2019 721 & V8 Mercury 250 Proxs

[Tom Edwards]

Tom in you case about starting with jack plate up, yes, with that Yamaha you can start out all the way up and work down and if you mounted that jackplate in the 3rd hole you will probably never go below half way down on the plate,

I mounted the motor in the bottom hole. I'd read that on BBC. Should I reinstall in the 3rd hole from the top?

[DREWTICK]

I mounted the motor in the bottom hole. I'd read that on BBC. Should I reinstall in the 3rd hole from the top?

no thats fine Tom. I was about to move mine to the bottom before I switched to Lithium Batteries, now I have to run deeper because the boat sits higher in the water

[Tom Edwards]

no thats fine Tom. I was about to move mine to the bottom before I switched to Lithium Batteries, now I have to run deeper because the boat sits higher in the water

Ok, I'll leave it. I have a tune up and oil change set for June 4th, after that I'll take it to the 'big lake' and test it. I don't want to take it up to speed again until the oil is changed. It hasn't been on the big lake since Oct or Nov. and 53 hours on this oil.

[Customsilverado]

UPDATE: So I took some ptp measurements this afternoon and seems like my motor is too high, which is really strange I would think my rpms would be higher than 5800 if the motor was too high.
My motor is mounted to the jackplate in the second hole from the top, and when my plate is at 17 on the digital gauge I am at 1" ptp which is about where I was running the boat when I got 5800 rpms at 72 mph and I had about 20 psi water pressure.
So the next time I take the boat out I will try running the plate lower and see what I get

[DREWTICK]

UPDATE: So I took some ptp measurements this afternoon and seems like my motor is too high, which is really strange I would think my rpms would be higher than 5800 if the motor was too high.
My motor is mounted to the jackplate in the second hole from the top, and when my plate is at 17 on the digital gauge I am at 1" ptp which is about where I was running the boat when I got 5800 rpms at 72 mph and I had about 20 psi water pressure.
So the next time I take the boat out I will try running the plate lower and see what I get

I dont have any seat time with a 4 stoke Merc but based on what you said Id come down to about 11 and then work on getting it trimed up some more as you get used to the feel.

[Captk88]

This is my second 721 and mine now just hit 10 hours on my 4 stoke merc, with 10” hydronic jackplate just normal no playing with anything and plate about half way up yes 75 is my standard number. That is one hand on the wheel and slight chop, now slick calm the other day playing with it I hit 76.8 and had some room to very little but some play but let off of it. Everything plays into it at those speeds I find a little air under the hull with wind chop helps, slick calm let’s the boat do what it wants. The higher the jackplate setting the more hill pushed into the water, also more chance of a blow out. The higher the plate more hull in water the lower the plate the less hull in water and boat will get squirly... it’s a fine line but when you find it mark it. I wouldn’t run it all the way up I would find that happy medium where it’s comfortable to drive and then play with trim and storage.

[Customsilverado]

Thanks guys
I am going to start at 9-10 which will put me at 3 ptp and i will run it wot from there playing with trim see what i get, then lift it to 2.5 and repeat
Just seems crazy to think with the plate all the way lifted the ptp is pretty much even. I wonder if that is normal for a 12" plate or if thats because the motor is mounted in the second hole

[Customsilverado]

On the other hand i do fish a lot of shallow water and its nice to know the motor lifts so high
Also i have taken off with the plate all the way up just to see if it was possible and it got up with minimal blowout.

[tuffnugly81]

Running mine at 12 or 13 I'm get full t load with 2 guys and 3/4 of fuel 74. Go up to 16 and it handles and rides better but only 70 to 71.

[Customsilverado]

Running mine at 12 or 13 I'm get full t load with 2 guys and 3/4 of fuel 74. Go up to 16 and it handles and rides better but only 70 to 71.

Thanks!

[Rolltide16]

Sent you a private message. Try that and let me know. I will be glad to answer any questions about that process.

[Customsilverado]

Sent you a private message. Try that and let me know. I will be glad to answer any questions about that process.

Thanks

[Customsilverado]

UPDATE:
I know this is an old post but wanted to give an update. After many trips after I made this post I still was only reaching 72, my uncle (who is experienced in running high performance boats) was finally able to make the trip down from Texas and we got to go run the boat yesterday evening and his first time behind the wheel he hit 76 mph with jackplate at 16 and 6100 rpms and trim maxed out. He did have to drive it a little but a lot of times he could take his hands off the wheel. With that being said I made a bunch of runs myself with me and him now knowing what the boat could do and I just cant control the chine walk. Im just glad nothing is wrong with the setup, I just need some seat time! Thanks for everybody's replys!

[RockYScouT]

Driving a boat that walks can be super scary to learn. Once you get it though,your done and it is so easy you don't even think about it. Don't give up!

[Customsilverado]

Driving a boat that walks can be super scary to learn. Once you get it though,your done and it is so easy you don't even think about it. Don't give up!

Yea thats what my uncle said too, its just super frustrating that i cant feel what the boat is doing to counter act it but in sure i will get it eventually

[Rolltide16]

You can bump that plate up some more. It will increase your rpms, speed and if yours is like mine you should hit the sweet spot where it will practically drive itself. Fortunately for you it sounds like your motor is like mine and it’s a little different than some of the rest. Guess ours were built on a good day of the week. I’m going to have some prop work to see if the rpms can be lowered a bit without sacrificing my top speed.

[Customsilverado]

You can bump that plate up some more. It will increase your rpms, speed and if yours is like mine you should hit the sweet spot where it will practically drive itself. Fortunately for you it sounds like your motor is like mine and it’s a little different than some of the rest. Guess ours were built on a good day of the week. I’m going to have some prop work to see if the rpms can be lowered a bit without sacrificing my top speed.

Yea once I learn how to drive it I will be able to play with the variables, because that was his first time behind the seat so I bet there is another mile an hour or 2 still left in it