Is this why Inboards are pigs ??

[kens]

I suppose we all have seen it or heard about it, the boat yards that convert inboard powered boats to outboard. Bertrams, Blackfins, you name it, all the boats that originally had inboards installed from factory. They strip out all the inboard hardware, install a transom bracket, then hang big twin outboards, then say "see how it goes faster" !! It's lighter is why it goes faster. !! Inboards are heavy, gas hogs, just pig-ish.
Well, I am now in the middle of just such an adventure. The local owner of a 25' Blackfin offered to anyone all the inboard hardware, just to strip it out and get it ready for a outboard bracket & its outboards. It is a 350 Chevy, PCM, TBI, roller cam, vortec heads, FWC example. I took the challenge.
Get this: the boat is a 25' HEAVY fiberglass hull, deep vee, lift strakes, and I mean really heavy , originally was delivered with a 3208 CAT diesel,
( a CAT in a deep vee??), since been converted to the gas V8.
As I am taking this thing apart, I begin to notice things.....
there is no tip clearance for the prop, a 16" prop with 1/2" tip clearance, yes, the eroded hull at the tips, this must have been a source for vibration.
the strut is located as any of us would have it about station 1, but it had a outboard rudder. with all the spacing between the rudder & prop this must have been a pig to steer.
the rudder was offset to the left, it had a L/H prop. this must have given a strong torque pig steer at the helm.
it has one of those really 'high speed' rudders, the wedge shaped ones for racing,,,,, all 21kts of it !!
I had interest because it is a 1 1/4 shaft as is my Double Eagle, hence I get a spare shaft out of the deal, correct??
Nope,,,it was aligned such that the shaft was rubbing the shaft log such the shaft now has a worn neck on it. Did that not give a pig squeel when running?
The whole Time I tinker with this, I reflect on the things we discuss on the forum, the inboard layout, how to make it run right, and this 25' Blackfin, supposedly a respected boat, has everything screwed up that could possibly be screwed up.
And then when it is done, the owner gonna say, "see there outboards are faster"
BUT, what he not telling you is he just went from single 300hp inboard to 2x 300hp outboards !!!
He DOUBLES the hp and blames the single inboard as 'the pig'
dont really matter, I get a Cracker Box engine out of the deal.........

[Hercdrvr]

Good luck with that little project.
Matt B

[hoodman]

Ken, I think you have the right train of thought. It's just easier for manufacturers to bolt on an outboard(s) than to do the work to get an inboard "right".

[Bill Edmundson]

This is old. But, I bet the prop-walk was awful on that boat!

Bill

[DrBryanJ]

Bill, forgive my ignorance, but what is prop walk?

[Bill Edmundson]

Bryan

Prop-walk is the tendency for the boat to pull one way or the other based on the prop rotation. This particularly true on inboards and is most noticeable when backing.

Bill

[DrBryanJ]

Got it. Thanks Bill.

[kens]

This is old. But, I bet the prop-walk was awful on that boat!

Bill

would be interesting to know if the deep vee helped or hindered prop walk.
Also noticed that upon inspection of spark plugs and cylinders, it had been running very rich.
And being a TBI, the only was to lean it any would be to reprogram the computer, which is $600 just for the software.
It probably was a fuel pig, the spark plugs are telling me that