Engine Alignment

[Afraal]

Hello forum,

My engine could use some re-alignment and I was wondering if you could provide some guidance/tips on how to get it done. I have watched youtube videos, but looking for some Cat310 specific tips. Also, has anyone here used the boom hoist the engine to help with realignment?

thank you!

andres

 

[valcour]

you can hoist the engine using a 4 x 4 on the cabin top or boom to replace the engine mounts and/or damper plate but to adjust the mount in place it is not necessary. disconnect the coupling, loosen the top mount nuts, and use a feeler gauge on coupling to adjust. No need to lift engine if the mounts are sound.

 

[Ralph Johnstone]

This is what I use. Once you read and thoroughly understand this, you will see that the first part is done only once to ensure everything is correct with the shaft and flange.

 

[Afraal]

Thank you @valcour and @Ralph Johnstone. Greta information and pics!

 

[Johnb]

Thank you @valcour and @Ralph Johnstone and also @kloudie1 for many valuable contributions.

I do wonder if there is any need to support the propeller side flange/shaft while the flanges are disconnected? My intuition says that with only the cutless bearing and shaft log serving to hold the flange in position it seems certain to "flop" around more than 0.002" as it is touched or rotated.

Appreciate your comments,
John

 

[Ralph Johnstone]

My intuition says that with only the cutless bearing and shaft log serving to hold the flange in position it seems certain to "flop" around more than 0.002"

The setup is pretty compact when you consider that the shaft and flange are pretty light over this section

No flopping in this setup.

certain to "flop" around more than 0.002" as it is touched or rotated.

Hmmmmmmmmm ! You haven't read the attachment from posting #3 have you ? You wouldn't ask that question if you had. Think parallel and non-parallel as you read.

 

[Johnb]

Actually very carefully and with some thought.

You are asserting then that the shaft log and cutless bearing are sufficient support?

 

[Ralph Johnstone]

You'd be a fool to believe me, so carefully put a good portion of your body weight on the shaft flange and see the amount of deflection. Then put your palm on the transmission and watch what happens. That presents food for thought when you talk about 0.002" flop. What is the author of the article (Jack Harden) talking about when he refers to misalignment and where does the error of 0.002" appear ?

Answer that question and all that's left is simply the smashing of your knuckles, the bashing of your thumbs, wrenching your back, a profusely bleeding crushed finger, and there's your maximum 0.002" misalignment. Voilà !

The flanges are separated, of course.

 

[Afraal]

Update:

I followed the steps in the document @Ralph Johnstone shared. I have all my measuring now. I created a simple excel file to help with the calculations. If any one wants it, drop me a note.

As per the Catalina 310 manual, the engine mounts should be mounted over some hardwood shims so the engine mounts screws are exposed no more than 3/8''. From another post here (engine bed related), it seems that in a number of boats, Catalina did not use shims. I'm going to take this opportunity to install some hardwood shims to rise the mounts a bit.

I also noticed that my engine is lower on the port side by a few millimeters. Shouldn't the engine be leveled on the beam axel, meaning same mount height on both port and starboard?

Thanks!!!

 

[jssailem]

Shouldn't the engine be leveled on the beam axel, meaning same mount height on both port and starboard?

Generally, yes. The builders of your boat did not use micrometers to construct the boat. That is why the motor mounts are adjustable.

 

[Afraal]

@jssailem thanks! I have about 10mm (about 3/8'') difference between port and starboard mounts. I'm going to try to level the engine a bit and see what I get on the shaft coupling.

 

[Ralph Johnstone]

I'm going to try to level the engine a bit and see what I get on the shaft coupling.

You are a brave, brave, man. Levelling your engine will affect the alignment somewhat because it doesn't sit horizontal lengthwise. And then it's back to the usual knuckle banging, finger crushing, back wrenching, aligning.

Congratulations, you're almost as OCD as myself.

As per the Catalina 310 manual, the engine mounts should be mounted over some hardwood shims so the engine mounts screws are exposed no more than 3/8''. From another post here (engine bed related), it seems that in a number of boats, Catalina did not use shims

Catalina completely throws me for a loop here. Why are they suggesting shims when you have adjustable feet ? And why hardwood ? When you are looking at the compressive forces the shim will be subject to, the shims are likely to split. This is bad juju.

Referring to Catalina's forgetting to use shims on some boats, I think somebody smartened up and realized what their specs called for was dead wrong and stopped the practice. I'm not yet clear on their need for 3/8 clearance.

This is interesting. Can you scan these instructions from your manual and possibly send a photo of your installation for us to have a gander ? If your manual is a .PDF, a couple of screen shots of this material would be excellent.

Also, has anyone here used the boom hoist the engine to help with realignment?

Also noticed this from your first post. The engine is just slid around (+0.001" here and -0.001" there) on the mounting surface for alignment purposes. No lifting allowed.

 

[Ralph Johnstone]

I also noticed that my engine is lower on the port side by a few millimeters.

Did you measure this from where the block is connected to the mounting brackets down to the solid surface the motor mounts are seated. I've never considered this before but I don't think its all that important. It's not going to affect the oil level by more than a few mm. if referenced to horizontal.

I would think if you were truly as OCD as myself, you'd be aiming for a perfectly horizontal installation and not reference it to the boat's mounting surface.

 

[Afraal]

@Ralph Johnstone . The way I see it Catalina suggests using hardwood shims so the thread exposure in the engine mounts bolts is kept to less than the recommended 3/8" max. They did not use any shims on my boat so the thread exposure in the front mounts is way more than 3/8''. I'm guessing that puts a lot of stress on the bolts, but again it is just my guess.

I attached a screenshot of what's in the manual for reference.

Regarding leveling the engine, yeah, that might be my OCD thinking that 10 mm drop to one side is too much. But I agree, I don't think it will have any effect on the engine's running.

 

[Ralph Johnstone]

After looking at Catalina's drawing for using hardwood for shims under the mounts, I can tell you this is 100% unadulterated bull :

Wood in this location is subject to every form of external contamination possible (water, oil, diesel fuel, heat) and as a result, will most likely produce dimensional distortion. Industrially speaking, wood is never used as shim material unless you're talking early 1900's saw mills. Far better to use metal, grout, or in this case of sailboats, King Starboard. And I can hear the purists rising out of their overstuffed chairs in protest already. Another old wives' tale which has been hanging around this site for years.

Lets ignore all the old wives' tales and only look at the numbers :

These numbers are taken from the King Starboard web site so there is likely some accuracy in these properties as opposed to what you find in forums. The underlined figures are saying, if you compress Starboard with a force which produces 4,950 PSI, its thickness will be reduced by 10%. If you continue to add additional compressive force, the compression value will not go beyond 4,950 PSI but the thickness will continue to be reduced. This is the equivalent of the Ultimate Tensile Strength found in metals. For the absolute purists here, ASTM D695 requires the compressive force to be applied to the end grain of the rolled plastic. In the case of Kingboard experiencing cross grain compression, the results are quite similar.

Given a 1,000 lb. diesel sitting on four adjustable supports, you can figure out the compressive stress on each piece of Kingboard shim for yourself. I've done the heavy lifting. Only a small fraction of the stated max. compression of 4,950 PSI is applied to the Starboard.

If you're using Starboard, check the numbers first to see where you stand.

A long strip of 1/4" thick Kingboard is used as a shim under the motor supports of my engine as shown :

No indications of creep in the Starboard were shown under the motor mounts during alignment due to the extremely light loading on the Starboard.

 

[jssailem]

I Believe! I feel redeemed!
When was this miracle of Starboard created? I think about 30 years ago.
Ralph has one of the first Hunter 310s; they were launched in 1999.
Even though we heard about PLASTICS in 1967

It is possible that the designer for the 310 envisioned Starboard as a construction tool for this specific task. But may have been told, "too expensive, spec hardwood. We know it will work, can easily be found, and is inexpensive."

Starboard would be a product I would consider if I was refitting my boat in this century.

 

[Ralph Johnstone]

I Believe! I feel redeemed!

Go forth my son and spread the word.
Pick up a few donations as well while you're out there.