ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

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Jaysen
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by Jaysen » Thu Sep 05, 2019 7:43 am

I don't think y'all should be discussing her holes in public....


Jaysen wrote:
Mon Apr 29, 2019 3:44 pm
I tried to say something but God thought I was wrong and filled my mouth with saltwater. I kept my pie hole shut after that.

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glossieblack
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Thu Sep 05, 2019 8:08 am

On refection, correct Jaysen. :lol: :lol: :lol:
Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by Spokaloo » Thu Sep 05, 2019 1:09 pm

Can you put up a photo of what’s left of your damper plates?

E

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glossieblack
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Fri Sep 06, 2019 2:38 am

Spokaloo, I don't have any pics of the first destroyed damper plate as it was only discovered when I returned the engine-trannie assembly to the engine builder. I'd assumed that the hydraulic pump had failed. I'll get and post pics of third destroyed plate when available - the engine-trannie assembly is in transit to engine builder once again.

The following pics are of the second destroyed damper plate which I took when I removed the trannie from the engine following failure 2. The first two pics show either side of the plate, and compare the destroyed pate with an in tact one. The second two pics show how the destroyed plate sheared into two components.

Image

Image

Image

Image
Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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glossieblack
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Fri Sep 06, 2019 2:53 am

Fuzz wrote:
Thu Aug 29, 2019 2:45 pm
It is my belief the problem lies between the tranny face and the fly wheel.
Fuzz, I've returned the engine and trannie to the engine builder and asked him to check that the splined engine output shaft is seating correctly within the damper plate. In the meantime, the pics in the post above to Spokaloo don't show any abusive wear or tear where the splined shaft sits in the damper plate.

I'll let you know what he reports.
Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by Spokaloo » Fri Sep 06, 2019 11:18 am

So with the way this damper plate is constructed I’m wondering if it is not giving enough ‘slop’ and relying on the pins too much. Essentially acting as a coupler exclusively and not damping things enough to tolerate vibration. It boggles my mind that it is breaking those diameter of pins with how limited the torque numbers are on that engine. You’re probably aware of all of what I’m about to type but this is to add the information to the body of knowledge as people search this in the future.

Here’s what I’m talking about. On a flex plate like we use on small block inboards, there is a wide bolt pattern that transmits torque from the flywheel down to a set of springs.These springs are the intermediary that transmit the energy to the hub, where a splined shaft slips in. These springs eat up all the violence imparted by the vibration of the engine and smooth the various cylinder firing, while also absorbing a bit of load when the transmission engages and the prop has to go from zero to idle rpm of the engine. Here’s a photo showing the springs and constructions:

Image

You’re dealing with a much smaller application size wise, but I would see if there’s a way to get set up with a better mass flywheel, a damper plate with springs, and my hope is that you’d keep it in one piece. As I stated before, the loads we put these things through are cartoonish with tow boats, and the only failures you see are metal fatigue due to age and corrosion.

Best of luck.

E

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glossieblack
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Sat Sep 07, 2019 5:09 am

Thanks Spokaloo. :D

The current engine-trannie setup has destroyed the recent steel-spring plate (failure 3) as well as well as steel-poly damper plates (failures 1 and 2).

This afternoon the engine builder texted me "the plate is destroyed and in pieces" accompanied by the pic below.

Three failures, and still no concrete explanation of what's going on, only theories. :help:

I'm over it. I've now instructed the engine builder to replace the ZF 45C 1:1 hydraulic trannie with a Twin Disc 1.5:1 mechanical one. The pairing of 20hp Kubota-based marine diesels (e.g. Nanni and Beta) with Twin Disc 1.5:1 trannies has been proved time and again.

It's time to move on. Or more accurately, to get going! :D

Image
Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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OrangeQuest
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by OrangeQuest » Sat Sep 07, 2019 7:52 am

So does that mean that the pitch and/or diameter of the prop will also be changed due to the increase in torque at the output shaft but reduction of available shaft RPM?

If the motor is doing 3000 rpm with the old trans the output shaft also does 3000 RPMs.
1.5:1 would be motor 3000 and output shat 2000 RPMs?
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by Fuzz » Sun Sep 08, 2019 1:32 am

I have to believe the new tranny will work out. During my commercial fishing career Twin-Disk trannies were pretty much the gold standard.

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glossieblack
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Sun Sep 08, 2019 4:36 am

OrangeQuest wrote:
Sat Sep 07, 2019 7:52 am
So does that mean that the pitch and/or diameter of the prop will also be changed due to the increase in torque at the output shaft but reduction of available shaft RPM? If the motor is doing 3000 rpm with the old trans the output shaft also does 3000 RPMs. 1.5:1 would be motor 3000 and output shat 2000 RPMs?
Can't change prop diameter due to the tunnel size. Can only increase pitch, but within the limits of laws of diminishing returns. I recall Jacques suggesting pitch for a ST21 1.5:1 trannie setup somewhere, but can't find it now. :help:

Because the 1.5:1 trannie's output shaft spins opposite to it's input shaft, the existing 10" left hand prop has to be replaced by a right hand one. Close to a US$500 changeover, and nobody, but nobody in the universe wants a used 10" LH prop. Ouch.

I've spent three years and thousands of additional dollars trying to make a 20hp 1:1 engine to trannie work, so that Jacques original ST21 design could be realised. Alas, it's proven to be beyond my ability.

Regardless,it's unlikely an ST21 with a 1.5:1 box will have a WOT speed as high as a ST21 with a 1:1 drive. Like Spokaloo, I'm sincerely looking forward to the day someone produces a 1:1 capable ST21 at WOT, to see what she achieves.
Fuzz wrote:
Sun Sep 08, 2019 1:32 am
I have to believe the new tranny will work out. During my commercial fishing career Twin-Disk trannies were pretty much the gold standard.
I have to believe too Fuzz! :help: :lol:
Completed R13 two part nesting rowboat. ST 21 under construction .... where seeking perfection is recognized as the enemy of the good.

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