Burger
Well-known member
Bprice and I were talking about jackplates and their function. I know jackplates maximize the performance of the boat but excatly how? I know speed increases but do you really need a jackplate?
Jackplates
- Thread starter Burger
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Bprice
Well-known member
I'll bump this... Who is knowledgable about this?
Bubbakat
Well-known member
To give you one straight answer ,No a jack plate is not a necessary item on a boat but this is my long winded version and some of it was taken from a fellow that is real knowledgeable about their uses.
Firsts as a rule of thumb I've used my own formula over the years and its worked fine for me . Put the boat on a level drive way and use a 4' carpenter level on the rear of the center pad near the transom, level exactly the boat center pad with the trailer tongue jack. Next remove the prop and use a torpedo level on the prop shaft , use the trim to get the shaft perfectly level. Take a RIDGE straight edge and lay along the rear 2 to 3 feet of the pad perfectly flat and let the straight edge protrude beyond the pad to the gear case. Calculate using the exact center of the drive shaft to establish how much you are truly above or below that pad bottom in correlation with the pad verses the center of the prop shaft. This is called in the racing world inches or tenths of inches on VEE bottoms high or low from "split shaft" this is where that dimension or plane strikes or runs from the exact flat bottom to the exact center of the shaft. If the center of the shaft is 1" above that plane your rig is 1" above split shaft and so on. In the THEORY I've used ( and this is a primitive starting point ) for Evey one inch your jack plate is in length you can raise the gear case up 1/8 the of an inch from exact split shaft and still remain in "clean" "hard" water.. If your engine is bolted directly to the transom I suggest no higher than exact split shaft high ..Example if a jack plate is 8 inches long ( dimension from the boat transom to where the motor bolts on to the other side of the jack plate ) you can in theory go up 8 - 8ths of a inch or 1 "..All boats are different and have their own sweet spots , alot has to do with the particular hull and or overall rig your working with. Raising a High Performance Engine ( or any engine as for as that goes ) with a low water pick up on the lower unit ( which is a must , if this is not a low water pick uped lower unit the engine being jacked will quickly run out of engine cooling water pressure and engine will be damaged BEFORE the optimal speed and handling can be achieved ) jacking to optimal and is the only way to get your ring to its ultimate potential and to handle to an optimal set up . Dialing in these boats,motors, gear cases, and props combos are a trial and error game and must be done in small increments and the results of each change needs to be recorded for future movements and to see what helped and what hurt...
Firsts as a rule of thumb I've used my own formula over the years and its worked fine for me . Put the boat on a level drive way and use a 4' carpenter level on the rear of the center pad near the transom, level exactly the boat center pad with the trailer tongue jack. Next remove the prop and use a torpedo level on the prop shaft , use the trim to get the shaft perfectly level. Take a RIDGE straight edge and lay along the rear 2 to 3 feet of the pad perfectly flat and let the straight edge protrude beyond the pad to the gear case. Calculate using the exact center of the drive shaft to establish how much you are truly above or below that pad bottom in correlation with the pad verses the center of the prop shaft. This is called in the racing world inches or tenths of inches on VEE bottoms high or low from "split shaft" this is where that dimension or plane strikes or runs from the exact flat bottom to the exact center of the shaft. If the center of the shaft is 1" above that plane your rig is 1" above split shaft and so on. In the THEORY I've used ( and this is a primitive starting point ) for Evey one inch your jack plate is in length you can raise the gear case up 1/8 the of an inch from exact split shaft and still remain in "clean" "hard" water.. If your engine is bolted directly to the transom I suggest no higher than exact split shaft high ..Example if a jack plate is 8 inches long ( dimension from the boat transom to where the motor bolts on to the other side of the jack plate ) you can in theory go up 8 - 8ths of a inch or 1 "..All boats are different and have their own sweet spots , alot has to do with the particular hull and or overall rig your working with. Raising a High Performance Engine ( or any engine as for as that goes ) with a low water pick up on the lower unit ( which is a must , if this is not a low water pick uped lower unit the engine being jacked will quickly run out of engine cooling water pressure and engine will be damaged BEFORE the optimal speed and handling can be achieved ) jacking to optimal and is the only way to get your ring to its ultimate potential and to handle to an optimal set up . Dialing in these boats,motors, gear cases, and props combos are a trial and error game and must be done in small increments and the results of each change needs to be recorded for future movements and to see what helped and what hurt...
2jigs
Well-known member
beetlespin
Well-known member
Jackplates allow you to get the prop in cleaner water but the main thing they do is help the boat lift better. I switched from a 6" to a 1O" plate on my boat and picked up 1-2mph but the boat really carries a load a lot better now. I hate it when a boat rides flat on the water. That is the reason I traded my Z-2O. In my view that boat would have needed a 2 foot jack plate to lift! Now I think the new z-52O may have that issue worked out. Especially with a big 25O pro xs and a 1O" plate hanging off the back of it.
Lance
Lance
Burger
Well-known member
Beetlespin,
speaking of rangers I love the ride in them but most I've been in look like they're about to nose dive into the water. How does your ranger ride. speed? holeshot?
speaking of rangers I love the ride in them but most I've been in look like they're about to nose dive into the water. How does your ranger ride. speed? holeshot?
beetlespin
Well-known member
Burger,
The z-2O was a very nice boat but it was a very heavy boat, especially up front. It was very difficult to lift the nose in rough water and spearing waves was easy to do. Part of the problem is that 225 HP is just not enough for that boat. The new z-52O is rated for a 25O and is supposed to be redesigned to increase lift. If that is the case I'm interested in one. I currently have a stratos 2OO xl and it is the best riding boat I have ever had.
Lance
The z-2O was a very nice boat but it was a very heavy boat, especially up front. It was very difficult to lift the nose in rough water and spearing waves was easy to do. Part of the problem is that 225 HP is just not enough for that boat. The new z-52O is rated for a 25O and is supposed to be redesigned to increase lift. If that is the case I'm interested in one. I currently have a stratos 2OO xl and it is the best riding boat I have ever had.
Lance
Possum
Well-known member
I have a 520 and I can testify that the 225 is not enough for that boat and it is heavy up front, speared a wave off an ocean linner in Venice, La and thought the boat was going to sink. But I will say this, it is a cadillac in rough water. I love my boat It runs plenty fast enough. I put a 6 inch jack plate on mine but it was for running in shallow water down south. I rarely use it here.
minner
Well-known member
And to add to what these guys were saying. It lifts the boat better and you can get your motor higher BECAUSE it changes the fulcrum point of the boat, i.e. the center of mass. It moves the entire weight of the motor back off the boat and the jackplate adds more of a cantilever action the farther back you put it. With the center of mass moved farther toward the transom, the nose will ride higher and less pad will be in the water, which means you will have less wetted surface. Less wetted surface means less drag, which gives you more speed. Now that you have the prop in "cleaner" (cleaner means less turbulent in this case, turbulence created by the keel of the boat) you are able to run the pop higher and the motor more level eliminating excessive trim which would have created more prop slip, and decreased your speed.
Burger
Well-known member
Now that makes plenty of sense minner... No offense but that first message was way over my head.lol Thanks though...
Bubbakat
Well-known member
Well Buger sorry about the misconception of my analogy of the jack plate. But if you will read it step by step instead of all one message it will make séance. I will refrain from making comments in this section then.
minner
Well-known member
I don't think he meant anything by it BK.
I was with you the whole time, I do believe that is one of the better descriptions of measuring prop height I have seen. It's very difficult to describe in words.
Fuzzy
Well-known member
Thanks BubbaKat. I am ordering a jackplate, and you helped me determine where I can start my "setup". For me the decision was easy. I have a 2007 Ranger 188vs with the Yamaha 150hpdi. It will only lift so high, you can't spin out the prop. I am running 53mph about 5800rmp, I want 55mph at about 5500rpm. Yours was a more technical version and suit my bill well! Once I get the jackplate in for the summer, hope to upgrade to a 175 next winter..
beetlespin
Well-known member
Forget the new motor. Just get a phase II Hydro_tec kit on that yamaha and you will outrun a 175.
BS
BS
beetlespin
Well-known member
Forget the new motor. Just get a phase II Hydro_tec kit on that yamaha and you will outrun a 175.
BS
BS
Fuzzy
Well-known member
The phase II is a thought, did not know about it. Wish I knew how much HP you get from the tuner, heads and reed add ons. I know the carbon fiber reeds don't flex as much and the tuner helps it flow better. I assume the high performance heads increase the compression a tad bit.
Thanks for the info,
Fuzz
Thanks for the info,
Fuzz
