Mounting bolt patterns

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halter
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Mounting bolt patterns

Post by halter »

I currently have a 1979 150hp merc on the back of my boat.
If i was to mount a newer motor(say a 2003 75hp merc).
How would i know if the bolt pattern would match up so i dont have to drill any more holes to weaken my transom?
Or does anyone know what motor would fit my bolt pattern?
Hoping these things are somewhat universal :lol:

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mikemicropterus
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Standard Pattern

Post by mikemicropterus »

The motor will fit without drilling new holes. Most motors NOW 50hp and up have the same bolt pattern regardless of manufacturer. This is what you would call an industry standard. Only why you would go from a 150 to a 75 is beyond me you will get half the performance and spend more on gas and wear that motor out faster. Drilling new would not weaken the transom unless it was full of water cause if drilling holes weakened the transom they would find a different way to mount the motors. The hole CUT in the transom to mount an I/O t-plate a 10 year old could crawl through. :D
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halter
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Post by halter »

Thanks for your help :lol:
The 75 hp motor would help out my trolling problem so i would only use one motor instead of buying a kicker.
I might try my friends plate in front of the prop and see if that will slow it down enough.

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mikemicropterus
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Drft socks or sea anchor

Post by mikemicropterus »

:DI understand what you are trying to do. With a trolling plate you will slow down but you may damage the seals. It has been evident in the last few years that trolling plates can lead to prop shaft seal failure. WHY?????
The heat from the exhaust remains trapped by the trolling plate and overheats the seals. Solution a 3 inch hole drilled in the middle of the plate that lines up with the exhaust housing. This will relieve the heat.
Have you ever tried draggibg a sea anchor or drift sock????????????????
No need to change motors, just drag a bag to slow you down. I always carry 2 a big one and a smaller one. Depending on the conditions I may use both at times and you still get the boat to perform properly. Just a thought.
Michael
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