I have a 79 Checkmate Eluder boat with a 79 150 hp Evinrude. I am currently running a 22p raker propeller, the problem I am having is I can only turn about 5000 rpm, when I should be turning about 5400 rpm at wot. I am considering purchasing a jackplate in order to get the motor raised up on the transom. I have been told that a jackplate with about 6" of setback would allow me to turn higher pitch props. I use the boat to cruise around on the river and to pull a tube for my daughter and her friends. The motor is very strong and the boat is pretty fast the way it is but I really want to turn the correct rpm in order to be more efficient and I believe it will give me more speed. I am also wondering if I will need to have a nosecone with a low water pickup installed in order to run the jackplate safely without overheating the motor. Thanks in advance for any advice.
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Jackplate advice needed
- Thread starter jdb35
- Start date
I've mounted jack plates on different boats and here is how I did it.
first of all its important to know where the motor is (height wise) in relation to the boat bottom before you do anything. I run a long straightedge off of the lowest point of the hull at the back of the boat and see where your prop shaft is located in relation to that edge. once you know that you can make changes in height after the jack plate is mounted. If your prop shaft is even with or below this point you can move it up and you will see the increase in RPM's that you are hearing about. I believe I put the motor so that the shaft was 2 inches above the straightedge line and with the 6 inches of setback I was always impressed with the difference in performance.If you decide to go higher keep an eye on your water pressure gauge to make sure you don't go too high and lose pressure. I suspect if you are tubing and skiing you won't be lifting it that high (because you need a good hole shot) to affect your water pressure.
first of all its important to know where the motor is (height wise) in relation to the boat bottom before you do anything. I run a long straightedge off of the lowest point of the hull at the back of the boat and see where your prop shaft is located in relation to that edge. once you know that you can make changes in height after the jack plate is mounted. If your prop shaft is even with or below this point you can move it up and you will see the increase in RPM's that you are hearing about. I believe I put the motor so that the shaft was 2 inches above the straightedge line and with the 6 inches of setback I was always impressed with the difference in performance.If you decide to go higher keep an eye on your water pressure gauge to make sure you don't go too high and lose pressure. I suspect if you are tubing and skiing you won't be lifting it that high (because you need a good hole shot) to affect your water pressure.
Mark
Well-known member
Nope, sorry, that is not what you want to do. Your motor mounted on the transom will have the prop shaft 6" below the pad. If you add a 6-8" jackplate you will be able to go to maybe 3" below the pad without losing too much water pressure. You will need to install a water pressure guage as it is a roll of the dice to guess. You don't need a nose cone but sometimes you have to plug the top couple of holes so they don't suck air. Better yet, is to install water scoops. Merc makes them, don't know about OMC. If it were my boat I would go with an 8" manual plate and run between 3.5 -4.5" below the pad. That should get your revs up to the 54-5500 range.
Mark
Well-known member
captainmorgan
Active member
when all else fails
jack er up, but make sure you have enuf beverage with you that in case the body filler breaks off the side intake ports you stopped up, or you were so drunk you filled bobs nose with mud, thinking it was jacked up enuf. get an air cooled motor. or in my case, weld some tubing on the sides of the gearcase to keep the crabpots and porpoises from tearing the hoses off. nothing worked for me so i got my tunnel boat that the hull hits bottom first. apart from the jokes, when you got her just right, theres no rooster tail, your turning 7500rpm, and your in total control with a mixed drink in one hand, and waving with the other,
and ur motor dont lock up and throw you into the dash. if thats not enuf height, put a snorkle on the air cooled hybrid ethinol burning grenade, 50/1 ratio of black velvet & gingerale, and tell me to shut the f up. ok, ive got a brain, and tell chris i aint paid my dues but want too, and im going to let you watch when i give barrack obama a free tour of tangeir island, " christ-allll-mighty", and ill buy his crabcake w/ cheese. ill drink to that. then i will drink to that. then i will drink to my drinking to my drinking to that. you know what im sayin yo bro. welcolm to watts island, land of the free home of the brave. tangeir island ferry is back in business, except you miss the hour long ride by 50 minutes, or a lifetime:cheers
jack er up, but make sure you have enuf beverage with you that in case the body filler breaks off the side intake ports you stopped up, or you were so drunk you filled bobs nose with mud, thinking it was jacked up enuf. get an air cooled motor. or in my case, weld some tubing on the sides of the gearcase to keep the crabpots and porpoises from tearing the hoses off. nothing worked for me so i got my tunnel boat that the hull hits bottom first. apart from the jokes, when you got her just right, theres no rooster tail, your turning 7500rpm, and your in total control with a mixed drink in one hand, and waving with the other,
and ur motor dont lock up and throw you into the dash. if thats not enuf height, put a snorkle on the air cooled hybrid ethinol burning grenade, 50/1 ratio of black velvet & gingerale, and tell me to shut the f up. ok, ive got a brain, and tell chris i aint paid my dues but want too, and im going to let you watch when i give barrack obama a free tour of tangeir island, " christ-allll-mighty", and ill buy his crabcake w/ cheese. ill drink to that. then i will drink to that. then i will drink to my drinking to my drinking to that. you know what im sayin yo bro. welcolm to watts island, land of the free home of the brave. tangeir island ferry is back in business, except you miss the hour long ride by 50 minutes, or a lifetime:cheers