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Old 26 April 2016, 09:32   #11
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>>>If I saved a £few and put a solas 11 on it, can I be sure it will give me the same step change as an 11" oem prop would?. Though both 11", one may have more or less cup than the other for example and it may muddy the waters if I don't stick with genuine Suzuki to make the comparison.


It's a valid thought. A few years back I wanted a same pitch spare for a Mariner 15 2-stroke and bought a Solas. When delivered it was obvious the blade profile was very different to the OE one but I expected it to be fine... until I got it on the water when the 3.6m SIB didn't plane so easily and was very prone to ventilation and over-revving due to slip.

The prop specialist after a little hassle swapped it for a new OE one which was perfect.

In the image below of two props you can see that the Mariner OE one on the left has a far more raked blade design particularly at the leading root. Also the webs the exhaust has to flow past were far finer on the OE one. The Solas is the right of the two and quite different.

The image of the single prop is of my Suzuki 11" which already has that upright leading root so perhaps the differences between that and the Solas would be less than my Mariner to Solas comparison.

But my experience does show changing brands might throw in an added factor.
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Old 26 April 2016, 12:12   #12
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Hi Dave, welcome to Ribnet.
I think you will know best whether to go for 11" or 12" pitch but we also have a DF20A running on the stock 10" pitch prop.
We run ours on both an Aerotec 380 and Zodiac 3.5 sibs and can easily hit the rev limiter at wot at about 24mph / 21 knots with two up. We usually tow kneeboard/wakeboard so being slightly underpropped solo isn't a problem as we prefer more grunt for hole shot and acceleration.
We briefly had a F-Rib 375 which is probably more similar to your TS370 (even the same weight at 62kg) and running solo with two up hit the limiter at around 26mph / 22 knots. It did feel slightly more underpropped than the sibs, and if we'd kept the boat, I would have tried an 11" prop, which at the same speeds would have reduced revs by around 200rpm.
Although no actual experience, my gut feel is the 12" may be a step too far, as it's an effective reduction of around 400rpm.
Personally I don't mind having the ability to hit the limiter on occasion, and with these motors at least we have the luxury of one!


Nice boats the Ribeye. We looked at the TS400 earlier this year but wanted the ability to upgrade to a 25 or preferably 30hp motor - and even though Ribeye rate the transom for a max 92kg motor, anything over 20hp would void the warranty.
Hope you get prop sorted.
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Old 26 April 2016, 18:42   #13
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Hi,
I'm also new to this site, although I've read and enjoyed much of the advice and content over the last few years.
(After much deliberating) I bought a Suzuki DF20efi last year, and reading this thread, would like to ask a couple of questions:
1/ Is there a difference between the prop slipping and over-revving - I think I may have been incorrectly assuming the former was causing the latter ?!
2/ Do users find the tiller vibrates uncomfortably ? I'd say it's ok but noticeable, whereas on the Suzuki 6 I had before, I don't recall noticing any vibration.
Thanks,
Tim
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Old 26 April 2016, 19:09   #14
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Hi Tim,
Prop slippage can be caused by either ventilation or more rarely cavitation and the result will be a rapid increase of engine revs coupled with a loss of power;

Propeller Ventilation

Propeller ventilation is caused by air from the surface or exhaust gases being drawn into the rotating propeller blades. This results in the propeller slipping more than usual due to the reduced water load on the blades. The obvious symptoms of this are a sudden increase in engine RPM as well as a possible loss of speed. This commonly occurs when trying to turn the boat at high planing speeds or if the outboard is mounted or trimmed out too high.

In racing conditions this can also occur when following another boat too closely. The small bubbles in the water created by the leading boat can cause ventilation of the propeller of the following boat, with a subsequent loss of speed. This is why you rarely see high speed race boats following directly in the line of the leading boats, even if they are far enough back to be out of the spray and wake.

Propeller Cavitation

Propeller cavitation is less obvious than ventilation, but can be far more damaging. When the propeller blade passes through the water at an increasing speed, the pressure that holds the water to the sides of the blades is lowered. If the water is sufficiently warm, and depending on the speed of the boat, formation of water vapour (boiling) can occur. These bubbles that are produced then immediately collapse, releasing energy that can cause a cavitation burn on the propeller blades. This is one of the great advantages of stainless steel propellers. Due to their superior strength they can withstand cavitation damage better than aluminium and can also be produced with thinner blades to reduce the occurrence of cavitation.

Funny you should mention vibration. The one criticism I have of my DF20 is slightly excessive vibration at low to medium revs. Not felt it excessively uncomfortable through the tiller though.
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Old 27 April 2016, 04:40   #15
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Chipko's explained it well. You should be able to tell if you are suffering ventilation slip as it feels like dipping the clutch on a car while still holding the throttle down then the rev limiter cutting in. If it is because you really need a higher pitch prop and it's just you are maxing out then it will be more progressive until the point the rev limiter cuts in.

If you run with one or two folks and you have a 10" pitch then the opinion is forming that you will likely be able to get to the rev limiter.

I noticed the vibration straight away as this is my first 4-stroke outboard and I'm used to the frantic buzzy revving of 2-srokes. On my DF20 the idle is slow (correctly so), smooth and very quiet and I'd not expected that offbeat vibration that starts just off idle and seems to continue to medium revs when it smoothes out.

It is mentioned in quite a few reviews and by other owners on the net so quite normal. If you look at the tiller twistgrip there is a bit at the end where the diameter reduces and seems to extend it for no purpose as there is no grip on it. There is a damping weight in there to try and minimise how the vibration feels.

I note the DF25 which is a 3cyl doesn't need or have this "weight".
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Old 27 April 2016, 07:27   #16
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Quote:
Originally Posted by Fenlander View Post
Chipko's explained it well. You should be able to tell if you are suffering ventilation slip as it feels like dipping the clutch on a car while still holding the throttle down then the rev limiter cutting in. If it is because you really need a higher pitch prop and it's just you are maxing out then it will be more progressive until the point the rev limiter cuts in.

If you run with one or two folks and you have a 10" pitch then the opinion is forming that you will likely be able to get to the rev limiter.

I noticed the vibration straight away as this is my first 4-stroke outboard and I'm used to the frantic buzzy revving of 2-srokes. On my DF20 the idle is slow (correctly so), smooth and very quiet and I'd not expected that offbeat vibration that starts just off idle and seems to continue to medium revs when it smoothes out.

It is mentioned in quite a few reviews and by other owners on the net so quite normal. If you look at the tiller twistgrip there is a bit at the end where the diameter reduces and seems to extend it for no purpose as there is no grip on it. There is a damping weight in there to try and minimise how the vibration feels.

I note the DF25 which is a 3cyl doesn't need or have this "weight".
df 25 true same dia reducing no weight has an offset crank too for smoother running.
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Old 27 April 2016, 08:49   #17
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I've renamed and moved this thread so future readers can find it.
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Old 27 April 2016, 14:21   #18
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Consensus seems to point toward an OEM 11" then. That's what I'll do and I'll let you know what happens. As Chipco Says at least we have limiters on these engines so should it over rev on the occasional one up trip it wont destroy itself. Don't forget though that the ECU on these engines records the number of times the limiter is deployed as well as % of time at various throttle openings. The dealer may frown come service time

Chipko, you're correct my boat has a 20HP limit but the newer TS370 has a redesigned transom allowing it to take a 30. Ribeye documentation is conflicting regarding this but I called them for clarification some months ago. As I need my engine to be portable, the 20 with the electric start is heavy enough and to be fair, fast enough for what I want it for. Listen to me all grown up.

Vibration - yes at lower rpm it's there but not that bad. My Honda Fireblade motorcycle used to give me vibration white finger on the throttle hand. This is nowhere near as severe and is unnoticeable at higher revs.

Can I digress a little. My engine has about 18 hrs on it and is 13 monthis old. The dealer who gave me poor advise at point of sale has quoted me £69 +Vat for an 11" prop and has offered to fit it "Free of charge" if I take it there for it's annual service. he's quoted me £186 +Vat and in a bid to justify it explained it includes plugs and new impeller. Neither of these are listed on the service schedule. OK it lists a valve clearance check (which I doubt he would actually do) but it seems a lot of money for engine oil and filer and lower leg oil change.

Normally I would service it myself but until I gain confidence in it I think a dealer stamp is a necessary evil. This "Main Stealer" price seems a bit excessive though. Anyone got any service bills to compare?

Cheers guys

Dave
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Old 27 April 2016, 15:44   #19
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Just had my 25 done £65 + vat first service oil filter oil & gear oil
And acording to the manual it's 20hrs or 1 month which ever sooner
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Old 27 April 2016, 16:12   #20
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Service costs seem to be all over the place.On this thread post #26 Jeff had been quoted as much as £257 but an alternative place was £65+vat. My local dealer said "about £100" for a yearly but of course it'll be a while before I test him on that.

Edit: oops Jeff beat me to it.

Suzuki DF20AS EFI - Impressions and review.

Daft to replace the spark plugs at 18hrs when they are just an inspect at 100hrs. Similarly why would he change the impeller at 1yr/18hrs when it's a 3yr/300hrs item!

If I'm reading it right I think the valve clearances are checked at 20hrs then every other year. That check is quite "invasive" by modern standards... if old hat to those of us brought up on older vehicles... so I hope the dealers take care doing this.

Yes the variety of data they can collect from the ECU is staggering and like you I'd prefer not to see it logged I'd been bouncing off the rev limiter time and time again.

The dealer stamp is needed for warranty and I think the killer service cost will be the 4yr with a timing belt change. If my outboard has been reliable up to 3yrs and 11mths I think I'll do that service and the belt myself foregoing the last warranty year.
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