Port Knee Reinforcement

TheGreatEscape · **Posted:** 18 Jan 2025 22:12

Hey guys, I wanted to share a project I just got done today that I thought might help someone if they're noticing a dimple on the hull where the port knee in the head is attached to the hull. Jfalsone actually described this repair to me, I just followed his instructions but thought I'd pass it along because I think it's a good fix. Time will tell!

We all know the design and construction of our T37's is top notch. However, the knee that anchors the port forward lower shroud is a weak spot. It only extends a few feet down the inside of the hull where it's tabbed in, putting a lot of pressure on a small spot of the hull which over the years has created a dimple on the hull that you can see from the dock. No bueno!

Last winter I cut out the old tabbing, retabbed about 16" out hoping to spread the load out more, and also made some "stringers" with the idea of stiffening up the hull. Well, that didn't do the trick. We painted Silver Lining over the summer and faired out the dimple so it was basically gone. Fast forward a few sails in over 30 knots and the dimple was back! So here's the repair Jfalsone shared with me that I THINK will be the real fix.

-Remove the forward cabinet in the head. Also remove the countertop (no need to remove the whole enclosure under the sink, just the top is fine)
-Sand down 10-12" of the hull, just forward of the knee to be prepped for tabbing later.
-Template out what will be an extension you'll glue to the existing knee. The extension should run down to just above the hole where the pan is that holds the toilet. See pictures
-Using 3/4" marine ply, cut out your extension
-Use thickened epoxy and attach extension to existing knee. I used 1.5" construction screws to attach the extension while the epoxy was curing. I'll leave the screws in place. I also used thickened epoxy to fill the gap between the new extension and the lip that is part of the fiberglass pan.
-Fillet to prep for tabbing
-Tab ply to hull. I used 17oz biaxial glass (2 layers)

I used a 12' 2x4 and wedged it between the chain plate and the ring on the track on the front of the mast (slackened the shroud). Then I ran a line from the ring down to a snatch block on a fixed ring we have at the bottom of the track, to the port side winch on the mast to apply force down on the 2x4 to help push out the dimple. It's hard to tell if it actually did anything but I think it did something...

That's basically it. The idea is to take the upward force and spread it as far down the hull as you can, kinda like how a full bulkhead does, just without the full bulkhead. I just made this repair today so we'll see how it holds up but I have a feeling this will do the trick.

While I'm at it, I'm replacing the countertop and the sink that never fully drained since the countertop will need to be trimmed anyway to make room for the extension. All of this should be hidden behind the cabinet and sink enclosure so once you're done, it'll all look the same.

Hopefully this helps someone in the future if they need it

theoden · **Joined:** 18 Jan 2021 20:46 **Posts:** 43

Great Escape -

This is nice work. Would you happen to have a picture of the dimple you have? I have one as well - seems to be right between the bulkhead you reinforced and the main bulkhead the supports the upper. Is that the same? See attached picture.

WayneH · **Posted:** 22 Jan 2025 11:24

When we had the mast down and the dimple relaxed, we were in the middle of replacing the rotten sink cabinetry with stained Okume 3/4" plywood. It looks wonderful.

But I took the opportunity to locate where the knee rested on the sink base. I put two #8x2" screws from underneath the sink base and into the knee which closed the small gap between the knee and the sink base. The cleats holding the sink base to the hull have sufficient screws to prevent motion and the two screws prevent the bottom of the knee from moving inboard. So the dimple is gone and the deck at the port forward lower is flat again.

I had a yard crew redo the glass tabbing on the knee a couple of years earlier as the tabbing "looked" dry to me and I was already concerned about the dimple at that time. That didn't stop the dimple, tho.

TheGreatEscape · **Posted:** 24 Jan 2025 21:56

Steve, unfortunately I don't have any pictures of the dimple but it looked just like yours, same size and depth. Ours was located right along the knee, you could also really feel the hump in the deck where the knee was being pulled up by the shroud.

I haven't been to Silver Lining since making the repair so I'm curious if I can still see much of the dimple, it was really only showing up in certain lighting. If it's still there I guess I'll need to fair again and blend some new paint!

We're planning to do some offshore sailing this year and this was one of those things I didn't want to leave the dock without fixing!

TheGreatEscape · **Posted:** 24 Jan 2025 22:01

Wayne, I bet that okume looks great. Were you able to source it locally? I've made a few custom drawers/steps out of iroko recently that turned out great but like to try out different types of wood

theoden · **Joined:** 18 Jan 2021 20:46 **Posts:** 43

GreatEscape -

Thanks - can't wait to hear how it is holding up. I'm going to look at my knee and connections this weekend.

Wayne - sorry to hear you still have the dimple.

Has anyone successfully removed the dimple? Do all the T37s have them or is it just some?

- Steve

Tartan37.com

Port Knee Reinforcement

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