Recoring fuel tank cover on 23 sceptre

[JohnB]

I pulled the fuel tank cover, and after visual inspection, decided to recore it. They did a terrible job doing the original core. The edges had air gaps all over one side that let water at it, and there where alot of areas in the center that did not have enough glass on them, and it did not bond well to the skin. The original core was balsa, and here is my question (finally).
I have 3 options for coring material,
1. Balsa
2. Plywood
3. Foam core
Does anyone have any suggestions or observations in doing this with any of the 3 materials above? The balsa would of held in fine if it was done correctly.
Anyways, what to the resident experts suggest?

[FELLOW-SHIP]

HA JOHN
I did mine with marine plywood for a few reasons first “I like a heavy boat” and that adds to the weight the other reason why I used plywood is because of all the screws what are in it plus mounting a seat behind it and the center console above it.
FellowShip

[jw]

John,
I used coosa composites for recoring all of my hatches.
I laminated the coosa to the hatch skin with thickend epoxy.Then covered the laminate with triaxial cloth, then painted the parts.
Came out strong and light and it will hold screws and not rot.
JW

[Ed]

John B-

I have done my fair share of recoring hatches (both marine ply and divinycell).

If you don't have too many things that get screwed into the hatch and rely on it (the hatch for support) than I would go with the divinycell. It is waterproof, lighter and pretty easy to work with. You can lay it down in either a wet layer of 1.5 ounce mat or you can trowel in Divinlite (Divinycell's own putty) and lay the Divinycell in that.

Marine ply isnt a bad way to go either. Like Fellowship said, it adds some weight which isnt always a bad thing. Just make sure that all holes for inspection hatches, mounting screws, etc. are coated with epoxy/cabosil mix and you should be ok.

Ed

[omaier]

John,
I did the same job as JW (coosa and a layer of glass) and it is extremely strong. Also, in the areas where the bar stools are bolted to the deck I dug out the coosa and filled the holes with layers of glass before applying the top fiberglass skin. It allowed me to through-bolt the mounting brackets without crushing the core material.

[strick]

I'd stay away from Balsa. Expensive and not really necessary for the gas tank hatch cover unless you are wanting to go extra light weight. I used high quality 3/4 inch plywood for mine. It is very heavy and sturdy. I wanted the added weight to the center of the boat plus I'll be bolting a leaning post/livewell directly behind the consel on the tank cover so I needed sturdy. One word of caution... make sure you have enough room under the hatch to clear the top of the tank and any rigging that may pass through there. It's a tight fit in my 1975CC. One layer of 1708 biaxal then coat the core with epoxy and cabosil into place on the skin then another layer of 1708 is all you need.

Strick

[thedink9]

Strick

Your second to last picture look like you beveled the edges of the plywood , but you last picture shows a straight edge.
The bevel edge sounds like a good idea as it will be less succeptable to cracking along it. Is that what you did?
Rich

[JohnB]

Thanks for the picts and input.
I went with Divinycell from Marine Liquidators (2 bucks a square foot). First time I have used the stuff, and so far, it is really nice to work with. I have no screws or holes in this hatch cover other than that mounting thru screws. I will let you know how strong it is once I get done with it.

[strick]

There is a bevel in the last picture as well... just hard to see because of the angle. The bevel allows the glass to taper down to the hatch edge. Also lets the hatch fit better because the plywood is thicker then the hatch depth.

Strick