h34 "Claude/Allan Hybrid" Compression Post Repair

dcalif

.
Feb 17, 2015
22
Hunter 34 Monterey Bay
The inevitable failure of the compression post began to show on our Hunter 34 :
cp-damage.jpg


So I studied the solutions here on the forum. Especially Claude Auger's outstanding summary of his post repair and Allan Hadad's milled solution. (Allan was even kind enough to send me his CAD drawings and later check out the results of my approach when we were done.) However, I don't know anyone who can mill, and the quotes I got were insanely expensive. Also, after removing the wooden traverse beam, it seemed I was working with far less space than it appeared Claude and Allan had. I chalked this up to differences from boat to boat. It may look like we didn't get all the wood, but we did.
cptraversecleared.jpg

cptraversespace.jpg


I went with hybrid from both approaches and went with welds. I chose to stay with the same metal, 6061 aluminum throughout and bought three pieces online. One "traverse beam," the post and the base plate. Oddly, I had to use two different sources for the aluminum, as I couldn't find a single supplier of plate and square tubing in 6061. Both were excellent. The pieces cut to order were exact and delivery was timely.

Traverse
Source: midweststeelsupply.com
Specs: 6061-T651 Plate, 1.5", 3.375" x 13" (your measurements will vary)
$25.62 after discount and not including shipping
Note: midweststeelsupply.com had a different special every day, usually 15%. If there's no discount today on "aluminum plate" or "all products," there likely will be tomorrow or the day after. Shipping prices are reasonable, considering the weight.

Base
Source: midweststeelsupply.com
Specs: 6061-T651 Plate, 1", 4" x 4" (we cut this down)
$6.36 after discount and not including shipping

Post
Source: onlinemetals.com
Specs: 6061-T6 square tube, 2" x .25", cut to '72 (this was the only piece not cut to order)
Price: $54.50 not including shipping

Construction
We pulled the stick and went on the hard. While I was getting bottom paint, we went to work on assembly. We used a drill press on the traverse beam to give it some grab on the epoxy and drilled an extended wire pass-through to be sure there would be space.
cp-traverse-welded.jpg


On the post tube, we drilled two holes. One to feed wires to port (all wiring, except the ground had been routed to port last year for convenience), and another for the ground at the bottom of the post to starboard. After much measuring, the post was cut and the pieces welded together.
cp-welded.jpg

cp-basewelded.jpg


We jacked the deck slightly and after epoxy, the apparatus was slid into place. Used a small amount of 5200 under the base to keep it in place. Then we pulled the jacks out let it dry through the weekend. Stepped the mast and and ran the wires. There was a small incident with adhesive and the wires we fed through the deck plate I'd rather not talk about, but that explains the crap on the wiring. My bad.

cp-portwireoutlet.jpg

cpstarbwireoutlet.jpg


Here's the install after stepping the mast:
cpfull.JPG


I still have to have the wood routed from the old post. Like Claude, I'll slide it in and install the door jam. I'll also do teak flashing to cover instead of glassing it in to allow for easy access to wiring. I'll post the final results.

I don't have much in the way of engineering aptitude, so given the options, I took from two approaches and sort of simplified them. Some may think its "under-engineered," or over-reliant on the welds. While it's not perfect and may not be as good as what Claude and Allan have done, it works. I am very grateful they offered their experience as a resource because this project stressed me out for months and I just want to sail. At the end of the day, I'm confident it's a hell of a lot stronger than what Hunter installed 31 years ago.

Full disclosure: I'm not particularly handy. This work was either done or supervised by the guys in the yard. I found a terrific welder who mostly works the on the fishing boats here. The welds set me back about $300. In my case, the money for the pro welder and pros in the yard was well spent. A man's got to know his limitations.
 
Jan 22, 2008
1,654
Hunter 34 Alameda CA
It's a magnificent repair! At the least, it passed my inspection. Once you wrap that puppy with teak, it will be perfect, especially when you notice the weird creaking sounds go away and the doors to the forward berth and head start closing again properly (at least mine did). By my calculation, it should support in excess of 30,000 pounds so you are good for another 31 years. The welds are quite fine in this application as the load is straight down. That was a good solution. My glass work alone cost $700 in 1997, so adjusting for inflation, you're getting off pretty cheaply. with no reduction in structural integrity. My original quote for the yard to fix just the compression of the beam was $5,000. By doing most the work ourselves we got new standing rigging, a painted mast and the repaired structure for less than $5K. Now that you have been through this one, you are ready to tackle the next project. And you are getting handier. As I've learned, boats give you the experience you need, after you really need it.

By the way, it's transverse. :biggrin:

Allan
 

dcalif

.
Feb 17, 2015
22
Hunter 34 Monterey Bay
Transverse. :(
That's hilarious. Allan, I told you I have no engineering aptitude. I think I proved that by traversing this project thinking a "transverse beam" was a "traverse beam" the entire time.
Watch out when you come down to sail with me. I'm working out the difference between "jib" and "jibe," too.
 
  • Like
Likes: Allan12210

splax

.
Nov 12, 2012
692
Hunter 34 Portsmouth
looks good ! let us know of any issues you might experience. I am sure it was an interesting time fishing that cable out the bottom.
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
A fine looking job ! Won't be a problem again.. As Allan says, those welds will be fine..
 
  • Like
Likes: Allan12210
Aug 15, 2013
193
Hunter 35.5 Legend 003 San Carlos, Sonora, Mexico
Great job, looks excellent. One word of caution would be the holes you ran the wires through need some kind of chafe protection. It might be as simple as some wood, or filing down and sanding to a smooth finish, as the wires may abrade during constant movement. Or you could just wrap copious amounts of tape around the wires where the come through the holes, Just a though, would hate to see your wires fail.
 
Nov 26, 2012
1,653
Hunter 34 Berkeley
Wow. I did the repair as well but mine was less "overkill" for lack of a better term. I pulled the compression post out (after removing the mast) then added a 1/4" thick steel plate to the underside of the wood cross beam to bridge the gap across the groove in the bottom of the and spread the bearing out and then put the compression post back in. I had to drill a hole in the plate for the wires as well. Seems to be holding up after a year.