I Need Jack-plate Education

[sowenssw]

I have another post mentioning that I might want to trade my jack-plate for less off-set. But I got to thinking I prob should get an education on jack-plates 101 from this group first. I'll try and keep this post short, but I want to lay the ground work / history of where I've been.

In 2003 I bought my Bullet 20XDC new with a Mercury 2.5 280. My dealer installed a 14" jack plate (manual) back then and it always seemed to work well. Fast forward to 2012, I put a (at that time) new 250 Sport XS on the same boat and was told I would need to go to a 12", so I did and it seemed to work well (manual).

So that brings me to current date, I have a 2020 250R (same boat), I had it originally mounted on the 12" manual but had a blow out issue on break over so I decided to go with a hydraulic plate (and that solved the blow out issue). I went with a Bob's 14" hydraulic, remembering how well the 14" did with the 280. But now it seems like the 14" is making it harder for the 20' boat to get on plane compared to the 12", feels like it wants to dig more of a hole.

I always thought the purpose of a jack plate was so that motor height could be fine tuned and the set back helped to get the motor in cleaner water to allow higher motor height to be ran. But is the bigger off-set actually hurting me getting out of the hole??? Seems like moving that much weight back 2" really changed how the boat comes out of the hole. With the Bob's it also moved my 10' power poles back about 5 inches from where they mounted on the 12" plate. So I'm wondering if I need to go back to a 12" or maybe even a 10"?????

Someone please educate me!

[ThomasD]

New 250R weighs almost 150# more then the old 2.5 280

[sowenssw]

New 250R weighs almost 150# more then the old 2.5 280

Exactly, and the 250 Sport I had did really good with the 12", and it was ~130 pounds heavier than the 280, so with the even heavier 250R I'm thinking maybe a 10" might even be better than a 12"??

[rocketmanjp]

The 250R & 300R with sportmasters weigh 561 lbs. I got this from another site where a reputable boat builder weighed a 300R with sportmaster. I caint remember exactly what a 280 weighed but I’m thinking 375 lbs. That would put the 250/300R’s at 186 lbs. heavier. Moving those power poles back 5” is a lot too.

[av]

Just a thought , I always have filled my jackplate with flotation so it sits up higher in the rear not sure if you can do that with a Bob's but it definitely helped hole shot.

[sowenssw]

Just a thought , I always have filled my jackplate with flotation so it sits up higher in the rear not sure if you can do that with a Bob's but it definitely helped hole shot.

I did the same thing on all my other jack plates. I was going to look and see if it was possible with the hydraulic, I haven't really studied it yet.

Do you all think a 10" or 12" might work better for this set up?? It feels like the 20' boat and 14" jack plate aren't playing well together. As I mentioned, I ran the 250R with the 12" manual before I went to the 14" hydraulic, and it seems like it completely changed when I went to the 14, seems ass heavy (and I also have lithium batteries to help shed weight).

My gut is telling me to go with either a 12" or maybe even a 10" hydraulic.

I always appreciate eveyone's thoughts and ideas, you guys are the bomb!

[Kyle08]

I wouldn’t go less that 12 but it’s also personal preference. I just got my 4” static to add to my 14” bobs hydraulic plate. I like top speed so most things are centered around that.

[KenHo]

Here is some general information that might be helpful from another post.

There is a lot of mis understanding out there on jackplates. The fulcrum is NOT the pad. The fulcrum is the face of the jack plate where the motor is attached. Think of it like this; wrap one arm around the front of the motor cowling and push forward on the prop with the other and attempt to raise the front of the boat. This is what the motor is doing. The farther back you put that fulcrum the harder it is to pick up the front of the boat. As Don said moving the motor back makes the effective length of the boat longer. Pick up a sledge hammer by the very end of the handle. Hold it out parallel to the ground. Now choke up about 6 inches and repeat. Which position is easier to hold the hammer parallel to the ground?

So why do we move the motor back on high performance boats? Many of these boats run motors very high. I would expect the OP's boat may have the prop centerline 3-4 inches below the bottom of the boat. A boat like mine runs the centerline of the prop 1-3/8" ABOVE the pad, some even more. If you run the motor that high without a jackplate, the prop would be more than half way out of the water. Therefore we have to shove the motor back to where the water is higher relative to the bottom of the boat and is better water. At higher speeds even with my 12" setback my prop arc will have the top blade 1-2 inches out of the water. It is a constant trade off with set back verses lift. In my case I have enough horsepower to weight to move the boat fast enough to start generating lift. Most boats with a pad generate little lift below 60 MPH. You have to stuff air under the hull along with the motor torque to actually "fly" the hull.
Many think pushing the stern of the boat down is the same as lifting the front, it is not.

I have no experience with a boat like the OP's but if what Don says is correct about lift it may help to make the effective length of the boat shorter thus getting the boat up a little easier.

Full disclosure: I stole some of the wording and examples from Paul Nichols over on the Bullet page. Many think Paul is one of the best in setting up high performance boats, I would agree.

[sowenssw]

Good info thanks!

[BulletTJ]

You should have bought a 12" plate. You are leaving performance on the table with a 10".

[sowenssw]

You should have bought a 12" plate. You are leaving performance on the table with a 10".

I'm actually running a 14" right now. I was running a 12". The 12" was working really good but needed a hydraulic plate to be able to get out of the hole without blowing out, and decided to go with a 14". Now it seems ass heavy after moving the motor and power poles back more.

I was thinking about going back to a 12" or maybe even a 10" (and I agree with you, I think the 10" might not be enough).

[gehol]

With all that weight you may get better performance with the 10". Call Tom at bullet.

[sowenssw]

With all that weight you may get better performance with the 10". Call Tom at bullet.

Will do, thanks!