Next... raising the motor

[jayw]

Hey folks, I need your help. I need some thoughts on another factor in the eternal propping equation - motor height.

In speaking with a number of people about all this propping biz, it's been recommended more than once that I raise my motor. I didn't give much thought to it until recently, but I'm really starting to think it may be making a big diff in performance AND fuel economy.

With the 15.25"/15.3" diam. SS props I can literally trim half way up the gauge, and only slip a bit on turns. Drop down to 3/8 up the gauge and pretty much that's safe WOT and turning, even under light load. With my spare 14.25" aluminum I'm still around that 3/8 (mid way between half and 3/4) mark on the gauge. Turning results in a small burst of RPMs but I don't lose grip.

After conversing with a famed prop shop in Burlington WI they strongly suggested I raise the motor. When I got the boat the dealer told me that JC provides the engine hole height for the specific motor. but I got to thinking, how can they know exactly where to put the engine unless they know the style/size of the prop and your typical load type? I think they may just play it safe, more for the dealer's benefit than the buyer.

The way it was explained to me, because I can trim so far up and still have so good hold, it's worth trying to raise the motor. Unfortunately I can't do it myself, so my marina will do it. It's about $100 a shot, and it's a trial and error thing, so I'm hoping to get lucky.

My question is this: is 3/8 up the trim gauge a lot? 1/2 way? I was told by the guys in Burlington that means the engine's energy is being misdirected, since the trim doesn't translate 1:1 into bow lift. More you have to trim, more energy gets pointed down and not horizontally. If that makes sense.

I plan to call the marina today to ask them to raise the motor, unless there's compelling evidence to the contrary.

Thanks all.

[teecro]

Raising the motor one hole at the time is generally the first step you want to take in maxing out speed and burn... This is also generally free as most people can find the means of doing it themselves. Two men and rolling floor jack can get the job done with little fan fair and if you should happen to be friends with someone with an engine lift your golden...

[smoker62]

With someone else driving the boat , run at top speed at your neutral trim angle or best mph. Look at your cavitation plate , it should be on top of the water surface . If it is not out of the water it is too low. Read this, it applies to most applications.
http://www.veradoclub.com/smf/index.php?topic=137.0

[Bamaman]

It's all trial and error to get to top performance.

Raising the motor 3/4" is a quick and easy project if you have a cherry picker or engine hoist. But you've also got to have the factory ring usually to lift by the top of the engine. Those that just use a set of straps on the bottom half of the cowling will crack it.

My Bennington's engine is mounted 1 notch or 3/4" above the transom. And with the right prop, I get just a little ventilation @ 3/4 up on the trim gauge--just like I like it. I'll trim it down 2 seconds if I need to make a sharp, fast turn--which is something I really seldom do. I mainly keep the engine at the same trim all the time.

[Xcursion]

i've been messing with the motor height myself.... You can move it with 2 guys and a floor jack... i have found a bottle jack and a 2x4 work the best.... put the jack on the ground and a 2x4 from the jack to the bottom of the transom bracket ....remove the top 2 bolts and loosen the bottom bolts and jack it up ..... It was almost too easy... I chose this method cause i was at the ramp making the adjustments...

I ended up 3" above the transom... 2014 25' Xcursion

[jayw]

This is helpful stuff, thanks guys. Unfortunately for a project like this I have the boat in dry stack storage, I don't even own a trailer. It won't be possible to do alone. I'll need to pay the marina their $100. Kind of a bite in the shorts but it would be worth it if it improves.

Afterthought: in theory does raising the engine change stern lift? i would guess it changes it 3/4" but that may not be right.

thanks all

[Bryden24shp]

Raising and lowering the motor will not change stern height. Just the depth of the L/U in the water. Different prop rakes and the configurations can change stern height. There are so many on the market, stern raisers, bow lifters Ski boat profiles which are designed to run flat and throw wakes. This new prop I ran, lifted the stern almost 3 inches over my Enertia. I could lower the motor 2" and probably be a bit faster, I can hear the prop blades striking the water, which is very hard on the prop. Unless they sent me a surface piercing prop. But I still have no idea what I am running. Looks like a cross between a Mirage Plus and an Enertia.
I'll be running with 2 other couples tomorrow night, so I can give it a good load test and play with it some more.
I used to lift/lower mt Etec all the time with a floor jack and buddy, but this Verado weighs in at 635 pounds. I use my lifting ring and cherry picker for this one.
Yep, your in a pickle with no trailer. Dry Stack storage is nice, until you need to do maintenance work. I would look at jack plates, if I were you. I still need to get one, but this summer is being devoted to the new shed.

[jayw]

I never heard the trick about checking the cav plate. I did yesterday, with the aluminum prop its right above the water line. I attached a video, slowed speed, sorry the quality could be better was bad it was really choppy and windy and I was worried, my wife was driving and she never drives. We were doing about 5000RPM. I had one eye on the camera and one on her. Anyhoo you can see the cav plate riding at the water line.

http://youtu.be/1MoSdAl1bF8

In any case I am questioning the conventional logic of the cav plate. I think it's a good starting point, but with varying prop diameters and prop characteristics who knows. Example, a 13" prop has a 6.5" radius. A 15.5" prop has a 7.75" radius. You are 1.25" deeper every turn with the wider prop. ALso if you have a stern lift prop, or a prop that has better grab, 3 blade vs 4, etc.

Jack plate is a good idea, but next yr I plan to do strakes and the thought of yet another $1000 isn't appealing.

My conclusion is this: for the aluminum prop the motor is probably OK where it is, I can trim 1/4 up the gauge and still hold solid even on hard turns. but the Mirage Plus could probably use 1 hole up. When it comes back Thursday I will r e-test. Perfect timing as I have an appt week from Monday with MY marina to raise the motor. Worst case is, I pay again to lower it. Sucks but still cheaper and less hassle than the trailer.

Here's something interesting. Yesterday I went to another marina with the boat as our on-water marina is 2 weeks out with work. I had an appt to raise the engine. Turns out it was too windy and he didn't want to lift the boat but that's fine, it was really choppy. But the owner, standing 150 ft away looks at my docked boat bobbing in the chop and says, "your motor looks high enough from here". Huh? This is a guy with 30 yrs as a marine mechanic. I said "I have a ton of room to trim, I may still raise it". he just looked at me and laughed arrogantly before walking away. Won't go back to him for anything.

I'm OK not working on the boat. It's a minimal inconvenience. Adding the trailer and pulling it around adds different hassles, so this is really the best setup for us. When we move to AZ maybe we get a trailer. Til then, it's good as is.

[rockhound]

Video looks like you are where you need to be,

[RcgTexas]

Video looks like you are where you need to be,

Yep! , but its still a free country, raise it a notch and see. Lowering is real easy just take out the top bolt loosen the bottom till she will slide down a bit. Catch it with a center punch, and tighten both and secure with lock nut.

[jayw]

Thanks. Yeah when I looked it seemed the plate was where it should be by the common school of thought. That was my first inclination. I definitely appreciate the opinions. But talking to Rich Junker and John Janaky bth suggest I raise the motor. And the Mirage has so much bite at this hole I feel I have to try. If it bombs I have it lowered. Again not really in the position to do ithe work with the dry stack storage and no trailer but I figure, it's a one-time make or break shot.

I am not sure the Suzuki 14.25 diam. aluminum prop will like it, but that prop is on its way out anyways. I am gonna buy a 4 blade Turning Point Legacy as backup, which is sure to have way better bite. And little flex. May have more stern lift than the 3 blade AL but not as much as the SS Mirage Plus. All guesswork til I run the setup.

I think the cav plate is in an OK place too, safe play, but I may roll the dice on this one. I will post my results soon.

thanks All!