Can 1999 272 sailfish handle pair of f250 30" shaft

[tomkim94015]

Hi Everyone
I was told this wouldnt be an issue but wanted to find out. I have an opportunity to repower with a pair of counter rotating f250 but has 30" shaft. Currently I have a pair of 225 ox66 with 25"shaft.

 

[Sea Shift]

I dont have the exact boat but I have the Express 265 powered with twin F250s and its been great!

 

[tomkim94015]

I dont have the exact boat but I have the Express 265 powered with twin F250s and its been great!

Im more concerned about the 30" length. Not sure if its going to be a problem. My centerline on the transom is exactly 30" however, its Dual motor setup. So where the motors are mounted the v bottom rises to more like 27 and the cavitation plate sits about 2" above the bottom of the boat.
I understand on a single motor setup the cavitation plate should not fall below the keel of the boat and in this case a single 30" setup on my boat would work. I cannot find anything about dual setups if 30" is OK.

 

[family affair]

Will it "work"? Yes. Is it a good idea? No.
The added length of the shaft puts more "leverage" on the transom. More than it was designed for.
Props throw water backwards, but also radially. Burying the props will hurt efficiency because prop will have more pressure above it.
As someone else mentioned on THT, the extra shaft length can cause proposing too.
If it weren't for the transom stress, I'd say go for it and see what happens, but once the transom is over stressed, you are hosed.

 

[DennisG01]

I don't have the definitive answer for your specific boat, but... in addition to the "rule" you stated about the anti-ventilation plate (cavitation is a completely different thing) should also be set 1" higher for every 1' they sit back from the transom. I'm not sure how they sit on your particular boat.

If I'm reading correctly regarding what you stated in post #3, though, this means that your anti-v plate will sit 3" lower than it should and that can cause quite a bit of excess drag. This is assuming your current engines are set correcty. Do you have any running issues... ventilating at higher speeds, excess drag causing lower fuel usage and/or MPH numbers?

Can you swap just swap the gearcases from your current motor to the new ones? Or... also look around for used, 25" gearcases that would fit the new motors.

How much higher could the new motors be mounted (mounting holes)?

I would think a jack plate for each new motor would solve the problem, if need be, though? Although the added stress that Family mentioned should at least be considered.

 

[SkunkBoat]

NO. don't do it

 

[Fishtales]

Review the capacity plate, I believe that it is over powered. You can check with GW regarding weight as the 4 strokes are heavier. I believe the biggest issue will be underwater cockpit scuppers.

 

[SkunkBoat]

Review the capacity plate, I believe that it is over powered. You can check with GW regarding weight as the 4 strokes are heavier. I believe the biggest issue will be underwater cockpit scuppers.

the issue is that you CAN'T use 30" motors on a 25" mount

 

[SouthFork]

30” no, 250’s yes but you have to raise the scuppers. I looked at a ‘99 272 with F250’s and it was quick but the back of the cockpit had a bit of water in it because of the weight of the engines.