Are there thru hull bolts for Com-Pac shaft log?

[HJ51]

Do Com-Pacs have bolts through the hull that anchor the propeller shaft / shaft log, stuffing box, etc?  If so, is that common and is it something else to worry about as a weak link in the hull?

Here is why I'm asking. 

I keep my boat in Florida most winters, but this year it stayed there year-round (Covid and other complications).  So I cannot check on it regularly.  I was having some rigging work done and the rigger called me and told me that my boat (CP27) was "taking on water."  There was salt water up to the first companionway step.  Not the kind of call you like to get. 

The marina is a working shipyard and I was able to get them to haul the boat out quickly.  They reported that at least one of the thru bolts that anchors and stabilizes the drive shaft / shaft log had corroded and caused the leak.

I had recently asked them to replace the bilge pump because the old one seemed to be acting up and since I am an absentee owner the bilge pump is a critical item.  They took out the old one but had not bothered to put the new one in.  While I still would have had a leak that needed to be addressed, the bilge pump would have at least kept the salt water out of my boat.

For multiple other reasons not even related to the bilge pump I have had a lot of concerns about the credibility of the service guys at this shipyard.  They have done quite a bit of work on my boat recently, including work on both the drive shaft and replacing the rudder and rudder post and it has been a battle to get the work done right.  So I am skeptical about their report that it was the thru bolts and not the seal at the rudder post or possibly the shaft gland where they had been working.  I didn't even know that there were thru bolts as part of the drive shaft system, but for all I know they could be exactly right. 

I'll be at the boat in a week or two and will try to inspect from the inside, but would like to have as much information as I can about what might be going on before I get there.  Any insight is appreciate.

[wes]

Ugh, boatyards. This is why I do all my own work, although I realize this isn't an option for you.

Some pictures below which may be useful. The bolts are substantial (3/8" if memory serves) and the hull is very strong in this area, probably 1/2" solid fiberglass. It's not impossible that a leak could develop, but it's not common and if it occurred I think the amount of water entering would be small; it would take a long time to fill up the boat to the companionway step.

In my experience there are two much more vulnerable points (in every boat, not just Com-Pacs). One is the stuffing box or shaft seal at the top of the shaft log, and the other is the engine raw water system (through-hull, seacock, water tubing, Perko strainer). Those are areas that require attention. I have seen at least one boat sink in its slip because the boatyard crew didn't check those areas for leaks before launching.

If I were an absentee owner and needed to rely on pro help, I believe I'd find an independent contractor - an experienced boat tech who has permission to work at your marina. There's one in nearly every marina, and because he works for you he will generally be more careful and responsible than the yard's own crew. He will also be more expensive. But he will be your eyes and ears when your boat is being hauled or launched. I've learned my lesson the hard way and I never, ever allow regular boatyard/marina staff to work on my boat.

Wes

#1 - External view. The factory installs the bolts with the heads outside and the nuts inside. This makes it nearly impossible to remove the bolts from the blind area under the shaft on the interior. I reversed mine for easier removal/replacement. Obviously this photo was made prior to applying antifouling paint. Note that I barrier coated the hull with Interlux 2000E prior to re-installing the shaft log, for uninterrupted protection of the hull under the hardware. Then bedded the shaft log with 3M 5200.



#2 - Prior to re-installing the shaft log. Note thickness of the hull in this area. Strong!



#3 - Shaft log on the bench for cleaning. Note Cutlass bearing is partially inserted. Also note the two small threaded holes for Cutlass bearing setscrews, and "dimples" lightly drilled on the bearing to receive the screws (this is done CAREFULLY after the bearing is fully inserted).

[deisher6]

Hey HJ51:
Wes as usual is right on. 

On our "86 C-27, I also found a weak spot / leak at the base of the rudder post.  There are pictures of the repair that I made somewhere on this blog.  I have not heard anything from Jim and Windrunner so the fix must still be working.

Good luck and Smooth Sailin'
regards charlie

[wes]

Thanks for the reminder, Charlie. I didn't think about the area where the rudder shaft penetrates the hull. On my 1988 this area is very solid; the shaft is metal and has an external plate that's very strong; similar in construction to the prop shaft log. But I believe some earlier models had a PVC tube and may have been more prone to cracking and leaks. HJ51, what year is your boat?

Maybe other 27 owners who have experienced leaks in the rudder shaft area can comment. It does seem logical that this area is more vulnerable to damage (such as a hard grounding) than is the prop shaft log.

An interesting side note: unlike some other makes, Com-Pacs don't have a stuffing box at the top of the rudder tube. It's just open to the air, but it's also well above the water line. Nor any kind of bearing at the bottom of the shaft. It's just a simple rudder post riding in a hollow tube.

Wes

[HJ51]

Thanks, Wes.  After haul out and further inspection, it turns out it was indeed at the rudder post and was the result of severe and rapid electrolytic corrosion.  I must have a stray current somewhere.  Both the post and the rudder post log or sleeve corroded in what must have been only a matter of a few weeks and that's where the water came in.  Unfortunate and expensive but there's no question that's what it was now.

[wes]

Yikes! Sorry to hear it. I've had a problem with rapid consumption of my zinc anodes, and believe it's due to being connected to other (poorly protected) boats at my marina via the ground connection of the shore power cable. I installed a galvanic isolator in the ground path and so far it's made a big difference. And of course staying on top of zinc replacement. Once the zinc(s) are consumed, the other metal parts are next in line for destruction.

https://www.defender.com/product.jsp?id=1353688

Wes

[moonlight]

Are you guys suggesting that all underwater metal, shaft and/or rudder logs, are part of a bonding system on your vessels?
If so, they'd be among the first ComPac's I've seen with that level of detail; i.e. a green wire connecting all underwater metals, the engine block, and going to shore power ground.

Absent a bonding wire, your underwater metals are electrically isolated, and thus would not be a conduit for "stray currents".  They'd pass them by like they don't exist. 

GALVANIC corrosion, caused by a galvanic cell of dissimilar metals immersed in the same electrolyte, i.e. stainless shaft, bronze prop, and the like ... well that's corrosion of a different sort.  And it's possible to have too much anode, just like it's possible to have not enough...

[wes]

Yes, every Com-Pac 27 I've seen, including mine, has a full bonding system.

Wes