!!! Jack plates !!!

[jrhubbard]

Hey guys, so I need to raise the motor as high as I can with the jack plate without losing water pressure, right and should it throw a rooster tail or I need not to worry about a rooster tail.

 

[Chris1956]

Re: !!! Jack plates !!!

You might tell us motor HP and year. Normally the motor sill ventilate before it looses water cooling. That is NORMALLY what happens! The best way to watch for this is with a water pressure gauge on the dash.

Usually rooster tails are power not put into moving the boat. Test with GPS and Tach. See if best speed is with max roooster tail or not.

 

[jrhubbard]

Re: !!! Jack plates !!!

The motor is a 1990 evinrude 150, I was told something about putting the anti vent above the keel hight but watch my water pressure, but I guess toake it simple I need to just play with it and try to get the best performance put of it right

 

[bob johnson]

Re: !!! Jack plates !!!

jack plates are installed for several different reasons.

we dont know your reason.

some people install jack plates to more easily tune their motor/boats performance
some people install a jack plate so they can use a motor they already have that wasnt designed for the height of their boats transom
some install jack plates to access shallow water, then return to a normal setting once back in deeper water
some guys install jack plates to just get more speed, via setting the motor back away off the transom and takign advantage of the rise in water as it leaves the rear of the boat,...thus, getting less of their lower unit in contact with speed killing water drag....

why do you have a need for a jack plate, and then we might better assist you


bob

 

[Chris1956]

Re: !!! Jack plates !!!

Bob, It sounds like he wants speed and a rooster tail if possible.....all legitimate reasons....

 

[jrhubbard]

Re: !!! Jack plates !!!

Yes speed and performance is what I'm trying to get

 

[emdsapmgr]

Re: !!! Jack plates !!!

You are probably monitoring your water pressure with a 0-30 lbs water pressure gauge. You can run the engine high till the water pressure starts to drop, then you need to be very careful. I'd be concerned when the pressure starts to get under 15 lbs at top end. A cyl temp gauge is helpful in these cases. A little rooster tail can be normal with a high engine mounting and a surface piercing prop. Probably in the 24" range. If you are getting a 48" rooster tail you are probably losing bite and speed-maybe to much trim angle. You can plug the top two water pickup holes in the lower unit to get the engine up higher.

 

[bob johnson]

Re: !!! Jack plates !!!

are you running a water pressure gauge ,and do you have a temperature gauge??? best get both if not.... if you dont have a surface piercing prop, i am wondering if you are wasting your time trying to get a rooster tail( if in fact thats what you want...)what is the set back of your jack plate????

you need to be carefull once you get it high enough that you are running good straight, that the prop wont wash out while making a turn!!!

does your boat have a pad or a tunnel or anything else funky???? that will play into this equation??



bob

 

[metriccrescentwrench]

Re: !!! Jack plates !!!

You mean a rooster tail like this one?

My Checkmate has a 6 inch jackplate, 23 pitch Renegade prop, with prop centerline 3 inches below the pad. DON'T TRY RAISING YOUR ENGINE THAT HIGH WITHOUT A WATER PRESSURE GAUGE. I've got over 20 psi of water pressure at all speeds above idle, but that could very well be different on your boat.