth I think the SSP 10 X 11 will do the job in your case. Probably your WOT will be in the high end of the Optimun Rev Range which is good as it gives you a margin for extra load and will certainly make your motor quiet responsive to throttle. Propping your motor to ( be capable off ) running in the Optimum Rev Range will give you best all round performance, fuel economy and engine longevity. Over propped motors ( not capable of ) running in Optimum Rev Range run hot, use more fuel, carbon up and don't live as long as they could. Don't just take my word for that, lots of verifiable info online eg http://www.veradoclub.com/index.php?topic=137.0 and BTW I used this as a guide to rigging and propping my motor.
Unfortunately not a lot of choice in props for us little guys, I run 4 blade 10.2 X 12 aluminium prop on my rig which is a stern heave boat, 30 HP pushing 450 - 500 kg. That prop really pops it up on the plane with good stern lift and my WOT is 5750 rpm. A happy combination of correct engine height and prop. I haven't tried SSP as I fish very shallow waters and aluminium prop is a lot cheaper than a new gearbox when I hit something. The idea being the aluminium prop is a lot softer than SS and will absorb the shock ( not the gearbox)
With the small HP motors not a lot of performance gains to be had by going to SSP but I suppose it all helps and SSP will certainly last longer.

Cheers
GEB

__________________
Stacer 389 Territory Striker
Model No.E25DTSLAFC
Serial No. 5503333
Mid North Coast
New South Wales
Australia 
The learner will not shear the rams.

GEB

Registered:
Posts: 2,175
Reply with quote  #17 
Hi jazzavac,
What I should have also said is that here in Australia up to and including the 30 HP E-TEC motors come fitted with an aluminium 3 blade prop. Mine came with a 3 blade 10 X 12 and the motor was installed and rigged by my dealer, Huey. As he couldn't know exactly how I would use and load my boat the motor height was rigged according to his previous ( extensive ) experience and initially it was exactly right but as my use and load in the boat changed I started to experience a lot of prop slip and ventilation even when trimmed right in on the turns. So using that Prop Gods article I rerigged the height, dropped it one hole, and changed to the 4 blade prop.
What I learned in the process was that unless the motor is rigged correctly with the anti ventilation plate just on or just above the water surface, on the plane, at WOT ( regardless of what WOT rpms are ) with the motor fully trimmed out to just before the point of ventilation, that it's a waste of time, effort and money trying to prop the motor. Only when the motor is verified to be rigged correctly and depending on the WOT rpms then achieved do you start trying to prop it to achieve Optimun Rev Range. Also very important to have an accurate digital tachometer as analog tachometers aren't accurate. Most accurate is the Evinrude Diagnostic software, reads rpm direct from the EMM.
My preference is to be propped near the top of the Optimum Rev Range with normal load as this allows a margin for extra load and as I've recently discovered a bit of " wear and tear " on the prop. Initially my WOT rpms were 5750 with the 4 blade prop but when I recently did a WOT check I could only reach 5650. Nothing has been changed except that recently I've had to file a few deep dings out of the prop and I attribute my slight loss of WOT rpms to the resulting change in blade shape.
Hope this is of some help to you.
GEB

__________________
Stacer 389 Territory Striker
Model No.E25DTSLAFC
Serial No. 5503333
Mid North Coast
New South Wales
Australia 
The learner will not shear the rams.

jazzavac

Registered:
Posts: 9
Reply with quote  #18 
Thanks GEB! Mine also came with aluminum 10x12 prop, but I guess they are delivered from the factory with that prop. So, dealer/importer here did not change anything... Reading the graph from EMM module (after 184 hours of regular use), I see that rpms are low. Only this summer I got a tacho to read them directly. This tiny digital did the job...

Anyhow, I will have to wait at least 10 more months before I will be able to update this thread... Boat and motor are winterized, serviced, washed, polished, tucked-away... 
rlebar

Registered:
Posts: 31
Reply with quote  #19 
As per my experience with brp stainless vs aluminum props for the 25 and 30 motors, same for same, you will need to drop 1 pitch going to stainless. Not the other way around. 

It appears the stainless props have more cupping

while the aluminum prop that will likely be ideal for you is the 10x11, don't be surprised if the 10x10 is what you need if you go stainless.

__________________
2016 E30DGTL behind a 2016 14' Smokercraft Big Fish TL
captainmorgan

Registered:
Posts: 5
Reply with quote  #20 
Thanks for all the information. I have come to the conclusion that if my 25 HP won't due the trick. I will be upgrading to a 50hp etec as I love them and feel like it would not be worth it to run the older Johnson. Any clue what the cost would be roughly for a 50hp power tilt/trim electric start if I traded in my 1998 40hp the electric start and my 25hp 2010evenrude power tilt electric start?
Thanks Morgan
jazzavac

Registered:
Posts: 9
Reply with quote  #21 
Time for the update as the new season is here ... 

After all, I ended up buying 10x11 BRP aluminum prop as practically every dealer talked me out of SS stating that I would not see a difference on 25HP. On the boat, I managed to get up to 37 kph = 23 mph = 20 knots. Not bad on fully inflatable zodiac. As for RPM, I got it to 5800 WOT. Two things that are making it hard to compare against the old (stock) prop. First, the old prop is not in perfect shape. I bought the e-tec used so it had some ground contacts before. Second, I cannot remember whether I tested the old prop with bimini up or not. Gut feeling is that bimini is taking ~200RPM, if I was not folding it before for tests...

So, FWIW, I am pretty happy with the results. I plain much easier than before and I even got higher top speed than before. Not really a fair comparison, but this should serve as a data pointer for some fellow boater using inflatables with e-tec....

Thanks to everyone who participated in this thread and shared the thoughts. I really learned a lot....!

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