ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

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glossieblack
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by glossieblack » Thu Oct 19, 2017 6:44 am

Got a little rat rod testing done today, in far from ideal conditions. The Noosa River was in partial flood after recent heavy rains, the wind was blowing 20+ knots, and there was intermittent to heavy rain.

The rat rod test team consisted of Craig (diesel drive), Chris (e-drive), and moi.

Given the conditions, our intention quickly became to gather basic data as quickly as possible, to minimise the chance of water damage to the electronics of the e-drive subsystem located under temporarily installed decks.

After launching, we first recorded Skinnydip’s waterline. For her estimated build weight, her draft should be about 7”. I had pre-marked a 7" waterline on the hull. Compared to this, her bow was floating 2” higher, while her transom was right. The diesel tank is located forward and when full, combined with some chain rode in the anchor locker, should help correct this. Additionally, I may need to move the e-drive battery banks in the stern a couple of feet further forward. Athwartships, she was spot on.

We then establsihed both the diesel drive and the e-drive subsystems of the hybrid drive system were hooked up correctly, as evidenced by idling, F-N-R engagement, and boat movement at low revs. All ok.


Next we checked cockpit drainage. Buckets of water were poured inboard and cleared almost immediately through the twin aft 3 ½” diameter aft scupper tubes. All ok.

It was time to test for diesel powered speed x rpm, and electric speed x amps (and approx. rpm).

We decided to test the e-dive subsystem first, as Skinnydip was launched with a fully charged 48V battery bank, and we wanted to deplete it in order to be able to test the ability of the diesel drive subsystem to recharge it when underway.

The initial e-dive tests were a revelation. As Skinnydip glided along at 3 knots, Chris scrolled through the data screens on the e-monitor and advised that she could do so for eight to nine ours, which is required to fully explore the e-motor only upper reaches of the Noosa River. Nice.

Well pleased, we decided to see what Skinnydip’s top speed was via her –e-motor subsystem. As we hit 8 knots, and smiles were increasing across our dials, a vibration started , and we soon discovered that one of the three fixing bolts of the e-drive pulley on the propellers shaft had sheared. Soon a second one had. Clearly the pulley’s fixing system was under sized.

We had learnt two things. Firstly, with the right pulley and belt system, Skinnydip’s e-drive subsystem is probably good for around 10 knots for perhaps ¾ of an hour, and 3 knots nearly all day.

Secondly, she needs spray rails. At only moderate speeds, running into a short chop on a relatively sheltered river, let alone on an open water, the cockpit is exposed to spray. For comfort, let alone for speed reasons, she needs spray rails. Given an aesthetic prejudice of mine, I’ve been resisting them, but today the evidence has spoken to me.

Regrettably, the destroyed pulley attachment on the propeller shaft put paid to any serious speed x rpm testing of the diesel drive subsystem, or testing of regen. Like a car with a wheel out of alignment, there was simply too much vibration.
Until then, it had been raining intermittently. Then it started to bucket down.

So we called it a day, disappointed that we had not learnt all that we had set out to do, but well pleased at what we had learnt.

It all happened so quickly, I didn’t think of taking a photo, let alone a video. My apologies.


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 Jaysen » Thu Oct 19, 2017 7:08 am

No apologies needed.

Are you using g8 bolts on the pulley?

From the sparky statements, do you have enough capacity for the inevitable cell death and "oops we've been here longer than expected"?

With the water line, are you counting humans forward as well?

Just my initial questions.

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by cape man » Thu Oct 19, 2017 7:51 am

All in all you learned a lot! 10 kts on e-power is awesome! 9 hours is also awesome, especially if the regeneration works as designed. How fast do they predict you could get the battery banks back to full strength on a regeneration setting?

How much damage from the sheered bolts?
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by BarraMan » Thu Oct 19, 2017 8:04 am

Congratulations Michael! Sounds like you are well on track for Skinnydip to meet all of your expectations.

Please forgive me for a little glimmer of refief that all did not go according to plan, but I look forward to driving the chase/camera boat for the real”splash” and sea trials in 2018, when I am confident that all outstanding issues will have been resolved.

I have four high resolution video cameras on the F’ing BIG Barra Boat to record the event for prosterity!

Best wishes

Lee

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by topwater » Thu Oct 19, 2017 8:34 am

With a few modifications she should be spot on , nicely done :!:
Novi 23 finally launched !

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by peter-curacao » Thu Oct 19, 2017 8:42 am

Thanks for the report it was a very good read 👍 8) about the sprayrails are your sure they are necessary? Reason I ask is: my CS separates the water fantastically from the hull trowing it all far to the sides, but because of the never ending trade winds here it happens that the spray is blown back in, making a perfectly dry ride a wet ride again. You probably had a good look at it but since you were reporting 20+ knots wind I thought I should mention. 8)

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by pee wee » Thu Oct 19, 2017 9:25 am

Thanks for the narrative, this was a big day for all of us! I know you were anxious to get that testing done before you take off, glad you were able to get that done. :D
Hank

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by fallguy1000 » Thu Oct 19, 2017 9:29 am

I enjoy Peter's comment about a wet dry ride. I can't tell you how many times in my little open boat I've been wet from wind spray. The boat can only do so much if it is open. period.
My boat build is here -------->

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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by jacquesmm » Thu Oct 19, 2017 10:10 am

Thanks for the report.
The propulsion system is very different from what most builders will use in that boat but the figures looks good.
Sorry about the mounting bolts failure but it's better for it to happen during this type of trial.
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Re: ST21 Hybrid Powered "SKINNYDIP" Noosa Australia

Post by MrPaul » Thu Oct 19, 2017 10:56 am

peter-curacao wrote:
Thu Oct 19, 2017 8:42 am
Thanks for the report it was a very good read 👍 8) about the sprayrails are your sure they are necessary? Reason I ask is: my CS separates the water fantastically from the hull trowing it all far to the sides, but because of the never ending trade winds here it happens that the spray is blown back in, making a perfectly dry ride a wet ride again. You probably had a good look at it but since you were reporting 20+ knots wind I thought I should mention. 8)
Yup...I've been soaked in the cockpit of a 52 hatteras because of the wind. The cockpit was normally a very dry place but at cruising speed with a strong wind coming from the side the bow spray was blow into the cockpit. Great info gathered on the trial run. The e-motor numbers are fantastic. It will be interesting to see how she runs under diesel power when the e-motor mounts are replaced. Congrats!

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