Pros an' cons of cored hulls

[Chris Nowell]

I recently read on the forum that some of the larger Sea Rays use cored hulls. Up until now I've personally avoided boats with cored hulls like the plague. Have I been wrong all these years? In MY mind, rot in a cored hull would be very difficult to diagnose if PO had done a good job of the fiberglass repair that covered the damage which originally led to the water intrusion. Note; I am thinking here about boat sizes which I myself can afford, +/- 28 feet. Opinions :huh::smt024 Thanx,
Chris

 

[BillK2632]

The idea behind a cored hull / deck / bottom is the coring material - balsa or a synthetic material - nidacore - is lighter and stronger than solid fiberglass. That said, every point in a cored hull or deck that has any penetration, be it a thru hull, screw etc is a potential place for the core to get wet. I don't think you will find many boats without some coring - I know my SR290 had a solid glass bottom with cored sides and deck. I inspected every single point on that boat periodically - found that a lot of the railing stanchions, one of the hatches and the windlass foot switches where not bedded properly. Every builder is different, but size wise, there is a point where you cannot build the hull with solid glass, it's just too heavy - so you can't avoid coring. Done properly there is nothing wrong with coring and in many ways (weight / strength) it is better. But when done wrong, it can wreck a boat in short order. Every single penetration on a cored hull or deck has to be sealed and things that have stress on them like stanchions and windlasses need to be re-checked - you can't see the damage happening from the outside and by the time you see a brown muck leaking on the inside you probably have a big problem.

Not knocking it at all, but on your 240 - that grab rail on your transom locker - on my 290 it attached to the deck, not the door (the door is solid glass) and it was not bedded at all. I found out when I noticed a brown muck seeping into the locker. I caught it soon enough that I could fix it myself by digging out the rotting core and sealing with epoxy. Same deal on the hatch above the V-birth. When that hatch was put it, it was sealed, but not very well, most of the screws were put in with no sealant. Luckily I caught these along with the stanchions early enough to seal them myself. But imagine a through hull installed in a cored hull - below the water line - and not done properly, now you have water constantly seeping into the coring. On a cored hull there should be sections of solid glass put in during construction that the thru hulls are installed in so you don't have below the water line penetrations going through the cored sections of the hull.

You should read some of David Pascoe's stuff - he might go a little overboard on some things, but his reviews of boats and coring are an eye opener.

 

[fwebster]

Adding to BillK's post a little bit..........

Everybody seems to get excited about cored hulls, but in the Sea Ray world, if you own a cruiser with a deck, then you already have cored construction. By far, the decks cause more core issues than hulls. This is primarily because owners assume because the deck isn't under water, they are home free. Actually, every hole that is sawed or drilled in the deck or transom for anything is a potential source of water ingress and each one of those locations needs to be checked and re-bedded periodically.

Since you are limiting yourself to about 28 ft, forget worrying about cored hulls because there are very few below about 40 ft. Every Sea Ray above that is cored because the boat would be too heavy to perform if they were solid fiberglass. Sea Ray does a good job with construction. Each boat has a solid pad or pads in the bottom for mounting transducers, intakes, etc. Depending upon how the hull vents are mounted, that means you only need worry about boats with transducers placed in non-factory locations (check your owner's manual in the owner's packet), or boats with a damage history where the core was exposed. A normal marine survey will find any serious problems so there is no need to rule out looking at boats just because they happen to be cored.

 

[quality time]

Something else to be aware of. Just because you are shopping for a particular model, does not mean that they were all manufactured the same way.

For example, the early 480DB's are cored around thru hull penetrations and have cored sides. Somewhere in mid 2002, Sea Ray changed to solid glass at the hull penetrations and switched to solid sides. We know this is also true for the 460DA due to the side vent issues.

It's always best to call Sea Ray with the HIN # before purchase if you are concerned.


Sent from my iPad using Tapatalk HD

 

[Gofirstclass]

Chris, I had a '96 330 Sundancer that was hit one night by a 25' Bayliner driven by a BUI driver. My boat suffered $~$150K in damage, enough to total it. The deck was cored, as was the hull down to the shear line.

He hit me on the port forward quarter and his boat ripped my forward deck almost completely across the deck. His boat came completely out of the water and ended up on top of my boat before it fell back into the water as the momentum from his boat transferred to my boat and my boat spun to the left.

As you can see in the pictures below, the top deck, which was cored, was split nearly across the width of the boat. The hull, which was cored down to the water line, was split part of that distance.

For myself, I would not hesitate to buy a boat that had a cored hull above the water line. It's relatively easy to see if there is water intrusion or rot in the coring by using a water meter and/or tapping on the hull with a ball pein hammer. The change in tone when the hull is tapped is obvious and can identify the extent of any water intrusion or delamination.

This shot shows the tearing of the non-cored part of the hull.


Same thing here


Here's the top deck. You can clearly see the coring in here.




Same thing here, but in this pic you can see the blue paint from his decorative strip above his water line. At this area his bow pulpit penetrated the top deck and as his boat came up out of the water onto the deck of my boat, the top deck of my boat was ripped up. You can also see the black paint transfer from his bottom paint onto the gelcoat. On the interior of the cabin there was a scrape along the ceiling where his bow rail rubbed against the ceiling material.


Here's what it looks like from outside. In a closeup of my bowrail you can see where his bottom paint rubbed off on the rail. Pretty nasty, but it would not keep me from buying another boat that had coring above the water line.