Prop pitch for 300HP verado on 228 grady white

M

mikep

Well-Known Member
trying to figure out what prop is going to work on my new engine, we got a killer hookup on a 300 verado. We were running a 15 pitch prop on the 225 verado and getting about 6100 rpm. I understand the max rpm for the verado is 6400 so I would like to be right up there. Now that we have gained 75 more hp I am sure we will have to change the pitch..........but by how much? I am looking a either a 18 or 19 pitch mercury prop to compensate for the hp change is this thinking correct? Engine is on a 1986 228 grady white. Any prop gurus out there?
 
What is the gear ratio on the 300 Verado? If it's 1.85:1 then you'd see about 6000RPM with a 19p. I would think a 17p or 18p would be the best bet if you want to reach 6200-6400 RPM.
 
I think you will be able to turn a 21 but... in my experience, you lose slow speed 'grip' with taller props. I mean the times when it is rough and you are running at low planning speeds. The 21 may give you max top speed but slightly less economy at open ocean running speeds. I run a 19 on my boat even tho it will turn a 21 well ( 250 Yami on 23' Monaro ) I have a 21 you can try - btw - I only use the 21 over the winter for cruising inside waters.
For offshore, I would look for a large dia. 19pitch. You'll get better 'bite' pushing up a swell and better overall econ. Just control the max rpms if it revs too high by slapping your right hand with your left - haha
 
I have a 275 verado on my podded 24' searay,running a mercury inertia 14.5 x 17 stainless.max rpm I get is 6100 and 47mph. Tried a 14.5 x 15 and it was horrible,revved right out but could only get just over 35mph out of it
 
Heres my guess.....
Revolution 4 17" for the days your loaded heavy and heading out offshore in the rough.
A large diam 3 blade like a Mirage+ 19" for the inshore not so loaded days.
 
Last edited by a moderator:
Wow its like christmas in july around here guys, thanks for all the help!! I am leaning toward the enertia line of propellers as we used it int the 15 pitch on the 225 and were really impressed. I can easily get my hands on a 18-19 pitch version and at this sencond in time i'm leaning towards the 18 pitch. I don't mind losing a little top end for some lower end grunt. I doubt this engine will see much full throttle operation but it will be nice to have the power when I need it. Before with the 225 we were able to get 43 mph out of her, I am hoping now for closer to 50!

Trendsetter yes the gearcase is 1.85:1 so It looks like the 18 pitch may put us in the sweet spot.

This boat will be used for a combination of long haul 300+ mile trips in the summer time and then mostly around town in the fall/winter.

All great information guys I am just itching to have this thing in the water its been on the hard for over 6 months now and my summer is slipping away!!!
 
most reputable shops have prop exchange when choosing the right prop assuming you don't damage the thing.
the best way is to figure a starting point i agree with most that a 19 is a great start, its important to load the boat the way its going to be run 90% of the time and give it a try, alot of times people overload the boat with " spectators " then go prop it. next time you use it by your self it over revs.
personally i wouldn't recommend running to the max of the WOT recommendations it should give you a range 5900-6400 aim for the middle.
 
Thought older 228's were rated to 250HP? Sure would like to hear your numbers once that puppy is installed...Its gonna fly.
 
I think thats what they were rated to but mine is a little different as it has a large hull extension pod which essentially gives me 2' more boat. Apparently at one point in time the boat had twin 150HP optis, I had the option of a 250 or 300 for the same price with no weight penalty so 300 it is! pretty excited to try it out.
 
combover said:
most reputable shops have prop exchange when choosing the right prop assuming you don't damage the thing.
the best way is to figure a starting point i agree with most that a 19 is a great start, its important to load the boat the way its going to be run 90% of the time and give it a try, alot of times people overload the boat with " spectators " then go prop it. next time you use it by your self it over revs.
personally i wouldn't recommend running to the max of the WOT recommendations it should give you a range 5900-6400 aim for the middle.
Click to expand...

When selecting the correct prop PITCH and DIAMETER have to be considered, along the boats weight. This isn't your normal run of the mill sport fishing boat... That is a heavy deep V hull that won't want to get up on plane with a 19 pitch prop. Diameter, diameter, diameter! If you are looking for top end speed, a 19 pitch prop certainly will work with a 14" diameter prop! However, fully loaded with passengers, gear, and gas... you'll be lucky to get up on plane. In rough water - forget it!

My Boston Whaler runs two 225's (total 450 horsepower) and with two four bladed SS 15 pitch props. Fully loaded with a weeks food, etc., even in flat water I am lucky to get it up on plane! For me to get it to plane in rough water, all gear along with everyone has to be moved upfront.

If WOT is 6400 rpm then that rpm should never be exceeded, which can be controlled by either prop and also throttle. To determine if the boat is correctly propped I recommend that WOT it read 6400 rpm or even slightly above for that expected extra weight. Even if it reads 6500-6600 rpm at WOT nobody ever said you can't control that with your throttle to not exceed your maximum 6400 rpm.
 
Thanks for that charlie, my old verado 225 which was running a 15 pitch enertia prop was able to do 6100rpm and I was really happy with the performace. We tried an 18 pitch enertia on the same boat and could barley make 5200 rpm. I would like to stay with the enertia line of props and I know 15 will be too little prop for the boat with the added hp. I belive the enertia is 14.75" diameter. Right now I can easily get my hands on a 15 pitch enertia so I will run that to find a benchmark and then go from there.
 
With all things being equal (gear ratio, prop design and boat weight) and the only difference is +75hp then I'd start with a 17p enertia. 19p will be too much, 18p will be close but still likely too much. If your 225 turns the 18p only 5200 RPM, no way the 300 will turn it 6400RPM.

You can forget about diameter if you are staying with the same design of prop. The higher the pitch of the prop the smaller the diameter typically. That doesn't apply if you change to another design (Solas Rubex, Vengence, Stiletto etc)
 
Well guys it looks like I found my prop, I went with a 17P enertia. The boat isint quite a 50MPH unit but we are darn close. I was able to get 48.5MPH out of her at 6300 RPM with four people and 60 GAL of fuel on board. I think with just me and a smaller amount of fuel she might do 50. I can't thank all of you guys enough for the insight on my prop question. So stoked to finally be out using the grady after all of the months of work done to it.
 
You must log in or register to reply here.

Similar threads

G
Proper prop pitch
Replies
24
Views
2K
spring fever
spring fever
bentley
GW 228 Yamaha 225 Prop
Replies
10
Views
1K
doug78
D
L
Grady White 228 for sale $31,500
Replies
3
Views
2K
Aces
Aces
Macdeep
Prop Advice for Merc EFI 115 on Malibu 182
Replies
34
Views
3K
Macdeep
Macdeep
67greengt
2005 Grady White 282 sailfish for sale
Replies
11
Views
2K
67greengt
67greengt
Back
Top