23 center console Cap recore
 

I have removed the cap and have it flipped over. The core in the bow are of the cap is completely rotted out and gone due to holes where the cleats were ripped out. The cap with no core had major sagging in the bow area when on the boat. Now that it is flipped over once I remove the backside skin what is the best way to core this area and any idea how to get the correct camber (get rid of the sag)?

I plan to use marine plywood and I assume I will cut out a piece roughly the correct size and then cut it into smaller squares about four inches each. Lay the squares on a layer of wetted out 1708 and put thickened resin in the cracks between the squares and then a new backside skin of 1708. Wondering if I will need to place some weight on the plywood to get the sag out and restore some of the camber to the bow area?

Any tips or ideas would be appreciated.

What is the size of the rotted section? I think you may want to use
end grain balsa as your core. Somewhere on YouTube their is a complete restoration
of a 23 with core replacement of the cap. You might want to view it.
About a 15 minute video. Mettan marine perhaps.

Thanks Brian...watched a couple of Metan Marine videos. Very helpful...wish I had their shop, tools, and manpower!

Just to add to this instead of another thread ... I want to use all composite on my 20 MA.... what should I use around the areas that will have increased stress such as the cleat area on the bow and rod holders and outrigger bases in the gunwales.... im going to nida or equivalent everything else ....

if you dont want to use plywood then a highdensity foam an be used in those places. Something like the 26 lb Carbon core foam. Use the honeycomb everywhere else and you will have a nice light/stiff cap.

so Honey comb in the areas that will have rod holders, pop up, cleats etc... ?

exact opposite . . . Honeycomb where you DON'T have rod holders, cleats, etc. You want to use the HD foam or plywood where you mount hardware or any place that needs compressive strength or needs to hold a screw or bolt.

FWIW - somebody over on THT had a bunch of end grain balsa (1/2"??) for sale cheap about a month ago - didn't seem like tons of takers.

I have seen articles where guys made curved, cored shapes with epoxy (slow cure) by doing the 2nd layup using double cut core on a thin (previously made) panel with the edges supported, laying heavy polyethylene sheeting over the top of the completed layup with the edges raised several inches above the piece (think poly edges stapled to a wood frame?) and then put a few inches of water on top of the poly to get the right curved shape. Also seems like the poly would eliminate blush and give a very smooth finish if you get the wrinkles out.

Ordered some 5/8 end grain balsa, checked the hull truth his was 3/8. Looks like the balsa will be easier than cutting plywood squares.

Thanks for all the help so far....now lots of grinding and sanding to be done.

JW

http://www.classicseacraft.com/commu...pictureid=2033 pic of cap before I flipped it


http://www.classicseacraft.com/commu...pictureid=2031 Swing sets are useful!

Yup, honey comb everywhere except for where you have fasteners. The honeycomb actually has excellent compression strength except for the edges (anywhere you cut a hole in it). It does not hold screw either, so that is the second reason to use ply/foam around rodholders, cleat, etc.

I would use 3/4" core, its really just barely heavier, but much stiffer than 1/2" core

no plywood for me ... ill check out the foam... but was thinking I would need something more substantial to hold screws..... so I may use coosa in these places ...

Coosa will work well . . . those bluewater panels are sold in 20- and 26-pounds lbs densities and will hold a screw just fine.

Good grief daddy, how can I use my swing set now ?

Some dad you are....:eek:;)

Next thing you know you will be charged with child abuse !

Great idea for an "A" frame ...

Good luck with the recore !

coosa/Penske board will not hold a screw - there's a specific technique required,when using fasteners with composites.i've described that technique,in detail quite a few times...

composites,require thru bolting and sleeving...

when blind,or self tapping fasteners are needed :

determine thickness - use a small piece of hosing over the drill bit - this will prevent drilling thru.drill the hole - avoid drilling through ! chuck up a sharpened allen bit,slide it in and remove some of the coring - fill the area with a thickened epoxy - I like west system,mixed with 403 adhesive additive.after the area kicks,locate where the fastener needs to be - use it this way: you want to use a 1/4-20 machine screw ? drill the hole 3/16" - put a dab of 3m 5200 over the hole and run the screw in with a screw gun - this will actually tap the epoxy.need to remove the screw ? back it out with a screw gun...


using self tapping fasteners with composites,without following that technique,the fastener will fail and become loose - the composite is brittle,vibration will cause it to fracture,making the screw hole loose - inexperienced individuals will use a larger screw - only to make the hole bigger ! you see this occurring on a bunch of foam cored boats - one manufacture used those stainless steel "toggle" style bolts to hold their T-tops onto the divinycell cored deck - I've repaired those failed fasteners,on more than 3 occasions.toggle style bolts will fail !

I have used solid plugs of fiberglass in the layup when I knew where I was going to be putting a threaded attachment or if I was going to have a lot of compressive load like a through bolt. I used solid round fiberglass rod from these guys: http://www.mgs4u.com/fiberglass-tube-rod.htm , cut it to the same length as my core material thickness, bored a hole with a hole saw to the right diameter (I used 1" but they have up to 1.5") and epoxied it into the core. Then did the whole layup. Seems to work well - FG plugs can even be tapped/threaded (but not as strong as threading into good metal).

In my experience there's a big difference b/w 26lb coosa and 5lb divinycell in holding fasteners. I've never had an issue with skinned coosa and screws backing out or not holding, but pelican's the professional. You will probably never put any screws into the cap's core to hold anything except maybe a bow light . . . which may or may not even touch the core.

i may just be thru bolting in the areas i need the strength... i will want my rod holders to handle deep dropping so i want as solid as possible... lights and cleats will all be pop up....

Bad Dad indeed...especially when I left the fuel tank hanging on their swing set all day a few months ago!

http://www.classicseacraft.com/commu...pictureid=2038


Opened up the Cap this weekend to see what I was dealing with...the bow core was balsa core the rod holders are plywood.

Bow area with inner skin removed.


http://www.classicseacraft.com/commu...pictureid=2034


Bow inner skin with balsa core stuck to it

http://www.classicseacraft.com/commu...pictureid=2035


Close up of balsa core and rotted balsa

http://www.classicseacraft.com/commu...pictureid=2036


Rod holder core rotten plywood

http://www.classicseacraft.com/commu...pictureid=2037