coring review

Hello,
Looking for a coring review. I wish we had a sticky or im new and just missing it.

Im looking for a review of best coring materials for use in fishing boats. Vinylester/fiberglass, hand layup. Im looking for info on coring for 1 hull sides, 2 above the waterline deck, 3 above waterline hand shaping then glassed, 4 stringer, 5 bulkheads, 6 backing plates for rod holder/tower/radar mounting A Blind (Screw) and B Through bolt.

Thanks in advance

 

There's a little guy on YouTube that's done some pretty good lamination tests with everything from polyester vinyl Ester and even epoxy on several different substrates. Don't think he's tested screw retention but definitely adhesion capacity. For the life of me can't remember the guy's name but he's a ponytail dude in brown coveralls from the Northeast it looks like, has an extensive backlog.

Overwhelming majority of Composites I see being used around various boat yards for hand layup is PVC like Divina cell whatever brand is your local. With transoms and stringers being made out of Coosa as well as sections underneath cleats and heavy potential Crush areas.

 

There is no "best" core. You choose according to price, local availability and only lastly technical specifications (yes I know I'm going to get crucified for this).

Cheapest foam at the moment is PET, disadvantage is the higher density needed for equivalent performance to PVC (wich is the de facto standard). Balsa can still be an option, longevity depends on initial workmanship and strict adherence to best practices when in service.

Nothing outperforms solid laminate for core in fastener areas. For backing plates metal is cheaper then composite.

 

Thanks for the replies. How well does coosa hold screws? Also, does anyone have experience with Aqua-Steel?

 

Is this sports fishing or commercial fishing? Commercial fishing classifies it as a workboat and its overall scantlings is increased by 1.25x than regular boat.

 

Coosa has good compression strength but not pull strength. That means bolt thru and backing plate. Need to insert high density wood or solid fiberglass laminate for screw holding.

 

Not as good as equivalent ply but much better than any other foam.

Anything on my boat structural is through bolted with backers....

 

No you're not. You said it right. Every core has its strength depending on its intended use. Styrofoam. weak shear yes but good for insulation. End grain balsa, heavy but good at compression for floorings.

 

1. Coremat + 1/2” PET 6 lb
2. Coremat sides , 1/2” or 3/4” PET 6 lb bottom

4. Hollow glass laminate preferred
5. 1/2 PVC
6. 1/4” 5052 aluminum

 

Just looking at Thermhex, polypropolene honeycomb core, for use in decks. Its far cheaper than coosa and looks to me to be even better.

 

It's cheaper, although after trying a few sheets on my last build I'll never use it again.

I suppose for deck applications it could be useful for building a structure. Still my least favorite material.

 

My guess is Andy Miller at Boatworks Today, formerly from WI, now in MI I believe.

 

I am looking at Tayana's but am concerned because I suspect all older boats of this type have sodden decks.

So of course I would like to have a plan to replace deck coring before buying one.

What about cedar plywood? Or even lumber. Naturally, it is reputed to last 30 years and with an epoxy soak it should be even longer. Its light but solid and holds screws.

 

Nothing wrong with epoxy-encapsulated plywood IF there are no direct fastener penetrations to let water in. IF you need screws, bolts, etc., then you overbore the hole and glass fill it, and then redrill to size. Standard method, just time-consuming if more than a few penetrations are required.

 

Okay about what I expected. Maybe too much work for this old guy. Keep coming back to solid poly boards. Heavy but indestructable. Hold screws and any fastener. Drills and cuts easily. Price is not outrageous.

According to the sales people: "Polyboard is everlasting, indestructible, rot-proof and termite-repellent, outlasting all other panel materials as it never rots, cracks, delaminates or rusts under any climatic condition - rainy, stormy, snowy or flooding."

Weight of poly is very close to plywood... probably the same compared with resin soaked wood.

Finding a reasonable price for polyboard might take some work but resin isn't cheap either, so if the poly is twice the cost of plywood, the price is going to end up slightly higher than the cost of treated wood.