Strut isn't lining up. Help!

[Jared1048]

So I gooped up the strut pretty good with 4200 and tightened it up to the hull snug but not fully torqued. Tried to slide in the shaft but its binding on the hull of the boat! I tightened the strut a lot more hoping it would 'raise' it closer to the hull and make it unbind but no luck.ugh

pulled strut off and cleaned up all the 4200 and cracked open a bottle of wine to re-evaluate my approach for tomorrow morning

I noticed that my sink door doesn't want to close now since the boat is on blocks and the hulll is twisted a little.hoepfully this isn't effecting the strut install.

Im thinking tomorrow I'll put the shaft on first then slowy tighten bolts until it starts to pull the shaft into the hull and stop. Let the 4200 dry, then tighten nuts a little more but not torquing them anymore? Now the strut might not be 100% tifht against hull but its close enough and the 4200 acts as a 'filler'?

This sound like a good approach?

I was going to have the yard do the final alignment but I might have them install the strut also at this point Monday morning.

 

[Allan12210]

Jared,

I still don't think it is a good idea to glue the strut to the boat. It can 't be adjusted later if needed without considerable effort or cost.Using a flexible material as filler is not good as the strut will move and either leak or lead to cutless bearing wear as it resonates at certain rpms. Leaving it to the yard....they'll probably glue it on and leave you with the consequences down the road.

With that being said, don' t get frustrated as you can do this. Please read the post again where I had to do this very same thing on mine. Start with the shaft in the strut and centered in the stern tube supported by a small piece of wood (un coupled from the engine). Dry fit the strut to the hull loosely and you can see by twisting or swinging it when it comes into alignment. The rest of the details for preparing a solid bed (if required) are in the old post.

http://forums.hunter.sailboatowners.com/showthread.php?p=670097#post670097

Regards

Allan

 

[Maine Sail]

Jared,

Fitting a strut "properly" is a tedious, time consuming and laborious process. Even builders royally screw this up...

The best way to do it is to properly support the hull so the vertical load is not unequally loading the keel either fore or aft. A laser alignment tool can the be inserted into the strut shooting through the shaft log. A laser bore sight for a gun, with a custom machined insert for the strut works well. The machining will run about $30.00 - $100.00 depending upon the machine shop.

You now "shim" the strut to line up dead center in the shaft log and dead center on the gear box output flange. All these items must be in as close to perfect centering as is possible so that once in the water it does not change much and cause "side loading" of the shaft by the stuffing box.

Once the proper shims are made you can then bed it and do a final tightening being very careful not to tweak it off where it needs to be. You simply can not line these up by eye and get it spot on....

You can also use the shaft but it does not come out quite as accurate due to shaft sag. A shim to go around the shaft OD and into the shaft log ID can help center the shaft in the shaft log but a laser works wonders.

 

[Richard Bryer]

On my H34, I used a piece of 1"ID, 1.25 OD steel tube to "shim" the shaft and hold it centered in the log. I split it down the sides so I had 2 pieces to slide into the shaft log. It fit perfectly

 

[sandpiper10471]

Maine Sail - could you elaborate on the laser alignment tool, please. Photo? Source?
Thanks for your suggestions. I have fought with this one for a long time.

 

[Maine Sail]

Maine Sail - could you elaborate on the laser alignment tool, please. Photo? Source?
Thanks for your suggestions. I have fought with this one for a long time.

You buy a "laser bore sight". Like these from Cabella's; Laser Bore Sight

Now measure the ID of your shaft strut CAREFULLY, or just bring the strut and bore sight to the machine shop with you, and have them machine you a sleeve to insert the bore sight into and that then fits snugly into the shaft strut.. A "marine tool" for this job would run you $$$$$$$$$$ but this can be done quite reasonably with a laser bore sight for a gun..

You can do this for well under $200.00... You'd pay a mechanic to do this job right many times that...

The bore sight & machined sleeve need to fit into the strut WITHOUT the cutlass bearing in place!!

 

[sandpiper10471]

Great tool and explanation. Thanks.

 

[kenn]

Nice tip re the laser, MS.

I've helped with a couple of strut re-installations, and can confirm the advice that good hard shims are necessary if the strut needs alignment. I think they were brass to match the strut bronze as closely as possible.

The strut is supposed to be a rigid extension of the hull.

 

[Jared1048]

So I'll trying this again by getting the shaft in the middle of the tube then shimming the strut to stay in that location. With the new cutless bearing its very obvious if its binding at all by turning the shaft by hand. Its got a seriously tight clearance of something in the thousands of an inch.

Ill take my time and see how it goes! Thanks for the replies!

Oh, what kind of shims? I have a bunch of different fender washers? Strut is bronze and obviously the hull is fiberglass. Maybe a thin layer of 4200 between the bronze and washer?

 

[tommays]

You need to remove the rubber cutlass bearing and replace it with bronze bushings*

Then with a piece of straight shaft guided by some more bushings in the stern tube you can see what your really dealing with*

In my case the stern tube was screwed and the rear of the strut was off .090 which does not sound*like much BUT it made the shaft OFF ONE INCH at the motor*

While the job is a PITA having a driveline you turn with two fingers when your finished is priceless I

 

[Bill Roosa]

You noted that the sink door will not fit so the hull is not properly supported. If you manage to get the shaft lined up and installed when you put the boat in the water it will be out of alignment!!!! MS mentioned this but there is no way to insure the boat is supported uniformly as it is in the water. Best effort is all you can hope for.

Good luck

 

[Ray Bowles]

Jared, If you plan on using fender washers for shims and then placing this assembly in salt water it will be a short term affair. You must use compatable metals or they will be eaten away faster than your zinks.
The time spent now, and accuracy, will determine how long until you do this again.
Ray

 

[Allan12210]

Jared,

Trying to get the right sized shims is a tedious affair. First it will be too much , then too little. It will probably never be just right. The previous poster said .090" at the strut resulted in 1.00" at the end of the shaft. Better to use a marble sized ball of epoxy putty inserted between the strut (wrapped with saran wrap). Tighten the screws until it just comes into alignment then stop and wait until the epoxy cures. Then you have an exact surface for the strut that won't flex. Take the screws out one at a time and put your sealant under the head, reinsert through the strut then fill the area around the screw where it comes through the hull, put a washer on it and the nut.Have a helper hold a Phillips screwdriver outside while you tighten the nut so you don't spin the screw. This gives you a total support surface instead of only against shims and avoids the use of sealant on the hull except to stop water ingress.

Allan

 

[Jared1048]

I was kinda lucky to have the boat next to me having its strut replaced and I've been watching there progress. I caught the guy today and picked his brain about the subject and he was doing the same (epoxy between strut to create perfect "spacer". After seeing the precision involved and his work decided to not touch it and have that same guy do mine. Its just too important to be "learning" on.

Really appreciate all the advice!

 

[David W]

Jared,

Trying to get the right sized shims is a tedious affair. First it will be too much , then too little. It will probably never be just right. The previous poster said .090" at the strut resulted in 1.00" at the end of the shaft. Better to use a marble sized ball of epoxy putty inserted between the strut (wrapped with saran wrap). Tighten the screws until it just comes into alignment then stop and wait until the epoxy cures. Then you have an exact surface for the strut that won't flex. Take the screws out one at a time and put your sealant under the head, reinsert through the strut then fill the area around the screw where it comes through the hull, put a washer on it and the nut.Have a helper hold a Phillips screwdriver outside while you tighten the nut so you don't spin the screw. This gives you a total support surface instead of only against shims and avoids the use of sealant on the hull except to stop water ingress.

Allan

The epoxy trick is brilliant.
/file for future use/

 

[tkanzler]

I caught the guy today and picked his brain about the subject and he was doing the same (epoxy between strut) to create perfect "spacer".

If it increases your comfort level any, synthetic formed-in-place chock creation is a very common approach in certain large machinery and marine applications, like ships. I've come close to using it a number of times for one-time large machine installations, but elected in the end to mill tapered (both ways) chocks instead, but only because it was less work for us to do it that way, and the two surfaces were machined already (flat and smooth, to within small tolerances). But liquid chocks are well accepted, including in some marine applications. I don't know how well a ball of epoxy forced into shape would work, but in concept it seems like a very good idea, especially with the questionable interface between the strut and the hull.

Here's a link to Chockfast, just FYI.

http://www.chockfast.com/itwproducts.html

 

[sandpiper10471]

I would shy away from making the epoxy shims with microballoons. These are hollow spheres which are capable of absorbing water. A better product would be cabosil (fumes silica). Won't absorb water and gives much more strength, particularly compressive, to the mix. Even stronger is a mix of cabosil and milled fibers.

 

[Witzend]

Although probable not the solution you would consider, but thought I again would expand on the possibilities. This is from http://forums.catalina.sailboatowners.com/showthread.php?t=114669&highlight=strut&page=3
My issue was that the strut was glassed 4" inside the hull and cutting it out to shim was going to be a very difficult process.

This is the way I solved the problem, granted unconventional, but I believe this to be the best approach for me. I'm sure there will be comments from the perfect world that I don't intend to live in, but the alternatives were in my mind much more arduous. If anyone believes this to be a logical approach to solving their mis-aligned strut and wants more information, please ask.
I used a 1.25" reduced shank S&D drill bit and put a .5" ID and 1.25" OD sealed ball bearing on the reduced shaft end of the bit. This provided a fulcrum point to apply pressure to the tip end of the drill only and helped keep from overloading the drill. By applying pressure in the opposite direction + ~30deg from where I needed to remove material while moving the bit in and out, I was able the cut away the inside of the strut bearing casing at the top aft end where needed. To further clarify if the top is 12 o'clock, I applied pressure at ~7 o'clock. I only figured this out from elongating holes in the past, (which gave me the idea of doing this in the first place). This probably has something to do with the drag force of a spinning drill bit, or something? From previous measurements I needed to remove ~50 thousandths from the top aft to correct the alignment. This took about 1 hr using frequent oiling. The cutting went slowly at first, but towards the end, as the bit had more of an angle, the cutting went faster. I doubt this approach would work without considerable difficulty on a larger diameter strut casing.
After inserting the cutlass bearing and checking that the alignment was correct by inserting the drive shaft. I then cleaned the oil off with acetone and applied a marine grade epoxy to the inside of the strut casing. I then placed a rubber stopper in the end of the cutlass bearing, (to keep the epoxy from getting inside) and inserted the bearing while rotating it to insure it was well spread.
I removed the cork and inserted a 16" piece of 1" tubing with a wedge against the hull forward of the bearing to force the aft end up. This was probably unnecessary because the set screws I turned in probably would have worked just as well, but just in case.
After the epoxy set, I removed the tube and inserted the drive shaft and it looks pretty dam close.
If the bearing ever needs to be changed again, just heat with a torch, that will destroy the epoxy, should come out easier than before as long as you don’t need to do it in the water.

 

[Jared1048]

Update.
We lined up the shaft into the middle of the tube and slowly tightened the screws on the strut checking for it starting to bind about every 2 turns. We then lined up the engine to the coupler (about half a mm above the strut resting on stuffing box) then attached pulling the shaft off its resting spot on the stuffing box. The engine is now aligned perfectly to the coupler, moving through the middle of the fiberglass through hull (the stuffing box is attached to) and through the strut that turns with relative easy.

Marked the screws and pulled it out. We then mixed up some west system epoxy and packed the in sunk strut housing. Used packing tape on the strut so it won’t stick to it and waxed up the screws so the epoxy won’t stick to them either. Pushed the strut up into the mix and tightened the screws to the predetermined locations. Strut turns a little bit harder than we had before but yard mechanic said it looked great.

Now we wait a full 24 hours for the epoxy (west 403 filler) to set properly. Hope we did everything right and the boat doesn’t move to much once we put it in the water!

 

[Charles Erwin]

If the rig is not tensioned (for example, if the the mast is off the boat you will need to reinstall and bring the shrouds/stays to the correct initial rig tension - 15% of break strength) please re check motor shaft alignment. There will be a slight change once final rig tension is established.

Charles