Article on inboard engine alignment

[tobnpr]

Pascoe fan or not, this is an excellent article on the realities of inboard alignments.
Sorry if it's been posted up here before...it's a good read.

http://www.yachtsurvey.com/Alignment2.htm

Includes an interesting perspective on V-drives as well.

He also makes a point of the proper clearance between the prop hub and the strut, which is to be no more than 1/2 of the shaft dia. I've always wondered if that is the issue with the 340's that seem to snap shafts behind the strut far too often. Anyone with a 340 ever measure that clearance?

 

[bankshotbankshot]

Alignment is key any time you are messing with straight inboards or v drives i can not stress this enough it will tear all types of stuff up if not done properly

 

[Presentation]

Thank you. That is a good read.

 

[Presentation]

Alignment is key any time you are messing with straight inboards or v drives i can not stress this enough it will tear all types of stuff up if not done properly

You didn’t read the article did you?

 

[stuckinforward]

I personally have a real hard time with this article, is it coming from speculation and drawings, possibly hear say? I can give you a good example, out of 2 river boats and 4 transmissions, all 4 transmissions needed the output housings re-bored and sleeved because of MA, thats 4 for 4, they were out at least .020 face to face.
5 out of 10 transmissions will show signs of MA, 3 of the 10 will fail due to MA, the shorter the shaft the more crucial, lets be real here, would you feel more comfortable running around in a aligned boat or a MA boat?
if this guy was talking about 1" shafts i may concur, you get up in the 2" ranges at 5 ft, they dont give, the load is transfered to the transmission.
im not a surveyor, im a realist with knees that ache, scars on my hands, and i see day in and day out the end results of misaligned boats, im not trying to sway the jury here but, to me the article doesnt make sense and mis-informs

 

[Presentation]

I’m not sure we read the same article.

David did stress the importance of alignment.

He also made the case for other things that could also cause issues like weak or failing engine mounts, struts, drive shafts that stick out past the hub too far, etc.

He also made the case for flexing during operation causing miss-alignment and gave some suggestions on how to check for this when running.

I don’t see the controversy.


David’s marine surveys are known as being harsh and self-serving.

His theories on boat accident investigation are widely accepted as the base for law enforcement boat accident investigations today.

His standards have been known to be too high, but at least they are not the fluff boat reviews we read in the printed magazines today with a advertisement for the reviewed boat on the opposite page.

Perhaps you don’t know who this guy is and think he’s just some clown that wrote an article.

I’m neither a fan nor foe. I do feel he adds needed balance to the industry.

 

[stuckinforward]

yes, I do know who he is and read the article a few years back and my feelings are the same. its hard to say this without bias, the article does hit on key points regarding alignment, but does stray and what i absorbed was its not as important as one thinks. 5 ' shafts dont whip, they dont go fast enough to whip, some boats, not all have deep reduction 6.17 to 1, and they dont whip, alot of boats at times will not use isolater mounts and will be chalk fasted directly into the stringers, maybe its me but thats what i took from the article, moot points, good points but not precise.
like i said, im not a surveyor, which if you break that word down it means "too look" I get on these boats and will be compensated for a professional opinion and hands on, based on a failure, why the transmission failed, what will it take to repair it, and my opinion was based on all boats and the article refers to all boats, it was merely my thoughts. I am always and advocate of perfectly aligned boats, because i know what the end result of mis-aligned boat. what i got from it was if its a little out you will be OK, and the shaft will whip you back into alignment.
If your mounts are worn you replace them, if your strut is worn you replace it, if its cocked you align the engine, these are the steps taken to get the boat in align, and they are worn for a reason...because of mis-alignment. maybe its just me

 

[Presentation]

OK, I think I now better understand where you are coming from.

Thank you for the follow up post.

 

[bankshotbankshot]

I'm sorry Presentation you are right I only work at a Sea Ray dealership and have only 10 years of mechanic knowledge to go with it. A aligned shaft on a boat=a happy boat, yes there are other factors that have to deal with it to make it straight, but alignment is key. And yes I did read the article :smt021

 

[stuckinforward]

should the article start out.....before you pay your surveyor.....lol