Motor height? Moonlighter?

[wilbur1]

I have a new 115atlss I just checked the engine height this weekend. At Max RPM Trimmed the Cavitation Plate is about 2in. under water, the smaller plate above it was at the waters surface. My ? is how much will I gain in MPH. Is it worth the work to raise it? Its a 20ft. Excel Bay Pro and now runs 37 GPS fully loaded at 5850 RPMs

Thanks Wilbur

[Moonlighter]

With the cav plate that far under water, you will be losing some revs and economy, and response to trim changes.

In my experience, it also affects the whole running stance of the boat and how it generally performs. Getting the height optimised can really make a big improvement in that regard.

I think you are likely to gain a couple hundred revs which should put you closer to 6000rpm, which is where you want to be. Plus it should improve trim response and overall stance of the boat - how flat it sits on the water, turns and lifts onto the plane.

But of course this is all not a precise science, and it is affected to a fair extent by your hull design and the prop you are running. A good stainless Suzuki prop will work at higher settings much better than the standard aluminium prop.

But I would say you are very likely to see good benefits from lifting the motor to the correct height. Being so far down, sounds like lifting it 2 holes to start with would be a fair option. If it was mine, it would be getting done!!

It is not difficult to raise the height. See the sticky thread at the top of the forum re how to do it yourself.

I have added a new post there on how we lift motors at home, using the boat trailer method. This is quite easy to do and can be applied to up to and including the larger 4 cylinder models and even smaller V6's. I lifted my DF115 this way and it was a piece of cake.

Good luck! Let us know what you decide and how it goes.

[Solarman]

If a dealership installed the motor recently (meaning very new motor), and they are near enough, it would be wise to question them about the change, and if it would affect any warranties? They may wish to correct it themselves?

Good luck.

[Moonlighter]

Yes, talk to the dealer. They should be told of the excess depth and be asked to correct the height to the appropriate level. Or at least be given the opportunity.

In the sticky at the top of the forum on props and motor height, I have added a post detailing the method we use at home to lift motors using the boat trailer. It is a quite simple, easy and safe method, provided you get some help and go steady.

[ChrigelKarrer]

Some Suzuki engines - the DF200 and th DF300AP for sure - are trickier to install than others and i have no clue why.

I changed to Suzuki on 3 of my boats from Yamaha and Mercury and both was a unsatisfying job.
On both boats the engine where installed in the same holes and they ventilated like crazy and i needed to lower the engines.
2006 29ft tunnel hull Panga with 2012 DF200 and Suzuki prop, still ventilate if not tucked in
2009 29ft v hull RIB with 2013 DF300AP and Solas 4-blade prop on a bracket, still ventilate if not tucked in
1999 34ft V hull Venture 34 with 2016 twin DF300AP (several props incl Suzuki props tested), still ventilate if not tucked in and ventilate at 3500-4000 rpm
Running the engine tucked in is not harmful but you waste some power as the engine is partially pushing upward (tucked in) instead exclusively forward (parallel to water surface).
Unfortunately i see no way as it is my experience to solve this problem on the desk, the only way to figure out the right engine height is to start to lift it up until the propeller ventilate and break free.

In your case there are two scenarios:
a) Your dealership know the right height and mounted your new engine accordingly
b) your dealership wanted to avoid several try and error scenarios to figure out the right height, so they installed it lower than normal.

My ? is how much will I gain in MPH. Is it worth the work to raise it?

There are several discussions in various forums regarding this argument and the conclusion is - as always - not really clear. It is clear that lifting your engine up to the height where the propeller never ventilate is a benefit,
but the way there can be "spiny".
If you are handy doing some manual work, your boat is on a trailer and have either a fork lift, backhoe or something similar to lift the engine SAFELY up, then go for it.
Just be careful that the engine don't swing back, fall down and be very careful to seal perfectly the holes for the bolts again.

Before you do a kick start:
- call at least one friend with mechanic skills to help you, you need to do this in two, athird one to use the fork lift/back hoe/winch
- check if the holes in the transom are drilled to allow to rise the engine
- buy 4200 or 5200 to seal the bolts and thinner to clean it up
- charge your battery powered (impact) drill and check to have the right sized wrenches, sockets and extensions

Chris

If you opt for lifting the engine, PLEASE make a list of RPM and MPH/Knoths before and after and post it.
This would be a nice before / after information for the engine height treads!

[wilbur1]

I might have to think about this a while. The boat runs great where its at with a good hole shot. If its not hurting anything where its at I might just leave it. But then again its an easy job to do, only 4 bolts and no wires to deal with. I was just planning on using a floor jack under the skeg. If I decide to do it I would call the dealer and find out the Torque spec on the bolts.

[ChrigelKarrer]

I was just planning on using a floor jack under the skeg.

You rather buy a cheap 1000lbs chain winch and hang it on a sturdy beam than use a floor jack.

You will need to push/pull/wiggle the engine in position and doing that on a floor jack poses the risk that the engine flip over.
Outboards get installed while hanging and for this they have attach points under the cowling.

If your engine has a row of holes and a slot where the lower bolts can slide then you may use the floor jack as the engine can't fall of the stern,
but still i would prefer to have the engine tied to something above to avoid that the comes completely off the transom.
Chris

[Marty D]

My motor was the same as yours. The plate was under water and the first plate was at water line. I came up 2 holes. My rpm was 5700 now 6000. My speed was 40. Now 44. It's the gas miles that was 1.8 to 2.2 now 2.8 to 3 I can be 3500 rpm cruise now. Was over 4000 rpm. Use boat life for the motor bolts. It's for under water. The 5200 gets to hard. You will be very happy with your speed, gas miles and your cruise speed.

[Marty D]

I might have to think about this a while. The boat runs great where its at with a good hole shot. If its not hurting anything where its at I might just leave it. But then again its an easy job to do, only 4 bolts and no wires to deal with. I was just planning on using a floor jack under the skeg. If I decide to do it I would call the dealer and find out the Torque spec on the bolts.

Your motor is smaller. If you do it, try to get two more guys. One for each side of motor and you jack it. It will be easy. I ask my boat yard for there fork lift. Pay him $50 plus lunch. Do it!!!!! You will be very happy.

[Solarman]

The skeg, and all fins on lower end are aluminum! A floor jack is very bad idea!

Go to a rental center, a rent an engine lift, this would be the smart way. This $35 cost could save you almost $4000 in repairs, it is worth it.

Good luck.

[Marty D]

The skeg, and all fins on lower end are aluminum! A floor jack is very bad idea!

Go to a rental center, a rent an engine lift, this would be the smart way. This $35 cost could save you almost $4000 in repairs, it is worth it.

Good luck.

I miss that part. Do not lift it like you said. Rent one, just make sure you have the height. You know a Mech. Will charge less then one hour labor rate. It should be around $100 to do it.

[wilbur1]

I have a hoist also, but its at a different garage. If I go get it that would make it a one man job, I can do by myself.

[wilbur1]

My motor was the same as yours. The plate was under water and the first plate was at water line. I came up 2 holes. My rpm was 5700 now 6000. My speed was 40. Now 44. It's the gas miles that was 1.8 to 2.2 now 2.8 to 3 I can be 3500 rpm cruise now. Was over 4000 rpm. Use boat life for the motor bolts. It's for under water. The 5200 gets to hard. You will be very happy with your speed, gas miles and your cruise speed.

Thanks Marty D I think you talked me into it. Wouldnt just plain Silicone work on the bolts? Looks to be whats on it now. I was talking to a buddy at work and he said the same thing 3-4 Mph. That would make the effort worth it. Do you think I would need a different Prop? Its 5850-5900 right now.

Thanks again. All of You.

[Marty D]

Thanks Marty D I think you talked me into it. Wouldnt just plain Silicone work on the bolts? Looks to be whats on it now. I was talking to a buddy at work and he said the same thing 3-4 Mph. That would make the effort worth it. Do you think I would need a different Prop? Its 5850-5900 right now.

Thanks again. All of You.

They say. Move motor first. Then do prop. Do the motor first and see if your numbers are good. Use boat life. I did put a 4 blade on. Only because I have a 2005 Parker. Ass heavy!!!! I will call you. I'm up in New York, my mom is in the hospital.

[Marty D]

Your rpm are almost there. What does the book say for your motor? 6100 max ? Your going to be at 5900-6100 after you up motor. Do not come up more then 2 holes.