Finished breaking need different prop advise

[Chris k]

At the end or breaking df30a read topic on motor height need to lift motor nearst susuki dealer 2 half hours away on my own vent plate is to low wide open throttle only 4000 rpm with dad and me in the boat with just me have gotten to 5200 takes forever to get on plane the prop on the motor is 10 1 4 x12 any suggestions would be greatly appreciated I'm 60 miles one way to A lake to test on so trying to save trips sorry for the terrible typing not a computer wise thanks for help

[Moonlighter]

Lift the motor first and get the height right, then see what max revs you can get. This will give you a much better idea of what prop change is required.

Lifting a 30 using the boat trailer method is easy, but still needs 2 people to be done safe.

[Chris k]

Moonlighter thank you for responding I should be able to see the cavitation plate when I'm at wide open throttle is that correct by looking at it I can tell it's way too deep in the water I as soon as I can raise it and get to the lake I will try that and then report back thanks for your help I really appreciate it I'm kind of on my own out here

[2014DF25ARS]

I made a few videos of the DF25A on my boat, as I was adjusting the motor height. I put them on YouTube. I mounted a GoPro camera to my transom and was changing engine height and trim to see how the engine rode in the water at different settings. The first video is here, showing the motor sitting in the "default" position atop the transom.

https://www.youtube.com/watch?v=pJacPa9buJo

My "final solution" video is here:

https://www.youtube.com/watch?v=27EeyHaW0Vo

You can see a couple others by searching for my videos on YouTube.

I first tried raising my motor by putting a 1" strip of wood atop my transom. That wasn't enough, so I ended up using a piece of oak bullnose window sill trim on the inside of the transom, which raised the motor 1 5/16 in from the "default" height. I don't think I got it quite as high as I could, but at that point the motor clamps were at the top of the transom, and it would have taken some more substantial mods to raise it higher. So I stopped at "better". In the last video, you can see my "cavitation plate" at the surface of the water. I think my performance might be improved if I could raise it to be just above the water. But then you risk ventilating and/or starving the motor of water in turns.

[Chris k]

Thanks for posting those videos that helped see it visually I'm going to raise my motor it's definitely too deep and I'm getting lousy performance thanks for helping a guy out it really is appreciated

[Chris k]

This might seem like a dumb question but while doing this motor lift testing should I worry about completely sealing all the bolt holes or wait till I'm finished

[Chris k]

Hey haven't bailed on lifting the motor we're just out of town till first of next week I'll report back then and pick your guys's brains thanks for the help

[Moonlighter]

Seal the holes properly each time. It might seem a PITA but you dont want ANY water getting into the transom core especially if there is wood in there.

[Chris k]

Just got back from camping going to raise the motor tomorrow and I will seal all the holes cuz there is wood in the core thanks for posting I'll update as soon as I can

[Chris k]

Just got back from testing lifted motor to the max that I can get on my transom much much better still performs 5200 RPM with just me and my eight year old son in the boat takes awhile to get on plane the prop I have is a 10 and 1/4 by 12 aluminum the boat is a flat- bottom Hull I built 16 foot think airboat Hull it's that flat Max Speed I. Was 24 miles per hour via GPS I did not have the GPS before I raised the motor but I could feel a noticeable difference in speed just from Raising the motor thank you for the Insight on that and any prop recommendations would be awesome thank you guys again

[Moonlighter]

Every inch less pitch in the prop generally equals about 150-200rpm gain, assuming you stay with the same make/model prop. Seems that you need something like 4” less pitch in that basis. See if you can find a prop shop or Suzuki dealer that will work with you to select the right prop and allow swaps until you get the right one. It can be a trial and error process.

There is a US based company The Prop Gods who are very helpful google them and get in touch.

[Chris k]

Thanks for responding moonlighter I was thinking maybe going to a 4 blade prop with a 9 pitch but having trouble finding one that's a 10 spline any recommendations

[Chris k]

I'm new to the outboard motor thing does it seem crazy to have to go to that low of a pitch prop

[Moonlighter]

Prop selection is a function of engine horsepower and boat length/weight/hull design.

A 4 blade prop typically gives more stern lift, but it is harder for the engine to push 4 blades thru the water than 3, so straight up a lower pitch will be needed on a 4 blade to compensate for that. You typically find them on larger hp boats. They are by no means a miraculous cure for an overproppped boat, which is what you may have at the moment - either that, or an under powered boat.

One thing you have not mentioned in this thread is the boat that the motor is fitted to. If you go to Suzuki’s website and look up your motor, they usually have test reports of boats running that motor. The idea is to find one test that is for a similar type, size weight as yours, and check the report to see what prop they ran to get the results. But bear in mind that those reports are usually done in ideal conditions with minimum weights on board, and everything tuned 100% so they get best possible results. In other words, a best case scenario.

Here is a link to Suzuki Australia webiste page where they have 2 boat tested with the DF30a.

https://www.suzukimarine.com.au/outb...s/product/df30

Also, read the sticky thread in the top section of this forum that talks about engine height and prop selection, suggest that you do the tests as detailed in that thread and then talk to an expert prop shop in your area. By providing them with the data as per that thread, and details of your boat, they should then be able to make a recommendation that at least gets you close.

[Chris k]

Thanks for your reply moonlighter I will take those suggestions to Heart a friend and I built the boat and around here nobody deals in Suzuki motors the nearest Suzuki dealer to me is 2 hours away so that's why I came on the Forum I appreciate all your guys's help I'll see what I can figure out on props thanks again