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I moved my engine up so it is now mounted at the third hole.

Max RPM did not change. 5300 RPM and 42 mph. No signs of ventilating. I added a T-top wrap which likely equalized the changes in mounting it up two more notches to No. 3.

Tom Clark originally suggested 4th hole mounting and Enertia 17P .

So I'm going to have them move it up one more hole to 4th hole and put on the Enertia P18. A bit more aggressive on the prop. I should see 5600 RPM and 45 mph.

News at 11.

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5400 RPM
42 MPH
3 holes up
With the enclosure off
Vengeance 17P prop

Into the shop today to:
4 holes up
Enertia 18P
T-top enclosure back on

Predictions?

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prediction?

5200 rpm
44mph

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Interesting. Moving up a notch unloads it, adding the pitch and the T-top enclosure loads it. I'm expecting 5600 RPM and 45 mph top end, though that's only a target for my real goal of 25 mph/6 mpg. 6 mpg would not be likely but it is the goal.

Though I wouldn't be surprised if the wind resistance of the T-top enclosure and the 18P load increases equaled the 1 hole up decrease in load and I stay at 5600 RPM, 42 mph. Even there, I would hope for an increase in mpg in the mid range of 20-30 mph where I use the boat.

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44 MPH at 5400 RPM.

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Same RPM and 5% increase in top end. That would be pretty good with the T-top enclosure.

Do you think it will increase my mid range, 20-30 mph, mpg?

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Got the boat back, 4/5 holes vs. 3/5 holes. They didn't change the prop to the Enertia P18 as it was back ordered.

The canvas wrap is back on also. Love the wrap. I can go out in shorts and be comfortable even in the cool evening wind...wind...what wind?

A rough day on the river so I didn't do any speed trials. But testing for most efficient cruising speed, 3460, 26 mph was consistently giving me 5+ mpg. A nice easy speed in the 2-3 foot wind/tide/current chop both running into it and running with it.

Boat seems to get up on plane much faster and no ventilation unless I've got the engine trimmed high.

They should have the Enertia 18P this week. Be interesting to see what a difference that makes.

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I have absolutely no idea what you are talking about here. None.

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Repowered my Outrage 22 with a Mecury 150HP Four Stroke 3.0L

Been using Tom Clark and other's advice on tuning it. Started out with Vengeance 17P prop and motor mounted at 1/5 hole, lowest possible mount of five holes available.

I've been progressively mounting the engine higher and higher 3/5 and now 4/5 with, I think, much better performance and no ventilation. Main goal is mid range cruise 20-30 mph with maximum mpg, 6 mpg the wished for goal with 5.X the realistic goal. Cruising around today with the just raised engine the 26 mph at 5+ mpg up and down river was nice.

Tom suggested some props, Enertia 17P and another person suggested Enertia 18P. So I thought I'd go aggressive with the 18P.

On the wrap, I replaced the original Mills full canvas with a Stryker T-Top and a windshield and side canvas wraps from Bentley's. The T-Top cut my top end from 45 mph to 44 mph and the wrap to 42 mph. But didn't seem to hurt the mid range mpg. Moving the engine up has likely mitigated the wind resistance of the Top and windshield wrap.

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Never heard of that.

Here is the normal that Tom Clark and the rest of the Whaler world use:
http://www.whalercentral.com/articles...cle_id=106

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Not sure the diagram works as I've got five holes and they show only four. 1/5 first hole lowest down. 5/5 last hole highest up. Easier to do X/5 vs those diagrams and if people have different number of mounting holes, provides baseline.

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5, 6, 7, 8, holes etc.. Doesn't matter.

We all have to talk the same language and that is the standard.

You would be trying to start your own language here that no one understands.
That is why there is also a BIA Standard bolt mounting pattern so everyone can understand what it is.
http://www.whalercentral.com/articles...icle_id=82

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The common layman's terms used for describing the mounting position for an outboard motor can be described as follows:

In looking at the top set of mounting holes from the rear of the boat:

0<-----Bolt here referred to as "all the way down"
0<-----Bolt here referred to as "1 hole up"
0<-----Bolt here referred to as "2 holes up"
0<-----Bolt here referred to as "3 holes up"
0<-----Bolt here referred to as "4 holes up"

This terminology is used on almost all boating forums and is known universally.

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It does matter actually. If you don't know how many holes there are, you don't know if the motor is halfway up or all the way up. So a 1/X is more informative way of noting the setting, more precise. A question might arise as to whether the top or bottom hole is one, first hole would be the top hole as the question is "how high is the mounting of the engine?"



Completely different so that example doesn't work. Industry has agreed on a common mounting bolt pattern. They have not agreed (nor do they need to agree) on how many increments they use on vertical adjustments.

For vertical, which is not an industry standard, as long as it describes it accurately, no worries.

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Why reinvent the wheel?

There is an industry standard for increments of vertical motor mounting, it is three quarters of an inch, the distance between the mounting bolt holes in all modern large outboard's mounting brackets.

Remember, it is not the distance above the transom a motor is mounted that actually counts, it is the vertical relationship between the motor's cavitation plate (anti-ventilation plate) and the surface of the water that counts. This is why outboard motor manufacturers offer four or five sets of mounting bolt holes on all their large motors.

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The mounting bolt hole pattern is an industry standard. The vertical bolt holes are not. Similar due to engineering parameters (amount of metal between holes etc) but, as you note, some use four, some use five.

Don't see the description issue as an issue, some do and trying to elevate it to an "industry standard" is a bit of over reach.

Curious...when they say 25" shaft which is an industry standard, that is 25" from where to where?

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Please tell us what manufacturers do not use 3/4" vertical sepertion of the motor mounting bolt holes.

There are none because it is an industry standard. No issue there.

25" shaft means the motor is designed to fit a boat with a transom height of approximately 25". Nothing more, nothing less.

How did the 18" Enertia do?

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Backordered. So I'll have to put it on myself...on the water...that will be interesting.

Hope to do full performance data for the engine three holes up, T-top wrap Sunday and then compare those results after putting the Inertia 18P on.

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Do it all the time, pull up on a sandbar, trim the motor up, get in the water and change the prop.
No big deal.

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Until I drop something in the water and have to come home on the kicker <grin>.

Neighbor has a catamaran dinghy. I put that under the engine and tie it to the boat and it provides a stable work space where anything that drops goes into the dinghy...in theory..but anything over the water is risky bidness.

No data yet but with the T-Top wrap and three holes up.
Top speed has dropped to 41 mph.
Cruising 25-30 is 4.5 mpg.

Boat seems to get up to speed faster and with less bow rise. If engine is trimmed up for running, it will ventilate if I don't trim to level for start.

T-Top and wrap wind resistance has had a big effect, in total T and wrap, about 4 mph and 0.5 mpg. Of course, it's made the boat much more comfortable by blocking the wind.

The center console, T-Top with wrap appears to create a lot more wind resistance and lower performance on boats. Comparing identical hulls (Edgewater 245 center console and dual console versions) the dual console gets 3.4 mpg vs. 2.85 mpg for the center console and that is without a wrap just a half windshield on the center console. The DC did have a hard top.

Take off the hard top and go with a more aerodynamic soft top with integrated arch and I'd bet the DC boat could get to 4 mpg.

We were talking yesterday about making my T-Top wrap more aerodynamic by creating a V using the consoles curved grab rail but it would mean losing my two front cooler seats with back rest cushions and not sure I'd gain much.

First see how the Enertia 18P effects it.

Have to say, I do like where I am with the 150HP and the 22' with the T-top wrap. The 22' and 21 degree V allow me to cruise the windy white capped Columbia in comfort. The 3.0L 150HP is as fuel efficient as it gets.

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You'd think that would be some kind of industry standard as to what portion of the engine shaft (props, cavitation plates,, ventilation plates etc) are below the 25" apex of the hull with the engine mounted at its lowest position.

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Why?