1973 16ft SS repower

[txbandit44]

Looking to repower the OL SS with a 4 stroke 70 hp that weights about 350# I have redone the transome already with marine grade plywood and epoxy like I have seen on countless threads here. I have been running a 70 hp johnson 2 stroke for the past year with no transome issues. Seems to be very solid. Just dont know about hanging that kind of weight on this style boat. I plan on running a 3'' vance mfg jack plate as well. What everyones thoughts on this? Any experiancees to share? Normally I would say do it and see what happens but Im down to 1 boat and dont want to be down to --0--- boat

 

[wheeldriver]

Re: 1973 16ft SS repower

You have good reason to be concerned. Keep in mind that wooden transom is not the only thing holding things together back there. Metal fatigue with aluminum over time is a serious issue, asked any Boeing engineer and he'll give you a ear full. Your boat is now 40 years old. Designed with a max rating of 85hp that in its day averaged about 250-260 lbs. Safe to say the boat engineers were thinking in those lines of weight. To put a 350lb motor on, plus create more leverage on the transom with a jack plate is a concern indeed. My 74 SS and many others I've seen in photos have cracks near the top of the knee brace just inside of the transom. To quote Scotty "She won't take much more Captain".

My two cents.

 

[GA_Boater]

Re: 1973 16ft SS repower

You have good reason to be concerned. Keep in mind that wooden transom is not the only thing holding things together back there. Metal fatigue with aluminum over time is a serious issue, asked any Boeing engineer and he'll give you a ear full. Your boat is now 40 years old. Designed with a max rating of 85hp that in its day averaged about 250-260 lbs. Safe to say the boat engineers were thinking in those lines of weight. To put a 350lb motor on, plus create more leverage on the transom with a jack plate is a concern indeed. My 74 SS and many others I've seen in photos have cracks near the top of the knee brace just inside of the transom. To quote Scotty "She won't take much more Captain".

My two cents.

Almost every cracked transom/knee braces was caused by waiting far too long to replace the transom ply. My two cents.

Bandito - You are probably adding about a hundred pounds. The boat will sit a little in the stern at rest. Do you need the jack plate? Three inches isn't much, but it does move the added motor weight aft and add stress to the transom. BTW - the transom won't fall off as long as you have a good, solid transom. Also, since you aren't overpowering her, the jack plate might not cause any problems. Again, my two cents.

 

[ezmobee]

Re: 1973 16ft SS repower

The additional weight by itself shouldn't be too big a deal. Not a big fan of the jack plate idea on top of that though.

 

[barato2]

Re: 1973 16ft SS repower

i'm with GA and EZ....motor is fine, but the jack plate might not be a good idea. or you could add extra knee braces to be safe, but this is not real easy to do unless you'll have the floor out.