13' Standard 30-HP: Propeller for Water Skiing

Optimizing the performance of Boston Whaler boats
MartinDupre
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13' Standard 30-HP: Propeller for Water Skiing

Postby MartinDupre » Thu Jun 03, 2021 5:14 pm

I have a classic 13 Standard with Evinrude E-TEC 30 HP.

I already have a three-bladed 10 x 13 BRP stainless propeller for speed with light loads.

I want to purchase a four-bladed stainless propeller that optimizes four adults in the boat, or two adults in the boat and one adult waterskier. No fancy skiing, just a ski on each foot for a little fun. In either case assume adults average weight 185-lbs.

I have boiled it down to two Solas propellers, both HR Titan 4: 10 x 11 or 10 x 10.

My thinking: with the 10 x 11 propeller, the boat would perform best just for running around with four adults in the boat; with the 10 x 10 propeller [the engine could accelerate more rapidly and] would yank-up a water skier a little faster, and [the gain in acceleration under load from a standing start] may be [of equal or greater] worth [than the loss of top speed].

Which would you choose?

jimh
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Re: 13' Standard 30-HP: Propeller for Water Skiing

Postby jimh » Tue Jun 08, 2021 8:44 am

I would buy both propellers on the basis I can return one after a sea-trial to determine the best choice.

Will 185-lbs water skier with 370-lbs crew be able to easily pulled up with a 30-HP? Perhaps, but it may be a struggle.

MartinDupre
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Re: 13' Standard 30-HP: Propeller for Water Skiing

Postby MartinDupre » Wed Jun 09, 2021 4:03 pm

I ordered both the [new] propellers [of undesignated pitch, perhaps a 10 x 10 and a second 10 x 11] , but I cannot return either if the propeller was used. I could re-sell as a slightly-used proeller.

When I posted the original message, I had not yet had the boat on the water. I was leaning toward the 10 x 10, because I read when going to a four-bladed propeller from a three-bladed propeller, the propeller pitch should be decreased by one-inch [in order to produce an outcome of] more-or-less equal engine [loading, otherwise known as the propeller power curve].

Using that rule of thumb, a 10 x 12 four-bladed propeller [require from the engine] the same power [to turn] as my 10 x 13 three=bladed-blade. That would suggest a 10 x 11 would not be enough difference. That line of thinking led me to lean towards the 10 x10.

I took out the boat for testing with the 10 x 13 three-bladed propeller still installed on the [E-TEC 30-HP engine, with just me and my son, both about 200-lbs. Most of the trip was at idle speed with shallow water, but when I finally got to open up the engine, I was impressed immediately [by the performance of the E-TEC 30-HP. At around 5,000-RPM engine speed--which is actually just a guess as I do not yet have a tachometer--the [E-TEC 30-HP engine] suddenly gave a surge of power, and soon the boat was going so fast it was downright scary. I began to see why 20-HP was the recommended maximum with tiller steering. I need to tighten the swivel friction.

Due to the sea state being a considerable chop, I reduced speed quickly. I did not feel like taking the time for a speed measurement from my GPS receiver, thus my sea trial was not a very good [propeller selection] test.

If the E-TEC does so well with the 10 x 13 three-bladed propeller, maybe the 10 x 11 four-bladed propeller blade would be a better choice after all.

Still haven't decided which propeller to lose money on.

jimh
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Re: 13' Standard 30-HP: Propeller for Water Skiing

Postby jimh » Thu Jun 10, 2021 2:15 pm

In order to get serious about propeller selection, the engine speed MUST BE MEASURED accurately. About all you can tell now would be for the engine speed to exceed the maximum allowed RPM, and then you would notice the Rev-Limiter acting to prevent more engine speed.

A tachometer costs less than a stainless steel propeller for a 30-HP engine, and it will be a very useful instrument even when done with propeller selection. Your next purchase should be an Evinrude tachometer. They usually include a SystemCheck lamp annunciator gauge, which is MANDATORY for proper installation of any E-TEC as a minimum level of instrumentation so that you will be alerted to engine problems like over-temperature, low oil reservoir, no oil flow, or a general check-engine condition.

Small boats are very sensitive to crew weight. If you test four crew or two crew and a water skier, the performance will be much different than what you will see with just two crew aboard.

MartinDupre
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Re: 13' Standard 30-HP: Propeller for Water Skiing

Postby MartinDupre » Thu Jun 10, 2021 3:32 pm

Thank you, Jim for taking the time to respond.

I am certainly aware how small boats are very sensitive to crew weight. I suppose I was hoping for someone who had had a similar quest and could therefore give me a shortcut answer. Too optimistic, perhaps.

As far as installing an Evinrude tach, keep in mind this is a Standard with no console. I was intending to use one of the "Tiny Tachs" temporarily to tune my system, then dispense with it. They are cheap ($23) and supposedly are accurate. They just read the pulses of one spark plug wire; you have to set it for either one pulse for one revolution (2 stroke) or one pulse for 2 revolutions (4 stroke).

I will probably add a battery for running lights (just in case I get caught after dark). With a small box added at the stern for wiring junctions, and for mounting the all-around white light. I would then have a place to install a tachometer with the warning lights you speak of. However, I am trying to keep my setup as simple as possible (which explains my preference for tiller steering).

I find it hard to accept that Evinrude would sell portable tiller-steering engines with the expectation that the boat would be instrumented. I just assumed the EMM the would shut down the engine before damage could occur. Not that one should not pay attention to what is happening with the engine.

For the record, the Solas SS propellers cost $200 each, more or less.

Can I find an OEM tach with the necessary wiring harness in that price range?

What about the Faria tachs that say the are made for Evinrude?
Last edited by MartinDupre on Fri Jun 11, 2021 9:54 am, edited 1 time in total.

jimh
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Re: 13' Standard 30-HP: Propeller for Water Skiing

Postby jimh » Fri Jun 11, 2021 5:04 am

For prices for a Systemcheck Tachometer see

https://www.defender.com/product.jsp?id=6776053

A wiring harness kit from BRP will be needed. I don’t know the part number or price—but probably not cheap and perhaps not readily available these days.

I am not familiar with the required rigging for “portable” E-TEC engines. Refer to the Operating Guide for advice.

A TinyTach is better than no tachometer for propeller selection.

MartinDupre
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Re: 13' Standard 30-HP: Propeller for Water Skiing

Postby MartinDupre » Fri Jun 11, 2021 8:37 am

I am not familiar with the required rigging for “portable” E-TEC engines. Refer to the Operating Guide for advice.


There are LEDs on the EMM. Here is what the operating guide says:

WARNING SYSTEM - S.A.F.E.
This outboard is equipped with Speed Adjusting Failsafe Electronics (S.A.F.E.). S.A.F.E. is an engine warning system controlled by the Engine Management Module (EMM). The EMM monitors engine sensors. If conditions which could cause permanent engine damage exist, the EMM limits engine speed to 1200 RPM.

If engine is in S.A.F.E. mode, the outboard will shake noticeably when accelerated above 1200 RPM. For additional protection during severe operating conditions the EMM will shut OFF the engine.

The EMM activates S.A.F.E. mode for:
  • NO OIL warning; indicates a nearly empty oil tank. Refer to Filling the Oil Tank and Priming the Oil System on page 19.
  • OVERHEAT warning; indicates an engine or EMM overheat condition. Refer to ENGINE OVERHEATING on page 43.
  • FAULT warning; indicates a problem exists. The EMM has identified a problem with the outboard. Seek assistance and/or return to harbor immediately. See your Dealer.

DIAGNOSTIC LEDS
The Engine Management Module (EMM) has four LED indicators located on the top corner of the circuit board. The LEDs provide quick reference to the status of several outboard systems. The LEDs can be used to identify specific warning functions of S.A.F.E. mode activation without ending a day on the water.


Again, I am very impressed with the technology in this motor.

MartinDupre
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Re: 13' Standard 30-HP: Propeller for Water Skiing

Postby MartinDupre » Fri Jun 11, 2021 1:37 pm

My research indicates that a BRP Tachometer with System Check will only report engine speed and Low Oil when used with the 15HO, 25, and 30 motors.

https://www.manualslib.com/manual/82528 ... =26#manual

Since it is easy enough to make sure the reservoir has sufficient oil, I do not think it worthwhile to invest in an official BRP tach.

It is just not possible for me to use up the entire 1.5 quarts of XD100 oil in a day of operating the motor. So I just top it off every time I go out, and no worries.

jimh
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Re: 13' Standard 30-HP: Propeller for Water Skiing

Postby jimh » Sat Jun 12, 2021 10:32 am

MartinDupre wrote:My research indicates that a BRP Tachometer with System Check will only report engine speed and Low Oil when used with the 15HO, 25, and 30 motors....


Good job finding that rather obscure announcement posted in a dealer-only publication describing model-year product revisions.

I agree with your view: there is no need for a System Check tachometer if three of the four System Check annunciator lamps will not be functional.

I still think a permanently installed tachometer is a very useful instrument to have on an outboard-engine powered boat. It will alert you to any changes in engine performance that reduce engine speed from previously attained engine speeds, particularly the full-throttle engine speed under normal load.

Only three conductors are needed for the typical classic analogue outboard engine tachometer: 12-Volt power positive circuit, 12-Volt power common or negative circuit, and tachometer signal (referenced to common circuit).

MartinDupre
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Re: 13' Standard 30-HP: Propeller for Water Skiing

Postby MartinDupre » Mon Jun 14, 2021 5:52 pm

Jim, thanks again for your thoughtful replies.

I did install a Tiny Tach right on the tiller; it was easy to do, although I followed the setup instructions, it read double RPM at first, but I got that straightened out and it now reads correctly.

On my second and third sea trials I was able to evaluate two propellers (at least an initial, if incomplete evaluation).

3-blade 10x13 SS propeller: With two 200 lb adults aboard, it reached a maximum speed of 29 mph at 5700 RPM. I have not been able to test speed yet with only one adult.

4-blade 10x10 SS propeller: With 3 adults aboard, it reached 25 mph at just a tad over 6000 RPM. With 4 adults aboard, 24 MPH at 5700 RPM.

I have not tried pulling a skier yet.

Also I have not optimized trim and motor height as of yet. I have the trim set on the highest hole (remember this as a manual model). This puts the propeller shaft as near as I can tell parallel to the keel. Porpoises with only one on board, but with two runs true.

Also as near as I could tell, the AV plate was below water, so I have to raise the motor.

Even without this fine tuning, based on these results I am convinced that the two propellers I am using are exactly right for the conditions under which I expect to use the boat.

Unfortunately, there were engine running problems that I have asked for help with on Barnicle Bill's e-tec owners forum. If anyone is so inclined. please respond there.

https://www.etecownersgroup.com/post/30 ... 1326731933