Raised outboard up two holes . . . and WOW!

[Expidia]

After seeing a few mentions in threads of where the cavitation plate should be . . . I had thought it was supposed to be even with the bottom of the boat after taking delivery on this new rig last June.

I've always had a lot of spray no matter where I had the trim set.

I just figured the dealer who I bought my boat from knew what they were doing when they prepared the boat and mounted the motor. WRONG!

After I reading some opinions on tuning the outboards setup, I recently read that the cavitation plate can be tried riding about 1-2 inches above the bottom of the boat for possible better handling. So I figured I'd give it a shot to try and move the outboard up two holes "myself" rather than go back to this same dealer a year later.

Holding a straight edge on the bottom of the boat and out to the plate showed it to be about 1 1/2 inches below the bottom edge thus the reason for the spray in most trimmed positions. I've looked before by eyeing it and it always appeared even with the boats bottom, so I did not think that this was the problem.

I didn't want to go back to the dealer and lose it for a week. So I cut a V in a flat block of wood and set it on top of my small $20 hydraulic trolley type car jack I had. I made the V to hold the skeg from slipping on the wood. Next I used two transom ratchet tie downs and hooked them onto the top loop of the outboard after removing the cover and hooked the other ends to the boats cleats on each side of the boat. This prevented the outboard from falling back once I removed the 4 bolts which go through the transom.

I had my Daughter hold each bolt head with a wrench while I spun off each nut.

Then it was a simple thing to just pump the jack a little and raise the outboard two holes (one might have worked too but I didn't want to have to do this again if 1 hole was not enough).

Smeared a little 3M 4200 sealer on each bolt (was $5.00 a tube at Walmart on clearance so I bought the 3 that they had hanging to stock up . . . sweet price).

Took it out on a lake today and I was immediately amazed. Hole shot was great. Almost no need to do any trimming now and NO SPRAY. No cavitation or ventilation on sharp turns that I was having before. That spray was so bad before in certain trim positions that if two people were seated in the back they would get their backs soaked. Now NO SPRAY at all!

Just thought I'd post this for people that think some of these dealers know what they are doing. This guy was in business for 30 years too, but the tech's that worked on my boat when it came from the factory last June were clearly sub par!

So I've put up with all that spray and wasted gas for the past 200 hours on the water because I didn't know any better until I read about proper outboard setup in the forum and I trusted them to have known what they were doing as Lund dealers . . . Big Mistake!

Took me about 30 minutes to do the job myself. Cavitation plate now sits about 1 to 1.5 inches up above the boat's bottom and I couldn't be happier with it's handling. It's like I just picked up another new boat

Don't know if it also improved my top end speed until I put the OEM prop back on, but I'm sure it will add another 1 or 2 MPH. I still have the higher pitch prop on it since I was going to have 4 people on board today after I test drove it myself for awhile.

Just wanted to send a thanks out to the board because this is where I get most of my good advice and tips from.

 

[Joe_the_boatman]

Re: Raised outboard up two holes . . . and WOW!

Just goes to show no one knows your boat better than you; congrats on the fix and thanks for sharing.

 

[dave11]

Re: Raised outboard up two holes . . . and WOW!

Glad to here it worked. I am thinking about doing the same thing.

 

[Expidia]

Re: Raised outboard up two holes . . . and WOW!

Always keep in mind the safety factor if you attempt this yourself. These outboards are heavy, especially the 4 strokes.

You will need a second person to hold the bolts or nuts from turning, so you don't want the motor to slip and injure them or you.

It takes a while with all 4 bolts to turn the nuts off and back on again when the space you are working within only allows for a quarter to half a turn with a standard socket and ratchet. My bolts were overly long too, so if I had to move any holes again I'd hook up my electric impact wrench to speed things up. But don't go too fast or you will melt the plastic in the self locking nuts, if others have the self locking type nuts.

As above, I approached it from the bottom up using the hydraulic jack method, but after doing it though, definitely the safer way would be to "lift" the motor by the loop under the outboard cover which is why it's there. Since I used a jack, I used my loop to hook tie downs to, so the outboard would not pull away from the boat when pulling the last bolt and slipping off the jack.

You could simply throw a chain over a rafter in a garage or a strong branch that you backed the boat under and use a cheap block and tackle or rachet which can be bought a Walmart or Harbor Freight. Or do it where someone has one of those hydraulic lifts for changing an auto engine.

This would be much safer than the way I did it.

On the setting the dealer installed it (two holes lower) I always had to trim the outboard all the way in before a hole shot. Now it doesn't matter where it's trimmed and once I'm on plane I only have to inch it out just a little to have ZERO spray.

Before I was getting cavitation or ventilation (I don't know which is the correct term) on sharp turns or since I had to have the motor trimmed way out to get rid of some of the spray. I figured I was going to eventually burn out the electric trim because that's all I was constantly doing last season and all of this season until I moved up two holes last Thursday.

When the trim was way up I'd also lose the bite of the prop as soon as the water got a little choppy which would cause the motor to over rev.

So this is why I was leery of moving up two holes as I figured I'd lose even more bite if the prop rode higher. But I got just the opposite result after raising it two holes. The prop bites better in turns, so far.

I don't remember who suggested "before" you try and improve performance by re-propping (maybe Silvertip or TashasDaddy), one should first try and fine tune the outboard for the most efficient height setup.

Whichever forum members have been touting that were absolutely correct!

The second prop I bought a few months ago was for a spare and it was a higher pitch model for the times when I have 4 people on my small boat.

 

[NSBCraig]

Re: Raised outboard up two holes . . . and WOW!

Yeah they call that the x dimension.

It's real important to get that right before you try to dial a boat in.

It seems a lot of people get a boat that's either been repowered or just rigged wrong from a dealer like yours and then spend a lot of effort and money trying to make them work right.

What kind of boat is it?

Did you try any offset ( moving the motor back )?

Just make sure your getting cooling water.

 

[Expidia]

Re: Raised outboard up two holes . . . and WOW!

Yeah they call that the x dimension.

It's real important to get that right before you try to dial a boat in.

It seems a lot of people get a boat that's either been repowered or just rigged wrong from a dealer like yours and then spend a lot of effort and money trying to make them work right.

What kind of boat is it?

Did you try any offset ( moving the motor back )?

Just make sure your getting cooling water.

It's the one listed at the bottom of each message and in my Avatar's picture. A 2007 Lund aluminum with a 40 Merc 4 stroke.

Seems fine now!

 

[tahoeQ4]

Re: Raised outboard up two holes . . . and WOW!

I have a question...

Should the cavitation or anti-ventilation plate be even with the bottom of the transom or the bottom of the boat? On my Q4 the bottom of the boat is a step in and down a couple of inches from the bottom of the transom.

THANKS!

 

[redfury]

Re: Raised outboard up two holes . . . and WOW!

What kind of hull is this...is the transom/back of the boat flat or have a V to it at all? I'm curious, because I get a spray from my 14 ft boat with a flat backed bottom and eventually I'll be powering a V backed boat in the future....I'd be interested to find out so I can reduce my monkeying around time with both boats in the future.

 

[gotboostedvr6]

Re: Raised outboard up two holes . . . and WOW!

i would say that 90% of boats have the outboard too deep moving up one hole almost always helps. as does a setback plate but thats another dicussion

 

[tahoeQ4]

Re: Raised outboard up two holes . . . and WOW!

I have a question...

Should the cavitation or anti-ventilation plate be even with the bottom of the transom or the bottom of the boat? On my Q4 the bottom of the boat is a step in and down a couple of inches from the bottom of the transom.

THANKS!

 

[Irv964]

Re: Raised outboard up two holes . . . and WOW!

Great read, I am going to put this link in the prop topics section as it is discussed over there quite a bit.
My cav plate sits about 3 1/2 to 4 inches above the bottom of my boat, it has the big "V" keel that runs the entire length of the boat so I took my measurement from the bottom of that to the top of my cav plate.
When water skiing behind my boat I can somewhat see my cav plate just above/below the water line which tells me(I think) that I am in the right place as far as height goes...............Irv964

 

[Dhadley]

Re: Raised outboard up two holes . . . and WOW!

If the boat has a stepped or notched transom the motor can be mounted higher. On pad bottom hulls that have a step it's not unusual to hear the guys talk about the X dimension in relation to the propshaft rather than the AV plate. You'll hear them talk about being 1" below or 2" up. They're not refering to the AV plate, they're talking about the propshaft or bullet of the gearcase.

The stepped transom acts like a setback. Generally speaking and to a point, the further back you go, the higher you can go. That's due to a couple of things - first the transom is usually at a negative angle. The further back you go, the further down the motor would be. The other is that water comes off the hull at an upwards angle. To a point, the further back the water is, the higher it is.

Finding that sweet spot is what it's all about.

 

[INJUN]

Re: Raised outboard up two holes . . . and WOW!

I had mine raised when I had to replace the tilt/trim unit. What a difference an inch or two makes.

 

[Expidia]

Re: Raised outboard up two holes . . . and WOW!

What kind of hull is this...is the transom/back of the boat flat or have a V to it at all? I'm curious, because I get a spray from my 14 ft boat with a flat backed bottom and eventually I'll be powering a V backed boat in the future....I'd be interested to find out so I can reduce my monkeying around time with both boats in the future.

Mine is a V going back to almost flat with a center keel and a row of big rivets across the back edge.

I wouldn't start with the large cavitation plate even with the bottom. I'd go up about 1 1/2 inches from the bottom and you may not have to do anymore adjustments.

 

[erlindbl]

Re: Raised outboard up two holes . . . and WOW!

I ran across the same problem myself. I bought my boat from Glastron. It is a gt 180 with a 150 E-tec. You would think they would know how to rig the boat. They rigged it on the lowest setting. The cavitation plate was a little more than a 1/2 below the bottom of the hull. Fortunately a person on the E-tec site noticed the problem on a picture I posted.

I too raised the engine myself two holes as was recommended and the difference was amazing. I picked up over 300 rpm putting me in the recommended rpm range with my 19P prop. The boat handled much better. When it was lower it had a strong pull to the right. When I raised it, the problem went away. Now when running the cavitation plate is just above the surface of the water. I have learned from the experts, the first thing to do when correctly propping an outboard is to get the engine height right. Then you can work on dialing in the correct prop pitch and type.

 

[redfury]

Re: Raised outboard up two holes . . . and WOW!

This is great info....The goofy Aqua Lift 2 hull I've got ( glastron ) isn't flat and it isn't a "V" either...kinda like a flat, V'd tunnel hull....

Seems like we should have some drawings in this thread that show different hull types and the approximate locations for the cavitation plates.

 

[Expidia]

Re: Raised outboard up two holes . . . and WOW!

I ran across the same problem myself. I bought my boat from Glastron. It is a gt 180 with a 150 E-tec. You would think they would know how to rig the boat. They rigged it on the lowest setting. The cavitation plate was a little more than a 1/2 below the bottom of the hull. Fortunately a person on the E-tec site noticed the problem on a picture I posted.

I too raised the engine myself two holes as was recommended and the difference was amazing. I picked up over 300 rpm putting me in the recommended rpm range with my 19P prop. The boat handled much better. When it was lower it had a strong pull to the right. When I raised it, the problem went away. Now when running the cavitation plate is just above the surface of the water. I have learned from the experts, the first thing to do when correctly propping an outboard is to get the engine height right. Then you can work on dialing in the correct prop pitch and type.

That's interesting cause it was the exact same experience I had too relying on who I thought to be experts "the Lund dealer" in setting up my new boat.

Question: a 150 Etec is heavy . . . just for my curiosity, how did you do it yourself? Did you use some type of lift on the top loop?

 

[Expidia]

Re: Raised outboard up two holes . . . and WOW!

This is great info....The goofy Aqua Lift 2 hull I've got ( glastron ) isn't flat and it isn't a "V" either...kinda like a flat, V'd tunnel hull....

Seems like we should have some drawings in this thread that show different hull types and the approximate locations for the cavitation plates.

I thought about posting pics. What I wanted to do was post before and after video of the boat underway. Showing spray and then no spray two holes up.

Now that the cavitation plate is riding in the right position I know what was happening before . . . that plate was dragging along the water like I was pulling a small ski!

Unless you purchase a boat from a dealer on the water they are not going to test drive the outboard's correct height like they should. Basically, my Lund dealer helter skelter bolted the motor on and tossed me the keys to my new boat.

Last season they originally put on a new 2006 30 hp Merc 4 stroke that immediately bogged down so much it would take 100 yards to get it up on plane and that was with having to shift my weight a few steps towards the front of the boat.

I brought it right back to them and they never offered to take it to a river and test drive my complaint. So I said to put a new 2007 40 HP Merc 4 stroke (which is the max for this boat and what was recommended by some forum members).

Just happened too that I read the 2007 40 hp was now made much lighter than even the 2006 "30" hp. I thought my problems were over since it now popped up on plane in 4 feet and only cost me $500 more to go with the newer and lighter and max hp.

That 2006 30 hp was sitting on an opened pallet in the shop and I'm sure now that he gave me a deal on that motor because it was a bounce back from another boat they had sold. Who would ever think a new and used "boat salesman" would ever lie to you

But I always had lotsa spray even with the max motor and it was a pain to constantly have to keep looking back adjusting the trim to lessen (never could eliminate) the spray.

Several months later I saw the tech/salesman and he said the person he sold my 2006 30hp too had similar problems and said when he (the tech) took it out on the lake he found that the motor had linkage problems and that's why it was not getting up on plane quickly.

A month ago, some dealer in NH called me as the person was now trying to trade that 30 hp motor back to him for another one.

So the bottom line is this Lund dealer never tested my setup or they would have known about a "supposed" linkage problem and the incorrectly mounted outboard' height on my new one. But they never test drove either motor. They just dumped the motor on another customer.

They even mounted the boat incorrectly on the trailer with an incorrect tongue weight. When I would unhook it from the ball the tongue would start to rise up and the outboard's skeg would hit the ground. I finally had to bring the boat down to the river, float it while I moved the axle back one hole on the frame which now gave it the manuals 5-7% recommended tongue weight.

Scary thing is this Lund dealer after 30 years, was now selling his dealership and this same tech/salesman who couldn't setup my boat correctly got a new job as a REGIONAL Lund Rep!

If that isn't THE BLIND leading THE BLIND . . . I don't know what is???

If it were not for me reading through various the threads here and asking questions, I would not have ever known things were set up incorrectly with my new boat and would have blamed Mercury or LUND for poor design.

I still blame both of these manufacturer's for the **** poor training they give to their so called "certified" tech's.

 

[erlindbl]

Re: Raised outboard up two holes . . . and WOW!

Expidia, I placed a block of wood under the bottom of the bracket and used a floor jack. I took out the top two bolts and just loosened the bottom two. I had a helper and held the outboard flush against the back of the boat as I jacked it up.

It went very smooth. I then resealed and installed the bolts. The whole thing only took about 15 min to do. It was much better than taking it back to the dealers who rigged it wrong in the first place. I got the torque numbers from the E-tec guys. I would have to look it up but I am pretty sure they were torqued to 40lbs.

 

[Expidia]

Re: Raised outboard up two holes . . . and WOW!

Expidia, I placed a block of wood under the bottom of the bracket and used a floor jack. I took out the top two bolts and just loosened the bottom two. I had a helper and held the outboard flush against the back of the boat as I jacked it up.

It went very smooth. I then resealed and installed the bolts. The whole thing only took about 15 min to do. It was much better than taking it back to the dealers who rigged it wrong in the first place. I got the torque numbers from the E-tec guys. I would have to look it up but I am pretty sure they were torqued to 40lbs.

Thx, that's the method I used too. But I never thought about proper torque. I'll email Merc for their torque specs on an aluminum transom.