Kaboat Motor Lift

[martyv]

Several people wanted to see how I mounted my lift on my kaboat. Hopefully this photo gives the gist of it. I have a 2x6 across the tubes connected to the rear oar locks. The front braces of the lift mount on that, I also use it as a seat.

The back is a little different because I mounted the pivot point on the transom, so the motor hangs about 8 inches back of the transom. It also sits about 4 inches higher and that may be my problem.

It works great at the slow speeds you would normally use a lift, It lifts the motor almost out of the water, (about 1/2 the prop is still in the water).

But at high speeds it cavitates. I'm not sure if that is caused by the lift or by the fact that I may not have the floor inflated enough. I am still having problems at high speeds with flexing.

I have the floor now up to 10 psi.

I'm using a 2 stroke evinrude short shaft.

[lonewolf2]

Very cool, good looking rig! I am having the same issues as you mentioned with my 18 footer. It's flexing and cavitating at any more than 2/3 throttle. I have tried a frame on top of the tubes which seemed to make it worse.. I don't have a lift but may try a set up like yours. I'm gonna try 12 psi in the floor and see if that makes a difference with the cavitation.

[Sid]

the reason you have problems on cavitaiteing , water gets under the plate, need to drop the motor down some , when you going fast there should be in lots of water under the rig , when it is shallow you go slow an can pick the eng up some, keep an eye on the oar locks blocks , as you are pushing the rig from that point not the transom an the Kaboat was not made to be pushed from the oar blocks , you realy don't want the prop out of the water very much as the water pump houseing is plastic an it will melt [ I NOW THAT ] just remember the props are cheep, you will use a lot 1 or 2 a season I think,

SID roud:
PS:: that is a lift out of FAIRBANKS AK correct ?

[martyv]

Actually Sid, this is pushing just as much from the transom as from the oar locks. This is the lift out of Fairbanks and there were two spots to connect. On a canoe they were both connected to the gunnel but on the kaboat the sternward connection is directly to the transom.

Also, the height of the motor is not my problem with cavitation. I took the lift off and ran is straight off the transom. I think it's my floor pressure, I can only get it up to 10PSI. It doesn't seem to go above that. I may have a slow leak or something. Can you buy the floors separately?

[kk alaska]

Marty, My 15 ft Kaboat will not cavitate with my Yamaha 8 HP 2 Stroke or My 9.8 HP 4 stroke Nissan both Short shafts. With stock transom and motor tilt in 3 rd setting.

My buddies 9.9 HP 2 stroke Johnson Short Shaft would cavitate on his 15 ft. Kaboat We put my 8 hp Yamaha and no cavitation. Same measurement
at cavitation plate? He bought a 9.8 HP Tohatsu 4 stroke and no cavitation at all.

Is lift and transom height the same? If lift in lowest position is higher than transom it will cavitate.

[kk alaska]

Marty get a hold of me and we can try my HP to see if it still cavitates. Cant expalin why my buddies 9.8 Johnson would cavitate and my 8 HP Yamaha would not both Short Shaft and good props. Equal in measurment also?

[Zack]

I bought an Evinrude 7.5, mid 80s model hoping it would make a good motor on my Osage Cargo Canoe with lift.
It would cavitate above half throttle. BUT, neither my old 9.5 Evinrude or my 4.5 Mercury cavitate at at speed. And they are both short shaft motors. Never did figure it out and sold the 7.5, just decided to keep what I've got. My best guess is that the cavitation plate on the 7.5 is larger and doesn't like to be that far out of the water. My lift puts the motor up about 2 inches above what it would be if attached to the transom.

[Sid]

I have that type lift on my canoe , when I don't hold the motoe up by the lifting handle, that handle is a little loose no force on it , so I figured ..that the force of the motor was pushing on the long ARMS only, that is why I said what I said , well at least it is that way on my rig , I have my lift installed so I can take it off, to but it on my truck with out taking bolts or nuts off , next time you are out with your rig see if the small arms under the back end of lift are a little loose no forse on them till you pick the eng up ,
PS not all motors are the same, prop shaft to cavitaton an the size of prop all makes a differance , a half inch will make a differance on the amount of cavitaion from what I know [ not very much ] some props are 9 inch to 10.5 inch DIA , SID roud:

[martyv]

PS not all motors are the same, prop shaft to cavitaton an the size of prop all makes a differance , a half inch will make a differance on the amount of cavitaion from what I know [ not very much ] some props are 9 inch to 10.5 inch DIA , SID roud:

I'll try changing the prop. If that doesn't work, I give up I think. Maybe I'll look for a grumman again.

[Sid]

can you drop the motor down about 1 inch even if you have to cut the motor plate off an reweld it back on so the eng can be droped down some
just an IDEA IT MIGHT HELP SID roud:

[mainer_in_ak]

I'm not even sure why you'd build a lift for this type of boat. they're not designed to run motors at a shallow height. the only way that will work appropriately, is if the prop is rear-ward of the tubes.

[martyv]

Hi Mainer, I have been trying to get ahold of you. But your message box is full.

The prop does sit back from the transom by about 10 inches, but it's not behind the tubes

[Sid]

lift on a KABOAT ? you will probly find that "" MARTYV"" had a lift an was trying to make the KABOAT run in shallow water an that was his answer
to the problem , just like a lot of us, we but things to gether to do things the rig was never ment to do , like putting 15 HP eng
on the back of a canoe that was made for about 5 HP MY 2 CTS SID roud: