03 521vx prop/motor question

[Vince521VX]

Hi. I have a 2003 521vx with a evinrude ficht 250 on it. Has a Ranger 6 inch hydraulic jackplate. Prop is a 4 blade renegade says 13 1/2 X 25 inside. With full tanks of gas, 2 people, tournament load of gear, jackplate all the way down, I was lucky to touch 53 mph on gps, rpm's in the 5,000-5,500 range. That seems way too low of speed. Can something this slow be just a prop issue? I just got the boat last year, and only had it out a few times. Always ran with full tanks of fuel, but alone I was still around 56 mph. Still too slow of course. Hole shot is great on it. Only thing extra in back is 1 PowerPole. Any help would be appreciated. Thanks

[FTMS]

I have a 225 on mine and will hit 68 mph with a 3 blade, no jack plate. I don't recall what pitch it is but I can take a look later.

[ROOD]

I have the same boat/motor with a 26P Trophy prop and run 67 mph at 5700RPM. I found the best prop for this boat/motor combo is either a 26P Tempest (3 blade) or Trophy (4 blade). Top end is same but I get better lift, hole shot, handling and low planing speed with the 4 blade prop. Your top end seem low and you should be at 5700-5800 RPM and WOT.

[Vince521VX]

Rood, I'm new to all of this, and first off thanks for the input, would the prop have anything to do with rpm at WOT as well? So you would more recommend the trophy 4 blade? I figured I would be sacrificing some of that hole shot for more top end speed, but if the trophy has the benefits you mentioned, then it doesn't sound like much of a sacrifice. What would be the advantage of the tempest then at that point? I would be thrilled if I can get into the 60's with it. I had a tournament on Thursday, I was boat #3. I watched 1 and 2 slowly fade away and eventually another guy blew by me like I was standing still. I know that boat with that motor isn't going to be a speed demon, but that sucked a little lol

[79Ranger168v]

You stated that your jackplate was all the way down. If that is the case it’s probably what killing your speed and rpms. I run a ‘03 521vx with a Yamaha ox66 250 that’s has a fresh power head with carbon fiber reeds. I’m currently running my prop shaft at 3 1/4” below pad. With my worked 25p Tempest I run 69-70 with full tanks by myself and 66-67 with a partner and have a pretty decent hole shot. With my unworked 26p Tempest I have fun a best of 72.8 by myself with 1/2 tanks of fuel. With a partner the hole shot is a little slow with the 26p. I can spin both props 61-6200 rpms. I’m still trying to get everything tuned in with the jackplate and prop. I also have a LOT of gear in the boat and it really matters where you place tackle in these boats from what I have found. I have gained almost 2mph by just moving tackle around from front to back. I would try to set your jackplate so the prop shaft is 3 1/2” below pad and move it up 1/4” at a time until you loose speed, hole shot, or water pressure.

[Vince521VX]

like I said i'm new to this. What does it mean 3 1/2" below pad? Below bottom of boat? Ive been around boats for about 10 years, but as a co-angler. So information like this is foreign to me. I asked the only guy I know personally with a hydraulic jackplate, and he said he keeps it as low as it can go. That's all I ever went off. I haven't had time yet to get it out this year other then on tourney day. I wasn't really doing much experimenting then with moving the jackplate.

[Vince521VX]

I am definitely listening to and appreciating any advice though. So much good help and information on here

[crashxx]

The 3 1/2 inches below pad, refers to the center of the prop shaft relative to the pad on the boat. If you level the pad which is the back part of the bottom of the boat that it runs on and then level your motor based on the cavitation plate, measure from the ground up to the bottom of the boat and then from the ground up to the center of the nosecone and subtract the two numbers. That will give you your distance from prop shaft to pad The 3 1/2 inches below pad, refers to the center of the prop shaft relative to the pad on the boat.

[79Ranger168v]

Yes. Park the boat on the most level area you can. Then make sure the gound is level from the motor to under the back of the boat. I don’t have a level area so I usually use a piece of steel or straight board then shim it to level. Then level the boat itself from front to back. Next level the motor by placing the level on the cavitation plate and trimming it until it’s level. Measure from the ground or board to the lowest point at the back of the boat under the hull. That is the pad of the boat, which is where it’s running on plane. Then measure from the ground to the center of the prop shaft. Subtract that number from the pad measurement. This will be your prop shaft to pad measurement. Then raise the motor with the jackplate until this measurement is 3 1/2”. If I had to guess yours is probably 5-6” now. If you need more info on this look at the sticky’s on the bass boat setups page.

[Vince521VX]

Easy enough Good place to start. Thanks again

[wmitch2]

If its a hydraulic jack plate, you dont need to go thru all the measuring. What you're describing, it sounds like you are not raising your jack plate up enough once you're on pad. Watch your Trim gauge, RPMS, your water pressure gauge, Jack plate gauge, and where the water is pushing out at the side of your boat.
Trim up until the steering is easy, RPMS @ WOT should come up to 6000-6200, water pressure should be +/-20, Jack plate height will set the water pushing out the side and should begin just behind the driver seat. Once you get all that dialed in, you'll know about how high to raise the jack plate and trim once on plane !! Sound harder than it is, lol !!

[Vince521VX]

I am not raising my jackplate at all. Like I said only info I ever got was keep it down, so thats what I did. I have thought of playing with it, but no actual procedures to try. Just haven't had the time yet, winter doesn't seem to want to leave northeast PA. So I should start with jackplate down, get on plane trim up to where I normally have, then start raising jackplate looking at the water spray coming out of the side of the boat? I have never got my RPM's that high with my current situation. I'm assuming raising jackplate will raise them then? Once jackplate is raised should I then play with trim after, or is it trim first then get jackplate where it needs to be then I'm Good.

[Phoenix 921]

you should only lower your jackplate all the way down in really rough water to keep prop in the water. The rest of the time it should be as spoken above raised up all the time. The jackplate rising up raises the boat up while running. The less hull in the water the less motor HP required. This will raise RPM's. You should watch water gauge to make sure you do not raise the motor so high the water intake comes out of the water and quits pumping water to cool motor. You need about 20# to keep motor cooled on most brands. The boat will start to get a little lose if you get to high to. Most boat brands put a lock plate on that is manual and it stays in same place all the time. Those are adjusted much higher then yours and its never moved. You won't hurt the boat or you if you raise it up as long as you watch the water pressure gauge and when it starts to get lose trim down a little till it gets back under control. Try it till you get comfortable with it with little steps