Hi Bendik,
What I meant is this. In a mechanical shifting of the lower section of an outboard, there are 3 gears. That is one pinion/drive gear, and 2 output gears. Both gears float on the prop shaft. Between these 2 gears, on the prop shaft, is a slide-lock sleeve that is splined to the shaft. When it engages either the forward or reverse gear, the power is transmitted to that gear, thus making the prop turn forward or reverse.
If you use this kind of outboard conversion, if you reverse the motor in the opposite direction that the ICE ran, the engagement of the gears is with the ratchet, and thus just goes, "click, click, click." So in my case, I had the reverse gear pinned solid to the shaft, so the drive was permanently in reverse. Now I can switch motor direction without any chance of ratcheting the gears. Also, in my application, there was not enough room practically to have a mechanical shifting linkage.
All this is mute if you have a conventional shaft and belt drive or geared drive like many of the other sailboaters are using. My discussion was in relation to using the lower portion of an outboard and affixing it to the bottom of your hull. In my case, a "pod style" or "sail-drive" was most efficient and practical, because I am making them individually steerable and throttleable.
You are correct in your assumptions otherwise. If you are using a straight shaft, with some form of speed reduction inside the boat, (NOT an outboard unit), then most "acceptable" gearboxes will be fine. There is usually no shifting in the simple ones. Do not over think it. Below are some examples of an eBay search. You will have to "go fishing" to find what you want, or some of the other guys on the forum have great ideas too. I did not check these for size or application specs.
If you check with a local belt & bearing retailer in your area, they can set you up with exactly what you are looking for, or at least give you some real practical ideas to do your own eBay search.
If your boat had an ICE already, a simple and practical option would be to keep the existing transmission, and have a local machine shop water-jet out an adapter plate to mount your motor at the bell-housing. If they have the transmission in hand, I have had this done for a couple hundred bucks or less. But before you go to this work, check to see if it has ratcheting gears in it first. FYI, the shop I took my shafts to, was sympathetic to my cause and only charged me $90.00 to pin both shafts today.
Dan H.
Sent: Monday, August 22, 2016 12:18 PM
Subject: Re: [Electric Boats] Need help with choosing the right motor!
Hi there Dan!
I am not sure if I understood all of what you wrote, but in my case I do not want a mechanical reverse gear. Do you mean there is difficulties with reversing an electric motor in a boat?
My tought was that with a programable motor controller (i.e the Alltrax SPM series), I can adjust parameteres concerning direction change (I did this with my Siemens car-motor).
I am planning to install a trust bearing on the propeller shaft, and belt drive from the motor a second shaft that is coupled with a flexible shaft coupler to the propeller shaft.
Regards
Bendik
On Monday, August 22, 2016 6:48 PM, "'Dan Hennis' dhennis@centurytel.net [electricboats]" <electricboats@yahoogroups.com> wrote:
Hey Guys,
RE: the using an old O/B lower unit for your gear box and drive. I am building an E-Tug right now. I am currently going through the pains of converting a pair of larger Merc lower units to use on the project.
Yes you can and it is the simplest, to use the mechanical shifting system (transmission) of the outboard. If you intend to electricly change motor directions, a word to the wise: This is not as simple as it may look.
First off, most if not all larger units have a ratcheting forward gear, and about half have the same on the reverse as well. So if you do not have the output shaft pinned to one of the gears (forward OR reverse), you will be in for a "special" ride. Some reverse gears have a 3-6 dogged ears on the drive clutch side. These are the best. Since they are extremely hardened, I had to go to a special machine shop that had some "cosmicly" hard carbide and titanium tipped tools to get the pin holes precision-drilled. This all has to be done by a machine shop that is willing to work to a tolerance of .0001 or less. Yes, I have enough zeros there. That is one ten-thousandths. Anything looser in the precision, and you will have a bag of chips and pieces at the bottom of the bay or lake in no time. Monday I'll get the bill for my pair, but I expect it to be over two hundred bucks... ($85/hr X 4 hrs).
If anybody is interested, I am using 5/16" roll-pins through the reverse gear for simplicity of assembly later. The drives are older 85 HP lowers.
When my rich uncle dies, the guys at: A.B. Marine in Rode Island, said they would sell me a pair of "Autoprops" cut to the exact max. diameter and balanced for a mere $2,800.00 + tax, title, and dealer doc fees, EACH! They ar ethe exclusive dealers for the trick props that has been discussed here in the last couple days. I am thinking I will test the 14 X 11s I have now, first.
Just thought I would clear that minor detail up.
Also, pinning the reverse gear will reduce my parts count in a drive by seven (7). But the controllers I was going to use anyway, will cost 100 times that ($700/ea.).
Happy motoring,
Dan
From: king_of_neworleans
Sent: Friday, August 19, 2016 10:45 AM
Subject: Re: [Electric Boats] Need help with choosing the right motor!
That looks like two motors. Well, doesn't hurt to have a spare, especially if you will be pushing the performance envelope.
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Posted by: "Dan Hennis" <dhennis@centurytel.net>
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