aqua lark not planing

[modman]

hello im brian im new here i recentley got an aqua lark it came with a 25 hp jhonson the guy i bought it from had a 40 hp evenrude with a 19 pitch prop it did 52 i put a jack plate and a yamaha 3cyl 40 hp with a 16 and i wont get out of the hole or plane motor seems like its running fine

[ProHydroRacer]

Go faster!

[Yellowjacket]

With the jack plate you are moving the motor back and on a boat that short it makes a difference. You could try kicking the motor in more, or try getting your weight out over the bow to get it planed off, but I'd try it without the jack plate first and see if that helps.

[modman]

i thought the jack plate would of helped plane better no its about 6 inches back u think it would be better without it

[Yellowjacket]

i thought the jack plate would of helped plane better no its about 6 inches back u think it would be better without it

aahhhh no the jackplate is making it worse, moving the motor back really hurts you getting up on a plane....

That thing is so short that even if you got it planed off, with the motor that far back it would probably porpoise like crazy anyway...

Lose the jack plate for a start and then get some more weight forward and it'll be fine.

[modman]

i measured it today its 3 inches back i have to keep the engine up because its a 15 inch transome and the motor is a 20 cavatation plate is even with botton of boat, and yes i can get it to plane leaning over front and it does porpoise would it help if i drop the motor down a inch or two

[Yellowjacket]

The first problem is that the motor is too far aft. The boat was really made for a short shaft and you need a short shaft motor for it to work right. Moving the motor 3 inches doesn't sound like much, but these newer motors are heavier than the older generation motors too, so you have more weight and it's further aft.

The second problem is that your motor is too deep. This puts the prop lower and this makes the bow want to lift. With the cavitation plate even with the bottom of the boat the prop is a lot lower than it needs to be and this is also is going to make it hard to get on a plane as well as porpoise once you get up there.

You might think about a set of planing flaps on the back of the boat. It's a bandaid, but it will give you more lift when you are trying to plane, as well as let you adjust them to get the nose down when you are up on a plane.

As I said, your basic problem is that the CG is too far aft, and if you add some more lift at the back you might be able to fix it. I'd think about a pair of flaps that are about 8 inche wide across most of the transom. You probably don't need sexy electric flaps, simple turnbuckles will work to adjust them. You need lift all across the range, from getting up on a plane to full speed and this will probably do it.

[modman]

how far up should i be with cavatation plate from bottom of boat sorry its 1-2 inches below bottom i can raise up about 4 more inches not sure where it should be u guys are helping alot thanks so far i want to get this thing in high 50s doing mods to motor too head reeds lightened flywheel want a ron hill 11/20 cleaver too need to smoke the other minies on the pond lol

[Fastjeff57]

You'll need nitrous to go that fast with a 25 John-Rude.

Jeff

[Yellowjacket]

The limit as to how far you can raise it is that it stops pumping water. Maybe somebody with experience with your motor can offer some advice, but higher is better.