40 horse Vs. 75 horse/transome ?

[MikeH71]

I have a Texas Maid 16' V hull, Aluminium boat. I have a transome height of 16 inches. My current Johnson 40 horse measures at 20" shaft. FIrst, is this an issue should I put a jack plate to raise the motor a few inches?
Second, I have a friend that is going to give me a 75 Johnson. The boat is rated for 85 Horse but his 75 measures at 25 inch shaft. Is it feasiable to put his 75 horse on my 16 inch transom?
Can someone also clarify the method of measuring shaft length. I have seen on here how to measure but my dad said years ago he was told to measure from transome hook of the motor to the hub of the lower unit. Was this a method used for older motors?

 

[steelespike]

Re: 40 horse Vs. 75 horse/transome ?

Measure from" transom hook"to the antivent plate just above the prop.Most motors will measure "about" 15 or
20" Some extra long shafts will measure "about"25 inches.It is possible to use a jack plate to alter height but my self I would try to find a motor/boat that fits the application.If the 75 really is a 25" I wouldn't even attempt it.

 

[tashasdaddy]

Re: 40 horse Vs. 75 horse/transome ?

with the 40 you need a jack plate, to get the AV plate about 1 inch above the keel of the boat. will improve performance tremendously. the 75 you need a different boat or a major overhaul of the transom. lifting one 10 inches is dangerous, you could possible convert it to a short shaft, but expensive.