What's the ideal surfing RPM of a EX343?

[JohnnieMo]

Yep, power loading is right down there with power turning as a cardinal sin of boating, justifiably punished by fines in the thousands of dollars for a first offense. In fact power loading is the worse of the two, since it causes lasting damage that affects everyone while power turning's waves eventually die out.

Our ramp at our lake has the same problem of erosion at its deep end. The lake level got especially low two years ago and we actually couldn't use the ramp to pull our boat for the season. We had to use a shallow beach between two people's property; the slope was so shallow that I had to back the truck into the water to the bottom of the front doors, and even then we barely got the boat on the trailer. I have a full size loader/backhoe and would have loved to smooth out the huge hump of sand and gravel dug out by the power loaders, but the State can't have a private citizen fix such things for free! No, they have to hire it out... to a guy who shows up with the same class of loader/backhoe and does the exact same job at taxpayer expense.

Ya, I hear you on that. I always thought this boat launch was immune because the lake basically empties every winter. It's very easy to put concrete out as far as you'd like. When I walked down the ramp you are at chest level water and then there is a two foot drop. Thankfully I have some large buddies who helped this poor guy lift his trailer out of the lake.

This particular launch charges $45 to use it, so you'd think you might get something a bit better for your ransom.

When I bought the boat, the dealer taught me to power load it. (granted not with a lot of thrust). However that is how I dinged my first propeller on that immortal 2013 Boatmate trailer. The scars are still there. Now I just winch the boat on having realized the plethora of advantages.

[JohnnieMo]

Early testing with the 1235 is promising. Full ballast 800/2600. Suckgate. 10.6MPH. No passengers. No vibration.

[IDBoating]

It's a magic prop!

Maybe the vibration you were feeling was cavitation, from a prop that could not adequately engage the water given the load?

[bsreid]

I find that strange. I’ve got same numbers in ballast, 1433 and no problems what so ever.

[JohnnieMo]

So a couple thoughts....

I did put the 1235 through its paces and it performed well. When totally loaded with ballast, adding people and a surfer would be too much for the boat to handle. It would struggle to get up to 10.6MPH. However I think that is reasonable. I'm asking that 343 to move a 5000lb boat, 3200lbs of water and then probably another 1000lbs of human. Oh - and I stick a cutting board out the side. However not at any point was there a vibration. Ever. RPM was a several hundred below the 1433 in comparable circumstances.

So I think we can conclude that the old propeller was "broke".

Or can we?

When I was installing the new propeller, I decided to google how to install a propeller. What I discovered was that I haven't been doing it right. I think it's possible my 1433 was tightened down on the key and perhaps not completely flush on the shaft. I can't be sure of this, but just based on how the key sits in there, it is possible. After watching a few videos I did a better job on the 1235. So what I'm saying is that there is a remote chance, this was user error all along.... but I kinda doubt it.

Now I just need to decide if I want to stick with the 1235, or get a bit more aggressive. Perhaps something like 2773. (15.00 x 13.000, 0.105 cup)

[chpthril]

FYI, larger is not necessarily more aggressive to the 1235. Going down in pitch would certainly be more aggressive without adding more load on the engine. Larger dia means more load on engine.

[JohnnieMo]

FYI, larger is not necessarily more aggressive to the 1235. Going down in pitch would certainly be more aggressive without adding more load on the engine. Larger dia means more load on engine.

Copy that.

I'm aware that increasing diameter and decreasing pitch are countervailing terms. I want a bit more pitch ( or maybe less pitch is the correct way to say it ) than what I'm at with the 1235. I figured a 13 pitch but offset against the larger prop could be about right. I could also just jump right in to a 12 pitch.

I am really amazed how great the 1235 worked though. It's been banged up in its life too so I wasn't expecting much. However I found the boat felt like "butter" again. It's hard to put in to words but when you drive the same boat every day you notice any little change. If I got a 1235 I wouldn't be unhappy about it.

[dj2]

I run a 1235 in my RZ4 with a MP 360, this weekend I had 3000lb of ballast, 4 adults, a 10 yr old, plus a Yeti 65 and 45 full of ice/drinks/food. We run 11.0 - 12.6 mph surfing and never have by issues getting to or holding speed. Lake altitude is 1900 ft.

[Jetter]

I have to throw a plug in for my prop which nobody seems to have or mention. I run a 1589 on my 08 Z1. 14.5 diameter with 16 pitch. I have zero issues pulling people out of water. Even big guys with a 6 foot wooden board [emoji6]! This prop allows me to surf at 11mph at 2500 to 2700 rpm. Top speed on my boat is 42 mph. Best of all is I can surf all day at about 15 or 16 litres per hour. That's 4 gph for our American readers. My motor is a 5.7 l Marine Power special edition 360 hp.

Sent from my SM-G930W8 using Tapatalk

[IDBoating]

I think it's possible my 1433 was tightened down on the key and perhaps not completely flush on the shaft.

If the key is too tall and doesn't let the prop move all the way onto the shaft, then by definition the prop will be off center on the shaft. The result - an off-center weight on a spinning shaft - is exactly how they build the little vibrators in cellphones!

[JohnnieMo]

If the key is too tall and doesn't let the prop move all the way onto the shaft, then by definition the prop will be off center on the shaft. The result - an off-center weight on a spinning shaft - is exactly how they build the little vibrators in cellphones!

I'm not sure if my PCM system is different but from all the videos I watched, but mine is unique. The keyway on the shaft is tapered as you move from the back of the shaft towards the v drive. Basically the depth of the key way decreases. If you push the key too far up the shaft it will bind on the prop.

I need to take a picture to have this make sense. However if the key gets too far up the shaft it would absolutely get off center.

In the past I would usually put the key in and then slide the prop on. The key could bind and ride up the shaft. This past time I put the key in at the same time and made sure the key stayed flush with the prop nut.

[JohnnieMo]

So I put the boat through its paces last week. Nothing tests out your poor surf boat like pulling a tube. Every year I take out a bunch of kids who don't ever get to boat and we go tubing. I think I had like 15 of the buggers on there. So the boat was slammed and forced to pull a giant tube at 25MPH. That Ex343 with the 1235 had no issues at all. It even sliced through those Chestermere weeds without issue. The kids had a great time, I burned a lot of gas, and as I do every year - I swear I'll never do that to my boat again....

So the conclusion is the 1433 is damaged or installed incorrectly. Either way, the 1235 looks like a fairly good option. As luck would have it, I found someone selling a second-hand, but new-in-box 1235 locally. I'm hard pressed to spend more on a 2773 or otherwise at this point. The surf wave is getting so big now I am actually finding it is too steep. I literally fall off it sometimes... I used to run TAPS at 8, and now I'm running it down around 3/4 just to lengthen the wave.