LONGSHAFT /STANDARD SHAFT

[FAST FISHER]

Hi I have just had the offer of a 90hp Mecury longshaft for the right money. The trouble is the transom on my boat is set for a standard shaft motor.I have a 50hp Mercury at present.I would like to know the possible pitfalls of putting the longshaft on the boat if any.Will I be wasting the extra power availible or wont it make any difference. Thanks

 

[Solittle]

Re: LONGSHAFT /STANDARD SHAFT

You will get lotsa input that running a longshaft motor on a short shaft tramsom will reduce the maximum performance that you can get from that motor and it is true to a degree. Maybe it is not the best comparison but I run a 9.9 longshaft on a 13' al skiff and it runs and performs just fine. You might check to see if you can convert it to a short shaft if you've a mind to.

 

[FAST FISHER]

Re: LONGSHAFT /STANDARD SHAFT

My thoughts were to raise the transom so the engine sat slightly higher.The longshaft is only approx 3 ins longer.

 

[JB]

Re: LONGSHAFT /STANDARD SHAFT

Hi, Chippy Ray.<br /><br />No such thing as a "standard" shaft length. Short is 15", long is 20", extra long is 25", etc.<br /><br />What boat do you have? What HP is it rated for? What is the actual measurement (vertical) of your transom?<br /><br />The implications of a 90HP engine on a boat with a 15" transom could be severe. There aren't many rated for over 50hp.

 

[TOHATSU GURU]

Re: LONGSHAFT /STANDARD SHAFT

While you don't hear anyone say "standard shaft" anymore, it did refer to 15" transom lengths back in the 60's...maybe before that too. I remember being dragged to marine trade shows in Jacksonville, in the mid-sixties and some boats were advertised as having "standard" transoms of 15". It may have been a regional thing rather than a industry wide term.

 

[FAST FISHER]

Re: LONGSHAFT /STANDARD SHAFT

Hi the transom as I measured it top to bottom is exactly 20ins. I will measure again using a level to make sure the measurement is vertical. I have a 21ft Cruiser I was told it was made by a company in Holland in around 1990 and thats all I know about it.

 

[FAST FISHER]

Re: LONGSHAFT /STANDARD SHAFT

Here in the UK 15ins = short shaft<br />20ins = standard shaft <br />23ins longshaft

 

[Dunaruna]

Re: LONGSHAFT /STANDARD SHAFT

As a general rule its the same here chippy. Hard to kick old habits I suppose.<br /><br />Aldo

 

[FAST FISHER]

Re: LONGSHAFT /STANDARD SHAFT

So getting back to the subject will the extra 3 ins make any difference. I know the missuses will say it does!!!!!!!!!!!

 

[JB]

Re: LONGSHAFT /STANDARD SHAFT

I would expect a "longshaft" engine to have a 20" shaft, Chippy Ray.<br /><br />I don't think you have a problem unless the 90 has an extra long (25") shaft. You need to measure it from the inside of the clamp to the anti-ventilation plate, not the propshaft. I suspect you measured to the propshaft.<br /><br />Good luck.

 

[roscoe]

Re: LONGSHAFT /STANDARD SHAFT

Can be compensated for, by using a jackplate, if needed.