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I have a 175 hp Etec on my 1984 Outrage20.
My motor is mounted at the highest position.
But when I'm going fast and I trim it up it seem like I have to go way up before I can hear it starting to slip.
I'm wondering if my engine should be mounted up higher. Has anyone found this to be the case with a Etec on a similar boat?
If I should raise it up, how can I do it since I'm at the highest position?

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Roger,

There are a lot of variables....
1. Pay attention to your Tach....... The RPM's need to be in the range that the manufacturer specifies.
If you can't achieve the correct RPS's, then you would need to do one of two things.
Raise or lower the motor, or change props...
What are your RPM's at WOT?

We can start from there.

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Thanks Joe,
I haven't done a lot of testing, but so far I have been up to 45.5 mph at 5700 RPM.

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Roger,whats your thoughts on a Jackplate? You would have total control of engine height,find more top end speed and most likely better fuel economy!

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I don't know much about them Jim. Are you using one?

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Roger,I'll be running a 6 inch setback Rite-Hite plate this year.

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How about some pic's so we can see where your cav plate is now in relation to the bottom of your boat?

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Let's hold off on discussing jack plates for a second and understand how the engine is mounted etc. Derwd is correct.

Let's get some information on how the engine is rigged.

1. What is the manfacturer's max RPM's for the engine?
2. Where is the top of the anti-cavitation plate in relation to the bottom of the hull? Above (by how much) at the same level or below (by how much)
3. What is the size and pitch of the prop?

Once we have this information, we can verify you are dialed in or how to change the setup.

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As CBO and Joe mentioned numbers are helpful !I'm not saying you need one of these but I do sense you like I love our toys A quick search showed nothing but performance enhancements for a Boston Whaler V-20 with Jackplate.

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Thanks Jim, That motor is way higher than mine.
My prop is a Rebel 15.5 X 17.

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Arthur:

When you say the engine is as high as it goes, how many holes are above the top set of bolts? Got a photo?

In looking at the Evinrude site, I see

WOT rpm for the engine is 5850
Gear ratio is 1:85

Maybe the prop guys can use this information.

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Here's my bolts CBO

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Is that a hole in the transom below the mount?

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The 175 RPM range is 4850 to 5850. Not much higher you can go, unless you want to change props.

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Arthur -

The bolt positions are definitely not what I am used to seeing. I would guess they just reused the old holes and made it work as best as possible

I have attached a photo showing my engine (rigged in repowered by a dealer in 2003). I have room to go up in both the top set of holes and the bottom slot. See below.

While anti-cavitation plate on the engine appears to be a bit low, you are getting good speed and rpm's. You are only 150 rpm's short of max. If you raise the engine (jackplate or re-drill) you would over-rev unless you change props. Do you want/need more speed? Are you interested in going this way?

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One of the biggest advantages I see in raising the prop is getting it off the bottom a few more inches. This area I live in has shallow spots all over the place. I constantly find myself in 18" or less of water and have to start feeling my way around. Good thing it's all sand around here.
From what I have read, the boat will get better gas mileage and run better if I set it up and back a little.

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Please let the sunshine......... CBO

'Too cold to work on my boat so I am focusing on yours.'

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lol, no that's bondo with a little primer on it. :D

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Arthur -

Getting it higher for shallow water is a good idea.

I would suggest a jackplate just so you can raise the engine without having to re-drill holes. What many have done is use the existing holes in the transom and bolted the jackplate on. Once there, find the position on the plate for your engine where the anti-cavitation plate is 1 to 1 1/2 inches above the keel. You many need to do some measuring to ensure the jackplate is the right size (vertically)

I have heard Bob's is a good brand for this application and not as expensive as CMC and others.

You may find that the bolts in the transom don't line up will with the jack plate. In this case you can drill new holes in the plate.

A second option is a setback bracket. The farther back you go, the more the engine will need to be raised.
I think that, regardless of which option you pick, you may need to change propellers.

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Trimming the engine out until the prop gives is not the right way to test props. What prop is on the boat now? I assume the 45.5 and 5700 was at WOT, pushed to the wall with how many people on the boat? Just you or you and a full tank of gas and several of your best buddies? What do you think your missing with 45.5? Do you want more speed, faster hole shot or better cruising or better fuel economy?

You can't raise the engine, but you can swap the prop, depending on what you want that may be all you need.

If you go with a jackplate or bracket, be aware that it changes the trim of your boat, yes you can possibly run in "skinner" water, but the stern sits lower, the drains that were not under water a rest may be now and you may not get what you want from a performance and speed perspective.

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Actually Kamie, I didn't feel it slip. It just started to sound different when I trimmed it up high. Maybe it was the exhaust making the noise I heard.
I have a Rebel 15.5 x 17 prop.
And it wasn't easy to get up to 5700 RPM in the boat by myself with 1/2 tank of gas. I expect I could raise the motor up a few inches and move it back a few inches and it would get beter gas mileage and my prop would probably be just about right for me and a couple friends and a full tank of gas.
A jack plate is $200 - $300. It wouldn't be the end of the world if I decided I didn't like it.
By the way, how's your prop testing going Kamie?

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I don't believe the Rebel's are know for top end speed. If that is what your looking for then you might have the wrong prop. Other than that, your in the upper end of the range which is good. Determin what your goals are, then Tom would be the best person to suggest props.

My testing will progress, as soon as the boat hits the water. With the current prop she will hit 6000 RPM, so a bit high. The current prop is a 17p Offshore 4 blade. The plan is to swap to the 19P Laser II, and see where the RPM's land, my guess is if I take the engine up a couple more turns, I will land at the 5700-5800 range. which would be just fine. If that is the case, I will swap to a 19P Offshore for my final prop. I prefered the hole shot and handling of the 4 blade when I was testing on the old Merc.

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fuel economy and usability are more important than top speed to me.

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Since I belive the Rebel was designed for the E-Tec and the goals were overall performance and fuel economy you might have the right prop.

From the Evinrude Website:

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I have one question related to the engine height of the Boston whaler 20’. The bottom of the boat seems to be 3” below the cavitation plate. I am wondering if you have any issue getting plane.

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Is it appear to be 3" or have you measured, using a straight edge, with the engine tilted out slightly to vertical?

What make, model and year of engine and prop are you running?