Mast Conduit Rivets

[Ron Hill]

Guys : Sorry, but I failed to talk to Gerry Douglas.  I went by the Catalina Booth 4 different times yesterday and he wasn't there.

I'm not sure we will know the cause of the loose/pulled out rivets until Paul and Dave are able to look at one of those rivets first hand.  I'll guess there are limited reasons for failure - corrosion?, poor quality rivet?, wrong size rivet?, improper installation? or a combination?

I think that Dave can give more insite as his mast has been pulled and he can find out first what's happening.
 
Until it can be determined why the rivets pulled out, it's only speculation on how to fix the problem.   My thoughts

[Dave Spencer]

I took a few pictures of the loose conduit in my mast while it is down and on sawhorses.  It's hard to get context from the pictures but looking up the mast from the foot, it looks like almost all of the rivets have let go except of one or two near the mast cap (does anyone have straight forward instructions on how to remove the mast cap?)
When I felt the holes in the conduit, they felt a bit ragged and I thought the conduit simply worked loose.  Looking at the upper LH corner of the picture, it looks like the rivet let go (and, I think I see some corrosion! ).  This is definitely fixable with the mast down. 

It would certainly be harder to fix with the mast up.  Pablosgirl has a good thought to hook the conduit through a second hole, snug it up to the mast and try to re-rivet while the mast is still up.  This could work bit I wouldn't want to drill any more holes than necessary in the mast and it would obviously require a trip up the mast to get to most of the rivets.  Pablosgirl's comments are on a separate but similar thread started at almost exactly the same time.  Is there an easy way to combine them?

[Ron Hill]

Dave : Your last post is interesting.

I know it isn't a solution to the rivet problem, but here is an option that you might want to look in to :
The cost of a new mast with "in the mast furling".  Don't know if that size extrusion will or could fit thru the opening in the deck?  You would definitely need the Admirals' approval and I don't know how long you plan on keeping the boat, but it might be an option worth checking into!?!

A thought

[pablosgirl]

Hi Dave,

Thanks for posting the picture of the inside of the mast.

Since you have your mast down anyway, why not simply replace the conduit with new?  I am sure that the PVC has become brittle with age and freeze/thaw cycles from being up north.  That way you could use the existing holes in the mast for new rivets and have a fresh tight hole in the new conduit for the rivet to grab hold of.  You could use the 2x6/2x8 method that Ron mentioned in an earlier post to hold the new conduit in place while drilling a hole in it for the rivet.  You should put a pull string in the new conduit while drilling the holes in it to avoid damaging your wiring.  For that matter you could also replace your wiring if it looks worn.  I would start at one end and work toward the other.

Paul

[Phil Spicer]

 Ron : Thank you for trying to talk with Gerry. Too bad you couldn't meet up with him.
Dave : to pull the cap, take tension off all lines & rigging. Pull the bolt, slide the cap out.You may want to pull the pins on the head & aft stays to make the masthead fitting slide out easier.
Another thought : On the back of the mast, (on the inside) on each side of the sail track there is a small slot. I wonder if that is for a special extruded wire run (conduit). It would have to be a conduit  with a small bulb on it that slides up the slot. I have seen this application on machinery. A check with some mast companies may find something. Well, now that I have said this, if you could find that kind of conduit, it would only work for the masthead light. It wouldn't do for the deck/steaming light since the conduit would be at the back of the mast & the deck/steaming light wires need to be in the front of the mast. 

[Ron Hill]

Guys : I wrote an article on removing the mast cap and changing out the sheaves to bb sheaves.  Look in the Mainsheet tech notes!! 

[Dave Spencer]

Paul,
"Good Idea" to change the conduit.  I was thinking of renewing the wires for the steaming / deck light , the anchor light, wind instruments and the VHF radio but hadn't thought about the conduit.  No doubt, that would be the least expensive part of the job!
Phil,
Thanks for the tip on how to remove the mast cap.
Ron,
I searched the index on the Tech Notes yesterday but couldn't find anything.  I think I see it now listed under Garhauer Sheave upgrade in Nov 98.  I'll examine your write-up carefully and ask if I have any questions.

[Ron Hill]

Dave : I believe that my write up on the sheaves was under the title "Installing a Hinkley TV antenna" ? ( me thinks)

[Dave Spencer]

Hmmm Ok.  I don't know why I didn't find that the first time I tried.   
Thanks as always for sharing your knowledge Ron.

[Dave Spencer]

Does anyone know the dimensions of the inside of the mast?  Dimension A and B in the attached picture.  Mk 1.5  No Furling.  I want to build a brace to help me install new conduit in my mast this month before we put the boat in the water and my mast is 265km away at the moment.  Outside dimensions would be fine too... this won't be a precision tool when I build it and I'm sure it will need some field modifications.
Bonus question -how thick is the mast material (to make sure I have the right rivets).

 

[Ron Hill]

Dave : I suspect that Catalina factory can give you the inside dimensions you need as well as the wall thickness.

Maybe a balloon or a ball would provide the resistance necessary to push against conduit - while you re-rivet it in place??

My thoughts 

[Stu Jackson]

Beg, borrow or steal Don Casey's "This Old Boat" book.  He has a GREAT description of how to do all this.  Don't reinvent the wheel. 

[Dave Spencer]

Good thought Stu.  I checked out my copy of Casey and you're right about his good approach to this problem.  Ill give it a try.  I can "reinvent the wheel" as my fallback plan.

Thanks for the idea Ron.  I was thinking of making a small "car" with pool noodles for lateral stability and a couple of wedges operated by a few ropes to centre the conduit and hold it in place while I drill and rivet.  The Casey method looks easier although it will involve lots of time lying on my back in mud.

I'll let you know how it goes.

[Dave Spencer]

Renewing an old thread, I finally wrote up my procedure to secure the mast conduit to prevent it from slapping in the mast. 

I took care of this preseason last spring while the mast was on the hard.  I took Stu's advice and checked out Don Casey's comments on this subject on his wonderful 2nd edition of This Old Boat.  In summary, p118 of Casey recommends drawing a line on the new conduit and then, with the mast lying track up on horses, fiddle around with a sharp awl to align the line on the conduit with the rivet holes that you have drilled and then drill and rivet the conduit. 

To start, I bought 5 10ft lengths of 1" PVC conduit and hauled them up to our boat on Georgian Bay.

I removed the steaming and foredeck light and pulled the wiring out of the conduit.  I then did the same at the mast head by removing the casting and pulling the VHF, wind instrument and anchor light wiring out the top of the mast and coiled it up out of the way.  Removing the masthead casting is straight forward.  Simply remove one bolt and then "persuade" the casting off the top of the mast extrusion.  See picture.  While I had the mast head casting off, I replaced the main halyard sheave with a Garhauer ball bearing sheave that I picked up at the Toronto Boat Show.

I then drilled out the rivets clearly visible along the leading edge of the mast and pulled the conduit out.  Fortunately, I had lots of room available to do this.  See picture.  I then examined the conduit and made the following observations:
- The conduit was in good shape with no sign of brittleness.  (It certainly has zero UV exposure.)
- There were several ragged holes in the conduit where the rivets had worn through and had finally let go
- The old conduit had much thinner walls and a larger inside diameter than the new conduit that I bought.  See picture.
- The conduit was in one piece with a hole part way up to allow for the steaming light wiring.  It was not split into two pieces with a break at the steaming light as one of the Casey options shows.

I elected to set aside the new conduit and reinstall the old one since the original conduit was in good shape, much lighter and had a noticeably larger ID,.  (Very few sailors have complained that the conduit is too big to pull cables through!)   

I was concerned about damaging or fouling one of the 5 halyards during the installation process so I pulled all of the halyards out leaving the inside of the mast completely bare eliminating the chance of catching a halyard with drill or trapping a halyard under the conduit.

I reused the original conduit rivet holes in the mast but also drilled out two or three additional 7/32" holes between each original hole to significantly increase the strength of the original installation.   I used 3/16" aluminum rivets.  Although I bought long rivets (3/16 x 1/2" long) I didn't need them since the standard length rivets gave more than enough purchase.

I then laid the mast with the track up on my horses and fed the conduit into the mast so that the conduit lay more or less over each hole that I drilled.  Lying on my back, it was easy to drill and rivet the conduit for the lower 15 ft of the mast where the conduit could be held in place by a helper, either by reaching through the base of the mast or by using a long screwdriver or other improvised device to hold the conduit in place through one of the numerous halyard exit plates.   It was far more difficult to align he conduit and hold it in place to allow it to be drilled and riveted above this point.     Here, I found the new conduit that I bought wasn't a complete waste.  I taped two lengths of conduit together with duct tape side by side forming a 20 ft long guide allowing the Admiral to reach into the mast and use the groove between the two pieces of conduit to hold the mast conduit in place allowing me to drill and rivet it in place.  Manipulating the improvised conduit guide was clumsy at first but it eventually worked.  I had trouble drilling into the conduit no matter how small or how sharp my drill bits.  Although the conduit was held in place with our improvised guide tool, the conduit would tend to squirt out of alignment when I applied any pressure with the drill.  Rotary tool to the rescue!  I found the very sharp pointed bit on my Canadian Tire rotary tool would bite into the conduit much more easily than the drill bit allowing me to start a pilot hole in the conduit then allowing my 7/32" drill bit to get some purchase and finish the hole.

Once all the riveting was done, I took my trusty rotary tool and carved out a new hole in the conduit at the steaming light for the steaming and foredeck light wiring.

I then pulled all of the cables through the newly installed conduit using a 50 ft electrician's fish tape.  Same for the five halyards making sure they all run true and on the correct side of the upper and lower shroud compression sleeves.

This project was a great success with quiet nights at anchor all summer and no conduit slapping.    Like all boat projects, this took me longer than expected but was easily accomplished on a cool spring weekend.  I can't imagine how this job could be done with the mast up.

Sorry for the long post... hopefully this is useful for those with slapping conduit but will be terribly boring for others.   

[Dave Spencer]

One additional picture for the above post.