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Nimue
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Propeller strut mounting diagram?

Anyone have a drawing of the prop strut mounting scheme?

I removed the aft centerline water tank yesterday (it leaked) to find out what the problem was. Turns out someone has built a giant fiberglass mound over the strut mounting area, which created a pressure point on the tank, causing it to crack.

Before replacing the tank I want to grind this thing out of there, but I'd like to know what it SHOULD look like underneath before firing up the power tools.

Help?

Jason V
Vancouver, BC, Canada

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TomSoko
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Jason,
It's on our website. I did a search for "strut" and it was the first hit:
[URL]http://www.c36ia.com/node/1385[/URL]

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GaryB
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If I recall when I replaced my strut just 3 years ago it is pretty much the bolts and nuts that is under the water tank. There may have been some putty or some material there but not much. I would be reluctant to grind. Based on your boats age though perhaps a repair by a previous owner was done.
I believe we put the tank back and just left the bolts and nuts exposed but we did use penty of 5200 around them.

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Nimue
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These pictures are probably resized too small now but someone has built a mound of 'something' covered in woven roving over the top of where those bolts are. It stands over an inch proud of the hull bottom.

Thanks for the diagram though, that helps me know when I'll be ok to stop cutting!

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pierview
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I had this problem on my C30 and Catalina fax'd or emailed (I forget which) all the diagrams you'll need. Might want to reach out to them.

As far as that stuff over the bolts, it is some sort of fiberglass filler which you'll have to grind out. Be sure to get a good mask because its a nasty, dusty job. At least it was for my son who actually did it.

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Nimue
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[QUOTE=TomSoko;15610]Jason,
It's on our website. I did a search for "strut" and it was the first hit:
[URL]http://www.c36ia.com/node/1385[/URL][/QUOTE]

Well I have finished the material-removal part of this project and have to say that the drawing on the site is laughably different (and more logical) than what is actually in my boat. I was thinking that this is a repair of a previous strut-damage incident but I also spoke to two fiberglass repair guys who indicated that what I have is pretty typical of what they've seen in old Catalinas.

Basically, under that tall mound of fiberglass, it does look a bit like what the drawing shows, except that the surface the nuts push on is not recessed into the skeg but actually is more or less flush with the inside of the hull.

This means the center water tank rests on the bolt heads and in my case eventually fails.

I've cut the exposed threads off the bolts but still have the nuts to contend with. Planning to build a 1/2" sub floor under the tank with some relieved areas around the nuts to prevent any high points.

jmflan
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Joined: 8/29/15
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Hi All:

Hauled the boat today for bottom job and prop replacement.  Turns out the strut is loose, and not loose as in the bolts are loose, but seemingly disconnecting at the hull.  As if it's cracked - and I can see light from one side to the other at the aft end of the strut.  I've looked at all the threads about replacing it.  But, question I haven't seen asked or answered is whether I can glass in the strut as is to effectuate a somewhat temporary repair.  Thoughts?

thanks, 
Jeff

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Chachere
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Jeff -
  Let's try to get some clarification here.  You said its "not loose as in the bolts are loose".   If that's the case, you are probably in good shape.  The only way to tighten the bolts is to remove the aft centerline water tank, and then -- in most of our boats -- grind out the glass that is covering the nuts, and then tighten.   It the links that I'm putting below you'll see some illustrations of what I'm indicating.   But I can't imagine how they would get loose unless the strut or shaft  struck something, in which case you probably have a bigger job on your hands
  But it doesn't seem like that's what you are describing, right?  I mean, if you grab the strut by both hands, its doesn't wiggle, correct?  If that's the case, what you seem to be describing is simply cracking in the glass fairing around the strut.    Again, take a look at some of the diagrams and photos in the links below, and you'll see that the strut is actually bolted into a large cavity within the small fin that runs down the middle of the hull in that area, and the cavity is simply faired out with a bunch of  filler. Here's a link to a picture of Gerry Douglas (the designer of the C36) at the factory showing the strut installation to some C36IA members a number of years ago: www.catalina36.org/community/photos/catalina-factory/prop-strut 
    I learned this myself when the filler around the strut six years ago  (while mis-using the cutless bearing tool in a way that put a twisting stress on the stut)  and could actually see right through it as you described, and was in a panic, but was reassured by other members that the fairing could just be patched, that it was not structural.  See   www.catalina36.org/forum/technical-discussion/cracks-around-strut-caused-using-cutlass-bearing-tool  and   www.catalina36.org/forum/technical-discussion/installing-cutlass-bearing-and-created-crack   (I had to replace the strut a few years later for entirely different reasons, and its a nasty job, but no need to freak you out on that right now!).

The links below should give you more of an idea of the structure of the strut area:
www.catalina36.org/members/technical/maintenance/replacing-prop-strut 
www.catalina36.org/comment/62604#comment-62604
www.catalina36.org/community/photos/catalina-yachts-strut-repair...

www.catalina36.org/forum/technical-discussion/water-pooling-aft-...
www.catalina36.org/forum/technical-discussion/prop-shaft-strut-n...
www.catalina36.org/forum/technical-discussion/strut-support
www.catalina36.org/forum/technical-discussion/propeller-strut-mo...
www.catalina36.org/forum/technical-discussion/strut-question
www.catalina36.org/forum/general-discussion/what-filling-should-...
 

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Chachere
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Scratch most of what I just said above (although the links will be helpful).  I just saw the vidoe on the FB page showing the state of the strut.  The strut appears to be cracked, and it will need to be replaced.  And no, you can't just glass it in, there is way too much stress on it from the torque from the propeller to keep it in alignment.  And not only that, but if its out of alignment the shaft tube where the prop shaft passes through the hull to the stuffing box will also get abraded away and will need to be repaired (another nasty job I've had to do!).
 
This is a do-able job for anyone with reasonable handy skills. But it will take time, mostly in building up the filler once you install the new strut.  The strut itself must be perfectly aligned with the shaft tube to the engine, otherwise the cutless bearing will have a pretty short life.
We obtained our replacement strut from Catalina Direct.  Catalina Yachts did not have them in stock, and directed me to the original manufacturer, who indicated they could produce it but it would take time and the price was higher.   We found that only 2 of the 4 holes in the replacement from Catalina Direct lined up correctly with the original installation, so we had to fill and then redrill the other two (I corresponded with Kent at CD about this, they couldn't figure it out, either).   But it all worked out fine.   I can supply photos of our replacement work, but the prior links have plenty of photos from other members who've done this job.

Given that it looks like there was damage from a blow to the running gear, you should probably also remove the shaft and have it checked at a prop shop.  They can straighten it if there is minor deviations (otherwise the vibration from the shaft will be a problem).   And while the shaft is out, make sure to check the condition of the shaft tube, which may have been damaged from a mis-alighted shaft (see https://www.catalina36.org/forum/technical-discussion/shaft-tube-removal to get an idea of the consequences)
 

jmflan
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Joined: 8/29/15
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Matthew, thanks sooo much for all the info.  And my apologies that I mis-typed in my post.  As you saw on FB group, I meant to say that the bolts are NOT loose.  Oops! Sounds like we had same experience with Catalina (not in stock) and CD has them.  I spoke with CD technical support and he gave me some rough measurements of the pre-drilled holes and suggested, as you did, that I fill and redrill if need be.  Sounds like my guys have a project ahead of them.  Again, thanks for all info here and on FB.

Jeff

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Chachere
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Here are some photos from our strut replacement project back in 2018, starting from the old strut.  What took the longest was slowly building up the filler and fairing it.

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Chachere
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Continuation of photo series of strut replacement project.   The last photo shows what the inside looks like (before the replacement) once the water tank is removed to access the bolts.  There are some layers of fibreglass over the bolts that need to be ground off to get at the bolt heads.  Gerry Douglas advised me that reglassing over them was not needed, as long as the strut and bolts themselves were bedded down with 5200.  But something should cover them to prevent digging into the bottom of the water tank.

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jmflan
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Matthew, these are very valuable photos to help me analyze. Much appreciated.  

This is the beauty of an active association!

I hope you get in some sailing as your season begins.  

fair winds-
jeff
 

 

 

jmflan
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Matthew, these are very valuable photos to help me analyze. Much appreciated.  

This is the beauty of an active association!

I hope you get in some sailing as your season begins.  

fair winds-
jeff
 

 

 

jmflan
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Strut replaced.  To add to Matthews photos for those that may come later, here are my pics.

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