Speed questions.

I noticed a post here that got me interested in our boats top speed.

The boat is a 2002 Lowe AN165S, a riveted aluminum deep V, 16.5'

It has a 50hp Johnson with I would assume the original prop, its a 3 blade (black painted) aluminum with no markings.

It runs on my gps a max of 28-28.5mph with just me, empty livewell, light gear. 24-25mph with another adult, livewell full, etc. It does have power trim.

Sounds like I should easily get 30+mph, even possibly closer to 40 properly setup. But what IS properly setup? If the prop is poorly sized for the boat, how do I find a better fit?

That's a hard question to ansewer. Different hulls will run different speeds with the same motor. My 17 Wareagle with just me and heavy loaded will get 31 if conditions are right with a 50 four stroke. Thinking 40 is way optimistic. Maybe in low 30's. Do you have a tach? What is max RPM for your motor? What size is the prop your running now? And if you have a tach how many RPM's is it turning?

It does have a tach, runs about 5500 it seems at what I consider about the proper trim. It does gain a bit more rpm if I fiddle with trim more, but I typically just run it at around the 5500rpm mark.

What is the highest RPM it will run? This will tell us if the prop is too small (pitch).

If it's a 2 stroke 2 cylinder 50hp Johnson, 40 mph is nearly impossible. Looks like you're about right on RPMs and speed for that setup. A good stainless prop might get you 1-2 mph.
There should be a number on the prop on the face of the hub (where the nut holding prop on is) unless it's been painted over or rusted.
You would need a little more HP to push that Deep V to 40 mph. What HP is the boat rated for?

Yea, its a 2 cyl, 2 stroke.

The boat- Its rated for a 70hp.

I think I've got it closer to 5700-5800 by trimming it out, thats about max.

It seems to hop up on plane really quick. I'm fairly new to boats and just thought from what I was reading perhaps something was possibly off. If 25-28mph is its max, then I'll continue happily fishing away :) Our main fishing lake is 5k acres, doesnt take too long to go from one end to the other really.

If your running 5500 to 5700 that's right at optimum rpm. You could spend a bunch of money to gain very little. Good hole shot and decent speed I say leave it alone and spend that money on tackle.


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:hesaid

theysaid

First thing to look at is where the planning plate on the engine is running at WOT it should be just above the surface of the water, if it is not then your motor needs to come up. Once the motor height is set right then you can look at props and top end.


The way I set my trim is watch my GPS speed keep bumping up the trim until your speed just drops off. Notice what RPM you are running if over or under the RPM range for the engine will give you an idea if propped correctly.

Good info, thanks.

I fiddled a bit today on a long run back to ramp, seems highest speed I'm seeing is closer to 5800rpm. I haven't checked to see how the motor sits in the water, I'll try that next.

For reference. I have a deep-V aluminum boat powered by a 40hp 2 stroke. Top speed is 25mph via GPS. Fully loaded with two adults I get 23-24mph. I'd say given your rpm's and other factors, your doing fine.