jackplate equation ?????

[phantom1704]

hi guys

i own a ring ranger 25 which is a front heavyboat

i have mounted a single outboard instead of dual outboard set up like many come with.

with the weight of 2 motors the boat would have a better balance but where i live the authoritys don't permit it.

now i have mounted a evinrude 250 ho ..25" gearbox

the actual transom of thew boat measures 28 "

the boat handles well but i think i need to lower engine 1 to 3 inch more a when i cruise in big waves she's want to nose dive but at w.o.t i have no problem..she just fly over them lol

another downside i have is motor steering touches transom when i want to tilt up in mooring
and leaves some of the motor in water which is not ideal.


I'm thinking of putting a 6" inch jackplate on the back of ring

what is the exact "equation" of each of every
1" of offset?

what difference will a 6 " backplate make and how much lower will it be in the water?

plz plz plz i need some serious advice ......

thanks guys

[The Docta]

Where does the gearbox bullet sit in relation to bottom of hull? Maybe you need to go up and try different prop and trim.

Typical is 1 inch up for every 12 inch setback according to merc at least.

[phantom1704]

hi doc

so if if have a 6" setback backplate i will only gain 1\2 " lower leg in the water?

[phantom1704]

so i got a 28 inch transom ,,,and a 25 inch gearbox.....im trying to "lower "between 1 to 3 inches of more leg in the water when there is chop without cutting the transom down ....thats why i asked about the equation of the setback as I'm not sure if u can lower the jackplate ..only higher it i think.........also the jackplate i will use is gonna be hydraulic from sea star solutions.....boats in water so i can't check exactly where bullets sits still...any other tips or info?

[glen76]

I have put a 6 inch jack plate on mine and the steering still impacts transom. 8-10" I reckon to get the steering to not touch transom. Mine only touches in last 1/4 ish so I am going to live with it

[phantom1704]

hi glen what make is your jack plate ?

seastar solution say there jackplate go up 6 inches?

do u have any pics?

[adykitcher]

My jack plate has a 8" lift and have different set backs of your choice, rated to 300hp and made by Detwiller which i think is part of seastar now!

[glen76]

Sorry I was wrong mine is 5.5". But with this clearance it still will hit when tilted.