1976 Seacraft 23 IB - Rear Deck/Hatch Core Replacement

[John3325]

Thanks Aldo! Great information.

How did you like using the Nida Core? Does it work the same way as if you were using marine grade plywood? I do like the idea of shedding some weight.

[aldo]

Nidacore is much easier to cut and work with than plywood.
It's incredibly light.
Just make sure you bond it the top skin with resin or a bonding agent, and remember that it won't hold hardware bolts. Just plan ahead like I did with the mahogany.

[Ed]

I did this on my 27 Tournament hatches a couple of winters ago. I vacuum bagged them but the same basic rules would apply.

Once all of the old rotten coring has been removed, I followed these steps:

1) Lay down a fresh piece of 1.5oz mat on to the inside of the cleaned out hatch.
2) Cut core to size. I drilled small holes in mine so that the bedding putty I made out of thickened epoxy resin would have a place to flow as the bag pulled down.
3) Then I laid down one layer of 1708, breather cloth and peel ply.
4) Being a glutton for punishment, I then applied System 3 Quick Fair over the 1708, faired it and then applied EMC Quantum Epoxy Primer followed by EMC Quantum paint.

[John3325]

Thanks Ed.

My next step is to determine whether I need to keep the core at 1.5" deep. Only thing I can think of is that it was made that the hatch was made that deep to rest on the "retaining walls" for the gas tanks, giving the deck added support. Going to measure this out and see what I find.

If there is no need to have it this thick, I think a 3/4'' core is all I need to reinforce this properly. If I go with Nida Core, I will use marine ply as my backing material.

Where do you pick up Nida Core? Does it have to be special ordered though a vendor or is this something they will stock at a lumberyard? I remember my last run at one of these my closest spot for marine plywood was Hingham Lumberyard in Hingham, MA.

[John3325]

Was able to get up in the boat after work while I had daylight.

The highest objects that are under the deck hatch are the gas sending units, which are 1 3/8" underneath the lip of the hatch. This would explain the 7" circle spots that had a center point 1.5" higher than the bottom.

My father helped me identify what was used before.....bulsa wood/core! I think that might answer some people's questions whether this was original or not. I am now leaning to think that this was done before.

I am thinking that I may sandwich a 1/2'" & 3/4" marine grade pieces together, and that creates my core. I will have cutouts on the 1/2" piece to leave space for the leaning post washers/nuts, and cut two holes to leave space for the fuel sending units. This will fill the entire void back up to 1 1/4", and will leave space to resin/mat the top surface back to that 1.5" mark. The more I thought about it, I want it back to 1.5" depth. It will get me essentially resting on the retaining walls for the gas tanks, and I doubt I'll ever have to worry about this thing getting soft again.

Took a few more pics, first one is of the stern area of the boat. The others are after sanding the deck hatch down and letting it dry out for a day. It's definitely a lot dryer in general than yesterday. I have cold temperatures working against me in NE, so I may have to invest in a space heater soon to continue progress.

Few pics of where I got a little chizel crazy. Nothing that can't be fixed but definitely a moment.

[aldo]

I'm sure that will work but all that plywood & fiberglass may make for a very heavy floor.
When you price out the nida core vs marine plywood it might not be much different in dollars, but much lighter. Good luck either way.

[John3325]

Thanks Aldo.

I picked up the marine ply today. Decided to go this route since I have used it before and comfortable working with it. It may be a little heavier, but I also don't plan to move this hatch around that often.

I am still weighing whether or not to just go with a single sheet of 3/4", or if I should double it up with another 1/2" sheet or 3/4" sheet. Either way, it's definitely going to be lighter than all that saturated bulsa core I pulled out.

Looking into heating options for the garage, I'd like to be able to startin glassing and getting this done.