Reply To: Random questions about my 1958 Johnson RDS 20

[David Stanton]

TJ Brandon wrote:

Should I get a deep cycle battery? I don’t think starting a 35 hp would need much cranking amps. I will be adding a solar panel for trickle charging. The prop shaft and prop hub are keyed but I do not have a key.

You are right – it doesn’t take much battery capacity to start it if it is properly tuned up and the choke is used when the motor is cold.  What used to be a somewhat “Standard” car battery , like a group 24, wills start it dozens of times if no other accessories are used.  There was a dealer-added option of a generator, but those were hardly ever added.   Terminal adapters that give you threaded studs and wing nuts for attaching cables are very available if you use a car battery, which is often cheaper than a marine battery.  If you run 100 watts of accessories, you are looking at a 8 to 9 Amp drain.  Check Amp-Hour ratings on batteries and buy one that does the job for you between charging.  Example:  A 100 Amp-hour battery, will supply 8 Amps for 100/8 = 12.5 hours.  Most of the big Deep Cycle marine batteries are 100 Amp-hours, and car batteries are less.  If your prop-shaft is “keyed” as you said, it has been custom-modified, and I would need a modified prop – I’ve never heard of that!  The prop-shaft should have a hole (approx 1/4 inch) near the end for a shear pin, or, on parts lists with HP that big, it is often called a Drive Pin, and the prop will likewise have a hole near the outer end to mate with the pin.  The drive pin is part #43 at the link below, and is still available.  At the link, look also at the other parts needed at the end of the prop (parts 44, 45 and 56) note part #45 is just a big cotter pin.  https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1958&hp=35&model=RDS-20&manufacturer=Johnson&section=GEAR+CASE+GROUP

Dave