What Shaft Length Do I need!

[Justin1323]

so after years of I/O boating I finally made the switch to an Outboard boat. Since this is my first outboard i have a question abouyt shaft length. The boat is a '99 starcraft fishmaster 176. The boat originally came with a 70hp Merc but I bought the boat with no motor. I would like to upgrade to a 115hp-150hp(max hp). the boat already has Merc controls so i just need the motor. How do I determine what shaft lenght I need(20"? 25"?)? Any help would be greatly appreciated. Thanks!

 

[JB]

Re: What Shaft Length Do I need!

Howdy, Justin.

Welcome to iboats.

Measure the vertical height of your transom. Use the shaft length that most closely matches.

 

[Justin1323]

Re: What Shaft Length Do I need!

Hey JB!!!

Thanks alot for the quick response! So i am measuring from the top of the transom to the bottom of the V? I am going to measure it today then all I need todo is find a motor!!! Thanks again!

 

[rg2]

Re: What Shaft Length Do I need!

Justin

Make sure the distance you get from your boat is the distance from the top inside surface of the transom clamp to the anti-ventilation plate (looks like a fin) above the propellar on the motor. These don't always come out exactly 20" or 25" but they are normally within an inch or two.

 

[Justin1323]

Re: What Shaft Length Do I need!

Hey guys!

So I measured the Transom, from the top to the bottom on the V and it measured 21 1/2", so i am assuming i need a 25" shaft then?

 

[Jeep Man]

Re: What Shaft Length Do I need!

Correct. You can always raise the motor to match the transom but you can't cut the transom to make up for too short a shaft.

 

[sschefer]

Re: What Shaft Length Do I need!

The boat is designed for use with a 20" shaft motor not a 25. Even at the highest position your cav plate will be too low with a 25. It will work but left hand turns will be hard and it will put excessive stress on the transom. It will probably contribute to porposing also.

If you need verification of this, just call StarCraft. They have great support.

 

[pamlicopanther]

Re: What Shaft Length Do I need!

Would it work if he used a jackplate?

 

[sschefer]

Re: What Shaft Length Do I need!

Would it work if he used a jackplate?

It would and a 5 to 5-12" offset is the max.

I do it that way so I can use SeaStarPro hydraulic steering rather than being stuck wth the BayStar transom mount type. It's the only way it will clear my transom when the engine is tilted full up.

 

[pamlicopanther]

Re: What Shaft Length Do I need!

It would and a 5 to 5-12" offset is the max.

I do it that way so I can use SeaStarPro hydraulic steering rather than being stuck wth the BayStar transom mount type. It's the only way it will clear my transom when the engine is tilted full up.

Thanks for the information. I got a 25" at a good price and was trying to put it on a boat with that size transom and was wondering if I could adjust my jack plate to make it work.