Backplate and tabernacle

[Mike25]

PstPlt.jpg

Hello all. I am restoring a 1975 25' MacGregor that has much neglect but all the pieces are present. The short list is:
Keel winch and turning ball repair
Fabricate rudder and castle w tiller handle
Backing plates for bow rail tabernacle/compression post and swim ladder

Has anyone else needed this repair/enhancement? The deck was incredibly flimsy and thin with the bolt holes already showing fatigue. The pics show unfinished wood I have since epoxied and finished. Inaccurate positioning caused my compression post to be twisted so the bulkhead will only contact the corner when attached but I don't think that's a structural strong point anyway I'm more concerned with the deck strength. There is no core on the deck just a thin layer of laid glass. Anyone else tackled this issue?

Here are pics of the compression post and bow rail backing plates.

[Wyb2]

My 25 was built 11 years after yours, but it definitely has a cored deck. How did you establish that yours didn’t?

The core doesn’t cover 100%, it ends before areas of any real curvature. Mine also has no core on the sloped transition from the cabin top to the foredeck, and that area is noticeably more flexible. It looks like you have the more vertical transition that won’t get stepped on.

Mine also has a vertical support that serves as the mounting point for the forward head bulkhead and head door. It also provides significant support for the deck forward of the mast.

The backing plates you put in look good.

[Mike25]

Thank you for the reply. You are right the transition is steep towards the front hatch. Now I'm noticing select areas that are thicker where there is core. The tabernacle and front cleat were thin and that's what I noticed 1st. My bulkhead does not contact the ceiling but has a brace from the keel trunk. Pics to come. I'm almost done. Made a rudder and castle but I'll put that on another post. IWTY Many hours and lots of epoxy. I can use practice on that guey mess but it's done.

[topcat0399]

Your boat is very similar to mine.

Generally on these old Venture/Macs anywhere on the topside that has
factory non-skid textured area will have a plywood core under it.
That includes the deck top that the tabernacle sits on.

I have done extensive work on this part of the top deck and there is no longer wood core under my tabernacle,
It is now 1/2" of solid glass with an aluminum backing plate under the deck that the compression post sits under.
I also have an organizer plate directly under the tabernacle which created a very solid plate/glass/plate sammich.
This area, and all the other fittings around there, love to leak if they get a chance.

I like my wheel barrow tiller handle just fine thank you and it came with a spare!

[Mike25]

How does one go about repairing a rotted core. It has taken me time to figure my deck has a core in select areas. It is a pop top and it appears most of that is with core. There 2 narrow areas sloping down away from the pop top away from center that may have a core. Other than that nothing forward of the tabernacle has a core.

My tabernacle and surrounding area is a single layer and was venerable but now its much stronger with 3 layer sandwich tabernacle/deck/backing plate. I'm glad I didn't glue the plate to the deck so I can inspect and enhance if necessary. [i]Maybe adding an aluminum plate. If adding such a plate would you recommend it below the backing plate or next to the deck above plywood backing?[/i]

I'm concerned because one repair day I had a pot of wet epoxy and duct tape, to seal the hole bottom, and I sealed every hole I could reach. Most glued up nicely but a few just sucked up the epoxy and took more. They never completely topped off like the single layer holes. These indicate a cavity or open space.

Any suggestions appreciated

[topcat0399]

Core repair is a huge subject discussed at length everywhere there are
serious boat discussions on the internet.

I have tried many of them.
Hole drilling to let a core dry and then pumping in a glue.With hole filling.
Top layer fiberglass removal, then core removal, new core installed and new glass laid over.
Bottom layer fiberglass removal, then core removal, and new core and glass applied from below (sucks big).
Top glass cut out, core removed and replaced, old top layer put back on with new glass around edges.
Complete top and bottom glass and entire core removed and replaced with all new.

None of this is hard, just seriously annoying sometimes and fiddly, especially if you want a really pretty result.
Theres a bit of a knack to it.

You would have to research the type of repair needed and decide on your approach, there is no one right way and it depends on what structure
significance the repair area is.

For example, my cockpit sole was soft and collapsing around the scupper pipe making the scupper the high point in the cockpit and was just generally spongy to walk on. The cockpit floor also sits atop the keel trunk supporting the middle of the boat. Also many people stomp around in the cockpit.
So for this I choose top skin and entire wet/rotted plywood core replacement with a 1 inch thick balsa cubed slab and laid all new glass on top of it.
It is seriously stronger than original and I don't think I need worry about it again.

Other places, such as around the stanchion feet, I was able to open it up, cut out the wet wood, glue some new in there, and top it off with new glass.
When the glasswork was done I put in wooden backing plates for the stanchions and they are much stronger than before and stopped leaking.

My old tub has had almost all of its cores worked on over the years. Every single one in varying degrees.
Most of it came about from my constant quest to stop water ingress from above.

I do not recommend GLUING any hardware to the deck ever. Proper Bolting, proper bedding of hardware, and backing plates will more than do the job and is removable, unless of course you are an optimist...

If you ever drill through a fiberglass/core/fiberglass sammich to install bolts, do yourself a favor and learn how to do it properly or learn to like wet pillows....

I can almost guarantee that there are cores in your fore-deck. Your boat has a liner so that may be hard to see from the inside.
My boat is pre-liner days.

[Mike25]

The liner is from the rub rail down. The foredeck has 3 fg stringers running port/starboard. After walking on it a bit the tabernacle area has more flex.

Made 1st launch yesterday see derails on "Keel position winch view obscured" thread