Re: [electricboats] Thunderstruck

I'll tell about my experience then. I have a 40ft steel long keeled heavy boat. It was fitted with a 34kw yanmar engine. I live on my boat and sail around the Atlantic with the seasons. I only use the engine going in and out the anchorage and never needed the full power of the engine. And then reading all of the stories of people with electric engines with how little power draw they could get good results I thought well if I take the 18kw kit and run it on 48v as a 12kw kit that should be more than enough for my needs. So I discussed that with thunderstruck or at least I tried, but they said it was impossible. It would give me a speed of max 3.5 knots. Because so was a calculation given to me: With half the power you would get half the speed. So I responded linear calculation doesn't work with speed calculation and especially not for a boat. Just the same reply after that that it wasn't going to work or would or would perform very poorly. I decided to go for it anyway, and they wrote on the bill of sale that the power was inadequate for my application which was fine by me. Then I asked about reduction and as my boat was fitted with a thrust bearing already I decided to build my own reduction. According to them the motor would have a max rpm of 1850, so did a calculation that I needed a reduction in between 1.5 to 2:1 Asked for a price of the parts to build this reduction and was given a price which didn't make sense to me so rejected that offer and sourced the parts myself. So then I installed the lot and the motor didn't want to rev past 1200 and only wanted to draw 170 amps. But when the boat got up to speed the revs and also the amps went up slightly. So I asked if there was a curve programmed in the controller that only allowed a maximum amperage vs a certain rpm which I didn't think of but is a good thing ofcourse. The reply was if I wanted to replace an engine which had a gazilion hp with an electric motor what was I going to expect. But the funny thing was with this amperage draw which was only a bit more than half the max continues draw I got a speed of 5 kts already. So I changed the reduction some more and to my surprise the motor revs up a lot higher than 1850rpm. How can you calculate a reduction without knowing the maximum rpm of a motor.... I now know after changing the reduction 3 times this motor will rev up to 2200 rpm which is a huge difference and I'm happy to tell it works really well for my application. It works even better than I hoped, and I can get to 6.5 knots of speed which was 7.5 with the yanmar on full chat. Other than that they reponded very quickly when I asked a question, but I was disappointed in the knowledge of their product. So all in all I would still recommend them. A bit of a long story, but with a happy ending after all :)

Op vr 6 nov. 2020 03:37 schreef Ryan Sweet <ryan@ryansweet.org>:

(Changed the subject)

I too will vouch for having had a fantastic experience with Thunderstruck support so far, both in preparing for my order as well as post-sale. They've answered questions quickly, thoroughly, and resourcefully. I would not hesitate to do business with them again or to recommend them to anyone. 

On Nov 5, 2020, at 15:57, Mich Pop <michpop@gmail.com> wrote:



I changed from a left hand prop to a right hand prop and all that was required was to tick a box in the controller settings to reverse the rotation.

Throttle positions remain unchanged.

Cheers

Mich

On Fri., 6 Nov. 2020, 05:34 Rob Temple, <robtemple@embarqmail.com> wrote:

Thanks!

On Nov 5, 2020, at 11:05 AM, Bob Jennings <heatnh@gmail.com> wrote:



I have the 10KW kit on my Sabre which had a Volvo MD7A turning a LH prop. 

I stayed with the LH  prop configuration, haven't had any trouble. If you get the Clearview Display you'll need to reconfigured the Sevcon controller so forward displays as forward, not reverse. 

On Thu, Nov 5, 2020, 10:39 AM Rob Temple <robtemple@embarqmail.com> wrote:

I'm hoping to replace my Volvo diesel (MD 2020) with a 10 KW kit. Since the Volvo requires a left hand prop almost any other diesel would require me to switch to a right hand prop. I called Thunderstruck and the man I spoke with said he didn't "think" it matters with the electric motor but it would be nice to know for sure. Can someone tell me if I'll need to switch props?

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