Flexing Strut

Rich Stidger · Nov 5, 2009

I'm NO expert on struts, but if the strut is moving AT ALL, I would get it repaired. It absolutely should not move.

Regarding the cutlass bearing with vertical slop and no horizontal slop, that is the normal way cutlass bearings fail.

The should be no discernible movement in any direction.

s sauer · Nov 5, 2009

Strut Fairing

I'd first use a wire wheel in a portable drill and clean everything off the strut base and onto the surrouding hull area. Take it down to shiny bronze and check if any sealant is missing around the base of the strut. Check the bolts inside to see if any moisture seepage is present. If it all looks solid, leave it alone and fair in the entire area with Marinetex in a couple layers.
Then primer the area with a couple coats of Interlux 2000 including the strut. Wet sand smooth with 240 geit wet or dry and bottom paint.

However, if there is seepage and or the sealant looks suspect, pull the bolts and rebed the strut, then do the same fairing in, primer and bottom paint, but check the shaft alignment after she's launched.

Ed Schenck · Nov 6, 2009

I think I would take a different approach. For peace of mind I would pull the strut. This will make it very easy to replace the cutlass bearing. Reinstall with new stainless bolts, washers, and lock nuts. Finish it as mentioned previously. Then have a pro help you align it, once before you splash and then check it in the water. I know that I would sleep sounder.

Ed Schenck · Nov 6, 2009

Flexing strut.

Yes, taking off the prop and sliding the strut off the end of the shaft should make the removal and install of a cutlass much easier. However if you are "bent" on removing the shaft so much the better. Then you could also add a shaft saver(picture). And you have the added advantage of being able to have the shaft checked for straightness. With the shaft saver you eliminate a little vibration and your alignment does not have to be as exact.

As for testing the mounts that's a hard one. Is there a neighbor with a new boat so that you could compare? I once had a problem where the mount seemed bad but it was the bolting to the engine bed. The lag bolts had loosened so that the whole mount was vibrating. You can see this pretty easily with the motor running at low rpms. Maybe you could discuss with a major mount builder - http://www.bushingsinc.com/marine.htm .

Naturally you will want the strut work finished(4200) and maybe a shaft saver before you begin an alignment. Then with the stuffing box and hose slid forward shim up the shaft so it is centered in the shaft log. If the strut went back into its proper location the shaft should turn easily by hand in the new bearing. In the picture you can see how close I was before even putting a wrench to the mount adjusters.

The other picture show tool that I rented to install the cutlass. Actually it was free since I bought a new shaft and the bearing from them.

Steve Dion · Nov 6, 2009

Don: You best bet for the prop is a prop puller. The heat is fine, but there is no guarantee that the heat will do the job.

Allan12210 · Nov 6, 2009

Don,

My strut was out of alignment and had to be removed and repositioned so the shaft would run true through the stern tube. One thing I did not want to do was to glue it to the hull as I may want to remove it again for some reason. Might be what your previous owner did and why you are having trouble removing it. With that being said, I will describe what I did and hope that there is something of value for you in my experience.

Fom my 2000 haulout: After removing the strut and installing a new cutlass bearing on the workbench, I reinstalled the strut in its recess in the hull and noticed that the shaft A) was cocked to the left against the stern tube (leave the nut off your packing so it is free to find its own resting point) and, B) the rubber in the cutlass bearing was squished on the lower side of the forward end of the bearing and also squished at the upper surface of the shaft at the back side when the shaft was pushed into the center of the stern tube like the packing seal would hold it. The shaft was very hard to turn. A surveyor that I had come by for my insurance warned me that it would wear out within 10 hours if I left it that way. He even had a magnifying glass with a light in it to show me. That tip alone probably was worth the survey fee that the insurance company had me cough up. I could see that the strut needed to be rotated to the right and then swung like a pendulum by shimming to relieve the pinching. The amounts would be very small as the distance would project up to where the shaft enters the hull. After taking the strut off the shaft again I used a disk sander to take off 1/16" off all four sides of the strut base so that it fit loosely in the recess of the hull. Then I could rotate it just slightly and the shaft would center from left to right. I then put a piece of wood inside the boat with a V cut out to support the shaft at the right vertical level. The shaft just laid in the V and passed through the exact center of the stern tube. To set the strut at the right angle, my wife mixed up a batch of West System epoxy with microballoons (like peanut butter) and put it into the recess. We wrapped Saran wrap on the strut ( you don't want to glue it to the boat!) and with the help of a 4 ft ladder, a few pieces of lumber and the jack out of my truck we supported the strut. Looking at where the cutlass bearing rubber met the shaft very closely with a maginifying glass showed a slight gap all the way around the shaft on both sides of the strut. The shaft turned very easily at thiat point. We stood back and waited 5 hours for the epoxy to cure. We just left what squeezed out until it was cured. It only took about 1/8" of epoxy at the front edge of the strut mount to get the angle we needed. The result is a recess that conforms exactly to the top side of the strut providing a very stable mounting that won't rock around. The last step was to pull the strut back down, sand smooth any excess epoxy on the hull, take off the Saran wrap from the strut and then after putting it back in the hull, re-drill or enlarge the holes in the hull so the screws would go back through. Just bed the holes, as you may have to remove the strut again some day. I used a Sikaflex product that is good below the waterline. I finished up the job by installing my new PSS dripless seal and aligned the engine.

The strut is rock solid when bolted tight and doesn't leak. And, if I need to, I can remove it easily. I did not put any filler on top of the strut mount to fill that void.

Regarding pulling the prop, I used a steering wheel puller on mine...available at your local auto parts store. I made a big split washer for the back side of my prop to attach the bolts through the puller. I attached a couple of photos for you to see.

Good luck,

Allan

Maine Sail · Nov 7, 2009

Was the strut moving, or could you physically wiggle it, before you loosened the bolts? If not, and it was in alignment with the stern tube, it would have been best to leave it alone.

Then cracking you see is quite common in strut applications as the fillers used to fair the hull at that location are usually a little to thick for the application and will show cracking as they rarely if ever have any reinforcing fibers in the filler which would do a little more to prevent this.

You can walk around many boat yards, and see the same thing, and most every strut you check will still be perfectly tight.

Also some previous owner could have used Bondo or similar which is not waterproof or designed for submerged use. It will absorb moisture then crack and split at the seams too. It is also quite possible that all the mold release wax was not totally cleaned off the hull. If this happens the the filler would not bond well to the gelcoat of the hull and would also split at the seams.

Now that you have it removed you'll need to re-align the strut to the stern tube and make sure the shaft passes through the cutlass perfectly centered. An easy way to do this is with a laser fit into the cutlass location, like one used for bore sighting, though they are expensive so the shaft will be your best bet.

When you set it back in use a lighter adhesion polyurethane like Sikaflex 291 and be sure to use bronze bolts. Many builders cut cost and corners mix bronze and stainless which can lead to galvanic issues. More than once I have seen a loose rudder shoe or strut that was only loose due to the corrosion between the stainless bolt heads and the bronze had bronze been used originally the fitting likely would have still been tight.

Ed Schenck · Nov 7, 2009

Yes, thanks Allan. Last night I had written a very similar answer sans pictures. When I clicked on "Post. ." the website was gone! All that typing.

And I know better. For longer replies I generally write them in Word and then cut and paste. But your answer is complete and includes the great pictures. Just two other thoughts:

Don, did you try tightening first to see if you can get rid of the "wiggle". Just to be sure that there is not something awry with the mounting. Then to remove you could put a sacrificial nut on top of the bolts and beat on them from the inside.

In the picture of the shaft saver you can see how closely aligned I was by simply centering the shaft in the stern tube. The stuffing box has to be slid forward to really see it. Also included a picture of the tool used for installing the bearing.

P.S. supposed to be mid-60s this weekend. Guess where all the boats are?

Allan12210 · Nov 7, 2009

Ed,

I've had my posts disappear like that too. This one was partially from a posting I did in 2000 which I found with the Search feature that worked well this time...Thanks Phil. I copied it to Word Pad and finished it there. I had my fingers crossed when I switched from Quick Reply to Advanced so I could include pictures.

Lots of good advice on this one from the rest. MainSail, now I am worried, I may have used SS bolts on mine...can't remember. I did drill a hole through my strut and have a zinc screwed to it so that may be helping ward off any corrosion problems. Good tip though, I'll add that to next haulout's list.

Allan12210 · Nov 8, 2009

I have never experienced a threaded on prop, but anything is possible I guess. Trying to figure out if it is a left hand thread onto the shaft would be another complication. Reminds me of when we sheared off the lug nut stud on my buddy's Chrysler trying to change his tire. We figured out what that "L" stamped on the driver's side wheels meant. Glad your prop came off ok.

Loose fiberglass sounds kind of scary...that part of your boat is pretty thick and not prone to flexing I would think once the nuts are screwed on tight. It should be stable. I do notice on your strut there appears to only be two screws which might make it prone to rocking. The strut on my H34 has four screws. Maybe you could drill another pair across from each other in the center of the mounting flange. You still may have to remove the existing screws if you disturbed them in any way as they might not be bedded any longer. The caulk bond could be broken from trying to turn them. Make sure there are washers under the nuts.

Regarding your alignment, I would check it before you remove the strut...especially if you don't really have to pull it. Make sure you screw it back tight first. Yes, you should remove the packing nut and move the engine on its mounts until the shaft is right in the center of the stern tube (up, down, left and right). Separate the coupling and while supporting the shaft with a block of wood still in the center of the stern tube, make sure that the coupling faces are in alignment. That means that the engine axis and the shaft are the same. Put the coupling back together and check if you can rotate the shaft easily making sure that it is not doing so just because the cutlass bearing is really worn out. A worn cutlass bearing should be replaced before continuing. If the bearing is good and the shaft is hard to turn, look real close and see if the rubber bearing is being pinched on each side of the strut. If it is, then you need to realign the strut to the shaft. You might be able to loosen the strut screws again and tweak it into place or even add a thin shim. If takes a lot of realignment and it won't tighten up firm (and stay that way) you will have to do the more extensive strut alignment like I did filling the interface between the strut flange and the hull.

If things do line up you can put the packing nut back on as it will not disturb the alignment as long as the shaft is in the center. If it is off axis, the nut will force a misalignment. You would certainly see that at the cutlass bearing and if you separate the coupling halves again they would pop out of alignment requiring moving the engine. When the boat is back in the water there can be some change due to hull flexing, but that is a relatively minor tweak of the motor mounts. That amount of flex shouldn't bring the stern tube back against the shaft but requires that you separate the coupling halves and check to the engine again. There is nothing like a well aligned system. It makes things so smooth.

I don't see the need to fill the exposed strut base area with anything as it just makes it harder to get to the mounting screws later.

If you have to change the motor mounts you can go to the Boat Info Tab >> Hunter Owner Modifications and search for New Motor Mounts. That will give you some info on how I changed mine. Your mounting may be different...I'm not sure on the H31.

Allan

jtm · Nov 9, 2009

Why not pull out the strut bolts one by one and inspect their condition. 2 of my 4 bolts were almost 1/2 the original thickness - thanks to "crevass corrosion' - a new word/term I've been introduced to on this site.

Allan12210 · Nov 10, 2009

Don,

Glad you found the hidden nut. Those things have fooled me on occasion too when I was rebuilding things like motorcycle engines and lawnmowers.

As you say, you might run the risk of messing up the new cutlass bearing trying to press the old one up the shaft with it. Better to get a piece of pipe that fits and do it with that first. Here is a link to a cutlass bearing puller that I have duplicated myself and used.

http://www.catalina310.org/Maintenance/Maintenance/Cutlass_bearing/Cutlassbearingremovaltool.htm

It is for a 1" shaft, so dimensions and materials would have to be adjusted accordingly. I don't know if the H31 has a 3/4" shaft, and if a 3/4" piece of pipe turned to the proper outer diameter could work, but it is worth a try. Make it long enough to extend past the end of the shaft so you can put a board on it and gently tap on it. Start by soaking the current cutlass bearing with some kind of penetrant, especially in the set screw holes. If you have something soft like a brass punch, you can start trying to tap all around the bearing from either side and see if you can get it to move out. Use brass so if it sllips, you won't mess up the shaft. It is good to be able to remove the bearing without having to remove the shaft or the strut if you don't really have to.

Allan

Flexing Strut

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