35 mph
 

does that sound right to you
v20 steplift with a 150 merc O.B. turnig a 15x17 aluminum prop
35mph @ W,O,T
if i switched to a s,s, prop how much more should i get in mph

It depends on your current prop. What is your WOT RPM's?

I am running a johnson 150 with a 15x17 SS prop. WOT fully loaded is around 39-40mph, light load and trimmed up I can hit 45. If you are 35 fully loaded then I think you are pretty good, but if that is trimmed up and light you may want to have the prop refinished.

-Svence

I still haven't taken the time to get mine dialed in right.
First prop was a 14x19 stainless, it turned 5100rpm & 42mph, this was a light load in the boat, 20gal fuel and smooth water.
The second prop was a 14.8x17 aluminum, it turned 5000rpm & 41 mph normal load in the boat for 2 people fishing , 40gal fuel and rough choppy water.

Sounds like you got your RPM's confused. Normally your RPM's will change @500 RPM's between prop pitches. And If the diameter is the same, you will turn @200 rpm's less changing from an alluminum to a stainless. Maybe this will help.

The new aluminum series for the OMC engines work like stainless props do for the most part. I ran a 19 VIPIR on my bowrider which would run 47-48 loaded down and turn 5600 RPM's. I then tried one of the newer large diameter aluminums that turned 5400 RPM's and ran 45-46 MPH. The diameter as well as blade design plays a large role in propping. I would think the APOLLO 4 blade in a 16 or 18 pitch would work really well on a V-20 for lower HP numbers. A large diameter like a MIRAGE would work well too probably, but I don't think a V-20 is really heavy enough to really need a 15"-15 1/2" prop.

I carry a lot of weight in my boats, when I had the V20 it would be 2 or 3 guys 60 gal gas, and all gear.
I liked the 15 x 15 1/4 prop, got out the hole fast and still manged mid 30's for speed.

Cuddy

W.O.T is 5800 rpms
is it a light load? not sure 2 adults 35 gallons of fuel
food,ice,fish it gets heavy, shucks my tackle bag weights about 30lbs

This sounds like part of your problem. If that is a 2.0L 5800 isn't horrible, but 5500-5600 would be ALOT better. And if you have a 2.5L you need to get the RPM's down to around 5300-5500. Around 5600 the porting in a 150 MERC is pretty well out of air, they just don't run much above 5600 stock. I'm guessing since you say you have a 150, and a 17 pitch you have a 2.0L though. Try a STAINLESS prop in a 17-19 pitch range. If your after cruise and economy go with a large diameter or a 4 blade, and if your after top end go with a 14-14 1/4" 3 blade stainless.

I thought Mercs run around the 6000 range. I've got a 2.5L 200hp Merc. and my mech says they should run in the 5600-6100 wot. My aluminum prop is so old and crusty that I can't tell what size it is any more, but with my curtains up and half tank of fuel, I can average 42 in a two way run. Without the curtains I can get 45-46. Given that's on a flat day with probably only one blade ever touching the water b/c of being trimmed up so much.