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Discussion Starter #1
Im running a 14’6 skimmer and I’m having problems with my bow coming down too far after I get on plane. I have tried raising the motor a notch and had the skiff running how I’d like but it squatted the stern down a lot and also caused cavitation. I have the motor mounted with the cavitation plate even with the bottom of my hull. Should I try getting a jack plate to add setback and maybe raise the motor a few inches? Or a cavitation plate and kick the motor up a notch? I’ve already tried moving as much weight out of the bow and all I have up there is a small dry box, my fly box, and a leaf/stripping basket.
 

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Motor should be a 1"-2" above bottom of boat
is the cavatation occurring when u are turning or all the time?
what rpms are u turning?
is trim vertical

options:
cup the prop for better grip
or increase pitch and get a raker style prop
 

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Discussion Starter #5
Trim her out! Do you have a pin to set your trim angle on the motor?
Yes, when I trimmed it up one hole with the pin that’s when cavitation occurred. I wish I had electric trim/tilt ... that would make this a lot easier

Motor should be a 1"-2" above bottom of boat
is the cavatation occurring when u are turning or all the time?
what rpms are u turning?
is trim vertical

options:
cup the prop for better grip
or increase pitch and get a raker style prop
Cavitation occurs without turning. I have a tiny tach on the way. I’m running a super basic Merc 25 2 stroke without electric trim or tilt. I’ll look into new props.
 

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Discussion Starter #6 (Edited)
see above...the bow being pushed down means the motor is mounted to low
and/or a severe trim angle
Sounds like I’ll try a jack plate and experiment with different motor heights. Would raising the motor 1-2” really make a drastic difference without creating a bigger cavitation problem? I feel like the trim angle of the motor would make a bigger difference than the height of the motor for the bow being too high or too low but trimming one notch up creates cavitation
 

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Hope all the suggestions sort you out.... A few years back there were some small skiffs (might have been called something like a skimmer) that weren't very well designed and did have some serious running hull attitude problems. Hope yours isn't one of those...
 

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Zephyr Cove is on FIRE!
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I think we have our terminology confused here. Trimming out is not motor height, it’s moving the lower unit angle out or in. Trimming out will cause the bow to rise. Jacking up is motor height in relation to the transom.
-Trim: To adjust the position of a boat moving in the water by altering the angle of the drive unit (or motor) to the boat.
 

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in this case cavitation while trimmed at real vertical means u need a prop w/ more pitch...and/or cup and u still have to raise the motor
 

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Zephyr Cove is on FIRE!
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A compression plate can help even the smallest outboards control the attitude of the boat more efficiently but yeah the wrong prop can cause all kinds of issues as well. Trim tabs won’t hell this “bow plowing” but the correct prop, motor height and possibly a compression plate will.
 

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Sounds like I’ll try a jack plate and experiment with different motor heights. Would raising the motor 1-2” really make a drastic difference without creating a bigger cavitation problem? I feel like the trim angle of the motor would make a bigger difference than the height of the motor for the bow being too high or too low but trimming one notch up creates cavitation
Yes!!!!!!but would create more cavitation....get her up and running and look down and see if the motor is vertical ....... or tucked in

the bow going down at a true vertical means the motor is to deep and cavitation at that point means u need a prop w/ more pitch.....unusual to have a bow down issue w/ cavitation
 
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Post up some pics of your setup, let us know what prop you have, trim that motor and raise it. But, at this point with your current prop... raising and trimming is only going to magnify the cavitation problem. Check the hull bottom for a hook using a straight edge also.
 

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Discussion Starter #13
I’ll post pics tomorrow when I’m home. When I run with the motor set in the notch that I don’t get any cavitation the bow plows but the cav plate on the lower unit is right at the surface level of the water(I can see it when I look back). When I trim the motor one notch up the boat planes how I prefer (bow not at a sketchy level) and I can still see the cavitation plate but it creates cavitation issues. If I set the pin into the higher position but add a hydrofoil will it allow the skiff to ride with the bow higher but prevent the cavitation?
 
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I’ll post pics tomorrow when I’m home. When I run with the motor set in the notch that I don’t get any cavitation the bow plows but the cav plate on the lower unit is right at the surface level of the water(I can see it when I look back). When I trim the motor one notch up the boat planes how I prefer (bow not at a sketchy level) and I can still see the cavitation plate but it creates cavitation issues. If I set the pin into the higher position but add a hydrofoil will it allow the skiff to ride with the bow higher but prevent the cavitation?
A hydrofoil wouldn’t help stop the cavitation but a compression plate will.
 

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Sounds like I’ll try a jack plate and experiment with different motor heights. Would raising the motor 1-2” really make a drastic difference without creating a bigger cavitation problem? I feel like the trim angle of the motor would make a bigger difference than the height of the motor for the bow being too high or too low but trimming one notch up creates cavitation
Really kind of sounds like a prop problem. Of course you understand that prop size is the one area I am no expert in. (Until the next subject comes up.)
 

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Brandon, FL
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You have a very lightweight skiff and any change is going to be amplified.

Try putting the motor what're you like it and then take a bag of play sand and a bucket. Put the bucket in the front hatch and start adding sand until the proposing stops.

Then mix some epoxy and mix the sand and put it all in a plastic bag and put it in the hatch on the hull and push it to contour the hull. When cured remove the plastic. Set this in when you are by yourself.

I say this because I did not see where you say it happens when someone else in with you.
 

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Zephyr Cove is on FIRE!
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You have a very lightweight skiff and any change is going to be amplified.

Try putting the motor what're you like it and then take a bag of play sand and a bucket. Put the bucket in the front hatch and start adding sand until the proposing stops.

Then mix some epoxy and mix the sand and put it all in a plastic bag and put it in the hatch on the hull and push it to contour the hull. When cured remove the plastic. Set this in when you are by yourself.

I say this because I did not see where you say it happens when someone else in with you.
I thought he said the bow is plowing? That’s the opposite of porpoising. Hydrofoils and compression plates are not the same thing either. A hydrofoil is a flat plate that acts like a trim tab on your motor, a compression plate has sides that angle or curve down to hold water around the prop and allow the prop to grip instead of blowing out. The compression plate also acts like a hydrofoil but with an even more exaggerated effect because of the curved or angled sides holding more water than a flat plate.
 

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Zephyr Cove is on FIRE!
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The correct prop is the first step, then the correct height for the prop while figuring out motor height and weight distribution to get the boat to level out as best as you can without creating more issues such as cavitation. There’s cavitation on hole shot, cavitation while running WOT and also cavitation while turning and most all of these can be cured by running the correct prop. A prop with the correct diameter, rake, pitch, cupping, blade shape, blade thickness and number of blades are all factors. If the boat still wants to act funny you’ll need more planing aids like trim tabs and a true custom prop. All of these things are useless without the correct prop and motor height.
 

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I think we have our terminology confused here. Trimming out is not motor height, it’s moving the lower unit angle out or in. Trimming out will cause the bow to rise. Jacking up is motor height in relation to the transom.
-Trim: To adjust the position of a boat moving in the water by altering the angle of the drive unit (or motor) to the boat.
Positive trim will push the stern down and raise the bow.
Negative trim will raise the stern and push the bow down.

It can be a balancing act...especially with a jack plate / tunnel. Add in trim tabs and you're running around doing geometry problems in your head as you're navigating. *lol*
 
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