SS Prop ?

I have a “High Five” Merc SS prop. The port plugs on the side of the prop, how are they used, and what is there purpose?

They affect hole shot depending on how many are open or plugged, when the holes are open they allow more slippage as water is drawn into the exhaust flow versus the prop biting all of the water around it.
That said,it’s late and I’m tired so I may have that backwards.

Yep, the plugs come with no holes, small holes, medium and large. You can drill a solid hole out to any size you want.

They allow exhaust bubbles to make your prop intentionally slip more during the holeshot (gets your rpm’s up).

The high five prop is/was super popular on big tiller boats. Mainly for the reason that their backward trust is terrible.

Five blades in reverse can’t grab much water, so tiller guys love them for slow backtrolling.

Here’s a video about PVS plugs from Mercury. I played with them a fair amount on my 186 Tyee with a 175 Verado. They made a huge difference in hole shot with different props.

Thanks for the info Sheldon and B-man for the video.
I’m not disappointed in the holeshot. Throttle down with just me in the boat my bow seems to rise less than half of my v8 sterndrive did. On plane very quickly!
My problem is I’m about 8 to 9 mph slow and I cannot trim up enough to get the boat out of the water enough to spray at a solid rear angle. If perpendicular to the sides of the boat at the helm is no trim. With full trim pushing 6000 rpm, factory max is 5750, it still is not getting the hull out of the water enough like I’m used to. The spray has only moved maybe 10 to 15 degrees to the rear. I know it can do majorly better!

Sheldon has been in my old v8 sterndrive boat when I’ve been under full throttle and fully trimmed. I’m wondering if a 23 pitch HighFive might be my answer. I would just hate to invest that kind of money and not be my answer. Mind you I’m not trying to achieve the Utopia match but I feel the boat is laboring because I cannot get it trimmed up properly. High octane non alcohol gas is near the price of diesel then add the oil to mix!!!

I think I can do better, anyone with a Opti 225 out there that is willing to advise?

Denny 4 blade props are known to lift the stern, I assume a 5 blade would as well.

I’d talk to a local marina/prop shop for their opinion, but I’m guessing a three blade would help to achieve what your looking for (they’re know more as a bow lifter).

With you running max RPM I would jump up a pitch size or even 2 in a 3 blade prop. You should loose around 200 to 250 RPM per pitch size increased.

5 blade props are well liked by boaters pulling people for water sports. Low speeds with plenty of torque and quick on plane.

My dad runs a 225 Opti Pro XS on a Z8 bass boat. He is running a 25 pitch on his.

Michael, A Z8 is a bass boat with what length (20ft?) and weight (2,000 lb?)?

I honestly think I could lose 750 +/- Rpms to achieve optimum balance. My new to me boat with the aluminum prop was slightly less desirable than my old Hi Five, both in a 21 pitch. The on plane was a bit better with the 5, actually much better than my I/O was. But weight distribution and HP are not comparable. I’m thinking at least a 3 or 4 blade 23 pitch stainless. I think if I went with a 25 pitch it might be quite a bit too much in a 3 blade, a 5 blade is only possible and it might be a bit sluggish to get on plane.

I went through the prop experimentation process last season. I had always run a 4-blade aluminum prop on my 18 foot aluminum fishing boat. It jumps on plane quick, but the top end speed is less than what I was hoping for. So I decided to try a 3-blade prop. The prop technician was absolutely sure that a 3-blade would get me a higher top end speed by a significant margin. WRONG! After using it a couple times it was obvious that it was not going to work. It took forever to get on plane and my top speed was 4 mph slower. I took that prop back. The technician was shocked by my results.

The lesson learned here is that there really is no way to know until you try it. I’ve since gone right back to my 4-blade.

What boat and speed are you seeing?

gim wrote:

The lesson learned here is that there really is no way to know until you try it. I’ve since gone right back to my 4-blade.

^^Best advice^^

Find a dealer that has a loaner prop program and figure out the prop that works best for your boat and load.

Also, I have never found any practical use for vent plugs on a walleye style boat. Keep them plugged up. You will thank me later!

Good luck,

-J.

Tom P. wrote:

What boat and speed are you seeing?

Ranger RT178 with a Merc 75 4-stroke. I get about 34 mph with the 4-blade prop. With the 3 blade prop I tried, I couldn’t even make it to 30.

A friend of mine has the same lund IPS2 hull design length and motor. His would run 54 gps. My old one would do 52, again the same length with a IPS hull. All three are Tyee 1950’s. With my friends doing 54 and I’m struggling to do 43/44 w/5 blade. The 3 blade 21 pitch aluminum was 41/43 gps. As far as the hole shot is, both props (3 blade 21 aluminum and the SS High5 are giving a far better hole shot on plane 2 to 3 times faster than my old I/O was with the High5!

I’m thinking a 4 blade SS 23 pitch.

Denny O wrote:

A friend of mine has the same lund IPS2 hull design length and motor. His would run 54 gps. My old one would do 52, again the same length with a IPS hull. All three are Tyee 1950’s. With my friends doing 54 and I’m struggling to do 43/44 w/5 blade.

One other thing to check out when comparing performance is the motor height on the hull. I’m going to guess your friend’s motor is up a bolt hole or two.

-J.

We have already covered that thought. We are the same.

Thanks for the thought, as it is very pertinent!

What was your friend running for a prop to get 54? If the setups were identical like you said, you should be able to run the same prop and atleast get very close to the same performance numbers. If you can’t you have something other than a prop to address unless you just have a ton of extra weight in your boat.

Have you put a straight edge to the bottom of your boat to check for a rocker or hook? Both will cause your boat to not lift the bow when trying to trim out. It sounded like you were concerned you weren’t getting much trim in a earlier post.

Denny O and I have discussed a few possibilities and I will throw those out here in case someone is having the same problem.
We know this is a very low hour motor, 40 some odd hours when the boat was bought but you never know what has happened in those hours.

1- is the tach reading correctly as well as the rev limiter?
2- was the lower unit trashed at some point and it now has the wrong ratio one on it?
3- weight distribution.
4- is the trim gauge working correctly? I know Denny O well enough he could trim the motor by ear if necessary.

Another thing I thought of last night has the computer been changed out and it now has a higher horsepower computer on it??
If that was the case you would of thought it was propped correctly when that change was made.

On my prior boat I tested a 20″ High_Five for a while and ended up going with a 22″ Quicksilver_2 3 blade which netted me another 4-5 mph at a simular rpm with plenty of lift. It takes a fairly light rig and alot of hp to be able to pull a 23″+ pitch prop on most rigs.

Iowaboy1 wrote:

Denny O and I have discussed a few possibilities and I will throw those out here in case someone is having the same problem.
We know this is a very low hour motor, 40 some odd hours when the boat was bought but you never know what has happened in those hours.

1- is the tach reading correctly as well as the rev limiter?
2- was the lower unit trashed at some point and it now has the wrong ratio one on it?
3- weight distribution.
4- is the trim gauge working correctly? I know Denny O well enough he could trim the motor by ear if necessary.

Another thing I thought of last night has the computer been changed out and it now has a higher horsepower computer on it??
If that was the case you would of thought it was propped correctly when that change was made.

I was going to bring up the tach and limiter incase something was changed. If he is really getting 6000 RPM’s(confirmed off a digital tach) something was changed from stock. The limiter on a standard 225 Opti should be 5800 and the audible misfire from the limiter should start around 5850-5900. A 225 ProXS or 250 ECM/cal would let him go as high as 6300.

Ratio could be checked pretty easy to determine if he has the standard 1.75 ratio or the high altitude 1.86 thats assuming it still has a standard opti ratio. Racing offered a couple other ratio’s but I believe that was only in the sportmaster version. A 225 ProXS still should have been 1.75.

The points listed above are very valid. Just one other thing to take in consideration is the actual blade type. You could be running the same pitch, as in my case a 23 pitch. You can have one That has Mickey Mouse ear style blades, and the other having a longer cutting edge. Considering only about the last quarter inch of the blade has the cupping that propels you forward, it makes a huge difference in how the cutting edge and the cupping works together. I have three props for my boat. Two of them are mirrored image of each other 23M. I picked up a mercury 23 for the right price to have as an additional spare and it sucks donkey balls. Amazing howell Barry subtle details makes a huge difference in the performance of a prop. You really need to try each and every style to find out what’s gonna work best for your rig. In the pic below the prop to the right gives me about 5 to 6 miles an hour faster with a similar 2 to 3 inch ripple on the water, and also is about 300 RPM less at wide-open throttle

Attachments:

1. 

   image-scaled.jpg