72 Johnson 135HP better prop for applications

[67lasvegas]

Okay second post since finding this site--See if I give you enough data to help me out:redface:

The boat is a 19' open bow fiberglass "Seira Las Vegas" boat it weighs about 2000#, seems wide. seems to sit low in the water. It is a tri-hull. It is rated to carry 6 people and much of the time I have that many in the boat for looking around the lake.

It has a 135HP Johnson (low profile?) V4 1972 with updated 1974 ignition.

I currently am running a 13 3/4 15 pitch AL prop, This gets me to around 40MPH at about 4500 to 5000 RPM which is my preffered speed for this outboard per my manual.

I have a 13 3/4 17 pitch al prop which I may try for general touring around the lake.

With the 15 pitch and the boat fully loaded I get to plane in okay time but nothing spectacular. With only two people in the boat the nose comes up high until I plane but it is quicker.

Problem is when I try and pull a skier. I usually have 4 in the boat and one in the water. I don't seem to come up quick enough. Would a 13 pitch be okay to run to get up quicker or would this cause some other problems?

Thanks

 

[Texasmark]

Re: 72 Johnson 135HP better prop for applications

Okay second post since finding this site--See if I give you enough data to help me out:redface:

The boat is a 19' open bow fiberglass "Seira Las Vegas" boat it weighs about 2000#, seems wide. seems to sit low in the water. It is a tri-hull. It is rated to carry 6 people and much of the time I have that many in the boat for looking around the lake.

It has a 135HP Johnson (low profile?) V4 1972 with updated 1974 ignition.

I currently am running a 13 3/4 15 pitch AL prop, This gets me to around 40MPH at about 4500 to 5000 RPM which is my preffered speed for this outboard per my manual.

I have a 13 3/4 17 pitch al prop which I may try for general touring around the lake.

With the 15 pitch and the boat fully loaded I get to plane in okay time but nothing spectacular. With only two people in the boat the nose comes up high until I plane but it is quicker.

Problem is when I try and pull a skier. I usually have 4 in the boat and one in the water. I don't seem to come up quick enough. Would a 13 pitch be okay to run to get up quicker or would this cause some other problems?

Thanks

First off, if it is a 1972 it is a 125 hp. 135 came out in '73. Cowl was seafoam white on both engines, 125 had a narrow red stripe with Johnson 125 on either side and continued around the rear. 135 had a big fat multi colored decal on each side, mainly black with 135 in large numbers.


I had the new 125 on an 18 1/2 Caravelle glass tri-hull bow rider. Had a nice V hull for a tri-hull (takes more power to push) and was a heavy glass boat (takes more power to push). Had 4 younger kids and wife and we went boating regularly. I didn't have a tach but sitting next to the engine you could hear it singing and to me, had lots of boats, it was running well into it's operating range. I had a 17P SST which was OMC's first SS prop. 39 was tops for me (speedometer measurement....accuracy?) but I wanted to ski and was stuck with it. Hole shot was fine, nice and crisp and wife could get me (220#) up on a slalom with the boat full of family and goodies with ease. I didn't have PTT so I was stuck with one tilt angle which could have been optimized for speed if I had it but it was ok as it was. At a company picnic, once Alone in the boat, I was able to get 5 skiers up simultaneously....had to try it several times, I think all were on 2 skis, and made it a couple hundred yards before one fell off and had to quit.....just to see if we could do it...for me and them.
-----

Bow coming up has to do with boat shape, load and distribution, power and trim angle. Normal.

Hole shot is dependent upon the ability of the prop to grab the water and the engine to deliver enough power to spin it up as fast as possible under the prescribed boat/load/hp/pitch conditions. Obviously a lower pitched prop will improve that and your skiers will love it as their time in the water is minimized.......nothing like feeling that you are hooked up to something serious about getting you out of the water.

Since you have a tach, just put the lowest pitch prop on that suits you and watch your rpm's on the top end. Don't know about you but I don't pay much attention to rpm upper limits. What the limit really says is that this engine will put out a "guaranteed" rated hp over that rpm range. Doesn't say how much above that it will deliver and doesn't have to.....it passes it's rated performance test.

For the record, I was fooling around with my current Merc 3 cyl 90 hp one day putting in some new linkage. I wound up getting it to auto ignite (turning off the ignition had no effect on shutting it down and for several minutes it had the tach pegged and I don't know how high it actually went. Tach pegs at 7k! Using it today and no apparent damage....for what's that's worth. My mercs over the past 25 or so years have been rated at an upper limit of 5500 but I regularly ran them into the 6k, sometimes in turns 6200 and they just love it.

Hope this helped.
Mark

 

[67lasvegas]

Re: 72 Johnson 135HP better prop for applications

Thanks Mark,

I know a fair amount about automobile engines but when it comes to outboards and boating I am very very green.

It must be a 1973 as it does have the 135 on the sides with the muti color decal(I will try and post a pic of boat and motor later tonight)

When I first got the boat and motor it would not run very well so I rebuilt the carbs. This engine has been underwater twice but even so seems to run just fine. The lower end lube gets changed every year. At around 4500 or 5000 the engine seems to just sing. The higher the rpm just the higher the pitch. I thought the boat weighed in at around 2000 but it may be more-- I need to double check this.

It seems to stumble some times on take off and after reading some on this site I am looking for a Jim Reeves link and sink thread, thinking my link and sink may be off and I am running to lean.

I may go to a 13P then as I don't need the speed when I am pulling inner tubes and skiers.

I cold use some help on the trim though. Does it help to angle the trim a little to get you outta the hole? And what about those flaps/wings they put on above the prop---- do those help get you to plane quicker?

Thanks in advance for a boating dump bunny

 

[steelespike]

Re: 72 Johnson 135HP better prop for applications

Trimming down(prop closer to the boat may help with a load and skiing.Also may help when cruising.
Hydrafoils can help but the motor needs ti be setup right.
The anti vent plate(just above the prop)needs to be about even with the bottom of the boat. If the foil drags in the water
at speed it can cause strange handling.

 

[67lasvegas]

Re: 72 Johnson 135HP better prop for applications

Thanks Steel , I have not checked my level it seems to me to be lower than the bottom of the boat. I will check it out.

I said I would post pics. See how this works.

We call it the banana boat.

 

[Texasmark]

Re: 72 Johnson 135HP better prop for applications

Thanks Steel , I have not checked my level it seems to me to be lower than the bottom of the boat. I will check it out.

I said I would post pics. See how this works.

We call it the banana boat.

Most assuredly a '73 as the cowl colors and the fact that it has factory PTT, which was first offered that year. Your boat is almost a carbon copy of mine so your performance should be about the same, little better, 10 more ponies, with the same load/prop and all, plus you have trim so you can select the best trim angle for what you are doing.

I wouldn't put a whales tail on the boat. If you do as you said and drop to a 13P, it will blow your socks off. Hole shot will be a neck breaker and your engine shouldn't studder on hole shot. Like steel said, tuck it in for hole shot and out once you get on plane....amount depends on how the boat responds and what you are doing/trying to do. With your dead rise at the transom, the exact height of the anti vent plate is somewhat arbitrary and for now I wouldn't worry about it; certainly not made for a whale's tail if you ask me. Try your 13P first and get back. You are going to be amazed and pulling water toys with it will be a walk in the park. You will be able to control the attitude of your boat exactly as you choose at any speed/load; none of this on plane, slip back, more power, on plane now going too fast, cut throttle, slip back. etc.

Mark

 

[jimmbo]

Re: 72 Johnson 135HP better prop for applications

That cowl has a 1975 decal