# Jacked-up 10-15 HP



## WhiteDog70810 (May 6, 2008)

My mudmotor has got to go. It has an upgraded muffler and it still spooks ducks 400 yards away. Once the motor spooks them up, that spot is burned for hours in the late season. I've seen this in Louisiana and now Maryland. 

I have to pursue a stealthier approach and I've needed to buy an outboard anyway. I am usually one the guys that tells others that setting a small outboard up to run shallow is an expensive boondoggle, but guess what? I need a small outboard that can run shallow. I don't expect it burn through mudflats and I'll idle with it tilted in shallow water drive at dead low tide, but I'd like to get the prop high enough on plane to only hit half of the stumps in my marsh the rest of the time. I'll probably use a River Runner skeg guard to protect my prop.

I will be getting a 4 stroke 9.8-9.9 HP and I have a few questions.

1.) What is the highest you got the cav plate of your 10-15 HP motor relative to the transom of a light, narrow, flat bottom, non-tunnel boat? ...at what setback?

2.) What accessories (4 blade/cleaver/cupped prop, compression plate, low water pick-up, pods, tabs, jackplate, etc) did you add to get it that high? Which had the biggest impact?

3.) Does jacking up a outboard make it louder? It doesn't do me any good to replace the loud mudmotor with an outboard that is popping because the exhaust isn't submerged enough.

Don't tell me how shallow you run; I won't believe you. Don't tell me I really need a tunnel hull; I ain't gonna get one. Don't tell me mudmotors don't spook ducks; the ducks say otherwise.

I already have a manual jack plate with 4" of setback and 4" of vertical travel. After the skeg guard, I suspect I'd get a cupped prop next unless you tell me otherwise.

Nate


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## Brett (Jul 16, 2008)

Minimum running depth will be draft at rest plus distance from anti cav plate to bottom of skeg.
You will need a cupped prop with the cav plate at 3/4 inch above the bottom of the hull when resting level on the trailer.
3/4 inch is that 6 degree running angle, remember?
Minimum idle depth 8 to 12 inches.


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## RunningOnEmpty (Jun 20, 2015)

Find a good ole boy to weld up a custom muffler.


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## Matts (Sep 2, 2015)

You are wasting your time with that size motor and wanting to run shallow. I’d just get the muffler fixed. I hunted ducks for years with a 1981 11 HP, long tail go devil and it was quiet. Besides, running jacked up in a stump field is a bad, bad idea.


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## WhiteDog70810 (May 6, 2008)

The best you can hope for is a mudmotor that is only as loud as a "quiet" lawnmower. Mine is already there and the ducks don't like it. The little 4-stroke outboards are about as loud as a sewing machine. My boat doesn't work well with a mudmotor anyway, so the mudmotor spooking ducks is just one last kick in the crotch.

I'll have to stick to the channels with an outboard, but I already do that to the greatest degree possible because there is so much sand. I'll have to pole more with an outboard and that is okay. I have no expectation of running on plane in 6" of water or other such foolishness. We have a few stumps in our channels, but it isn't a stump field. I know where most of them are, but there are a couple of ninja stumps who move around.

Nate


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## SWFL_Gheenoe (Aug 24, 2017)

I run my 30 2 stroke about 3.5" above the bottom of the hull, moderate cup in the prop and it blows out a bit until youre on plane then it hooks. 
Dont have any problem with water pickup, but id imagine that im pushing that edge. 
I run a Bobs stabilizer plate to help with holeshot, and feel that it helps a bit with the blowout as well. 

The tiller will want to rip out of your hands if you run a heavily cupped prop jacked way up. The difference from 3" to 4" was exponential.


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## WhiteDog70810 (May 6, 2008)

Brett said:


> Minimum running depth will be draft at rest plus distance from anti cav plate to bottom of skeg.
> You will need a cupped prop with the cav plate at 3/4 inch above the bottom of the hull when resting level on the trailer.
> 3/4 inch is that 6 degree running angle, remember?
> Minimum idle depth 8 to 12 inches.


I am hoping that I might be able to get the cav plate higher than 3/4" above the bottom of the transom with the right prop and possibly a compression plate. I don't expect an outboard to perfectly replace a mudmotor, but every little bit of height protects the prop a little bit more.

Nate


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## WhiteDog70810 (May 6, 2008)

SWFL_Gheenoe said:


> I run my 30 2 stroke about 3.5" above the bottom of the hull, moderate cup in the prop and it blows out a bit until youre on plane then it hooks.
> Dont have any problem with water pickup, but id imagine that im pushing that edge.
> I run a Bobs stabilizer plate to help with holeshot, and feel that it helps a bit with the blowout as well.
> 
> The tiller will want to rip out of your hands if you run a heavily cupped prop jacked way up. The difference from 3" to 4" was exponential.


What is your setback? Is the JP manual? How much top end speed did you lose with the cupped prop? I am not a speed demon, but I like to know what I would be sacrificing.

Thanks,

Nate


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## SWFL_Gheenoe (Aug 24, 2017)

Yeah I have a 7" offset Vance JP, which leads to about 14" of setback from the leading edge of the cav plate to the back of the transom (if I recall correctly)
Im still dialing in the prop/motor combo, and will ultimately end up with a different prop. But as-is I probably lost 2mph and 200 RPM's. 

On the flip side, youre able to run a cupped prop a bit higher than a prop with no cup, so that will allow your RPM's to come back up (somewhat)

Im by no means a prop genius, but this is what ive gathered!


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## Brett (Jul 16, 2008)

Remember, height of anti cav plate above bottom of transom
with boat sitting level on the trailer
doesn't give the height above the transom when on plane.
Bow rises about 3/4 inch per foot of hull length.
That's that 6 degree running angle that planing hulls have.
Bow goes up, stern goes down.
Any thing aft of the transom goes lower, 3/4 inch per foot from the bottom edge of transom.


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## SWFL_Gheenoe (Aug 24, 2017)

Brett said:


> Remember, height of anti cav plate above bottom of transom
> with boat sitting level on the trailer
> doesn't give the height above the transom when on plane.
> Bow rises about 3/4 inch per foot of hull length.
> ...


I dont disagree with that as a blanket statement, but in my specific case, I disagree. 
Im running on a Gheenoe, and there is next to now bow rise. Especially since my engine has a few degrees of negative trim, keeping the bow down further and helping holeshot/squat. With the stabilizer plate helping even more so. 

What youre talking about is definitely more noticeable on larger/heavier hulls though.


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## Brett (Jul 16, 2008)

Measure that angle for me on y'er noe, please.
I like hard numbers, every bit of data helps.
Running angle is critical to optimum planing speed.
Too high you plow, too low and wetted surface drag is a problem.

Side note, even noes show that bow lift of 5 to 6 degrees.
Take a look at pics of noes running on plane.


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## SWFL_Gheenoe (Aug 24, 2017)

Wasnt able to get the motor down low enough to make the measurement easy with a set of triangles... But hopefully you can visualize a couple of degrees here.

https://photos.app.goo.gl/GlgjFvmCKd3HuDOh2


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## Brett (Jul 16, 2008)

If that is your "tucked in" normal running angle on your outboard
You are at the 3/4 inch above the transom when running, from what I see.
I'm assuming the straight edge is the underside of the hull extended aft.


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## SWFL_Gheenoe (Aug 24, 2017)

I lowered the JP so it would be easier to see the negative trim. Usually run with it 3" higher than that.


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## Brett (Jul 16, 2008)

Copy that. Measure your running angle if you get a chance.
Inclinometer or ******* angle checker...

https://www.microskiff.com/threads/jack-plates-yes-or-no.2715/page-2


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## WhiteDog70810 (May 6, 2008)

Brett, 

Did you ever GPS the Slipper with that 9.9? I honestly don't know what speeds to expect and the Slipper is the closest hull to mine that ever used a 9.9. Everyone else runs a bigger motor. I'd like the upper teens and I'd be estactic if I got the low twenties, but it can plane around 11-12 mph.

Nate


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## Brett (Jul 16, 2008)

22 mph with just me aboard
20.5 mph with 2 people

averaged speed 4 passes up and back in a marked channel


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## WhiteDog70810 (May 6, 2008)

Awesome! Thanks. With a rock guard and cupped prop, I'll likely be in the high teens.

Nate


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## jimsmicro (Oct 29, 2013)

I recommend staying away from any of those rock guards, they only add weak points IMO. As far as noise once jacked up you should hear the difference on my tunnel hull. At the top of the jack plate and trimmed up it really starts to "gurgle" and you can hear the RPMs raise up.


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## free88 (Apr 18, 2017)

"Don't tell me how shallow you run; I won't believe you."

That's pretty much it right there. Absolute truth.

Getting a boat to run as absolutely shallow as possible and getting it to be a mostly useable boat is varying conditions are largely two opposing goals. You can get a boat like this to run super shallow, but then you cant turn, or carry a second passenger, or be able to trim the outboard up or down, etc. It would have to be set so precisely and with definite purpose that the boat would suck at trying to do anything but run as shallow as possible in a straight line under the most ideal of ideal conditions with almost no load. This is where people get their "this is how shallow I can run" numbers. Of course, they cant leave the boat set up that way. Its an unusable boat. So then you ask how shallow can you run while the boat is setup to be actually useable and they greatly resist telling you those numbers, as they are just not as sexy.

Realistically, 14-16 inches is the shallowest you can run on plane with any boat with an outboard. Just can't go less. Its impossible. You need to be able to accommodate different loads, i.e., one, two, three, ..., passengers. You need to be able to operate in a range of water conditions. You need to be able to turn, and so on. In order to do those things, you need to be able to use at least several outboard trim settings (or a range of trim), trim tab settings, etc. In order to be able to do those things, you can only go so high on the outboard and its considerably less than the highest you can go for that sensational number you tell everyone. 

On my Gheenoe 15 4, I have a manual 4.5 inch setback JP. I have it set so that the anti-cav is about 1.5 inches above the keel with the outboard trim neutral. That is about the highest you can go and still have a useable boat. I have no trim tabs, no special prop, no fins. I can run at 2.5 inches up and outboard trim all the way in and not overheat or even blow out on turns, but no other outboard trim positions would be available to me, and, therefore, I cannot accommodate a passenger or other loads. Doubt trim tabs or a fin will get me any more. On my KW 210BR, I have hydraulic 6 inch setback JP. I have it set that with the JP full down the anti-cav is about 2 inches above the keel with the outboard trim neutral. This is about the highest you can go and still have a useable boat. I have trim tabs, no fin. I can jack up about 1 inch on plane at cruise and still a small range of outboard trim and trim tab are available to me, but it becomes very dependent on load and conditions and you cannot turn sharp. 2 inches up (on plane at cruise) and it is very tight trim settings range and you almost cannot turn. 3 inches up (on plane at cruise) and its has to be a specific outboard and trim tab setting(s) along with near perfect conditions and no turning. On a boat like this JP's are basically full down on plane and full up at idle/slow speed, and you really don't care about the in between.


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## jonterr (Mar 24, 2013)

14 to 16 inches is as shallow as any outboard will run???
A lot of guys will dispute that!
I'm one !


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## free88 (Apr 18, 2017)

Ok. Good luck with that.


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## WhiteDog70810 (May 6, 2008)

Honestly, I think Free88 speaks the truth about setting an all-purpose built boat to run shallow. 14-16 " is usually the distance from the cav plate to the bottom of the skeg. A cupped prop may get you an inch or maybe two higher, but heavy cupping has it own detriments. Unless you have a way to lift or direct water to the prop (tunnels, tabs and sponsons all do this to one degree or another), you really are limited thereafter. 

His point is that you can set an all-purpose skiff up to run somewhat shallower, but the skiff becomes finicky about load and cornering at extreme settings. My understanding of physics tends to lead me to think he is right. My hull doesn't have any of the features that are used to run shallow except a flat bottom. It really takes a power JP and power trim to tweak the motor to accommodate the load. I won't have that because it is too complex and heavy. Trim tabs help feed water to a high prop. I won't have them because they will get in the way when I push the hull backwards through mud after I inevitably beach myself. 

I will set my motor height over a couple of weekends and never mess with it again unless I change my prop. I will always pick the conservative height based on a heavier load. I knew I could get the cav plate 1" above the bottom of the hull and was hoping to get it 2-3.5" up if I got a cupped prop and maybe a compression plate. I never realistically expected any more height than that.

There is no question you can set a hull up to run in 6", but such a hull looks like the XF20, not a flat-back pirogue. You need a pocket tunnel to feed the high motor. You need the width to provide lift and counter the loss of displacement from the tunnel. You need the length to counterbalance the power everything hanging off the stern. You need a low water pick up to keep the water pressure up. You need a more extremely cupped prop to run in the highly aerated water "fluffy" water coming out of the tunnel. My little hull is not made for such extremes.

Nate


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## free88 (Apr 18, 2017)

Whitedog,

Yes, having a hydraulic or similar jackplate does provide for quick and easy adjustment given loads and specific conditions you encounter. Same on the trim tabs. Same on the outboard trim. You'll be lucky (or unlucky depending on your philosophy) on these smaller boats to have any of those be powered somehow. Lucky means you get to adjust on the fly and you like adjusting on the fly. Especially beneficial if you load out quite differently every time you go out and/or run in greatly varied conditions. Unlucky means you just added a whole bunch of unnecessary weight and complexity and you are running deeper than you could possibly adjust for. Complex things tend to break more often, too. IMO, in general, you are better off simple and manual on smaller boats with lower HP like these. Its not a question of cost. Its a question of what is better. 

Being conservative, as you say, is the best way to set this up for sure. Your outboard will definitely last longer. Your overall boating experience will also be better. Find that conservative high sweet spot and leave it there. Its probably 1 inch down from the highest you can go. That 1 inch is not a thing. It will make no difference in the real world. 

Talking about cupped props, hydrofoils, and like items. In real life, for every time I have seen them used with success, I have seen a case where it only caused more problems. On the internet they work 110% all of the time. In real life, eh, not so much. My Gheenoe maybe might see at least one of those, but only if I have to. My bay boat will not be getting either, at least not while I own it.


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## CPurvis (Apr 6, 2016)

free88 said:


> Whitedog,
> 
> Yes, having a hydraulic or similar jackplate does provide for quick and easy adjustment given loads and specific conditions you encounter. Same on the trim tabs. Same on the outboard trim. You'll be lucky (or unlucky depending on your philosophy) on these smaller boats to have any of those be powered somehow. Lucky means you get to adjust on the fly and you like adjusting on the fly. Especially beneficial if you load out quite differently every time you go out and/or run in greatly varied conditions. Unlucky means you just added a whole bunch of unnecessary weight and complexity and you are running deeper than you could possibly adjust for. Complex things tend to break more often, too. IMO, in general, you are better off simple and manual on smaller boats with lower HP like these. Its not a question of cost. Its a question of what is better.
> 
> ...


Agreed! I have always liked simplicity. But for some reason I just had to have an Atlas micro. But now that I have used it for awhile I feel I could have saved the 800 bills and the 25lbs off the back. My thought process was that I would go with a Jack plate instead of T&T. I now know I could have lived without either like I always did before. My advice is to keep a small boat simple and efficient.


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## Boneheaded (Oct 4, 2017)

Just keep the motor tilt unlocked.


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## free88 (Apr 18, 2017)

CPurvis said:


> Agreed! I have always liked simplicity. But for some reason I just had to have an Atlas micro. But now that I have used it for awhile I feel I could have saved the 800 bills and the 25lbs off the back. My thought process was that I would go with a Jack plate instead of T&T. I now know I could have lived without either like I always did before. My advice is to keep a small boat simple and efficient.


They all seem like great ideas, and each have plenty of merit. They do have their place on some boats. Smaller boats, though, tend to be a lot more sensitive to weight and weight distribution. We all have to make informed decisions on what is worth the weight and what is not, and be very exacting with these decisions. 

I went with the Vance JPL2412SB 5 inch setback jackplate in anodized black. I modified it to only be 4.5 inch setback (you could actually go down to just over 4 inches if you really wanted to), and had to further modify it to accept the lower mounting bolts for the outboard. Other than that, I absolutely love it and would buy another for a smaller boat in a heartbeat. Simple, strong, light, great finish, awesome price (with or without color). I also like the Bob's Mini Jackplate, but the Vance is head and shoulders a better design, IMO, and for no extra weight.


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## WhiteDog70810 (May 6, 2008)

I should have bought a Vance. I paid more for materials to make my own than the Vance cost.

Nate


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## free88 (Apr 18, 2017)

I really, really wanted to make my own jackplate (or transom riser) for the Gheenoe. For me, this is part of boating. I like to make my own parts, install my own systems, gear, etc. I am not one to buy a boat with all the goodies installed. I prefer to DIY all or most of it. But the Vance is just so well-priced and well-designed that it is very hard to pass it up. I do not feel like I could have made something as good as the vance, and certainly not for that cost.

The pictures show it jacked all the way up. I have since lowered it about 1 inch. These come with a 1 inch starboard (white) where the outboard mates the jackplate. I replaced that with 1/2 inch starboard (black), and then 1/2 inch starboard on the other side so the clamps have enough width to clamp securely. This reduces the setback to 4.5, which I feel is in the right direction for the 15 4. These settings result in a vertical gain of about 4 inches vs just mounting the outboard directly to the transom, if I recall. Like I said before, it will run as pictured (except the outboard pretty much has to be trimmed in all the way, its trimmed neutral in the pictures) with no overheating, no blow outs, etc. I would rate that a poor setup, though, for all-around boating. Yes, it can technically run, but not well. If you are getting a 10HP outboard, it will probably have about the same anti-cav to bottom of skeg fin dimension as my Merc. Also, whatever jackplate will still get you the height as long as you mounted up high enough on the transom. I am sure your on your boat you can get some pretty shallow running without too much fuss. Could take several runs to dial it in, but you will get it in no time.


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## WhiteDog70810 (May 6, 2008)

free88 said:


> I do not feel like I could have made something as good as the vance, and certainly not for that cost.


Nope, you can't beat the Vance price without your own machine shop with a pile of "already paid for" aluminum scrap in the corner to play with and the experience to use them. I was able to get a favor from a machinist with a mill to cut the slots. That makes mine function as well as any, but my fit and finish is not as good as a pro's.

I can see where I could raise it up and trim it in during duck season and set it more sensibly during the off-season. I guess this conflicts with my "set it and forget it" philosophy, but if I wasn't going to ever mess with my jackplate, why did I make it adjustable?

BTW, your trailer ain't wide enough.

Nate


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## free88 (Apr 18, 2017)

WhiteDog70810 said:


> BTW, your trailer ain't wide enough.
> 
> Nate


Hehe, nah, it could be wider. Ive got a gulf access property and the bay boat stays on the boat lift. Therefore, this trailer sits empty most of the time. The Gheenoe stays in the garage on dolly's for now. I will probably get a dedicated, small trailer for the Gheenoe closer to the summer. I got to find one just right so I can fit it in the garage. Probably needs one of those folding tongue deals.


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## CurtisWright (May 9, 2012)

With a 4 blade Ptec I can trim the motor all the up to the "fast part" of the tilt trim range without porposing or blowing out. At this point, the entire prop and water intake is above the bottom of the boat. I can run almost anywhere there is water. I need about 2" to keep the tunnel full without suctioning to the bottom. Also, I have time to trim up. Its really cool, you feel the back end of the boat come up, your wake disappears, and you kinda lose control. The hull starts skimming on the boundary layer effects.

I need about 12" to get on plane. If you chicken out in 2" of water and let off the throttle you come to a screeching halt.


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## CurtisWright (May 9, 2012)

Also, I agree. Mud motors are the Harley Davidson of boat motors. They look cool, and are fun, but they are annoying as hell for everyone except the person driving it.
Whenever I see someone driving one, I always think of the South Park Harley Davidson episode. haha


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## firecat1981 (Nov 27, 2007)

Maybe it's already been suggested, but what about upping the hp and going jet drive? Seems to me that by the time you buy an outboard, buy a few props, jp, nose cones..... you could buy a jet for the same money.


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## free88 (Apr 18, 2017)

This thread went off the rails pretty quick. 

Anyway, Whitedog, good luck with your build. Post some pics when you get there.


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## Brett (Jul 16, 2008)

It's always fun to see outboards on jackplates sitting on the trailer with the obligatory side and rear views showing how high the engine is set up, then you notice the outboard is tucked in and the boat is sitting level on the trailer. If you were to tilt that hull 5 degrees bow up, as if running on plane, then look at where the actual waterline would be as it comes out from under the transom, all of a sudden the amount of setback and tuck angle has minimized your height advantage that you were attempting to gain. Look carefully, think of how running angle changes the geometry and the actual height gained with the jack plate. Most times it's not much.

Before anyone starts claiming their hull runs level, take your boat out, get on plane at full throttle and have somebody take a picture so you can see for yourself what your hull running angle actually is.


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## WhiteDog70810 (May 6, 2008)

I am not arguing your 6-7 degree running angle because I have seen your pics where you measured it, but I was dorking around with my dial protractor the other day just to see what 6 degrees looking like on the trailer. I placed the jack on a big block and cranked it up until the protractor on the sole of the boat read 6 degrees. Damn that looked bow high on dry land. I checked it with the protractor on my phone and they both agreed. I am gonna measure it next time I run the hull to confirm the planing angle holds true.

Nate


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## Brett (Jul 16, 2008)

Every planing hull has an optimum running angle.
It's a balance between minimizing wetted hull surface and limiting drag
while obtaining the most lift without plowing. With trim tabs, power tilt
and a functioning tachometer, you can set the the throttle at about 4300 rpm
then play with trim and engine tilt and watch the rpms slide up and down.
At optimum angle you obtain maximum rpms without changing the throttle position.

As an example of what happens with a jack plate and running angle
I screen snapped the set up previously posted and added a couple lines.

Here's the hull level on the trailer.
Add a horizontal line running aft from the underside of the hull,
it really looks like the setup is way high.











But rotate the image 5 degrees to illustrate running angle
then put that level line back in you can understand what takes place.


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## free88 (Apr 18, 2017)

Brett said:


> It's always fun to see outboards on jackplates sitting on the trailer with the obligatory side and rear views showing how high the engine is set up, then you notice the outboard is tucked in and the boat is sitting level on the trailer. If you were to tilt that hull 5 degrees bow up, as if running on plane, then look at where the actual waterline would be as it comes out from under the transom, all of a sudden the amount of setback and tuck angle has minimized your height advantage that you were attempting to gain. Look carefully, think of how running angle changes the geometry and the actual height gained with the jack plate. Most times it's not much.
> 
> Before anyone starts claiming their hull runs level, take your boat out, get on plane at full throttle and have somebody take a picture so you can see for yourself what your hull running angle actually is.


Obligatory side and rear views must be so old hat to you. LMAO.

I posted the pictures really just to show the Vance jackplate. I know what you are saying. In fact, I greatly minimize the claim of how shallow I can run. I think most people making their sensational super shallow claims, certainly on the webtube, are completely full of it. Part of the reason to install a jackplate on this particular boat (Gheenoe 15 4) is that the transom is rather a crappy mounting surface. The jackplate provides a much better installation surface. Am I running significantly higher than stock? Absolutely, and that's taking into account your rudimentary test setup, and the added weight, and the CG pushed aft (which isn't really a thing on this boat since it is weight sensitive and super easy to just move some weight forward to counter). 

All of the physics of this is pretty well-discussed and people are getting it. It is not special for one to have this understanding, and its become mostly common knowledge. 15-20 years ago, no. But its been a while since jackplates have become popular, and the knowledge has spread. 

I think one aspect that people seem to miss or at least not discuss much is the displaced water effect. When you are on plane you are still displacing water. Yes, on plane, you are tilted up however many degrees and water leaves the bottom of the transom to the rear and the water appears to rise as it gets further back. However, you are displacing water as you go through it. So, if lets say the water depth ahead of you is 12 inches. The water level at the bottom of the transom headed to the rear is not at a 12 inch depth. It is much less, because your boat displaced it down and outward. How much depends on your load, hull type, speed, etc. Assuming boats like the ones we are discussing here (minus the one post that seams to have nothing to do with their thread) on plane at cruise, this is going to be 3-4 inches minimum at the very most conservative estimation in an extremely light boat. Yes, water then generally goes upward from there, but not as much as people think and certainly not close enough for you to exploit that to some great advantage without installing a jackplate setback measured in feet rather than inches (which would be super problematic). Take into account that even the smallest outboards need to be in a minimum of 10 inches water (to run 100% trouble-free), there you go. Making a claim of being on plane in 12 inches of water (context of this thread) is ridiculous. However, perception trumps reality. If you believe it, well, then it must be at least possible. In reality, however, it is not. For there to be 12 inches of water leaving the bottom of your boat (on plane), you have got to have 16 inches ahead minimum (no matter what your running angle is). That means you are on plane in 16 inches of water, not 12 inches of water (your view of the water depth at the transom as it leaves the back of the boat). Bigger, heavier, well, you need more and more. Wider beam to weight ratio counters this a bit, but you are still going to displace quite a bit even in heavily optimized, non-specialized (tunnel, etc.) production boats. This is what largely mutes the whole, well, if you tilt it X degrees and then take a straight ruler and do Y, that's your running depth during event Z, blah, blah, blah. Yes, you get on the water, test, adjust, test, adjust, and so on. Eventually, you will find settings that work best for you. Your running numbers wont be as good as others claim, naturally, because you are not living in a fairy tale. 

I do love hearing fantastical claims, though. Oh, wow, you can be on plane in 2 inches, hugh? Lets do that in a bay lined with indestructible jagged rocks 2 inches below the surface and find out if its true, shall we. You should have nothing to worry about, right? You can do 2 inches all day, LOL. What a joke.


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## free88 (Apr 18, 2017)

Brett said:


> Every planing hull has an optimum running angle.
> 
> 
> 
> ...


Actually, the line placement a the transom on both those pictures is incorrect. The reference bottom of the Gheenoe 15 4 hull is roughly one inch higher than that. You can see it in the pictures. This hull has sort of a keel ridge that you really don't count as the bottom. It has no effect on the plane of the boat.

I know you are just trying to illustrate a point. But, you don't know how my boat is sitting in the picture. You are assuming it is perfectly level in the picture. The hull could already be plus 5 degrees, it could be neutral, or it could be minus 5 degrees. I did say the engine is at what I consider to be neutral trim, but made no such reference to the hull inclination at what I consider to be neutral engine trim. This outboard has limited trim positions that none of which may or may not be exactly neutral in relation to the hull. Therefore, your second picture line could now be plus 10 degrees, 5 degrees, neutral, or whatever degrees, and greatly distorts the truth. How about you not use my pictures to make your "points" or whatever it is that you are doing, since you were not there when these pictures where taken and do not have the information necessary to make a proper illustration with this source material.

Furthermore, actual testing showed that this jackplate position was in fact too high, and it needed to go down about an inch. Also, that the outboard needed to be trimmed in all the way at this height. I stated that when I posted the pictures. Also, I have made no claims as to how shallow I believe I can run with this setup. I still want to test a little more with varying loads and conditions before setting my final height. Maybe I end up having to install trim tabs. Maybe I end up having to use a cupped prop, etc. This will all affect the final setup. I will say that I believe 16-18 inches on plane with this boat is very possible without have to get too aggressive with the mods, and I would be fine with that. I don't know that 16-18 inches can be done yet (on this boat set up for all around boating use, and not just to achieve the absolute shallowest setting). Its a work in progress, as evidenced by the squeaky clean skeg.


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## Brett (Jul 16, 2008)

Picky, picky, picky....









It is the bottom of the hull though, the part that will go crunch, the lowest point right?


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## free88 (Apr 18, 2017)

Brett said:


> Picky, picky, picky....
> 
> 
> 
> ...


The keel ridge on the Gheenoe 15 4 makes no difference in this context. It provides no lift, no disturbance, no otherwise effect on the outboard. Pretty common knowledge to not use them as the reference point in this context. You see similar ridges on a lot of aluminum jon boats and the like. They also don't count.

Yes, I am being picky. That is because when some people (and I am not accusing anyone) really want to make a certain point, they start making highly skewed assumptions, significant over- or under-estimations to an effect, etc. Error adds up. You add up enough error and things look very different than they really are. I think a proper illustration can be done using the right camera, angles, etc. Everything carefully measured, carefully thought out, and carefully reasoned. My pictures were not intended for this, and, therefore, are not good source material to make that particular point. Fortunately, the proper illustrations have been done, like, 800 times on the internet, and peoples can always just look at those.


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## Brett (Jul 16, 2008)

Ribs and keels don't count?










Well, you run a hull up on rocks or oysters enough, where is the damage going to occur?

















It was my turn to be picky...we are talking draft, right?


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## WhiteDog70810 (May 6, 2008)

You two do realize you both actually agree with each other, right?

Nate


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## Brett (Jul 16, 2008)

Slow morning at the office.
This is digital time wasting.
Verbal ping pong.


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## WhiteDog70810 (May 6, 2008)

Free,

FWIW, I knew what Brett would say before I typed the first letter of this thread, e.g. “stop making this difficult, raise the cav plate ~1” above the bottom at 4” of set back and don’t expect to run shallower than 14””. He is that voice of reason who always ends up being right ever when I really want him to be wrong. 

Dammit, I just need an outboard that can run with just the tips of the prop touching the water. That shouldn’t be too much to ask, but the physics and math keep falling Brett’s way.

Nate


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## Brett (Jul 16, 2008)




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## WhiteDog70810 (May 6, 2008)

Too loud and poles like shit.

Nate


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## CPurvis (Apr 6, 2016)

Ok so I have a question. I am running a 25hp Yamaha I have a atlas micro jacket and with the Jack plate all the way down the AVP is even with the bottom. While running I am able to raise the motor up about an inch before blow out. I am currently running the stock prop with 11 1/4 pitch(Yes Yamaha does have a 11 1/4 pitch). So would going stainless offer any significant gains for the money on a smaller outboard? Sorry to derail this thread any further but I saw and opportunity and jumped on it.


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## Brett (Jul 16, 2008)

You can spend the money for a cupped prop and gain that inch.
But is it worth the expense for that inch or inch and a half?
Ask the hull builder for the recommended cupped prop for that engine.


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## CPurvis (Apr 6, 2016)

Brett said:


> You can spend the money for a cupped prop and gain that inch.
> But is it worth the expense for that inch or inch and a half?
> Ask the hull builder for the recommended cupped prop for that engine.


What about any other performance gains and or losses?


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## Brett (Jul 16, 2008)

I've changed out a few props over the years.
Picked up a mile or two per hour top speed.
Able to set the outboard a notch higher,
trim out further without blowout, maintain bite in aerated water.
Useful on a high horsepower outboard, not so big a deal on a portable.
The question is do you want the expense for a small gain?
If you like fine tuning a hull for optimum results, if it's a hobby, go for it.
If you are thinking it's going to make a major difference, it's not.
It's just another tweak to be attempted.


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## WhiteDog70810 (May 6, 2008)

I'll eventually get a stainless prop because I like how they hold up and I don't usually fish around too many rocks. I feel actual performance is a wash in low HP use, but you might see some difference in a 25 HP.

Nate


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## CPurvis (Apr 6, 2016)

Brett said:


> I've changed out a few props over the years.
> Picked up a mile or two per hour top speed.
> Able to set the outboard a notch higher,
> trim out further without blowout, maintain bite in aerated water.
> ...


Kinda what I was thinking


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## free88 (Apr 18, 2017)

I think I was being overly sensitive a few posts ago, and for that I apologize. 

For setting the outboard anti-cav height in relation to the bottom of the transom, that keel ridge on the 15 4 (and similar ridges on other boats) does not matter. This is what I am saying. 

If we are talking about the static draft of the hull - a related, yet separate measurement - yes you count the ridges if they are the lowest point(s). Should also count your transducer while you are at it, and anything else that is affixed to your boat and hangs lower than the lowest point on your hull. For example, high speed pickups, etc.


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## free88 (Apr 18, 2017)

Brett said:


> I've changed out a few props over the years.
> Picked up a mile or two per hour top speed.
> Able to set the outboard a notch higher,
> trim out further without blowout, maintain bite in aerated water.
> ...


I totally agree with most of this. But there also is a sort of psychological handicap with things like this. It is real easy to give into it. I spend effort A and money B to get effect C. I had to convince myself, my wife, etc., that this was totally the right thing to do (especially the money part). I did it, and, well, maybe it didn't really work out. But you don't want to appear dumb and foolish, so you tell people that it totally worked and how I am a genius for having done this. Of course, because other guy is just not as awesome, he could never duplicate even close to the same results with the same exact gear installed. Hilarious! Awesomeness must be what makes the difference, and I guess I am just not awesome enough.  I should have realized this when it was the crappy wand chose me in Harry Potter land.

I don't fully agree with the larger boat/HP setups somehow being more worth it to do stuff like this. It is still a game of tiny number gains for relatively big dollars and effort spent. If I had a do-over on my bay boat, I would rig it with far less than it currently has.


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## permitchaser (Aug 26, 2013)

I guess this thread is about running skinny. free88 is one verbal poster. Just sayen Any way. My big fat boat can run pretty shallow with the jack plate all the way up (6"). If I'm on a flat and the tide starts going out, if I pole or TM to 1.5' I can run. The motor gets plenty of water jacked up and I just can't go very fast. I don't know how shallow I am while running with the motor jacked up but its less than 1.5'


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## free88 (Apr 18, 2017)

permitchaser said:


> I guess this thread is about running skinny. free88 is one verbal poster. Just sayen Any way. My big fat boat can run pretty shallow with the jack plate all the way up (6"). If I'm on a flat and the tide starts going out, if I pole or TM to 1.5' I can run. The motor gets plenty of water jacked up and I just can't go very fast. I don't know how shallow I am while running with the motor jacked up but its less than 1.5'


Its about trying to help the OP get set up, or at least headed in the right direction. There is a lot of BS out there on this particular topic. People making ridiculous claims, saying they can do things "all day" that are impossible even for just a second. 

I hope I have helped Whitedog and other watchers of this thread. When it comes to jackplates and/or trying to run super shallow, its not all rainbows and gumdrop smiles. Its best to have realistic expectations on the conservative side, and set up that way. Your boat is going to run better, outboard will last longer, and so on. Don't try to chase the dragon. Its just not worth it.


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## Brett (Jul 16, 2008)

> When it comes to jackplates and/or trying to run super shallow, its not all rainbows and gumdrop smiles.


Ain't that the truth.
I wonder what it costs now, to do a low water pickup/nosecone,
surface piercing prop, along with an 8 inch vertical hydraulic jack plate?
It can't be cheap...


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## permitchaser (Aug 26, 2013)

Brett said:


> Ain't that the truth.
> I wonder what it costs now, to do a low water pickup/nosecone,
> surface piercing prop, along with an 8 inch vertical hydraulic jack plate?
> It can't be cheap...that engine


I could not see if that engine was peeing or not. Mine does when its jacked up all the way .low water pickups are sold by Bob's machine shop


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## WhiteDog70810 (May 6, 2008)

Bob's machine nose cone is $599.99 installed. Bob's doesn't make a 8" vertical JP for under 50 HP, but a 6" runs $849.99. Racing props start at around $700 and go up from there.

I ain't doing any of that. What little I know about making a small HP engine of any sort give you 110% of its capability is that it results in burnt out motors. I don't have the the money nor do I enjoy twisting wrenches enough to pretend that is my thing. I just want the damn thing to start every time I ask it to and push me fast enough to feel like I am fishing more than running.

Nate


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