1638 gd boat with 23 GDLT. gas tank up front under deck and small starting battery in back. Ive bent cav plate up maybe 1/4-1/2" its better but will still pop out at WOT. 3/4 throttle and you can drive it like a shortail. Loaded to the gills it will stay in water and run 15mph but empty or with one passenger and a cooler you have to keep pretty steady pressure up on handle. Do I need to bend it more or is there something else I can do

Ran a 16 GDLT on a 16x44 Lowe, bending the cav plate is the only thing that I know of or only driving at 3/4 throttle.

Its prob an inch or so past the sides

Whats your transom height.
Years ago i installed a gd made for a tall 20. " transom onto a 16 " transom boat,no matter how much bending she would always pop up past 12 mph.
I could be wrong but i think a cav plate for a tall/short is welded at different angles.
My shaft is 74 inches,i welded my plate at 28 degrees.....required very little adjustment to stay floating at 19 mph,only a few lbs of pressure to pop her out of the water.

Its a short transom. As far as i know its right one. Thats the motor i ordered anyway, unless they sent wrong one

Can you post up a pic of your cav plate,that may help.
Probally needs some more adjusting.

It does seem to be bent up quite a bit, I've seen them even added onto worse than that . You might be close . You moved in the right direction ,Find a sand bar, bring your wrench or what your using to bend that cav. Run and tweak it till you get it right . The only way I know to dial it in. I'd rig your boat with the load you most use it with. Good luck.

H Finn

That is alot of adjustment,way more than i expected to see.
I would set up bottom of boat level while on trailer,then get the top of cav plate level with bottom of your boat.
When my boat is level on trailer,my cav plate is around 1 in higher than the bottom of my boat but level.
My cav plate rides 2 inches below the waters surface once ontop.
But my setup is homemade with a 74 inch shaft,my cav plate is at 28 degree from level(if you put shaft level)
Hope this helps

Finn has given great advise

Heres a shot of my angle when i threw it together.
But as stated 74" shaft....28 degrees.
Shorter or longer shaft will need a different degree of angle on the cav plate.

I just didnt want to bend it too much. Its a factory gd boat and motor so shouldnt be anything unusual i dont think. Ive driven lots of longtails and never had one fight like this. I think im close as it will almost stay down. I emailed GD today asking if they had any suggestions. I heard they made some bolt on trim tab thingy to extend the trailing edge of cav plate to give little mote angle. Ill bend it a hair more and try it saturday

Something else that can be tried it to bend the foward edge of the cav plate slightly downward,ive seen this done before.
But maybe the best thing to do is to wait and consult with godevil......before making any more mods.
I honestly think your cav plate angle is wrong,but i havent seen it in person.
Something else to consider,does your gd have a trim height adjustment.

When idling your gd should be at a good bit of angle,once on throttle you should feel the handle drop down as the cav plate planes up to float.
What im getting at,if your trim stop screw is too high.....it may be keeping your lower unit to high up allowing her to break plane.
With a loaded boat all this is affected.....going slower means your boats wake will drag more water over your lower unit,going faster will bring the boats wake past the lower unit.and if trimmed too high .....means you will cavitate and pop out of the water.
I have my trim screw adjusted to allow my cav plate to go down 1 ft lower than bottom of my hull when idling.once on plane she finds her own comfort zone and floats 1.5-2" below my boats wake.going slower wide open with a liad my cav plate is about 4-6 " below my wake,due to the boat having a slower speed.

Hope ive made sense,not stating thats your issue.....but its sound logic.

My lt has the swivel bracket and doesnt have that bolt that lets you limit the downward movement of tge motor.

Any updates?

Hadnt heard back from GD yet. Gonna try and put it in water tomorrow or monday

They said bend it a little more if that didnt work they would send me the bolt on trim tab

My friend had a 23hp made for a short transom installed on a tall transom and worked just as you described.

Perhaps the swivel bracket raises it a couple inches higher which changes the cavitation plates angle.

You already have it bent at the highest angle I have ever seen.
When I have my boat on a trailer with a 15" transom when the cavitation plate is level it is about 1" below the bottom of the hull.
But cavi plate is level like it should be.
If you have to hold yours in the water that indicates to me that your motor is too high for the plate to ride level on the water or your tail is too short for the factory set angle.
Simple test with boat on trailer.place cavi plate same height as bottom of hull,Is it slose to level?

Ill get a pic demostrating tomorrow.
Even if mine is wrong.......it rides flawless on both boats I had it on.
A 14x42 and a 16x48,you can let go of handle let boat drive itself.

I agree with red,my first instint was wrong angle.

If so then they sent me the wrong one. Mine is a short transom boat. Ive never seen one bent this much either. I had a mblt many moons ago on a 542 war eagle and then a 1648gd boat and it wasnt bent at all. Ive been smoked at work and hadnt had time to go drive it. As far as on the trailer if i let mine go the skeg will sit all the way on the ground. No stop

Best I can do right now to explain,this is a surface drive pic but look at the near levelness off the cavitation plate when near same height as bottom of hull,should be very close to level.


Same principles apply.
If your popping out of the water I suspect either your motor or transom is too high

Or manufacturer put wrong angle to match shaft lenth and transom height.

Popping out of water your cavitation plate probly has the rear angled down which will force the tail up out of the water.
If that is not the issue I would have no clue whats wrong.

Is it a long shaft or short shaft?
I know the swivel mount does add a lil height but should not change the angle that much.
Ill get a pic of mine tomorrow.

I gotcha now. I was having a brain fart. It is a short transom, i told them that when i ordered so im assuming they sent me the right one. After doing some reading though i see that only diff in short vs tall transom gdlt is angle of cave plate. Maybe mine is wrong. Ill pull mine out tomorrow and check angle with bottom. Problem is if tgey sent wrong one i surely doubt they would replace it now that its been run

Weather mine is right or wrong,it rides flawless and I can let go of the tiller and the boat slowly steers left which isn't an issue.
When the cavitation plate is level itlooks to be about 4" below the hull,maybe more.

My last boat had a 16" transom height so I thought gap was less,this boat has a 15".

At this angle it looks like a foot diffrence but its not,the boat nor the camera is level


When on plane I believe the cavitation plate is not level,the rear slightly angles upwards in turn holding your prop into the water.


No actual measurements taken,just refrence pics of how my 6 foot shaft Go-devil longtail on a 15" transom is set up.
Wrong..........maybe but it operates well and is very tame.I perfer this over an outboard anyday.
On a very heavy 16x48 16mph deepwater.

mine wont stop like ya'lls, it will go all the way to the dirt.

went home at lunch and spun it around. It looks to be about right. It goes almost to the ground before the bolt hits the frame. I guess bending it a bit more and trying it. Godevil said if that didn't work they could send me bolt on trim tab. I'm guessing that just bolts on cav plate and extends it

Edit,double post

My will hit the ground too if I let it I tied it with the ratchet strap so the cavitation plate would be the height it sits when riding.

I got in the hull,set handle at its normal riding position in deep water.I knoe the height it is when I ride at 16mph.

That is my ride height and correct cavitation plate angle.
71" from rear of transom to back of cavitation plate


Normal height on my set up


Hope it helps,I have a 2006 25hp kohler Godevil Longtail.
Please check everything out and let us know.

You can see as I suspected the cavitation plate slightly angles up to counter act the force of prop.
My brother built his homemade using my angle and works well for him,cept his is longer.

Mine is more level instead of angled. Yours points more down. Ill bend back edge a little more. May try to bend front down a hair to point it down

A little makes a lot so bend in small incraments at a time.
Im willing to bet the higher swivel mount is the cause of your angle being slightly in correct.

that's what several have told me

I dont think I would bend the front of the cavitation plate,Its the leading edge that makes the final pressure force on the water.
I would get with Go-Devil and do as they suggest since its new and you paid well for Customer Service.

I bent it up maybe 1/8" more yest. I'm on call this week so prob be next week before I can try it out. I'll let ya'll know. If not i'll get GD to send me that tab