RT198P 45mph max

[JHintson]

Looking for some advise on my slow boat. 2019 rt198p with 150 Pro XS, 23p tempest. Boat is currently at the dealer investigating the speed issue. They have checked for a hook in the hull and have told me that the hull is in good shape. Myself 210lb and 2 small kids [120lb combined] with gear and 1/2 tank of fuel we can only hit 45mph. They have increased the trim limit by 10%, did not change the top end speed. Has anyone had this type of issue. No jack plate on my boat, any help will be greatly appreciated. Seems like everyone is running 55mph +

[pmgoffjr]

There are universal rules for boat setup.
Your prop is 90% of your performance, until it's right, nothing else will be.
So, to judge your prop, one needs to look at what it's doing, so at 54 mph, what's your rpms? How high is the roostertail? Is the steering really stiff? where does the water break at full speed? Out the sides or straight back?

[JHintson]

There are universal rules for boat setup.
Your prop is 90% of your performance, until it's right, nothing else will be.
So, to judge your prop, one needs to look at what it's doing, so at 54 mph, what's your rpms? How high is the roostertail? Is the steering really stiff? where does the water break at full speed? Out the sides or straight back?

Thanks for the reply.

5900rpm
Large rooster tail, I would say the steering is fairly stiff. The water breaks at or in front of the console

[pmgoffjr]

Ok,
Now that's a description that gives you a clue.
High rpms/low speed/high tail/flat running hull/stiff steering are all symptoms of motor being too high for the prop you're running.

Your choices from there are: start swapping props to see if you can find one that runs at that setting. Drop the motor one hole and see what the results are.

I would have probably rigged it with a 6" rapid jack plate, iron hulls can be wildly inconsistent and just because something worked on one, the next one needs something way different. A proper plate will really help finding exactly right.

[JHintson]

Thanks Pat, what you said makes perfect sense. I'll be talking with my dealer today and see what we can work out. I love this boat but want to be able to use it to its full potential.

[pmgoffjr]

True fact there.

[Goliac7]

I have a 2018 RT 198 P with a 150 Pro XS that had the same bow lift problem. I was sitting at 5400 rpm and 50-52 mph WOT. I got a 4” manual jack plate installed. This initially gave me 1-200 RPM but only 1 mph. We lowered the engine on the plate about 1.5-2” and now the bow flies out of the water and I got 60 mph GPS at 5800 RPM. It’s funny how something that seems so small can make a huge difference. I’d say try to lower your motor if you can.

[JHintson]

My boat is currently at a repair facility. They determined that the weld along the bottom of the transom was protruding below the bottom of the hull creating drag. Hopefully this fixes my problem, I should have the boat back in about a week. Fingers crossed!0222201752a_HDR.jpg

[pmgoffjr]

Yeah, that would sure cause all manners of problems.