More Speed?

[Bob Horn]

I have a 87 ranger tiller with a Yamaha pro 50 on it. Totally loaded and water in the live well I can get 26mph. Unloaded and just me I get 30. Used my gps to check speed. Is there some way I can get 35mph when the boat is loaded or is this it?

[Northlander]

What are you running for a prop and whats your hole shot and rpm's at WOT?

[Bob Horn]

I don't know the answer to either question. I believe I am at 5400rpm. I think but not 100% sure I have a 13 pitch stainless prop.

[Northlander]

Im sorry I forgot to ask how big of a boat? 17'?

[PerchJerker]

Assuming that the prop you have on now is the right prop (or close to the right prop) for your setup .......... and assuming that your motor is at (or close to) the right mounting height ...... and that your motor is tuned and running right ....... then you are not going to be able to increase speed by very much.

And you should face the facts too --- you have a 50 hp motor, that's a motor that should troll down well but not blow past everyone at WOT --- and you have a Ranger, a boat that has a great ride but is not a fast hull. It's just not a "good" combination to try to squeeze a lot of extra speed out of.

[Bob Horn]

17ft is correct. I was thinking it was maxed out but hoping to get a little more speed. I don't need a fast hole shot just top end to go fast to the next spot. I am going to check the prop today and get the info off of it. Let you know. Thanks for the help.

[hanson]

I have a 16' Mirrocraft w/ a Johnson 60hp on it. Older boat from the early 80s. I just had the motor rebuilt earlier this summer as I had a ring break and take out a cylinder.

Anyway... before the rebuild I was hitting 30 mph, sometimes 31 mph.

This weekend, I finally got it back over 28 mph. I've been running a heavy oil mix for break-in still and am starting to lean it out to 50:1 now. Prop needs some work as well which will help me out.

Sort of comparable boat & engine size and any day I break 30mph is exciting. LOL!

[Northlander]

Ya I would guess your about what your going to get with that 50.

[Bob Horn]

Pitch is 11 1/2 x 13G. I noticed the prop was a little loose but I don't think it will make up 5mph.

[hydro]

Bob, there's good and not so good news here for you. I looked up the Yamaha Pro 50 and found a 1990 version, and that had a max RPM rating of 5500 and a gear ratio of 1.85:1. With those parameters and a 13" prop, you could see a maximum speed of about 31 MPH assuming 12% prop slip which is probably close for your type of boat. If the prop is cupped add about 2 MPH in theory. The good news is you are exactly where you should be with that prop and a good setup.

Now if you want to go faster, you could try a 14" prop and see what happens. If your motor can maintain WOT RPM between 5400 and 5500 lightly loaded you have a winner, but if it cannot hit those RPM's you have too much pitch. To fix that you will need more horsepower and that's where the increase in speed is equal to the money invested squared!

[Bob Horn]

I think I am going to keep it the way it is. I will just have to buy a bigger boat next year. Oh darn. Don't want to invest anything into it with this market. Thanks for everyones help.

[Northlander]

Ya lots of nice used rangers on the market at good prices these days. Buyers market for sure.