Speed is WAY slow. Any gueses?

[wdr2064]

Hi, I have an AVX 1980 that currently has a top speed of 45 mph. I got in touch with Vexus and Keith Tripp got back to me right away and told me my boat is not running right. He got in touch with my dealer and they now have it to see what is going on. My boat should occasionally at least touch 60. I am curious as to what is causing this and figured I would get input from you as to what you think it is. Here is what I have:
1. Mercury 150 4 stroke Pro XS.
2. Slide master jackplate.
3. 23 Tempest plus prop.

On the original 2 hour break in period when we would go full blast for 1 minute every 10 minutes with my wife. It touched 50 mph a couple of times with her. Then I started adjusting the jack plate. I did it at factory setting, 1/2" up, 3/4" up and 1" up. At all settings the RPM's were around 5,700 to 5,800. Speed touched 46 and RPM's were the same at all settings. The higher I went the lighter the front end seemed. That was the only difference. Motor runs very, very smoothly. I did ding the prop idling looking for fish and brought it to a local prop shop and they repaired it. It did not seem to make any difference in speed. My friend also has an AVX 1980 with no jack plate and a Mercury 4 stroke 150 that is not a Pro XS and he has seen 58 mph. I figure mine should touch 60.

So, my friend thinks it is the prop and I tend to agree. I presume we shall soon find out what the issue is. When we do I will be sure to tell you.

[LDraper]

Check the fuel line. I have a friend who had the same problem and his fuel line had a pinch in it.

[Sinisterj]

I feel the same way about mine, I have a 150 pro xs and fastest I have seen is 50-51 on gps. I keep seeing people posting numbers of 57-60. Not mine...

[Huckleberry]

It’s a 20’ boat, it should have a 200 on the back.

[quikcarl61]

The 2080 does have a 200 on it.

[TxCruzr]

Took out a 1980 with the 150 evinrude out on Pleasant a few months ago, topped out at 45mph. Cant remember what the fuel was at but pretty sure it wasn't full. After driving some different boats, it felt sluggish. No help, I know.

Phx heat certainly doesn't help. Good luck!

[wdr2064]

Well my friend hits mid to high 50’s with his. Regular Mercury 150 4 stroke with no jack plate so it doesn’t make sense.

[Jimbug]

I have the 1980/G2 so no experience with your setup, but if it is turning 5800 RPMs and only going 46mph something isn’t right. Prop isn’t lifting the boat it seems to me, as the prop is turning enough RPMs for you to get much better speed if the boat lifted more. Just a guess on my part if everything else checks out. Good that the dealer has it and can check all the numbers on the computer to see if he notices something. The 1880/115hp runs 48mph WOT when set up correctly most of the time by comparison. Hope they figure something out on your rig, and smart to get it looked at early in the warranty period.

[mdtritn21]

The regular 150 is geared at 1.92 and and turns 5800 rpm's. The Mercury site says the new 150 pro xs is geared at 2.08 and turns 6000 and if thats right the new 150 will never be as fast as the regular 150 turning the same pitch prop.

[Lou22]

I have the 1980/G2 so no experience with your setup, but if it is turning 5800 RPMs and only going 46mph something isn’t right. Prop isn’t lifting the boat it seems to me, as the prop is turning enough RPMs for you to get much better speed if the boat lifted more. Just a guess on my part if everything else checks out. Good that the dealer has it and can check all the numbers on the computer to see if he notices something. The 1880/115hp runs 48mph when set up correctly most of the time by comparison. Hope they figure something out on your rig, and smart to get it looked at early in the warranty period.

48mph is my top end at WOT with my 115 pro-xs.