Jack Plate Purpose?

[samm835]

I have never used one....i see them a ton, and always see them for sale. Whats the main reason for a jack plate? Raise or lower your outboard a couple of inches? Thanks just thought i would ask, the sad part is i should probably know this seeing I have been boating for the last 20+ years....thanks for not making to much fun of me. LOL

 

[Expidia]

Re: Jack Plate Purpose?

To position the cavitation plate (that first fin above the prop) to even or 1 inch above the bottom of the transom (boats bottom). If that plate is too low it will cause the motor to drag in the water while under way and reducing your top end speed . . .

Some boats don't have enough holes to raise or lower the outboard. Sometimes outboard owners want to mount a 20 inch shaft motor on a boat that calls for a 15 inch shaft so they have to raise the 20 inch shaft up.

They are touted to: Add top-end speed, boost hole shot and fuel economy, and improve overall handling . . .

280 posts and you have not seen this mentioned and discussed yet ???

Waas up wit dis?

 

[rodbolt]

Re: Jack Plate Purpose?

love my jackplate about as much as my trim tabs.set the jack up 5 inches and trim the gearcase enough to just keep the water intake in the water and the hull hits before the prop making skinny water idling a dream,or better.
good for flats hunting.
lower it to 2 inches and tuck the motor fully,lower the tabs fully and as long as the depth sounder shows 1.8ft of more,slam the throttle and it takes off without disturbing the mud.
for normal cruise trim it out a bit and play with the jack while watching the flow meter and water pressure guage and I can cruise about 31 MPH burning 6 GPH.
not bad for a 21 seapro with a tower and second operating station.
F150 and the hull holds 65 gallons of fuel .
not a bad cruising range.

 

[seabob4]

Re: Jack Plate Purpose?

The second benefit of a jack plate is to give the prop "cleaner" water due to the setback, which is typically 6". Cleaner water (less aeration) gives it better bite...

 

[4JawChuck]

Re: Jack Plate Purpose?

The second benefit of a jack plate is to give the prop "cleaner" water due to the setback, which is typically 6". Cleaner water (less aeration) gives it better bite...

...plus if the boat is a little nose heavy it places the balance point farther back which makes flying the bow easier with the boat loaded.

 

[seabob4]

Re: Jack Plate Purpose?

...plus if the boat is a little nose heavy it places the balance point farther back which makes flying the bow easier with the boat loaded.

I love it...jackplates in Manitoba! And we thought they were only for the flats guys down here!

 

[ddrieck]

Re: Jack Plate Purpose?

Here is a good FAQ from Bob's Machine that should shine a little light on the subject.

http://lib.store.yahoo.net/lib/yhst-92092659365530/Bobs-Asked-Questions.pdf

 

[samm835]

Re: Jack Plate Purpose?

Thanks for all the heads up on this subject. Has anyone tried one on a Pontoon? Would you get the same effect from a toon that you would on a fiberglass hull? I have a 24ft tooner, with a 90 HP Merc, not sure it is going to help with any hole shot....or better gas, just asking questions. THanks

 

[rodbolt]

Re: Jack Plate Purpose?

on a toon?
I would not bother.
get a bigger engine.
wont make much difference.

 

[ddrieck]

Re: Jack Plate Purpose?

The main advantage to having one on a pontoon would for running in skinny (shallow) water. If its a hydraulic model you can raise the outboard with the push of a button and keep your prop out of the rocks. You just need to be careful not to raise it to much or you risk overheating due to the water inlet sucking air. However, you can install a low water pick-up to avoid the sucking air problem but this also adds the possibility of sucking sand into the outboard if your low water pick up is to low.....

Its all a careful dance.........

 

[samm835]

Re: Jack Plate Purpose?

Well I was thinking about this last night....if my boat or toon needed a 25" instead of a 20" leg would the jack plate help in this situation by lowering the motor the needed 5inches?

 

[ddrieck]

Re: Jack Plate Purpose?

Yes, you could lower the outboard with a jack plate but there are few things to take into consideration.

- Most jacks will only give you about 4'' max of lowering ability.
- With the outboard lowered, you would not be able to tilt it up because it would not hit the top of the transom area


Best bet would be to use the correct midsection length. Depending on your outboard make and model, there are kits available to lengthen the mid-section and I believe pricing is comparable to the price of a hydraulic jack plate.

 

[riverjet502]

Re: Jack Plate Purpose?

I'm in the process of installing a CMC 6 inch set back on my 16ft jon boat.. Yep jon boat you read right.. Hoping to end up about 2 or 2-1/2 inches higher on the motor and pitch my little 35hp tiller up to a 15 inch wheel.... Should be interesting...lol.lol..