This post is the continuation of Refinish your swing keel for best performance – Part 4: Sealing and painting and the last post in the series. I describe: how to prepare the hull, tips for keeping the keel centered in the trunk, the proper method to tighten the hanger bolts, and end with a materials list and a brief project cost analysis.
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Prepare the hull
Before I bolted the keel back in place, I prepared the hull to receive the refinished keel. Part of that job was cleaning and painting the keel trunk and slot as I described in the previous post. More specifically though, I also prepared the keel hanger weldments to go back in service.
The first obstacle that I encountered was one of the weldments that protruded about 1/16″ from the surrounding fiberglass. This meant that the keel hanger didn’t sit flush in the molded pocket. Instead, that end was supported only by the weldment, not a stable connection for the 550 pounds of keel to pry against. It must have been that way since the sailboat was made. The other three weldments were flush and looked like they had been machined flush. Only the protruding weldment still had a chamfer around the outside edge and makes me wonder if somebody missed it during manufacturing.
The next time you remove your keel hangers for inspection or maintenance, check that the weldments are all flush with the surrounding fiberglass.
To make the weldment flush like the rest, I used the largest twist bit that would fit in my portable electric drill and reamed the end close to flush. I finished up with a small sandpaper drum.
The second issue was a problem that I had with the hanger bolts the last time I replaced them. The two bolts on the port side would not screw all the way into the weldments. The bolts on the starboard side screwed in completely. I measured the depth of the weldments and they were all the same, 1″ deep. All of the bolts were also the same length. I was stumped for a while until I noticed that the countersinks in the port side hanger were deeper than the starboard side hanger. Aha! I thought, and shortened the port side bolts by 1/4″ and then they fit. Or did they?
This time in anticipation of installing new bolts again, I cleaned the threads thoroughly to remove any filings, dirt, or LOCTITE residue. I used a paint gun cleaning brush, acetone, and compressed air. With the keel out of the way, I was able to look more closely up into the weldments and I discovered that the weldment threads stopped 1/4″ short of the end! The starboard side weldments were tapped all the way to the end. That’s actually why the bolts wouldn’t fit. The real problem was only made worse by the deeper countersinks.
Check that your weldments are tapped completely and that the bolts seat deep enough to hold the hangers tight.
To resolve the bolt problem once and for all, I used a 5/16″ – 18 tap and cut new threads the rest of the way in the problem weldments.
The moral of this story is don’t assume your sailboat was built to precision tolerances and highest quality. Maybe the manufacturing department of Catalina Yachts had trouble keeping up with sales in 1981. That was in the middle of the C-22 heydays when 1,000 were built each month—that’s a lot. Here on my boat alone were three defects in the keel attachment to the hull, not a good place to cut corners or compromise quality.
Keep it centered
In the picture below, you can see where the keel used to scrape the inside of the trunk on the port side when the keel was lowered. The worst gouge is through the gelcoat and into the glass mat. These pictures were taken before I painted the inside of the trunk and the keel slot with epoxy primer and bottom paint, which resealed the fiberglass.
Originally, there were no centering spacers on the keel and there was about 1/8″ of clearance between the keel and the hanger brackets on each side. Obviously, that was too much play side to side and it allowed the keel to scrape the inside of the trunk.
To prevent future scraping and to reduce the stress on the hanger brackets, I bonded centering spacers to the keel as described in the previous post in this series. Fairing the keel reduced the clearance to the brackets to 1/16″ on each side. I fabricated a 1/8″ thick washer out of scrap fiberglass to shim the keel to the starboard side during installation for the best fit of the centering spacers.
Then came the hard part
That is, getting the refinished keel back into place under the slot and ready to bolt up to the hull. Basically, I reversed the process that I followed when I removed the keel as described in the first post of this series. Installing the keel is more difficult than removing it. Getting everything to line up just right takes lots of little adjustments of the keel’s position. This job is much easier with a helper.
Before I bolted the hangers back in place, I packed the bottoms of the pin holes with Sta-Lube marine grease. I used just enough so that it would squeeze along the length of the pivot pin when inserted into the hangers without excess.
Tighten with care
I used new bolts in the hanger brackets and applied blue LOCTITE on the threads before I used a torque wrench to tighten the bolts to 12 ft. lbs. That is one half pound over the maximum recommended dry torque specification for 5/16″ – 18 stainless steel bolts according to the Engineer’s Handbook and fastener distributors like Fastenal. I have yet to have a bolt loosen when torqued to 12 ft. lbs. When you consider that the LOCTITE acts as a lubricant during tightening, that’s probably about 25% over the maximum recommended wet torque, which is lower than dry torque due to the lower friction.
Some owners tighten their bolts to 20 ft. lbs. (74% over maximum) without problems. In the past, the owner of a certain online Catalina parts retailer has recommended 30 ft. lbs. (160% over maximum). The Owners Manual insert that came with my ’81 C-22 recommends 35 ft. lbs. That’s three times the maximum specification and more torque than recommended for the strongest bolts you can buy, SAE Grade 8 medium carbon alloy steel! The really scary part is that, unless you shear a bolt off while overtightening it, it is likely to only partly weaken and then snap when its put under a load when your boat is in the water. You won’t even know it happened. Then its sister bolt is under double the load and also likely to snap, especially if you overtightened it too.
I can say from experience that torque of 30 ft. lbs. or more shears stainless steel bolts off easily, either when tightening or loosening. DON’T DO IT.
Extracting a broken stainless steel bolt is very difficult and runs the risk of damaging the weldment threads. Replacing a damaged weldment is even more difficult. Instead of brute force, rely on lock washers, LOCTITE, and regular inspection to keep the bolts tight enough.
Here’s a tip that I use to watch for loosening bolts. After torquing the bolts, draw an index line across the hanger bolts holes and through the center of the bolt heads with a permanent marker like in the picture above. Then you can tell at a glance if the bolts have loosened.
Repair or replace the lifting hardware
All that remained was to install a new winch cable. If you do this project and you reuse your existing cable, be sure to install a new cotter pin on the cable fork. Don’t rely on the old one to keep your keel attached to the cable.
Here’s a money-saving tip: I saved over 70% on the cost of a new keel cable by having an industrial rigging company make it using the same materials as opposed to buying one from that online Catalina parts retailer. I enjoyed similar savings when I replaced my standing rigging, as described in Standing rigging replacement.
For more information about maintaining a swing keel lifting system and how to avoid some common blunders, complete with pictures of some epic fails, see Five swing keel maintenance blunders and how to prevent them.
The proof is in the putting
Into the water, that is. I wish I had a big gantry crane in my boat garage (barn). Then I could hoist Summer Dance up off her trailer and test the keel for fit and free movement during lowering. Since I didn’t have one, I towed her to a local lake for a quick test. The keel lowered completely on the first try but I could hear it rubbing a little inside the trunk. Back on the trailer, I confirmed that only some of the bottom paint was rubbed off between the spacers and the trunk. That was good news and meant that we could take her out for a pre-planned extended cruise a week later.
Well into our cruise while waiting for wind on a doldrum day, I put on a dive mask and snorkel and went down for a closer look. Pushing as hard as I could on the end of the keel underwater, it had zero play or wobble yet I could rock the boat above. Mission accomplished.
Following is a list of the materials and quantities that I used for the methods described in this series.
- USC Pro-Glas fiberglass reinforced body filler (3 gal. plus hardener)
- West System 105A Epoxy Resin (Quart)
- West System 205 Fast Hardener (half pint) (2 each)
- West System 406 Colloidal Silica Filler (1)
- Interlux Interprotect 2000 (1 quart kit)
- Interlux Vc17m Extra Antifouling Paint (1 quart kit)
- U-Pol Dolphin sanding glaze (1 tube plus hardener) [Optional]
- 4″ Fiberglass Tape (25′) [Optional]
- 6″ plastic spreaders for applying filler (2)
- 3M 05517 3M Wetordry Rubber Squeegee for applying sanding glaze (2) [Optional]
- 3″ chip brushes for applying epoxy and tipping the primer (6)
- 4″ trim paint roller frame (1) and roller covers (6)
- 80 grit sander belts and 80 & 120 grit sandpaper sheets and strips for sanding block and plane
The Bottom Line
This project was less stingy than it could have been, in retrospect. I could have done without the Swing Keel Refinishing DVD. It helped but it wasn’t critical to the project. Much of the same info is available in Internet forums and blogs nowadays. I also could have skipped the sanding glaze, which was included in the process described in the DVD but was not necessary. Theoretically, I could have used regular body filler instead of the more expensive fiberglass reinforced body filler. And as explained in The error in a popular DIY DVD that will slow down your C-22, fairing to a 13% or less foil shape instead of the 16.5% foil produced by the template probably would have saved a gallon or more of body filler.
Together, those items cost about $192. Decide for yourself whether they are worth the additional cost. Still, doing this project myself saved me about 74% opposed to paying someone to do it, even with the unnecessary costs.
This project definitely took longer to complete than I expected, but since I did it during winter, I had the time available anyway and I wasn’t tempted to hurry or cut corners to get the boat back on the water. I should have also kept track of the hours I invested in this project but it would probably scare you away from refinishing your own swing keel!
You can do this project too. Nothing about it took exceptional skills or tools, just good old-fashioned hard work and attention to details. Considering its non-critical nature and the price to have it done by a boatyard compared to the value of the average trailerable sailboat, if you’re not going to do it yourself, you might as well not do it at all and put the savings to better use elsewhere.
Suggested price: $2,000
$tingy Sailor cost: $529.08
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